li^C'^^ ^l^^l^^ a^ ' f ? I ^/ f The Dyeing '//T^ OF Textile Fabrics BY J. J. HUMMEL, F.C.S. PROFESSOR ANL DIRECTOR OF THE DYEING DEPARTMENT OF TUE YORKSHIRE COLLEGE, LEEDS WITH 97 DIAGRAMS NINTH THOUSAND CASSELL AND COMPANY, Limited LONDOX, PARIS <£ MELBOURNE ALL RIGHTS BESERVEP RARH BOOKCASE First Edition Septejuher 1885. Reprinted April xZZd, 1888, 1890, 1893, 1896. dTo THE WORSHIPFUL COMPANY OP CLOTHWOEKEIIS OF THE CITY OF LONDON, AMONG THE EARLIKST AXD MOST MUNIFICENT PATRONS OF TECHNICAL EDUCATION IN ENGLAND, THIS WORK IS, UY PERMISSION, RESPECTFULLY INSCRIBED BY THE AUTHOR. PREFACE. The object of this Manual is to provide the teacher and student of Dyeing with a useful text-book giving exact scientific and practical information. It is intended also to supply the Dyer ^vith explanations of the scientific principles involved in the operations of his art, in order that he may take a more intelligent interest in his work, and be stimulated to criticise it, and to determine, by means of well-devised experiments, whether his methods are rational and incapable of improvement, or the reverse. Certain details have been furnished relatinsj to the mode of applying the various Colouring Matters and Mordants, but these must not be regarded as fixed and unchangeable I'eceipts, but rather as starting-points for further experimental work. The Art of Dyeing being a special branch of Chemical Technology, no apology is ofi"ered for leavening the work with a wholesome amount of chemistry. The Dyer is especially urged to make himself acquainted with the general principles of chemical science, for assuredly the more such knowledge is brought to bear upon every detail of the art, the more rapid will be its progress. It seemed necessary to give the somewhat complex chemical symbols and scientific names of the Coal-Tar colours in order to identify them, since, in the course of time, many of the present commercial names may be re- placed by others, or applied to colouring matters not yet introduced. The advanced student will find them useful, for they show at a glance the chemical relationships VIU DYEIXG OF TEXTILE FABRICS. existing between colours which possess similar dyeing properties. The metric system of weights and measures has been adopted because of its advantages both to the teacher and the student of Dyeing, and it is now becoming more and more generally known and appreciate For those who prefer the English system, however, tables of equiva- lents are given at the end of the volume. Considerable care has been bestowed upon the arrangement of the subject matter, to prevent, on the one hand, confusion arising in the mind of the reader as to which fibre is being referred to in any given connection, and, on the other, to enable comparisons to be readily made of the treatment to which e-ach fibre — cotton, wool, or silk — is submitted when applying any given colouring matter or mordant. To my old and valued friend, Prof. li. Liechti, of Vienna, I tender my best thanks for his friendly criti- cisQis during the progress of the work, and his kind assistance in the revision of the proofs. My obligations are also due to those Colour-Manu- facturers and Engineers whose names are mentioned in the text, and also to the proprietors of the Textih Manu- facturer^ for the loan of a complet-e set of their well- known joiu'naL All the principal English and foreign standard works and journals on dyeing have been consulted, and the information has, as far as possible, been brought down to the latest date, J. J. H. CONTENTS, PIBKES. UBkVrCT.R VAGI I. — OOTTOT^ ... 1 II. — Flax, Jute, and China Grars . . . .12 III.— Wool 22 rV.— Silk 43 OPERATIONS PRELI]\nNARY TO DYEING. V. — Cotton Bleaching ... . . 71 VI. — Linen Bleaching .... . . 86 VII. — Wool Scouring and Bleaching . . . .91 VIII. — Silk Scouring and Bleaching . . .115 WATER IN ITS APPLICATION TO DYEING. IX.— Water 121 THEORIES OF DYEING. X, — About Dyeing 144 MORDANl-S. XI. — Use op Mordants . . ... 166 IVIETHODS AND MACHINERY USED IN DYEING. XII. — ^Notes on Cotton, Wool, and Silk Dyeing . 248 X DYEING OF TEXTILE FABRICS. APPLICATION OF THE NATURAL COLOrRING MATTERS. CHAPTEE PAGB Xni. — Blue Coloubixg Mattebs 295 XIV. — Red Colouring ^JIatteks 338 XV. — Yellow Colourixg Mattebs .... 356 APPLICATION OF THE ARTIFICIAL COLOURING MATTERS. XVI. — AxiLixE Colourixg Matters XVTI. — QurKOLDfE Colourixg Matters . XVIII. — Phexol CoLOURix'-r Matters XIX. — Azo Colourixg ^Iatters XX. — AXTHRACEXB COLOURING MATTERS XXI. — ^Artificial Colourixg Matters coxtaixixg Sul PHUR 373 397 398 412 125 459 application of the meneptal colouring :matters. XXn . — Chrome Yellow — Irox Buff — Maxgax-ese Browx — Prusslan- Blue 461 'THE DYEING OF MIXED FABRICS. XXm. — Fabrics of Cottox and Wool .... 466 EXPERIMENTAL DYEING.. XXIV. — ^Method of Devisixg Experimexts ix Dyeixo . 473 XXV. — Estimation op the Value op Colourixg Matters 492 XXVI. — The Detectiox of Colocrs ox Dyed Fabrics 497 Tables of Colour Tests 498 Tables of Thermometer Scales, "Weights and Measures, &c. 526 LIST or ILLUSTKATIONS. PAGE Cotton Plant 1 Appearance of Cotton under the Microscope 3 Transverse Sections of Cotton Fibre 3 Transverse Sections of Unripe Cotton Fibre 3 Transverse Sections of Cotton Fibre after Treatment with Caustic Soda 9 Flax Plant, A; Flovrer, b ; Fruit, c 13 Flax Fibre under the Microscope 18 Microscopical Appearance of Wool Fibre 24 Cells of "Wool Fibre under the Microscoi>e 25 Cross Section of Typical Wool Fibres 26 Silk Moth (Bombyxmori) 43 Silkworm on Mulberry Leaf 44 The Silk Glands of the Silkworm 45 Section of Silk-bag 46 Microscopic Appearance of Raw Silk Fibre 46 Silk Cocoon 47 Silk-reeling Machine 49 Microscopic Appearance of Tussur Silk Fibre 52 Stringing Machine for Silk; 64 Details of Silk-stringing Machine 56 Silk-lustreing Machine 58 Conditioning Apparatus 60 Section of Conditioning Chamber 61 Apparatus for Chemicking, Souring, and Washiiig 74 Plate-singeing Machine 76 Barlow's High-pressure Kiers 79 Section of Injector Kier 82 Wool-steeping Tanks 96 Wool-steeping Tanks 97 Section of Furnace for Making Yolk-ash 98 Eake Wool-scouring Machine 100 Yam-stretching Machine 103 Woollen Yam-scouring Machine 104 Continuous Woollen Yam-scouring Machine 105 WooUen Cloth-scouring Machine 106 Section of ditto 107 Woollen Cloth open-width Scouring Machine 109 Treble Crabbing Machine 110 Sulphur Stove for Woollen Cloth Bleaching 113 Plan of Porter-Claxk's Apparatus for Softening Water .... 132 Porter-Clarfs Apparatus for Softening Water (elevation) . . . 133 Gaillet and Huet's Apparatus for Softening Water 135 Gaillet and Huet's Precipitating Tank 136 Plan of Purification Works for Waste Dye-liquors 140 Mordanting Bath for Silk 186 Sqaeezing Machine used in the Mordanting of Silk .... 187 Washing Machine used for Silk 189 XU DYEING OF TEXTILE FABRICS. PAGE Hank-dyeing Machine 25\ Section of ditto 251 Boden's Hank-dyeing Machine 252 Warp-dyeing Machine ........... 253 Wash-stocks 254 Scotch Hank-washing Machine 255 Plan of ditto 255 German Hank-washing Machine 257 Perspective View of ditto 25S Continuous Hank-drying Machine 259 Spiral Dyeing Machine 261 Lancashire Ji^er Dyeing Machine 262 Washing Machine for Calico , 263 Side View of ditto 264 Square-beater Washing Machine ......... 265 Squeezing Eollers 265 Birch's Squeezing EoUer (front view) 266 Side View of ditto 267 Hot-air Drying Machine 268 McNaught's Wool-drying Machine (section) 277 Ditto (side view) 278 Continuous Wool-drying Machine 279 Woollen Yam Dyeing Machine 279 Pitt's Woollen Yam Dyeing Machine 280 Hydro-extractor 281 Arrangement for Drying Yam in the Open Air 282 Pair of Winch Dyeing Machines for Cloth 282 Union Cloth Dyeing Machine (front elevation) 233 End Elevation of Ditto 283 Woollen Cloth Squeezing Machine 284 Side View of ditto 285 Cylinder Drying Machine 286 Tentering Machine 287 Indigo Grinding Mill 296 Continuous Indigo Dyeing Machine 301 WoadVat 305 Apparatus for Preparing Hydro sulphite Vat Liquor .... 310 Auiliiie Black Dyeing Machine 392 Turkey-red Yam-wringing Machine 428 Trampin? Machine for Turkey-red Yam 430 Clearine Boiler 433 Plan of Ditto 434 Hydraulic Press 435 Oil-padding Machine 439 Section of Liquor-padding Machine 440 Ground Plan and Sectional Elevation of Tnrkey-red Stove . 441 Steaming-chest for Turkey -red Yam 445 Plan and Elevation of Continuous Steaming-chest 447 Plan and Elevation of Experimental Dyeing Apparatus . . . , 4S3 Section of ditto «•«••• 434 Dyeing of Textile Fabrics. F I B E E S . CHAPTER I. COTTON. 1. The Cotton-Plant. — Cotton is the white, dowuy, fibrous substance which envelopes the seeds of various species of the cotton- phmt, Gossi/phcm, be- longing to the natural order Jlalvacece. The seeds, to which the cot- ton fibres are attached, are enclosed in a 3- to 5-valved capsule^ which bursts when ri})e ; the cotton is then collected and spread out to dry. The seeds are after- wards separated l>y the mechanical opera- tion termed " gin- ning," and the raw cotton thus obtained is sent to the spinner. The cotton-plant (Fig. 1) is cultivated with success only in warm climates. There are numerous varieties, of which the following are the principal : — - Jig. 1.— Cotton Pl;iut. Z DYEIN'G OF TEXTILE FABRICS. [Cliap. L (1) Gossypium harhachnse. — An herliaceous plant, bearing a yellow fiower, and attaining a height of 4-5 metres. A Yariety of this species yields the Sea Island cotton, much prized on account of the gi-eat strength, length, and lustre of its fibres. It is grown in the North American States of South Carolina, Georgia, and Florida^ and on the neighbouring islands of the "West Indies. (2) Gossypium hirsutum. — A haiiy, herbaeeons plant, about 2 metres high, with pale yellow or almost white flowers. It is gi'own in the States of Alabama, Louisiana, Texas, and Mississippi (3) Gossypium herbaceuni. — A small herbaceous plant, 1 metre high, and bearing yellow flowers. Varieties of this species are grown in India, China, Egypt, and America. The ^Madi-as, Surat, and short-stapled Egyptian cotton, also some American cottons, are obtained from this species. (4) Gossypium peruvianum. — This species, a native of South America, grows to a height of 3-5 metres, and bears a yellow flower. It yields the long-stapled and much esteemed Peruvian and Brazilian cottons. (5) Gossypium religiosum. — This is a low annual shrub, about 1 metre high, and bearing a yellow flower. It is grown in Cliina and India, and yields the so-called Nankin cotton, remarkable for its tawny colour. (6) Gossypium arhoreuni. — This is a perennial tree, growing to a height of 6-7 metres, and bearing reddish- puqile flowers. It is a native of India, and produces a good quality of cotton. 2. Physical Slxucture. — If cotton wool is examined under the microscope, it is seen to consist of minute fibres. Their general appearance is that of spirally- twisted bands, ha^'inor thickened borders and irresrular markings on the surface (Fig. 2). In the better qualities of cotton — e.g.f Sea Island — the spiral character is less Chap. I.] SECTIONS OF COTTON FIBRE. prominent. Transverse sections of the fibres sliow tliem to be flattened tubes, having comparatively thick walls and a small central opening (Fig- 3); A single cotton fibre is_, in- deed, an elongated, tapering, and collapsed plant-cell, the thin end of which is closed, and the other (namely, that by which it was attached to the seed) irregularly torn. Sometimes broad ribbon- like fibres may be noticed, which arc remarkably transparent, and possess irregular folds. Their transverse section exhibits no central opening at all (Fig. 4). They are, indeed, unripe fibres, in wliich no separation of the thin cell walls has yet taken place. They refuse to be dyed Fig. 2. — Appearance of Cottou under the Microscope. Fig. 3. — Transverse Sections of Cotton Fibre. like ordinary ripe fibres, aiid appear occasionally as white specks in indigo- and madder -dyed calicoes; hence the name dead cotton has been given to them. In half-ripe cotton fibres the cell walls are still so closely Fig. 4.— Transverse Sections of Unripe Cotton Fibre. pressed together that the ultimate central canal is indi- cated in a transverse section only by a fine line. Wlien steeped in water, however, such fibres gradually swell up and form hollow tubes. Cotton fibres vary in length from 2-5 to 6 centimetres, and in breadth from 0-017 to 0-05 millimetres. 4 t)YEIXG OF tE;!:TILE FABRICS. [Chap, t The spiral character of the fibre makes it possible to spin exoeedicgly fine yam, and also accounts for the elastic character of calico as compared -vrith linen, the fibres of which are stiff and straight. Tlie microscoY)ic appearance of cotton serves to distinguish it from other vegetable and animal fibres. 3. Chemical Composition.— -The substance of the cotton fibre is called Cellulose. This is almost universal in vegetable cells, forming the so-called lig- neous matter or vroody fibre of plants, but whereas in vroody fibre the cellulose is encrusted with a large proportion of foreign matter — such as dried-up sap, resin, <51x., — in the cotton fibre it is in a tolerably pure condition. The impurities present amount to about 5 per cent., this being the loss sustained by raw cotton when submitted to the process of bleaching, the main object, indeed, of which is the total removal of these impurities. The princij^al bleaching operation consists in boiling the cotton with a solution of sodium car- bonate or hydrate. From the dark brown solution thus obtained, acids throw down a voluminous light loown precipitate, which, when washed and dried, ■mounts only to about 0-5 per cent, of the weight of " "J employed. This precipitate is found to consist of :^-. : jUowing organic substances: — Pectic acid, brown colourrng matter, cotton wax, fatty acids (margaric acid), and albuminous matter. Pectic acid exists in the largest pixjportion, and it is not improbable that the 4 "5 per cent loss by ble-aching still unaccounted for, represents certain pectic matters, modified and rendered soluble by the action of alkalis, but not precipitated by acids. In addition to the above-mentioned impurities of the cell wall, the raw cotton fibre seems to be covered with ■an exceedingly delicate membrane, or cuticle, which is not cellulose. If cotton, when under microscopical obser- vation, be moistened with an ammoniacal solution of cupric hydrate, the fibre swells up under its influence, whereas the cuticle is unaffected and shows itself as Chap. I.] CHEMICiL COMPOSITION OF COTTON. 5 band-like strictures or rings of various breadths. If a drop of sulphuric acid be then added, tlie cellulose separates out as a gelatinous mass, which, on adding a drop of iodine solution, becomes coloured blue, whereas the cuticle is coloured yellow. By moving the cover-glass aside a little, the cuticle rings are seen to be in the form of tubes, possessing apparently a spiral structure. Some observei-s state that during the bleaching process this cuticle is removed, while others say this is not the case. The average moisture in raw cotton is about 8 per cent., so that, reckoning the 5 per cent, impurities already alluded to, one may consider that raw cotton contains 87 per cent, of pure dry cellulose. "When submitted to chemical analysis, cellulose is found to be composed of carbon, hydrogen, and oxygen, the formula assigned to it being C^HjoO^. It is closely allied in composition to starch, dextrin, and glucose, and is classed along with them as a carbo-hydrate. It is colourless, possesses neither taste nor smell, and has a density of about 1-5. If heated above 130^ C. it becomes brown, and begins to decompose. In contact with air it burns without emitting any very strong odour, a fact which mav sometimes serve to distinsjuish it from wool and silk. It is quite insoluble in the ordinary solvents, water, alcohol, ether, itc, but, as already in- dicated, it dissolves in an ammoniacal solution of cupric hydi-ate ; from this it is precipitated by acids as a gela- tinous mass, which, when washed with alcohol, forms an amorphous white powder. Action of various Agencies on Cotton. 4. Action of Mildew. — Owing to its comparative freedom from imjmrity, cotton may be stored for a long period without undergoing any change, more especially if it is bleached and kept dry. When, however, it is con- taminated with added foreis^n organic matter, such as starch, gum, pling," which has for its object the removal of the seed capsules. This operation is performed by hand, by drawing successive bundles of flax-straw through the upright prongs of large, fixed iron combs, or " ripples." If the pulled flax has been dried and stored, the removal of the seeds is usually eflfected bv the seedim^-machine, which consists essen- tially of a pair of iron rollers, between which the flax- straw is passed. Fig. 6.— Flax plant, a; flower, b; fruit, c. 14 DYEING OP TEXTILE FABRICS. (Chap. IT. 13. Retting. — The most important operation in separating the fibre is that of "retting," the object of which is to decompose and render soluble by means of fermentation, as well as to remove, certain adhesive substances which bind the bast fibres not only to each other, but also to the central woody portion of the stem, technically termed the " shive," " shore," or '' boon." The various modes of retting . may be classified as follows : — (1) Cold-water retting. This may be carried out either with running or with stagnant water. (2) Dew retting. (3) Warm-water retting. Cold-water Retting. — The best system of retting in running water is said to be practised in the neighbour- hood cf Courtrai, in Belgium, where the water of the sluggish river Lys is available. The bundles of flax straw are packed vertically in large wooden crates lined with straw. Straw and boards are afterwards placed on the top, and the crate thus charged is anchored in the stream and weighted with stones, so that it is submerged a few inches below the surface. In a few days fermentation begins, and as it proceeds additional weight must be added from time to time, in order to j)revent the rising of the crates through the evolution of gas. As a rule, after steeping for a short period, the flax is removed from the crates, and set up in hollow sheaves to dry; it is then repacked in the crates, and again steeped until the retting is complete. According to the temperature, quality of flax, &c., the duration of the steeping may be from ten to twen by days. The end of the process must be accurately determined by occasionally examining the appearance of the stems, and applying certain tests. The flax bundles should feel soft, and the stems should be covered with a greenish slime, easily removed bypassing them between the finger and thumb ; when bent over the forefinger the central woody portion should spring up readily from the fibrous sheath. If a portion of the fibre is separated from Chap, n.3 f-LAX RETTING. 15 the stem and sucldenlj stretched, it should draw asundei with a soft, not a sharp, sound. When the retting is complete, the flax is carefullj removed from the crates and set up in sheaves to dry. Eetting in stagnant vxUer is the method usually adopted in Ireland and Eussiii. The iiax in this case is steeped in ponds, situated near a river if possible, and provided with suitable arrangements for admitting and running off the water. This mode of retting is more expeditious than when running water is employed, because the organic matters retained in the water very materially assist the fer- mentation ; there is, however, always a danger of " over- retting," that is, the fermentation may become too energetic, in which case the fibre itself is attacked and more or less weakened. This danger is minimised by occasionally changing the water during the steepin^^ process. The quality of the water employed in retting is of considerable importance; pure soft water is the best, calcareous water being altogether unsuitable. The waste flax water, being strongly impregnated with decomposing organic matter, poisons the streams into which it may run, and destroys the fish; but it possesses considerable value as a liquid manure. After retting in stagnant water, the flax is drained, then thinly spread on a laeld ; it is left there for a week or more, and occasionally turned over. This process is termed "spreading," or "grassing." Its object is not merely to dry the flax, but to allow the joint action of dew, rain, air, and sunlight to complete finally the destruc- tion and removal of the adhesive substances already alluded to. After a few days' exposure the stems begin to " bow," the fibrous sheath separates more or less from the woody centre, and the latter becomes friable. Dew retting simply consists in spreading the flax on the field and exposing it to the action of tlie weather for six or eight weeks, without any previous steeping. Damp weather is the most suitable for this 16 DYEIi;rG of textile fabrics. (Chap. li. method, since all fermentation ceases if the flax becomes dry. Dew retting is practised largely in Kussia and in some parts of Germany. Warm-water retting was a system recommended in 1847 by E,. B. Schenck. It consists in steeping the closely packed flax bundles in covered wooden vats, filled with water heated to 25° — 35° C. By this means the fer- mentation is much accelerated, and the operation is completed in two or three days ; the process seems^ how- ever, to have met with only limited success. Of chemical retting processes, that recommended by R. Baur may be mentioned. It consists in first squeezing the fresh or dried flax straw between rollers, and then steeping it in water till the latter ceases to be coloured yellow. It is next drained and steeped for one or two days in dilute hydrochloric acid (3 kilos, concentrated HCl per 100 kilos, flax), until the bast fibres can be readily separated. The acid liquid is then run ofi", and the flax is well washed with slightly alkaline water, or such as contains a little chalk. A further treatment with dilute bleaching powder solution to dissolve away still adhering woody matter, and a final washing, complete the process. A well-retted flax is said to be thus obtained in the course of a few days only. 14. Chemistry of Retting'. — Experiments by Kolb in- dicate that the ♦ adhesive matter which cements the flax fibres together is essentially a substance called pectose. During the retting process the fermentation decomposes this insoluble pectose, and transforms it into soluble pecthie, and insoluble pectic acid. The former is washed away, the latter remains attached to the fibre. 15. Breaking. — The next operation is to remove the woody centre from the retted and dried flax, after which the fibres must be separated from each other. It is rather beyond the province of this manual to give more than a general account of the nature of the various mechanical operations for eflecting this. They comprise "breaking," "scutching," and ''hackling." Chap. II.] FLAX HACKLING. 17 The firsb operation aims at breaking up the brittle woody centre of the flax into small pieces, by threshing it with an indented wooden mallet, or by crimping it with a many-bladcd " braqiie." The operation is now exten- sively done by machinery, the flax being passed through a series of fluted rollers. 16. Scutching. — In this process handfuls of the flax are beaten with a broad wooden scutching-blade ; the particles of woody matter adhering to the fibres are thus detached j and the bast is partially separated into its constituent fibres. Scutching is also performed by machinery. The waste fibre obtained is called '^ scutching tow," or "cedilla." 17. Hackling. — The subsequent Hackling, or Heck- ling, has for its object a still further separation of the fibres into their finest filaments, by combing. "When done by hand, a bundle of flax is drawn, first one end and then the other, through a succession of fixed upright iron combs or " hackles " of diflerent degrees of fineness, beginning with the coarsest. When machinery is used, the flax is held against hackles fixed on moving belts or bars or on the circumference of revolving cylinders. The product of thfe operation is twofold, namely, " line " and " tow " ; the former consists of the long and more valuable fibres, the latter of those which are short and more or less tangled. ' 18. Flax- Line. — The appearance of flax-line is that of long, fine, soft, lustrous fibres, varying in colour froui the yellowish-buff" of the Belgian product to the dark greenish-grey of Russian flax. This difierence in colour is chiefly owing to the system of retting adopted. Flax retted in running water has a more or less pale yellowish-buff" colour, while that retted in stagnant water possesses a greyish colour, probably because of the presence of the decomposing organic matter in the water. 19. Physical Structure and Properties. — Examined under the microscope, a single flax fibre appears (Fig. 7) a 18 DYEING OF TEXTILE FABRICS. [Chap. U. as a long, straight, transparent tube, often striated longitudinally j it possesses thick walls, and an exces- sively minute central canal. At irregular intervals it is slightly distended, and at these points faint transverse markings may be detected. When examined with high powers, they seem to consist of a succession of very minute fissures, and, according to Vetillart, are simply breaks, or wrinkles, produced by a bending of the fibre, and not cell divisions, or nodes, as frequently stated. Fibres which have been vigorously rubbed between the fingers, or have been subjected to the lengthened dismtegrating action of alkalis, exhibit well-marked longitudinal fissures, and the broken end of a well-worn fibre presents the aspect of a bundle of fibrils. These appearances evidently indicate that the cell wall of the linen fibre possesses a fibrous structure. -pig. 7.— Flax Fibre under the The a^'erage length of a Microscope, single fibre is 25—30 milli- metres, and the average breadth '020— '025 milli- metres. In transverse section, the linen fibre shows a more or less rounded polygonal contour. The chief physical characteristics of the linen fibre, when freed from all encrusting material, are its snowy whiteness, silky lustre, and great tenacity. This last feature is no doubt owing to its fibrous texture as well as to the thickness of the cell walls. Its straight, even, prismatic, and transparent character accounts largely for the lustre. Linen is hygrometric to about the same degree as cotton, and contains, when air-dry, about 3 per cent, of moisture. It is, however, a much better conductor of heat, and therefore feels colder than cotton. It is also less pliant and less elastic. Chap. IL] PHYSICAL STRUCTURE OF FLAX. 1 9 20. Chemical Composition. — Treated with sulphuric acid and iodine solution, the thick cell wall is coloured blue, while the secondary deposits, immediately enclosing the central canal, acquire a yellow colour. The linen fibre consists therefore essentially of cellulose, but in its raw unbleached state it is mixed with about 15-30 per cent, of foreign substances, chief among which is pectic acid. Fatty matter, to the extent of about 5 per cent., colouring matter, and other substances not investigated, are also present. Action of various Agencies on Flax. 20* — Being cellulose, the action of various chemical agents on pure linen fibre is much the same as on cotton, but generally speaking, linen is more susceptible to disintegration, especially under the influence of caustic alkalis, calcium hydrate, and strong oxidising agents, e.g., chlorine, hypochlorites, tfec. As to the action of these a«jents on the encrusting materials of retted flax, boiling solutions of caustic and carbonated alkalis saponify and remove the fatty matter, and also decompose the pectic acid and any pectose which may have escaped the action of the retting pro- cess. Under their influence the insoluble pectic acid is changed into metapectic acid, which at once unites with the alkali to form a soluble compound. By successive boiling with alkali the fibre entirely loses its brownish colour, and retains only a pale grey shade, readily bleached by hypochlorites. The system of bleaching linen is based on these reactions. Water-retted flax (whether retted in running or stagnant water, it matters not) is capable of being well bleached. Under the influence of boiling alkalis it always assumes a lighter colour, and when submitted to the reducing action of stannous chloride it acquires a yellowish tint. Dew-retted flax, on the contrary, bleaches with much difficulty. When boiled with alkalis it becomes darker and stannous chloride has little or no efiect on it. 20 DYEDfG OF TEXTILE FABRICS. [ChBp. IX These reactions may serve to discover by which process of rettins: the fibre has been obtained The linen fibre is even less readily dyed than cotton, a fact which, although well known to dyers, has not yet been satisfactorily explained. Its physical structure and the possible presence of pectic matters no doubt exercise some restraining infiuence. 21. Jute consists of the bast fibres of various species of Corchorus {e.g., C. olitorius, C. capsularis, *tc.), belong- ing to the family of the Tiliacece, and is mainly cultivated in Bengal. The fibre is separated from the plant by processes similar to those employed in obtaining the flax fibre, namely, retting, beating, washing, drying, &c. The rsLvr fibre, as exported, consists of the upper five-sixths of tlie isolated bast, and occurs in lengths of about seven feet. Under the microscope, it is seen to consist of bundles of stiff, lustrous, cylindrical fibrils, having iiTegidarly -thickened walls, and a comparatively large central opening. The colour of the fibre varies from brown to silver-grey. It is distinguished from flax by being coloured yellow, under the influence of sulphuric acid and iodine solution. According to Cross and Be van, the substance of the jute fibre is not cellulose, but a peculiar derivative of it, to which the name basfose has been given. Under the influence of chlorine, a chlorinated compound is produced, which, when submitted to the action of sodium sulphite, developes a brilliant magenta colour. This colour reaction is also exhibited by tannin-mordanted cotton, with which jute shows great similarity ; this is fuilher exemplified by the fact that jute can be readily dyed in a direct manner with basic coal-tar colouring matters. Jute may indeed be considered as consisting of cellu- lose, a portion of which has become more or less modi- fied throughout its mass into a tannin-like substance. Alkalis actually resolve jute into insoluble cellulose and soluble bodies allied to the tannin matters. Fui-ther, dhap. rLl JUTE AND CHINA GRASS. 21 when large masses of jute are allowed to lie in a damp state, the substance of the fibre is decomposed into two groups of bodies, namely, acids of the pectic class, and tannin like substances. Acids, notably mineral acids, even at low tempera- tures, readily disintegrate jute, resolving it into soluble substances. This destructive action of acids must be specially borne in mind by the dyer and bleacher of jute. Strong solutions of hypochlorites produce the chlorin- ated compound above alluded to, and there is then always a danger of the fibre being disintegrated by subse- quent manufacturing operations, e.g.^ steaming. Weak solutions bleach the fibre to a pale cream colour, at the same time oxidising it, and thus forming compounds which precipitate soluble calcium salts. In bleaching jute, tlierefore, weak sodium hypochlorite should be used in preference to ordinary bleaching-powder (calcium hypo- chlorite), since the presence of soda prevents the forma- tion both of the chlorinated fibre and of insoluble calcium compounds. By thoroughly impregnating the bleached fibre with sodium bisulphite, and drying at 80" — 100° C, the colour is still further improved through the action of the disengaged sulphurous acid ; the neutral sodium sul- phite remaining in the fibre prevents its oxidation and disintegration under the influence of ordinary atmospheric conditions, and even steaming. Jute is readily bleached by the successive action of permanganates and sulphurous acid. The loss of weight experienced by jute in bleach- ing may vary from 2 to 8 per cent., according to the method employed. 22. China Grass. — This fibre, also called Rheea, Eamie, (tc, consists of the bast cells oi Boelinieria nivea (Urtica nivea), a perennial shrub belonging to the nettle family, Urticacece. The plant grows abundantly in China, Japan, and the Eastern Archipelago generally. No perfectly satisfactory method of obtaining the fibre with little loss has yet been devised ; the native methods of splitting and scraping the plant stems, steeping in 22 DYEING OF TEXTILE FABRICS. [Chap. III. water, e the efNthelial scales are less distinct^ or even invisible, and viewed by transmitted light, either the whole substance of the Hkxe seems mote dense and sometimes even opaque, «• the mednllary portion only is 0}:»aque. Th^J are defiaent in tenacity, lustre, and felting power, and in their attraction for colouring matt^ers. They may occur even in good qualities of wool, e.g,. about the neck and legs of the animals, where the wool gradually merges into hair.- In coarse wools they may be found in any part of the fleece. A merino wool fleece is made up of an immense number of small bundles or strands of wool fibres, which, in the best races of sheep, show a perfectly regular and Chap. HLJ FOREIGN WOOLS. 2? fine wavy character. The individual fibres are also more or less w^avy, but not with the same degree of regularity as the strand of which they form a part. When tlie fibres adliere to each other, as in the strand, the regular wavy character is very marked. Besides sheep's wool, the hairy covering of other animals is used in the woollen industry. 25. Foreign Wools. — Alpaca, Vicuna, and Llama wool are obtained from diflferent species of the .G^enus Auchenia (^A. alpaca, A. vicugnia, A. llama), which in- habit the mountains of Peru and Chile. MoJiair is obtained from the Angora goat {Copra hircus angoren^is) of Asia Minor. Cashmere consists of the soft under-wool of the Cash- mere goat [Capra hircus laniger) of Tibet. The soft under-wool of the camel, which it sheds each spring, is also used. Of all these, the alpaca and mohair are most largely employed. Certain of these foreign wools, more especially Van Mohair, also AJpaca, Camel's haii', Cashmere, and Persian wool, are apt to be dangerous to the health of the wool-sorter. They seem to contain the microscojjic organism known as Bacillus anthracis, the same which excites splenic fever in cattle and hoi^es. When taken into the bronchial tubes of man, it induces a kind of blood-poisoning known as " wool-sorter's disease." The wool-sorting rooms ought, therefore, to be well ventilated, and the sorter should wear respirators during their work. 26. Physical Properties — Hygroscopicity. — The wool fibre is capable of absorbing a large amount of water with- out appearing damp, i.e., it is very hygroscopic. Exposed to the air in warm, dry weather, it contains 8-12 per cent moisture ; but if kept for some time in a damp atmo- sphere, it may take up as much as 30-50 per cent. This moisture probably fills up the interstices between the cells of the fibre, which under ordinary circumstances contain air, but it no doubt also permeates the substance 28 DYEING OP TEXTILE FABRICS. [Chap. IlL of the cells themselves. It is noteworthy that damp wool is not so liable to mildew as the vegetable fibres are. The amount of moisture in unwashed wool varies with the fatty matter it contains, the less fat the more moisture ; while in washed wool it depends upon the arransjement of the cells. The wool which has least tenacity — i.e., that in which the cells are more loosely aiTanged — possesses the greaitest hygroscopicity. This hygroscopic character of wool renders it very desirable that those trading with it should know exactly its condition in this respect at the time of buying and selling, hence, on the Continent, so-called " Wool-conditioning" es- tablishments have been instituted in various centres of the woollen industry — e.g., Roubaix, Rheims, Paris — where the exact amount of moisture in any lot of wool may be officially determined. These establishments are arranged on the same principles as those for silk- conditioning p. 61). As wool is more sensitive to heat than silk, the drving of it is effected between 105°-110° C. The legal amount of moisture allowed on the Continent u 18-25 per cent. If wool fibre is steeped in warm water, it softens and swells up very considerably, and, like all homy sul> stances, becomes plastic, retaining any position which may be forced upon it, if, while the mechanical strain i? continued, the moisture is more or less evaporated. This hygroscopic and plastic nature of wool comes into play in the processes of ''crabbing" and "steam- ing " of unions, in the " boiling " and " finishing " (" hot- pressing*') of woollen-cloth, and in the "stretching" of yarn. Elasticity. — Closely connected with the hygi'oscopic nature of wool is its elasticity, which it possesses in a high degree, not merely because of the wavy chai-acter of the fibre, but also on account of its sub stance and structure. One important manifestation of its elasticity is shown if a dry wool-fibre is excessively stretched ; when the ends are released, or rupture takes place, not only does the fibre or do the separated parts Chap, mj PHYSICAL PROPERTIES OF WOOL. 29 rebound to the original position, but an additional shrinking and curling up of the ends are exhibited. If a single wool lib re is softened by heat and moisture, then stretched and dried in this condition, it is found to have lost this curling property, but it reappears whenever the sti'etched fibre is again softened, and allowed to dry in an unfettered condition. In conjunction with pressure, friction, and tenipera- ture, many of the above-mentioned physical features — e.g., the scaly surface of the fibre, its waviness, and its hygroscopic, elastic, and plastic nature — play a most im- portant part in the processes of " felting " and " milling " woollen cloth. The lustre of wool varies very considerably. Straight, Bmooth, stiff wool has more lustre than the curly merino wooL The differences exhibited depend partly upon the internal structure, but cliiefiy upon the varying arrange- ment and transparency of the scales on the surface of the fibre ; the flatter these are and the more they lie in one plane, the greater will be the lustre. Such wools as possess a silky lustre in a high degree — e.g., Lincoln and Leicester wools, &c. — are classed as lustre wools, as distin- guished from non-lustre wools — e.g., Merino, Colonial, etc. Wool with a glassy lustre, e.g., bristles, &c., is harder and more horny than non-lustre wool ; the surface is smoother, the scales are less distinct, and wools of this kind do not dye so readily. The best kind of wool is colourless, but lower qualities are often yellowish, and sometimes variously coloured— e.^., black, brown, red, itc. This coloration is caused by the presence of an organic pigment in the cortical portion of the fibre, either as a granular pigment situated between the cells, or as a colouring matter diffused throughout the cell substance. Generally, both forms are present, but in brown and black wool the granular pigment pre- dominates, while in red and yellow wools the diffused colouring matter is more prominent. These natural pig- ments are not so fast to light as is generally supposed, a 30 DYEING OF TEXTILE FABRICS. [Chap. HL facD which is ah-eady revealed by the bleached appearance of the exposed portions of the Hecce. The worth of any quality of wool is determined by carefully observing a number of its physical pro- perties — e.g., softness, fineness, length of staple, waviness, lustre, strength, elasticity, flexibility, colour, and the facility with which it can be dyed. Fleece wool, as shoin from the living animal, is superior in quality to ''^ dead v:ool,^^ i.e., wool which has been removed from the skin after death, if lime has been used in the process, but if it be removed from the skins by cutting, the wool is practically equivalent to " fleece wool ; " indeed, it is said to felt better than the Litter. Individual dead fibres occur occasionally in fleece wool ; they have been forced out by the roots previous to the time of shearing, and constitute the so-called "■ overgrown " wool. This class of wool is comparatively harsh and weak, and is said not to dye so readily as other kinds. This is the case also with the wool of an animal which has died of some distemper. 27. Chemical Composition. — With regard to the chemical composition of wool, a distinction must be made between the fibre 'proper and the foreign matters encrusting it. The latter, while consisting partly of mechanically adheiing impurities derived from without, are mainly secreted by the animal, and constitute the so-called Yolk (Fr. Suint). Wool fibre which has been entirely cleansed and freed from these foreign matters possesses a chemical composition very similar to that of horn and feathers, and consists of what is termed Keratin (horn-substance). Its elementary composition varies somewhat in different qualities of wool, but the following analysis of German wool may be taken as representative : — Carbon . . . . . . 49"'25 per cent. Hydrogen 7-57 „ Oxygen 23-66 ,. Nitrogen lo-86 „ Sulphur 3-66 ., 100-00 Chap, ni.l CHEMICAL COMPOSITION OF WOOL. 31 The question as to whether the sulphur is an essential constituent or not has been much discussed. It is removed to a greater or less degree bj most solvents, hence it is difficult to obtain constant analytical results. Its amount has been found to vary in different wools from 0"8 to 3*8 per cent. Its constant occurrence, and that in comparatively large proportion, precludes the idea that it is merely an accidental constituent, and it has hitherto been found impossible to deprive wool entirely of its sulphur, without, at the same time^ modifying somewhat its structure and in large measure destroying its tenacity. This presence of sulphur in wool is attended with some practical disadvantages. The wool is apt to con- tract dark-coloured stains under certain conditions, and on that account its contact with such metallic surfaces as those of lead, copper, and tin should be avoided during processes of scouring or dyeing. In mordanting with stannous chloride and cream of tartar, especially if an excess of these ingredients be used^ the wool is frequently stained, by reason of the formation of stannous sulphide. A boiling solution of plumbite of soda at once blackens wool, and may thus serve to distinguish it from silk or cotton. For practical purposes, much of the sulphur may be removed by steeping the wool in cold w^eak alkaline solutions — e.g., milk of lime, — then washing it in water, in weak hydrochloric acid, and again with water, repeating the operations several times. The amount of mineral matter in wool free from yolk- varies from 0-08 -0-37 per cent. It consists mainly of phosphates and silicates of lime, potash, iron, and magnesia. Action of various Agencies on Wool. 28. Action of Heat.— If heated to 130° C, wool begins to decompose and give off ammonia; at 140-150° C. vapour containing sulphur is disengaged. When wool fibre is inserted in flame it burns with 32 DYEING OP TEXTILE FABRICS. [Chap. IH. some diflBculty, and emits a disagreeable odour of burnt feathers. It lias the appearance of fusing, a bead of porous carbon being formed at the end of the fibre. Submitted to dr}'' distillation, it gives off products containing much ammonium carbonate, which may be readily detected by its smell or by its colouring red litmus-paper blue. These reactions serve to distinguish wool from all vegetable fibres. A cold ammoniacal solution of cupric hydrate has no action upon wool, but if it is used hot the wool is dis- solved. 29. Action of Acids. — Dilute solutions of hydro- chloric and sulphuric acids have little influence upon wool, whether applied hot or cold, further than opening out the scales and making the fibre feel somewhat rougher; but if used too concentrated, the fibre is soon disintegrated; in any case their destructive action is by no means so energetic on wool as on cotton. This fact is made use of to separate cotton from wool in the process of " ex- tracting " or " carbonising " rags containing both fibres. The rags are steeped in dilute sulphuric acid, and after removing the excess of liquid, are dried in a stove at about 110° C. The disorganised cotton can then be beaten out as dust, while the wool remains compara- tively little injured. Another method is to submit the rags for a few hours to heated hydrochloric acid gas. The above mineral acids are frequently added to the dye-bath in wool-dyeing. Nitric acid acts like the acids just mentioned, but it also gives a yellow colour to the wool, owing to the production of so-called xanthoproteic acid. Because of the compara- tively light yellowish colour thus imparted, boiling di- lute nitric acid is frequently used as a " stripping " agent for wool, i.e., to destroy the colour in wool already dyed, for the purpose of re-dyeing (job-dyeing, rectifying mis- takes, (fee). Care must always be taken not to have the acid too strong (about 3°-4° Tw. — Sp. Gr. 1'02), and not to prolong the process beyond three or four minutes. Sulphur dioxide {sulphurous acid gas) removes the C?hap, III.] ACTION OT ALKALIS ON WOOL. 33 natural yellow tint of ordinary wool, and is the best bleaching agent employed for this fibre. It is important to remember that the gas is very persistently retained by the fibre, and should always be removed from bleached wool previous to dyeing light colours. This is effected by steeping the wool in very dilute solutions of carbonate of soda or bleaching-powder, and washing well. When the .first reagent is employed, the acid is merely neutral- ised, but with the second the sulphurous acid is oxidised to sulphuric acid. Should this precaution be neglected, the wool will not dye properly, or, when dyed, it will be liable to become decolorised asjain throuo^h the reducing action of the sulphur dioxide retained by the fibre. 30. Action of Alkalis. — Alkaline solutions have a very sensible influence on wool, but the effects differ considerably according to the nature of the alkali, the concentration and temperature of the solution, and the duration of contact. Caustic alkalis (KHO, ISTaHO) act injuriously on wool under all circumstances. Even when they are applied as cold and weak solutions, their destructive action is sufficient to warrant their complete rejection as " scouring " agents. When they are applied hot, even though but little concentrated, the wool is gradually dissolved, producing a soapy liquid from which it may be precipitated, on the addition of acid, as a white amorphous mass. This fact of the solubility of wool in hot caustic alkalis is utilised for the purpose of recovering indigo from vat-dyed woollen rags, this colouring matter being insoluble therein. Solutions of alkaline carbonates and of soap have little or no injurious action on wool, if they are not too concentrated, and the temperature is not higher than 50° C. Soap and carbonate of ammonia have the least injurious action, while the carbonates o/jwtash and soda impart to the wool a yellow tint, and leave it with a slightly harsher and less elastic feel. 54 DYELSG OF TEXTILE FABRICS. [Chap, ttt This marked difference of action between the caustic and carbonated alkalis makes it an all-important matter for eveiy wool-scourer to know the exact nature of the agents he uses : soaps should l>e free from excess of alkali, " soda ash " should contain no caustic soda, «tc. Calcium hydrate {lime) acts injuriously, like the caustic alkalis, but in a less degree. It eliminates the sulphur from the wool, but thereby renders the fibre brittle and impairs its milling properties. 31. Chlorine and Hypochlorit-es act injurionsly on wool, and can therefore never be applied to it as bleach- ing: agents. A hot or boil in sr solution of chloride of lime entirely destroys the fibre, with evolution of nitrogen gas: if, however, wool l^e submitted to a rerys/?^//^ action of chlorine or hypochlorous acid, it assumes a yellowish tint, and acquires at the same time an increased affinity for many colouiing matters. This effect is possibly due to an oxidation of the fibre, and not merely to a roughening of its surface. Practical use is made of it by the printer of Muslin Delaine (mixed fabrics of cotton and wool) and occasionally by the woollen dyer. 32. Action of Metallic Salts. — In common with all fibres of animal origin, wool has the property of readily dissociatino: certain metallic salts when in contact with their solutions, especially if the latter are heated. When, for example, wool is boiled with solutions of the sulphates, chlorides, or nitrates of aluminium, tin, copp>er, iron, chi'omium, arated ether to dryness, and weigh the fatty residue. The weight gives the amount of icool-fat present. Evaporate the separated wash-water to dryness, weigh the residue, and add the weight to that of the portion soluble in water, i.e., the oleates. (c) Wash the ether-extracted wool several times with cold distilled water, and evapointe the solution to dryness. The weight of the residue added to the weight of the oleates dissolved by water from the ethereal solution gives the chief amount of the alkaline oleates present The wool is then washed with alcohol ; this always dissolves further minute quantities of oleates, the weight of which must be added to the abova Earthy oleatea Chap ni.I ANALYSIS OF WOOL. 37 which remain in the wool are decomposed by wash- ing the latter with dilute hydrochloric acid ; the acid •is removed by washing with water, the wool is then dried, and extracted with ether and alcohol. From the weight of the residue obtained on evaporating the two last solvents to dryness, the amount of earthy oleates present in the wool may be calculated. With very dirty wool a good deal of lime is dissolved by the hydrochloric acid, not because of lime soaps but of calcareous dust present. {d) The wool remaining is dried and thoroughly well shaken and teazed out by hand over a large sheet of paper, in order to remove dirt, sand, &c. ; care is taken not to lose any of the fibre, the detached particles of which are collected on a fine sieve, and washed with water till free from dirt. The wool is dried and weighed ; the sand^ dirt^ drc, are determined by difference. The following analyses of law wools give the results obtained by the above method of Miircker and Schulz : — Wool of Lowland Slieep. Wool of full-bred Eambouillet Sheep. Pitchy Wool. Moisture 23-48 12-28 13-28 Wool-fat . 7-17 14-66 34-19 > r Soluble in water (wool- •^fl persjjiration) . 21-13 21-83 9-76 11^ Soluble in alcohol 0-3o 0-55 0-89 Soluble in dilute HCl . 1-45 5-64 1-39 « p Soluble in ether and ^ alcohol 0-29 0-57 Pui^e wool fibre . 43-20 20-83 32- 11 Dirt .... 2-93 23-64 8-38 100 100 100 35. Wool-fat. — The composition called wool-fat is found to be of a of what is somewhat here com- 38 DYEING OF TEXTILE FABRICS. [Chap. lU. plicated nature. By treating it with boiling alcohol it may be separated into two portions, the one soluble, the other and larger amount insoluble in this liquid.* Further analysis has shown that the soluble portion consists mainly of the alcoholic and fat-like body choles- terine^ together with isocholesterine, each in the free state, and probably also of compounds of both these bodies with such orojanic acids as acetic acid. The insoluble portion consists essentially of compounds of cholesterine and isocholesterine ^vT^th oleic acid, and in lesser amount with solid fatty acids, e.g., stearic acid and hytena acid. There seems also to be present in a similar state of combination, but in smaller quantity, some other amor- phous body or mixture of bodies, readily fusible, of an alcoholic nature, and containing less carbon than choles- terine. A portion of these various alcoholic bodies, and sometimes also a part of the high atomic fatty acids, are present in the free state. Wool-fat is certainly not a compound of glycerine, and hence is not a fat as ordinarily understood. This accounts for the difficulty experienced in remo^dng it by mild scouring agents from so-called "pitchy wool," which, as shown in the above anal}sia, contains it in excessive quantity. 36. Wool-Perspiration. — With reference to the chemical composition of that portion of the yolk which is soluble in water, the wool-perspiration, it has been shown by the experiments of Yauquelin, Chevreul, Hart- mann, and others, that it consists essentially of the potassium compounds of oleic and stearic acids, and probably also of other fixed fatty acids ; it contains further, but in smaller amount, the potassium salts of certain volatile fatty acids (acetic and valerianic acid), potassium chloride, phosphates, sulphates, kc Ammonium salts seem to be present in dried ex- tracted yolk in small quantity [equivalent to 0-5 per 2ent. NHo] ; not sufficient, however, to account for the Chap. 111.) YOLK-ASH. 39 amount of nitrogen found in yolk (3 per cent.) ; some other nitrogenous body is evidently present. Asa rule, the wash-water of raw wool has a strong alkaline reaction, since potassium carbonate may be present to the amount of 4 per cent, of the weight of raw wool. Some observers have found it to be entirely absent, in which case, hoAvever, it may still be con- sidered to Imve been secreted by the perspiration glands of the sheep, but to have afterwards acted ener- getically upon the wool-fat and saponified it, so that while disappearing itself, it has given rise to an increased amount of potash-soaps in the wool-perspiration. In washing wool on the sheep's back, this potassium carbonate, when present, plays a not unimportant part along with the potash soaps of the yolk, in greatly facilitating the removal of dirt, &c., from the fleece. Dried extracted yolk contains about 60 per cent. cTrganic matter and 40 per cent, mineral matter (free from CO.,, The following are two analyses of yolk-ash by Marcker and Schulz : — Potash 58 '94 per cent. 63-45 per cent Soda 2-76 trace Lime 2-44 2-19 Magnesia . 1-07 0-85 Ferric oxide trace trace Chlorine . 4-25 3-83 Siilphuric acid . 313 3-20 Phosphoric acid 0-73 0-70 Silicic acid 1-39 1-07 Carbonic acid . . 25-79 26-34 Yolk-ash consists essentially, therefore, of potash salts, principally carbonates, the carbonic acid arising mainly from the burning of the organic constituents of thf yolk. Maumene and Rogelet give the following analysis which closely agrees with the above : — 40 Potassium carbonate . Potassium chloride Potassium sulphate SiO» PjOg, CaO, MgO, FegOj, MnaOa, CuO r TEXTILE FABRICS. [Chap. III. • 86 78 per cent. 618 ^ ^ 2-83 AI.O3, 4-21 10000 It is evident from the above that when wool is washed on the sheep's back a considerable quantity of potash is entirely lost to the farmer. It has been estimated tliat 100 kilos, raw wool yield 8| kilos, yolk-ash (free from CO2), and if the nitrogenous matter and phosphates also washed away are taken into account, it will be seen that the wash-water of raw wool possesses an appreciable manurial value. 37. The Wash- Water Products of Raw Wool.— The great bulk of the wool dealt with in commerce is, how- ever, in the unwashed or " greasy " condition, so that an opportunity is afibrded to the woollen manufacturer of extractincj the whole of the yolk, and makino; it serve as a supplementary source of potash. It is interesting to know that since 1860, and l)ased main]y upon the observations of Maumene and Rogelet, the manufacture of potash salts from the wash-water of raw wool, used in the centres of the French and Belgian woollen industry, has become an accomplished fact, the annual production of potassium carbonate being estimated at about one million kilograms. After systematically washing the wool with water, tho saturated solution is evaporated to dryness. The residue is heated in gas retorts, and the gas evolved may be used for illuminating pui-poses. The resulting coke is either calcined with access of air or lixiviated with ^\'ater, and jdelds crude potassium carbonate. One hundred kilos, "gi-easy" wool yield 7 — 9 kilos, crude potassium car- bonate, containing 85 per cent. K0CO3. The total amount of wool employed for manufacturing purposes in Great Britain in 18i;4 was 173 million kilos. If the whole of Chap, rU.] WASH-WATER PRODUCTS OF RAW WOOL. 41 this wool had been treated as above described, it would have yielded over 13 million kilos, of crude potassium carbonate, having a money value of £240,000. It may not be practicable to treat the whole of the wool in this manner, since much of the wool is washed on a com- paratively small scale, and central washing establishments would be needed. Much of the wool is washed before importation, so that it might be well for colonial wool- growers to examine this question of the recovery of potash salts from the wash-water of raw m*oo1. To the agriculturist the question is also of con- sidei'able interest, since it is evident that each year there is abstracted from the soil a large amount of valuable constituents. The wool produced in Great Britain alone (60 million kilos.) robs the soil annually of nearly 5 million kilos, of potassium carbonate, which is at present entirely lost to the farmer, who could only replace it at a cost of .£84,000. Another mode of utilising yolk is that recommended by Havrez, according to whom, it is the natural raw material for the manufacture of yellow prussiate of potash. The ordinary method of making this salt is to heat a mixture of crude carbonate of potash, waste animal matter (dried blood, leather clippings, itc), and iron filings. The resultinsj fused mass is extracted with water^ and on evaporating the solution the desired salt is obtained. Havrez says that when yolk is submitted to dry distillation it yields a residue, which is an extremely intimate mixture of carbonate of potash and nitrogenous carbom This residual coke contains, therefore, just the necessary elements for the production of yellow prussiate of potash, and experiment has shown that it gives even a greater }"ield than the ordinary mixture, containing an equal amount of K^COg, because of the perfect and inti- mate mixture of the various insfredients. Havrez has calculated that the money value of the yolk, when used for the production of yellow prussiate 42 DYEING OP TEXTILE FABRICS. IChap. HL of potash, Ls more than twice that of its ordinary com- mercial value. He further maintains that when it is used for the simultaneous production of carbonate of potash and yellow prussiate of potash, instead of the former only, there is a gain in value of 50 per cent. For this purpose the dried yolk is mixed with an equal weight of waste animal matter, and heated somewhat longer than usual. Experiment showed that carbonate of potash oVjtained from 100 kilogi-ams of the residual melt was accompanied by 17*3 kilograms of potassium cyanide, which was capable of yielding 19 kilograms of yellow piiissiate of potasL One hundred kilograms of yolk treated in this man- ner are said to yield 32 kilograms of carbonate of potash and 4 '3 kilograms of yellow prussiate of potash. If these data are coiTect, what important amounts of these salts might be obtained from this source is seen by the fact that in 1884: England imported from the Australian and Cape colonies, *i:c., 247 million kilogiams of raw wool, containing about 80 million kilograms of yolk. This amount would vield about 25 6 million kiloorams of potassiuui carbonate, valued at £448,000, and alx)ut 3 -4 million kilos^ms of yellow prussiate of potash, valued at about £329,000. Previous to its employment in mannfacturing or in dyeing, the raw wool must be thoroughly cleansed from the yolk, but since only a portion is removed by a simple treatment with water, recourse is had to the detergent action of solutions of soap, alkaline carl:K)nates, *tc. 2so attempt seems yet to have been made in England to collect separately the soluble portion of the yolk for the purpose of recovering the potash salts. The pre- liminary extraction "«"ith water, or steeping, alluded to, is dispensed with by the manufacturer, and the wool is at once washed with the solutions mentioned above. This operation is tenned '' scouring," and will be treated of in detail in a future chapter : but it may be well to Chap. IV. I THE SILK FIBRE. 43 state here that, although in tlie English method the potash salts are entirely lost, the alkaline and detergent properties of the soluble portion of the volk are utilised. CHAPTER IV. SILK. 38. Origin and Culture of Silk.— Silk differs entirely both from the vegetable fibres and from wool by being devoid of cellular structure. It consists of the pale yellow, buff-coloured, or white fibre, which the silkworm spins round about itself when entering the pupa or chrysalis state. The numerous varieties of silk may be conveniently divided into two classes, cultivated and wild silk. The latter is the product of the larvte of several species of wild moths, which are natives of India, China, and Japan. The former and more important class is produced by the common silkworm, or cater- pillar of the moth Bombyx mori (Fig. 11), which has be-, come the subject of special culture. The chief seats of the silkworm culture are Southern Europe (including the South of France, Italy and Turkey), China and Indfa. The eggs of the European silk moth are about the size and shape of poppy seeds. One gram weight of Fig. 11. -Silk Moth {Bomh]jX mori:. 44 DYEING OF TEXTILE FABRICS. [Chap. IT. them contains about 1,350 eggs. They have at first a yellowish colour, which, however, on drying, changes to grey. The rearing of the silkworm is mainly conducted in specially-arranged establishments, called Magnaneries. In these, the incubation-chamber is a well-lighted, airy room, where the eggs are spread out on sheets of paper resting on lattice-work. A certain suitable degree of moisture is maintained, and the temperature is gradually raised in the course of about ten or twelve days from 18° C. to 25° C. The young caterpil- lars, as soon as they appear, are taken to a more roomy chaml^er, in which there is erected a lath framework strung across with threads and 'fleets of papei'. Here th e anim al s are regularly fed during thirty to thirty-three days, till, indeed, they begin to spin. Their food consists of the leaves of the mulberry tree, Morus alba, hence the silk is fre- quently termed Mulberry silk. During the feeding period the silkworm (Fig. 12) increases enormously in size, be- coming at length about eight to ten centimetres long and about five grams in weight. As might be expected, such a rapid and enormous development necessitates a frequent renewal of the skin, and moulting takes place three or four times, at tolerabl}'^ regular intervals of four to six days. On or about the thirtieth day the animal ceases to take food, and evinces a restless activity. At this period it is placed on birch twigs, tfcc, where it soon begins to spin- Fig. 12.— Silkworm on Mulberry Leaf. Chap. IV.j SILK GLANDS OF THE SILKWORM. 45 The silk substance is secreted by two glands symmetri- cally situated on each side of the body of the caterpillar, below the intestinal canal. Each gland, as shown in Fig. 13, consists of three parts : a narrow tube IC with numerous convolutions, the veritable secreting portion ; a central part (c b) somewhat expanded, and constituting the reservoir of the silk substance ; a capillary tube B A, connecting the re- servoir with a simi- lar capillary canal at A, common to both glands, and situated in the head of the animal, whence issues the silk. The silk sub- stance as contained in the central re- servoir is a clear, colourless, gelatin- ous liquid. Accord- ing to Duseigneur, this is surrounded by a layer of another substance, colour- less when the silk is white, coloured when it is yellow, and which possibly constitutes the silk-gum to be alluded to subsequently. The whole is enclosed in a thin membrane. A transverse section (Fig. 14) shows that it occupies a space equal to 20 — 25 per cent, of the total volume, a proportion which corresponds somewhat to the loss sustained by raw silk during the operation of "boil- ing-off." Arrived in the capillary tube at A (Fig. 13), the silk substance solidifies, and issues from the spinneret in the Fig. 13.— Tlie Silk Glands of the Silkworm. 46 DIEIKG OF TEXTILE FABRICS. (Chap. IV. form of a douLle fibre, as represented in Fig. 15. Occa- Kionallj the two fibres ma}- be slightly separated at in- tervals, and form then at these points two transparent solid cylinders. In the beginning of its spinning operations the silk- woiTQ throws round about itself a light scafiblding, as it were, of sliort fibres connecting the neighbouring points of sui> port When this is completed its movements become slower, and by moving its head from side to side it gradually forms and lines its dwelling: with numerous layers of what may be termed silken lattice-work. Towards the interior the layers become firmer and Fig. 14.— Section of Silk-bag. Pig. 15. — Microscopic Appearance of Raw Silk Fibre. denser, while the innermost one, which immediately pro- tects the animal, forms a thin parchment- like skin. The egg-shaped product is called a cocoon (Fig. 16). It is made up of a double fibre, only rarely broken, varying in length from 350 to 1,250 metres, and w^ith a diameter of about 0*018 millimetre. Each fibre is thickest in the outermost portion of the cocoon, and becomes thinner Chap. TV.] SILK COCOON. 47 towards the interior, owing to the exhaustion of the cater- pillar from want of food during the spinning process. The cocoons are white or yellow, contracted in the centre, about 3 centimetres long, and 1 '5 — 2 centimetres thick. As soon as the metamorphosis of the caterpillar into tiie chrysalis state is comj)leted, the cocoons are collected. Those which are intended for breeding purposes are left to themselves in a room heated to 19^ — 20^ C. Three weeks after the spinning of the cocoon, the silk moth, which has now been formed in the interior, emits a peculiar kind of saliva ; with this the animal softens one end of the cocoon, and pushes its way out. A few days after the females have laid Fig. 16.— Silk Cocoon. their eggs they die, not being provided with any organ of nutrition. The eggs are slowly dried, and stored in glass bottles in a dry dark place till the following spring. Experience has shown that the worms issuing from 100 gi-ams of eggs consume 3,500 — 5,000 kilograms of leaves, and produce, under favourable conditions, 87,900 — 117,200 cocoons, weighing 150 — 200 kilograms, and these yield 12 — 16 kilograms of reeled silk. In their natural state cocoons contain generally : — Moisture .... 68-2 per cent. Silk 14-3 ,, Floss (bonn-e) ... 0-7 ,, Chrysalis . . . . 16-8 ,, The good silk is obtained from those cocoons of which the pupa? are killed, either by heating the cocoons for two to three hours in an oven heated to 60^—70^ C, or by means of steam. The latter method is the more creneral, the apparatus consisting essentially of a boiler for gene- rating the steam, and a steam-box in which the cocoons 48 DYEING OF TEXTILE FABRICS. [Cliap. IV are placed. When subjected to steam, the pupae are killed in ten or twelve minutes. The external loose flossy silk is first removed, and the cocoons are throw-n into baskets, which are then placed in the steaming-box. When taken out, the cocoons are put between woollen blankets, so that the heat may be retained and its effect continued a little longer. After a few hours they are spread out on tables, and shovelled about till perfectly dry. This last opemtion is specially requisite with such cocoons as cannot be reeled off at once. Although the killing of the cocoons by steam has the great advantage that there is no fear of the sUk itself being damaged by overheating, still it has certain defects. The most serious are, that some of the pupae burst and soil the silk, and that the fibres soften somewhat, and tend to stick together, rendering the subsequent reeling more difficult. After killing, the cocoons are " sorted," or divided into classes of different quality. In every piece of woven silk the wai-p threads have to bear the greatest strain, and, as a rule, must appear on the surface of the fabric, hence the best cocoons are chosen for the warp, since they must yield strong, smooth, even, and lustrous fibres. These fibres, too, in the subsequent process of reeling, are manipulated somewhat differently from the weft-fibres. The product of this choice and particular treatment forms the best quality of sdk, i.e., warp-silk, which is known as Organziiie. A. somewhat inferior class of cocoons is worked up to form weft-silk, or Tram. 39. Raw Silk. — In the reeling/ process a number of cocoons (4 — 18) are thrown into a basin of waiTu water, in order to soften the gummy enveloj^e of the fibres, thus permitting theii- ready separation from the cocoon, and also to cause the subsequent agglutination of what- ever number of fibi*es mav be thrown too:ether to form a suigle thi-ead. During this reeling process two threads, composed of an equal number of fibres, are passed separately through two perforated agate guides ; after Chap. IV.] SILK-REELIXG. 49 being crossed or twisted togetlier at a given point, they are again separated, and passed tbrougli a second pair of guides, thence through the distributing guides on to the reel. The object of this temporary twisting or crossing Fig. 17.— Silk-reeliug Macaine. {Fv croissage) is to cause the agglutination of the indiW- dual fibres of each thread, and to aid in makincr the latter smooth and round . ^^f 17 shows a silk-reelinor machine as used m Italy and Southern France. The following are the principal parts : a, a tinned copper basin of hot water, containing the cocoons for reeling : it is heated either E 50 DVEING OF TEXTILE FABRICS. [Chap. IV. by steam or by means of a stove; B, "filieres," or per- forated agate discs, througli which pass the several fibres destined to form a raw -silk thread; c, a " cix)iseur," used for the purpose of crossing the fibres together; D, a guide which moves slightly from side to side, and distributes the silk on the reel to prevent the threads from sticking to each other ; e, the reel proper, which is made to revolve and wind the silk from the cocoons. The unequal diameter of each fibre at different portions of its lenjrth is taken into account bv the reeler when introdu- cing new fibres into the thread to replace those which have run out. The quality of raw-silk depends very much indeed upon the care bestowed on the reeling process. The loss through removal of the external floss {hourre) varies from 18 to 30 per cent., according to the cocoons and the care besto^ved by the worker. Reeled -silk, or raw -silk, as it is generally termed, constitutes the raw material of the English silk manu- facturer. Before beinsr used for weavins:, two or more of the raw-silk threads are " thrown " together and slightly twisted by the silk spinner, or " throwster/' and in this way the various qualities of Organzine and Tram — also embroidery-sewing silks, ic. — are produced. A very brief description of the operations involved may suflice. The preliminary processes of " winding " and " cleaning " are followed by that of " doubling,^' which simply consists in placing two threads (" singles ") side by side, and winding them together without t\s^st. The so-called " spinning " of silk consists merely in twisting the threads either before or after doubling. The " Tram," already alluded to, is the product of the union of two or more single untwisted threads, which are then doubled and slightly twisted- " Organzine " is produced by the union of two or more single threads sepai-ately twisted in the same direc- tion, which are doubled and then re-twisted in the oppo- site direction. 40. Waste-silk is that which proceeds from perforated CLap. IV.] WILD SILK 61 an .1 double cocoons, and sncli as are soiled in steaming ; also the extreme outer and inner portions of the cocoon : in short, all silk obtained from cocoons in any way soiled or unable to yield a continuous thread. The killed chrysalides can be used as a source of oil, and the residue after extraction may serve for manure. All such waste- silk materials are washed, boiled with soap, and dried. They are afterwards carded and spun like cotton, and yield the so-called Spun silk. Schappe silk is a similar product, made from waste silk without previous boiling. Careful examination of the perforated cocoons has revealed the fact that their fibres are not discontinuous. The moth does not eat its way out of the cocoon, but rather pushes aside the previously softened fibres. At- tempts made to reel these cocoons by the ordinary methods have failed, since the cocoons soon fill with water and sink. The problem of causing the cocoons to float is said to jiave been recently solved by introducing small india- rubber cells in a compressed state, and then blowing them out. 41. Wild Silk.— Of " wild silks," the most important is the Tussur silk (Hindustani, Tusuru, a shuttle), also called Tusser, Tasar, Tussore, and Tussah. It is the pro- duct of the larva of the moth Anthercea mylitla. The Tussur moth is found in nearly all parts of India, where it seems to feed on a large variety of })lants. In some districts it is reared by the natives. The cocoons, which are much larger than those of Bomhyx mori, are egg-shaped and of a silvery drab colour. They are attached to the twigs of the food-trees by a peduncle having a terminal ring. The outer silk is somewhat reddish, and consists of separate fibres of various length, while the rest is generally unbroken to the centre of the cocoon. The cocoon is extremely firm and hard, the fibres being cemented together by a peculiar secretion of the animal, wl*ich permeates the whole wall of the cocoon^ and imparts to it its drab colour. 52 DYEING OF TEXTILE FABRICS. [Chap. IV. Tussur silk is used for the manufacture of the well- kuo-w-n drab or bufl^^oloured Indian silks. The cocoons are boiled and carded, or even reeled, although this latter pix>cess jjresents difficulties. Silk plush is largely made from carded Tussur silk. Other "wild silks are, Uria silk, fi-om Attacus ricini ; Muga silk, fixjm Anihercea assama ; Atlas silk, from Pig. 18.— Microscopic Appearance of Tussur Silk Fibre. Atfacifs atlas : Yama-mdi silk, from the Antheraia yamor ma'i of Japan, kc. Under the microscoi>e a raw mulberrj-silk fibre ap- pears as a double fibre (Fr. hare) consisting of two solid structureless cylinders (Fr, brin), more or less united together (Fig. 15); after " boiling-ofi" " with soap, how- ever, this double fibre separates into a pair of distinct fibres, ha^^llg a more or less irregulai', somewhat rounded triangular section- Wild silk is distinguished fi*om mulberry silk by the longitudinal striations seen in each of the double fibres when under microscopic examination (Fig. 1 8), and by the Chnp. TV.) SCROOP. 53 apparent contraction of the fibre at certain points. The former are due to the fact that the wild-silk fibre is com- posed .of a large number of fibrils, while the latter appearance is seen because the more or less flattened fibres are twisted at the contracted points. 42. Physical Properties. — The most important phy- sical properties of silk are its lustre, strength, and avidity for moisture. One other distinctive property which it possesses in certain conditions is that of emitting a peculiar crisp, crunching sound (Fr. cri), e.g., when a bundle of silk yarn is tightly twisted and pressed together. This peculiar property is called the " scroop " (Fr. craquant) of th(i silk, and no doubt gives rise to the rustling noise heard when two pieces of silk fabric rub lightly against eacli other. The intensity of the phenomenon varies with the nature of the dyeing and mechanical processes adopted, with the diameter and twist of the threads, &c. The property is absent in raw-silk and in "boiled- ofF," or in "souple" silk; it is only manifested if the last bath or solution through Avhich the silk has passed contained an acid salt or free acid. Silk which has been worked in a neutral or alkaline bath — e.g., a soap bath — jiossesses no " scroop." No sufficient explanation of the action of acid in producing scroop has been given, but it is not improbable that acids Cciuse the fibres to become more rough or irregular on the surface, so that when submitted to pressure they slip past each other with a jerky movement. When it is desired to impart scroop to the silk after dyeing, it is submitted to a special treatment. Very often it is first passed through a weak soap bath or an oil emulsion, and tlien into a weak acid bath, or it is introduced into a bath which is both oily and acid. {See Black Silk Dyeing, p. 337.) In order to develop all the qualities of softness and brilliancy of which silk is capable, it is submitted (while 54 Chap. TV.) STRINGING. 56 still in the form of hanks of yarn) to the follo\ving mechanical operations : — ■ 43. Shaking Out (Fr. secoiiage). — The object of this is to open out or beat out the hanks of silk, and to give the latter a uniform appearance by removing all tendency to curl or wrinkle. It is generally performed after dry- ing, but if before, the drying is gi'eatly facilitated. It consists in hanging the hank of yarn on a strong smooth wooden peg fixed to the wall, and inserting a smooth wooden rod in the loop, which is then vigorously and quickly pulled. The point of suspension is frequently changed, and the shaking out is repeated. The operation may also be done by a machine of M. Cesar Corron, St. Etienne, with the utmost regularity. 44. Stringing or Glossing (Fr. chevillage). — This operation, which was originally only performed in con- junction with the " shaking- out" for the purpose of straightening the threads, and dressing the hanks after diveree operations of the dye-house, has now acquired increased importance, particularly in the case of souples. "With these it forms the final operation, the silk being operated upon in the dry state. Its object in this case is to complete the separation of the double silk fibre into its constituent fibres, and to add lustre. The o]Deration consists in twisting the hanks of silk when perfectly dry. They are hung on pegs, as in the last operation, which it generally succeeds. A stated and progressive tension is thus given, which adds soft- ness and brilliancy to the fibres. This operation can also be performed with a machine, a representation of which is given in Figs. 19 and 20. The stringing machine (Fig. 19) is composed of a series of horizontal pegs A, which can be made to revolve by means of the lever and ratchet l and the cog-wheels k. A second series of horizontal rollers b, situated directly beneath the pegs a, are fixed on elbow- shaped spindles. They are capable of two movements, namely, that of revolving on their own axis — i.e., the 56 DYEING OF TEXTILE FABRICS. [Chap. IV horizontal axis of the elbow — as loose pulleys, and also at right angles to this, by the revolution of the vertical spindle of the elbow. This last movement is caused as follows : Each spindle is supported by a collar on a box u, enclosing a cog-wheel, which is revolved by a ratchet ; this is actuated by the backward and forward movement of the horizontal arm cl imparted by the frame h, through the medium of the cog-wheels f and G and the pulley E. Each spindle is also capable of sliding up and down. Attached to the bottom of the roller-pegs B (Fig. 20) are the weights c, which can either be raised separately by the jointed levers m pressing against the pulley v, or all together by means of the handle R. When this handle is turned, the cog-wheels s cause the pulley p to revolve, the counterpoise o descends, and the weights c, together with spindles, and roller pegs b, are raised. Suppose now the hanks of silk are slung over the pegs A and B ; by the action of the ratchet and lever D the roller pegs b revolve and the hanks are twisted, the pegs, weights, &c., being at the same time raised by the shortening of the hanks. Automatically the movement of the level- d is re\'erse i. the hanks untwist, and are Cljap. IV.] LUSTREING. 57 kept ill the stretched condition by the descending weights. At a given moment, namely, just when the hanks are entirely untwisted, the lever l comes into play, and causes a slight rotation of the pegs A, so that the hanks become Buspended in a fresh position, to be again twisted by the action of the lever d. The whole of tlie movements are automatic, and by a few repetitions of this twisting, untwisting, and displacement of the hanks, the operation is complete. In some cases {e.g., with sewing silks), stringing con- sists simply in twisting the hanks of silk as tightly as possible, then placing the peg in a locked position, and leaving the hanks in this tightly twisted condition for several hours. The operation may be repeated frequently during from ten to fifteen days. Its object is to give increased lustre, 45. Silk Lustreing. — This operation, effected by means of the machine represented in Fig. 21, serves to impart the maximum of brilliancy to the fibre. It also fa cilitates the subsequent winding. The dyed and dried, or sometimes incompletely dried, silk is submitted to a gentle stretching between two polished steel rollers, c and D, revolving in the same direction, and enclosed in a cast-iron box, the lid A and side b of which can be rapidly removed when necessary. During the rotation of the cylinders, steam at a moderate pressure is allowed to enter. The stretching is effected by drawing the roller c away from d by means of the hook F, actuated by the cog-wheels at E. The brilliant mother-of-pearl lustre possessed by silk undoubtedly gives it the place of honour among all textile fil)res. 46. Tenacity and Elasticity of Silk. — The specifio gravity of silk is 1-367. Its tenacity and elasticity are remarkably great. The former is said to be little inferior to that of a good quality of iron wire of equal diameter, while the latter is such that a silk fibre can be stretched 1. — 1 of its orifjinal length without breaking. Theso 58 DYEING OF TEXTILE FABRICS. [CLap. IV. properties are taken advantage of in the operations of shaking out, stringing, and lustreing, as described abo"ve. The finest silk is proportional!}" the strongest and most tenacious. Damp silk is less tenacious and more elastic than dry silk. If perfectly dried silk is wetted with water, it con- ti'acts about 7 per cent., and still more if the watei Fig. 21.— Silk-lustreing Machine. contains mineral or organic substances which penetrate the fibre and cause it to swell up. These effects take place during the various operations of dyeing ; hence the necessity of stringing, stretching, and lustreing, above al- luded to, in order to prevent or counteract the contraction. The tenacity and elasticity of raw silk reside largely in its external coating of silk-glue. By boiling-off" with soap, it loses 30 per cent, of its tenacity, and 45 per cent, of its elasticity. Chap. TV.] COKDITIONINO. 59 These i)roperties vary in weighted silk, according to the nature of the weighting. If the fibre is simply coated with such substances as gelatin, albumen, starch, &c., the tenacity will be as a rule increased, but if the weighting materials employed penetrate the substance of the fibre, and cause it to swell in a greater or less degi-ee, the natural properties of the silk will be modified accordingly. Some agents, like the simple colouring matters, have no appreciable influence, while others, e.y., astringents and metallic salts, when used in large excess, gi-adually destroy the valuable properties of silk entirely. {See Black Silk Dyeing, p. 332.) If silk is heated to 110^ C. it loses all its natural moi.sture, but remains otherwise quite unchanged. Exi.osed to 170^ C, and higher, it soon begins to decompose and carbonise. If a silk fibre be inserted in a flame it has the appearance of fusing like wool, but it does not give off quite such a disagreeable odour. Silk is a veiy bad conductor of electricity, and since it readily becomes electric by friction, this condition, once acquired, is very persistent, and is apt to become a source of trouble during the mechanical ojjerations involved in manufacturing. The most efl'ective mode of overcoming the difficulty is to keep the atmosphere of the work° rooms in a suitable state of humidity. In its boiled-off and pure state silk resists ordinary decay most thoroughly, and it is rarely attacked by insects. 47. Silk Conditioning.— If raw sQk be kept in a humid atmosphere it is capable of absorbing thirty per cent, of its weight of moisture without this being at all perceptible. This circumstance, coupled with th^e high price of raw silk, makes it of very gi-eat importance to those who trade with it to know exactly what weight of normal silk there is in any given lot which may be the subject of commercial dealings. To ascer- tain this information there have been established, in about thirty-seven centres of the silk industry, so-called Fig. 22.— Can diti o ai iig Appiatos. Chap. IV.] CONDITIONING. 61 conditioning establishments, e.g., in Lyons, Crefeld Zurich, Bale, Turin, Milan, Vienna, Paris, London, &c., &c. Fig. 22 shows the external appearance of the essen tial apparatus of such an establish- ment, namely, the desiccator. It consists of an enamelled cylin- drical hot - air chamber. One arm of a fine balance sustains a crown of hooks, to which are at- tached the skeins of silk to be dried. The sus- pending wire passes through a small opening in the cover of the cylinder. The other arm of the balance carries the ordinary pan for weights. Fig. 23 gives Fig. 23.— Section of Conditioniug Cliamber. a vertical section of the chamber. Hot air at 110° C. enters by the tube a from a stove situ- ated in a cellar below, passes into the space b, and thence by thirty-two vertical tubes, t, placed between the two concentric cylinders c and d, it enters the upper por- tion of the inner cylinder d. The hot air descends, dries the silk, and escapes by tlie tubes e, which com- municate with the exit flue. The apparatus is provided 62 DYEING OF TEXTILE FABRICS. [Chap. IV with a valve v, actuated by the lever k (Fig. 22) for resrulating or shuttiiifc off the current of liot air. The air v>"hich passes outside the brickwork of the stove, and is thus heated only to a moderate degree, passes upwai"ds between the cylinders c and d into the space r; by means of the button l, which actuates a .slide-valve, its entrance into the central chamber can be regulated. By means, therefore, of the lever k and the button l, the supply of hot and cold air into the central chamber can be regulated to a nicety, and the temperature of the mix- ture is ascertained by the thermometer t. The button s actuates the valve M, which cuts off communication with the exit flue and stops the current of air during a tinal weighing operation. Several hanks of silk are taken from the bale to be tested and divided into three lots, in order to be able to make two parallel determinations, and a third if neces.?ary. The weight is fii^t ra^^idly taken, under ordinary cii'cum- stances, on a fine balance ; the hanks are then suspended Ln the desiccator and countei'poised, and the hot air ciUTcnt is allowed to cii'culate till no further loss of weight takes place. One operation may last from a half bo three-quarters of an houi*. The average loss of weight usually met with is about 12 per cent Absolutely dry silk is not reckoned as the standard article, but such as contains about 90 per cent, dry silk and 10 per cent, moisture. Tlie legal weight is really obtained by adding 11 per cent, to the dry weight. 48. Chemical Composition. — The silk fibre has been the subject of numerous chemical researches, the general result of which may be summed up by saying that it is composed essentially of two distinct parts : first, that constituting the central portion of the fibre, and secondly, a coating, or envelope, consisting apparently of a mix- ture of substances mostly removable by hot water, or, at any rate, by solvents which have little or no action on the central portion. Chap. lY.l ANALYSIS OF SILK. G3 Fibroin. — In order to determine tlie character and amount of these several substances, Mulder submitted raw Italian silk to the successive action of boiling water, alcohol, ether, and hot acetic acid, and in this Avay obtained in a comparatively pure state the central silk substance, to which he assigned the name Fibroin. The following numbei-s give the results of his analysis : — Silk fibre (fibrom) Matters soluble in Yellow White Italian silk. Levant silk. , 53-35 54 05 water 28-86 28-10 alcohol 1-48 1-30 ether 001 005 acetic acid 16-30 16-50 100-00 100-00 By a further examination of the substances which each solvent had extracted, he arrived at the following more detailed analysis : — Yellow White Italia,n silk. Levant silk Fibroin • • • • 53-37 54-04 Gelatin • • • . 20-66 19-08 Albumen • • • ■ 24-43 25-47 Wax . 1-39 1-11 Colouring matter . 005 0-00 Eesmous and fatty matter 0-10 0-30 100-00 100-00 Mulder explains that on evaporating the aqueous solution to dryness, the residue would not entirely re- dissolve in water. This insoluble portion, therefore, and that which is dissolved by acetic acid, has been reckoned as albumen. Exception has been taken by Bolley with regard to the presence of this albumen, for if it is borne in mind that the temperature employed in killing the cocoons, and that of the water used durincr the reeling process, is such as to coagulate any albumen which might possibly be present, it is highly improbable that raw silk would contain any soluble albumen- 64 DYEING OF TEXTILE FABRICS. [Chap. 1 V Further, it has been shown that living cocoons, which have not therefore been submitted to any steamiug process, but have simply been opened and heated with tepid water, contain no albumen. Fibroin itself, too, is known to be somewhat soluble in strong acetic acid, so that it may, on the whole, be concluded, that what Mulder found to be soluble in acetic acid was not albumen, but altered fibroin, and that the percentage of this latter sub- stance in silk which he gives, is too low. By heating i-aw silk for several hours with water at 133° C, a residue of fibroin is obtained which, after the removal of fatty matter by ether, and colouring matter by alcohol, represents 66 per cent, of the weight of the silk. Even this figure may possibly be too low, .since the usual loss in practice dui'ing the operation of " boil- LQg-ofi"" is 25-30 per cent. The percentage composition of pure Fibroin has been variously stated, probably owiug to the difierent hygro- metric state of the fibres examined Cramer gives the formula as Cj5Ho;5X^Og. Sericin. — That portion of silk which is soluble in wann water can be precipitated from its solution by lead acetate. By submitting this precipitate to a somewhat tedious series of opei-ations — such as washing with water, suspending in warer and decomposing with sulphuretted hydi'ogen, filtering, and evaporating the filtered solution, precipitating and exti^cting ^Wth alcohol, then with ether — it is possible to obtain the essential constituent of the external envelope of the silk fibre as a colourless, odoui'less, tasteless powder. It swells up in cold water, and is somewhat more soluble in hot water than gelatin. A six per cent, solution of it gelatinises on cooling, and its solutions are precipitated by alcohol, tannic acid, and metallic salt solutions. Altogether, its physical and chemical properties are very siuiilar to those of glue ana gelatin ; hence Sericin is often called silk-glue, sometimes also silk-gum. Its chemical composition is represented by the formula— C,^H^N A- Chap. rV.) ACTION OF WATER ON SILK. 65 It is distinct fi'om ordinary glue, however, according to some observers, since when boiled with dilute mineial acids it yields diflerent products. If the formulae given for fibroin and sericin be com- pared, a relationship is apparent which may be expressed by the following equation : Ci5H23X,Oo + + H20=Ci5H,,N508 Fibroin. Sericiu, Although these formulae can only be considered as representing approximately the percentage composition of these two bodies, the above comparison has been taken by some as an indication that originally, i.e., at the moment of secretion, the silk fibre is probably a homogeneous substance, which, by the action of the air and moisture, rapidly becomes altered superficially. This view is supported by the observation that if moist fibroin be left exposed to the air for a lengthened period it becomes partially soluble in water. Bolley and Rosa have found also that the silk-bags taken from living worms are composed almost entirely of fibroin, since only 17 per cent, is soluble in boiling water, and the ele- mentaiy analysis is consistent with the formula of fibroin. The physiological studies of Duseigneur, and especially his examination of the transverse section of the silk-bag, already alluded to, appear to contradict this view. Injluence of Reagents on Silk. In contact with various liquids silk not only absorbs them rapidly, on account of its great porosity, but some- times retains them with extreme tenacity ; this is the case, e.^., with alcohol and acetic acid. For the same reason it has great aptitude for fixing mordants and colouring matters. 49. Action of Water. — Prolonged boiling with water removes from raw silk its silk-glue, but it has little efiect upon the fatty, waxy, and colouring mattei-s present. The tenacity of the fibre is reduced even 66 DYEING OF TEXTILE FABRICS. [Chap. IV. more than by the ordinary methods of unijumming witli soap solutions. A similar solvent action is exercised by all liquids ; for this reason it is not customary to mordant silk with hot solutions, and the dyeing is jonducted at a temperature as low as circumstances will permit. 50. Action of Acids. — Speaking generally, concen- ti'ated mineral acids rapidly destroy silk, but if sufficiently diluted their action is insensible. "Warm dilute acids, however, dissolve the sericin of raw silk, and hence these may be used in ungumming (soupling). Concentrated sulphuric acid dissolves silk, giving a viscous brown liquid ; on diluting the latter with water a clear solution is obtained, from which the fibroin is precipitated on the addition of tannic acid. Concentrated nitric acid also rapidly destroys silk ; but if diluted, the latter is only slightly attacked and coloured yellow, in consequence of the formation oi xanthoproteic acid. Thi? "reaction is made use of in distinguishing silk from vegetable fibres. Formerly it was also utilised in dyeing ; a method, howe\'er, not to be commended, since the colour is produced at the expense of the silk itself, which must inevitably be weakened by the process. Hydrochloric acid, if applied in the gaseous state, destroys the fibre without liquefying it, but a concen- trated aqueous solution readily dissolves it. Hydrochloric acid 38° Tw. (Sp. Gr. 1'19) when applied cold, dissolves an equal weight of silk without even then being saturated. Dilute hydrochloric acid has no sensible action, except upon the sericin of raw silk, which it more or less removes. Phosphoric and arsenic acids in dilute (5 per cent.) aqueous solution act like other weak acids in removing the sericin from raw silk, and have been proposed as ungumming agents instea^l of soap, but they are not used in practice. Permanganic acid, either in the free stat€ or in combination with potassium, acts energetically on silk ; Chap. IV.] ACTION OF ACIDS AND ALKALIS OX SILK. 67 it oxidises and colours the fibre brown by deposition of hydrated manganic oxide. If this be removed by immersion in a solution of sulphurous acid, the silk is left in a remarkably pure white condition. Although recommended on this account for bleaching silk, it is not altogether suitable, since the silk thus bleached always has a tendency to become yellowish under the influence of alkalis. Suljyhurous acid is used in bleaching silk. Chromic acid and chromates, like permanganic acid, oxidise silk, leaving the fibre of a pale olive tint. The action of organic acids on silk has been little studied ; it varies, no doubt considerably, according to their concentration, temperature, &c. Hot dilute organic acids remove the sericin from raw-silk but do not aSect the fibroin much. Cold glacial acetic acid removes the colouring matter from yellow raw-silk without dissolving the sericin. Silk is entirely dissolved when heated under pressure with acetic acid. 51. Action of Alkalis. — Concentrated solutions of caustic soda and potash rapidly dissolve raw-silk, espe- cially if applied warm. Caustic alkalis, sufficiently diluted so as not to act ap- preciably upon the fibroin, will dissolve ofi" the sericin, and have been tried as ungumming agents. For ordinary use, however, they must be avoided, since the silk is always left impaired in whiteness and brilliancy. Pure ammonia solution, even if used warm, has no sensible action on boiled-oflf silk, but if it is at all impure the silk becomes dull and dirty from absorbed 3arry matter. Ammonia seems to favour the absorption by silk of salts of calcium, magnesium, &c. Alkaline carbonates act like the caustic alkalis, but in a less energetic manner, and they are not employed as ungumming agents. Of all alkaline solutions, those of soap have the least injurious efi'ect. When used hot, they readily remove the sericin from raw-silk, and Ipnve 68 DYEING OF TEXTILE FABRICS. [Chap. IV. the fibroin lustrous and brilliant; hence soap is par excellence the uns^imming agent employed. Borax acts somewhat like soap, but cannot replace it in practice. If raw silk be steeped for twenty-four hours in clear, cold lime-icater, it swells up considerably, the lime seeniinfj to have a stronsr softenincr action on the sericin ; when this is removed by dilute acid and a subsequent soap bath, the fibroin seems not to have suffered otherwise than by the loss of its natui-al brilliancy. Prolonged contact, however, with lime-wat^r rendei^s silk brittle and disorganised. Chlorine and hypochlorites attack and destroy silk rapidly, and cannot be used as bleaching agents. Applied in weak solutions, with subsequent exposure of the fibre to the air, they cause the silk to have an in- creased attraction for certain colouring matters. 52. Action of Metallic Salts. — If silk is steeped in cold solutions of several metallic salts, e.g., of lead, tin, copper, iron, aluminium, kc, it absorbs and even partly decomposes them, so that less soluble basic salts remain in union with the fibre. The methods of mordanting silk with aluminium, tin, and iron salts de- |>end upon this fact. Sometimes, as in the case of ferric and stannic salts, the quantity of basic salt which may be precipitated on the fibre is sufficient to serve as weighting material Concentrated zinc chloride, 138° Tw. (Sp. Gr. 1-69), made neutral or basic by boiling with excess of zinc oxide, dissolves silk, slowly if cold, but very rapidly if heated, to a thick gummy liquid. This reagent may serve to separate or distinguish silk from wool and the vegetable 6bres, since these are not affected by it. If water be added to the zinc chloride solution of silk, the latter is thrown down as a flocculent precipitate. If this is wa.shed fi-ee from zinc salt and dissolved in ammonia, it is said that the solution may serve to cover cotton and other vegetable fibres with a coating of silk substance. Dried Char. IV.] SOLVENTS FOR SILK. 69 at 110° — 115° C, the precipitate acquires a vitreous aspect, and is no longer soluble in ammonia. An ammoniacal solution of cupric hydrate dissolves silk, the solution not being precipitated by neutral salts, sugar, or gum, as is the case with the analogous solution of cotton. An ammoniacal solution of nickel hydrate also dissolves silk. A most excellent solvent for silk is an alkaline solution of copper and glycerine, made up as follows : dissolve 16 grams copper sulphate in 140 — 160 c.c. distilled water, and add 8 — 10 grams pure glycerine (Sp. Gr. 1*24) ; a solution of caustic soda is dropped gradually into the mixture till the precipitate at first formed just re-dissolves ; excess of NaOH must be avoided. This solution does not dissolve either w^ool or the vegetable fibres, and may serve therefore as a distinguishing test. 53. Action of Colouring Matters. — Generally speaking, silk has a very great affinity for the mono- genetic colouring matters. It can be dyed direct -with the aniline colours, for example, with the greatest facility. It has, however, little attraction for mineral colouring matters. An examination of sections of dyed silk reveals the fact that the colouring matter (or the mordant) penetrates the substance of the silk fibre to a gi*eater or less degree, according to the solubility of the colouring matter, the duration of the dyeing process, and the temperature employed. If the silk is dyed only for a short time, a section of the fibre shows an external concentric zone of colour, w^hile if the dyeing operation is continued suffi- ciently long, it is coloured right to the centre. If a mixture of two colouring matters be applied, either simultaneously or successively, both are absorbed, the more soluble, or that which has been allowed to act longest, penetrating the fibre most deeply. Externally a mixed effect is produced in this case, but a section of the fibre reveals in most cases two concentric zones of colour. Silk thoroughly mordanted with a ferric salt presents in section a uniform 70 DYEING OF TEXTILE FABRICS. [Chap. TV, yellow tint ; if dyed subsequently in an acidified solution of potassium ferrocyanide, the ferric oxide deposited in the silk gives place to Prussian blue, at first in the outer portions only, but by degi'ees even in the centre, especially if the temperature of the bath be raised. A similar eifect is produced if a bath of tannin be sub- stituted for that of potassium ferrocyanide. It is indeed difficult to say what number of substances might be successively absorbed by the silk, and penetrate it either by juxtaposition or by reacting upon each other. The action of colouring matters on raiu silk is similar; but in many cases^ e.g., in the black dyeing of souples, the colouring matter is situated principally in the external silk-glue, which, becoming brittle through the large amount of foreign matter it then contains, breaks up and assumes the form of microscopic beads. 71 OPEEATIONS PEELIMINAEY TO DYEINa. CHAPTER V. COTTON BLEACHING. 54. Object of Bleaching. — As already noticed in treat- irg of the cotton fibre, raw cotton is contaminated with several natural impurities, and although these are com- paratively small in amount, they impair the brilliancy of the white belonging to pure cellulose. Hence cotton yarn as it leaves the spinner has invariably a soiled or greyish colour. When such yarn is woven it is still further contaminated with all the substances (amounting some- times to 30 per cent.) which are introduced during the sizing of the warps, e.g.y china clay, grease, &c. Bleaching consists in the complete decolorising or removal of all these natural and artificial impurities, either for the purpose of selling the goods in the white state, or in order to make them suitable for being dyed light, delicate, and brilliant colours. 55. Bleaching of Unspun Cotton (Cotton-wool). — Although cotton-wool is now largely dyed, it is seldom or never bleached in this form, because it would become more or less matted together. As a rule, the only treat- ment previous to dyeing which it receives is that of boiling with water until thoroughly wetted. It would no doubt be better to boil with a dilute solution of caustic or carbonated alkali, and afterwards to wash well with water — e.g.^ in machines similar to those used in loose-wool 72 DYEING OF TEXTILE FABRICS. fCliap. V Bcoui-ing {see p. 100) — since bv tins means the natural waxy matters, (tc, woald be more thoroughly removed. More complete bleaching would be tedious, and is pro- bably unnecessary. 56. Bleaching of Cotton Yarn. — When cotton yarn has to be dyed black or dark colours, it is as a rule not bleached, but merely boiled with water till thoroughly softened and wetted. For light colours the dyer frequently effects a rapid, though perhaps more or less incomplete bleaching, by passing the wetted yam {e.g.^ warjDs) through a boiling weak solution of soda-ash, then steeping it for a few hours in a cold weak solution of chloride of lime or hypochlorite of soda. It is then washed in wat^er, stepped in dilute hydrochloric acid, and finally well washed. A more complete and thorough bleaching is that effect-ed by the operations now to be briefly described. " Wai'ps " are loosely plaited by hand or machine, in order to reduce their lengtL If the yam is in hanks it is either retained in that form, or linked together to form a chain, the latter l^eing the better and more econo- mical method. 1. Ley boil — For 1,500 Idlos. yam, boil six hours with 2,000 litres water and 300 litres caustic soda 32° Tw. (Sp. Gr. 1'16) ; steep in water for forty-five minutes and wasL 2. C/ieinicking. — Steep the yam for two hours under sieve in a solution of bleaching powder 2^ Tw. (Sp. Gr. 1*01), then wash for half an hour under sieve. 3. Souring. — Steep the yam for half an hour under sieve in dilute sulphuric acid 1^ Tw. (Sp. Gr. 1-00.5), then wash for half an hour under sieve and afterwards through washing machine. If the yam is intended to remain white and not to be dyed, it is run through a so-called ''dumping" machine "svith hot soap solution and blue (ultramarine, «fcc.), then hydro-extracted and dried. Chap, v.] COTTON YARN BLEACHING. 73 When bleaching cotton thread, owing to its closer texture, the first three operations are repeated. The boiling (also called "bowking" or "bucking") with caustic soda solution takes place in large iron boilers or " kiers." These are either open or provided with a lid capable of being screwed down, in order to be able to boil with a slight pressure of steam. The general appearance and internal arrangement of a low- pressure bleaching kier is well shown in Fig. 88. The usual order of procedure is first to fill the kier with the yarn, and after blowing steam through for an hour or so, to run in the soda solution and boil for ten to twelve hours. The mode of circulation of the liquid through the goods is described on page 434. The operations of chemicking, souring and washing under sieve, are carried out by means of the arrangement shown in Fig. 24. It consists of a stone tank e, with a false bottom F, and a valve G, communicating with the cistern d below ; b is the shaft which works the pump c ; f' is a movable perforated drainer or sieve covering the whole surface of the tank e; a is a winch for drawing the chain of yam into the tank. Supposing the tank to be packed with yarn, the pump is set in motion, the liquid in D is thus raised to the sieve f', whence it showers down on the yarn below. It filters, more or less rapidly, through the yarn and collects again in the tank D to circulate as before. Complete separate arrangements of this kind are required both for chemicking and for souring, but the washing under sieve is performed in either set of tanks as required, it being only necessary to stop the pumj), close the valve g, and allow water to flow from a tap placed over the sieve, and to escape at the bottom of the tank e by a separate plug- hole into the nearest drain. The final washing after souring is best given by means of a machine similar to that represented in Fig. 62. The " dumping " machine referred to is essentially the same in construction as the final washing machine, 74 DYKmO OF TEXTILE FABRICS. [Chap. V. P -g. :^4:.— Aj p^raTU-s for Chemicking, Soorii^, and Waslun^ the main difference being that the square beater is re- placed by a round roller, and that the upper squeezing Chap, v.] CALICO BLEACHING. 75 roller is covered with cotton rope and rests loosely with its own weight on the lower one. As the cotton yarn, soaked with soap solution and blue, passes rapidly between the squeezing rollers, the irregularities produced by the plaiting or linking impart a constant jumping motion to the upper roller, and the liquid is effectually beaten and pressed into the heart of the yarn, thus enhancing considerably the purity of the white. When the yarn is bleached as separate hanks and not in the chain, the washing is effected by one or other of the machines illustrated in Figs. 54, 55, 56, and the " dumping " is done in the "stocks" {see Fig. 52). 57. Bleaching of Cotton Cloth or Calico. — The mode of bleaching is varied according to the immediate object for which the bleached calico is intended ; thus, one may distinguish between the M adder-bleach j the Turkey-red- bleach, and tlie Market-bleach. Madder-bleach. — This, the most thorough kind of calico-bleaching, was originally so-called because it was found specially requisite for those goods which had to be printed and subsequently dyed with madder. Its object is to effect the most complete removal possible of every impurity which can attract colouring matter in the dye-bath, so that the printed pattern may ultimately stand out in clear and bold relief on a, white background of unstained purity. Although the madder-bleach is in general use among calico-printers, it may be also adopted by dyers whenever the calico is to be dyed subsequently in light and delicate colours, or if absolute freedom is desired from any impurity which resists the fixing of the colouring matter to be applied. Stamjnmj and Siitcliing. — For the purpose of subse- quent recognition, the ends of each piece are marked with letters and figures, by stamping them with gas-tar or other substance capable of resisting the bleaching pro- cess. The pieces are then stitched together, end to end, by machinery. Singeing. — This operation consists in burning off the 76 DYEING OF TEXTILE FABRICS. [Cbap. V. nap or loose fibres which project from the surface of the cloth, since these interfere with the production of fine impressions dui-ing the printing process. It is performed by rapidly passing the cloth in the open width over red- hot plates or cylinders, or over a row of gas flames. Fig. 25 shows a usual arrangement of the plate-singe- ing machine. By means of the rollers R, driven by a small engine, the piece g is rapidly drawn across the two Fig. 25.— Plate-singeing Machine. red-hot copper plates p p, against whicli it is depressed by the four bars of the iron frame D^ capable of being raised or lowered by the chain c. Immediately on lea%T.ng the plates, the piece passes between two j^erf orated steam pipes K K, and through the water trough b, so that all adhering sparks may be at once extinguished; h is a hood for leading away the products of combustion. The two plates are heated by means of the furnace below. The great difficulty in plate-singeing is to keep the plates at a uniform strong red heat, owing to the rapid cooling action of the passing pieces; hence the "revolving singeing roller " is a decided improvement on the plate. In this aiTangement the flames from the furnace pass through a copper cylinder which slowly revolves, so that a Chap, v.] CALICO BLEACHING. 77 fresh red-hot surface is contmnally presented to the piece, and a regular even singe is thus obtained. As a rule, hot-plate or cylinder singeing is preferred for thick heavy cloth, but for light, thin cloth — e.g.^ muslins, kc. — singeing by gas is generally adopted. The gas-singeing machine consists essentially of one or more rows of gas jets, across which the cloth is rapidly drawn. The gas is mixed with air just before being burnt, so that an extended line of the well-known smoke- less Bunsen flame is presented across the full width of the piece ; by means of levers the gas jets may be placed at any suitable distance from the cloth, or in case of acci- dent they can be entirely withdra^vn from it. The preliminary work of stamping, stitching, and singeing is succeeded by the bleaching operations proper, which, for 24,000 kilos, cloth and with low pressure kiers, may be summarised as follows : — 1. Wash after singeing. 2. Lime-boil: 1,000 kilos, lime, boil 12 hours: wash. 3. Lime -sour: hydrochloric acid, 2^ Tw. (Sp. Gr. TOl); wash. 4. Ley-boiLs : let, 340 kilos, soda ash, boil 3 hours. 2nd, 860 kilos, soda ash, 380 kilos, resin, 190 kilos, solid caustic soda, boil 12 hours. 3rd, 380 kilos, soda ash, boil 3 hours ; wash. 5. Chemicking : bleaching powder solution, ^^ — i' Tw. (Sp. Gr. 1-00125— 1-0025) wash. 6. White-sour: hydrochloric acid, 2^ Tw. (Sp. Gr. 1*01), pile 1 — 3 hours. 7. Wash, squeeze and diy. 1. Wash after Singeing. — The object of this operation va to wet out the cloth and make it more absorbent, also to remove some of the w^eaver's dressing. This was for- merly effected by simply steeping the cloth in water for several days until, by the fermentation induced, the starchy matters were rendered more or less soluble. At present, printers' calicoes are not, as a rule, heavily sized, and a simple wash in the machine represented in Fig. 60 is sufficient. The pieces are drawn direct from the adjacent 78 DYEING OF TEXTILE FABRICS. . [Chap. V. singeing house, guided by means of white glazed earthen- ware rings {" pot-eyes "), through the washing machine ; they are at once plaited or folded down on the floor and there allowed to lie "in pile" for some hours to soften. By this first operation, frequently called " grey-washing," the pieces, hitherto in the open width, assume the chain form, which they retain throughout the whole of the succeeding operations. 2. Lime-boil ("Lime-bowk"). — The pieces are now run through milk of lime, a portion of which they absorb. They are at once drawn by overhead winches into the kiers and there plaited down and well packed by tramp- ling under foot. Fig. 26 shows the arrangement of a pair of Barlow's high-pressure kiers, one being given in section. The two kiers a, b are of strong boiler-plate iron ; ^ is a false bottom, consisting of smooth water- worn stones, or a cast-iron grating, on which the cloth is laid ; d is the distributor which acts also as a strengthening stay ; the upper portion is perforated and closed by a stop at some distance from the bottom ; the block h at the bottom of the distributor is perforated to allow liquor to pass from the kier j above, the distributor is connected with the two-way tap t, by which steam is admitted from the main pipe m, and by the reversing of which the steam is shut ofif and liquor admitted from the adjoining kier ; pp is Si pipe connecting the top of the kier a with the bottom of kier b, and q q similarly connects the top of kier b with the bottom of kier a ; s 8 are branch steam pipes from the main w,', II are the pipes and taps through which the liquors are introduced into the kiers ; o o are the manholes for entering and removing the cloth, and which can be made steam-tight by means of an iron plate held against the inner side with two crossbars and screw bolts; w w are the draw-off taps connected with the pipes p and q, and which can be worked from the stage at c c when emptying the kiers of spent liquor, (fee. ; ii are glass tubes or water-gauges Chap, v.] CALICO BLEACHING. 79 which indicate when the liquor has passed entirely from one kier to the otlier ; w w are short iron columns for supporting the kiers. The kiers are usually about three metres high and two metres in diameter. g: n When the kiers are filled with cloth the manholes are closed, the pipes connecting the kiers are shut off, the emptying taps below are open, and steam is blown through for about a quarter of an hour to drive out the air, and to wet and heat the goods through. After running the necessary liquid into one of the kiers, the 80 DYEING OF TEXTILE FABRICS. [Chap. ?. two-way taps are suitably arranged, high-pressure steam is again admitted, and the liquor is forced through the goods, out by the bottom, up the connecting pipe, and tlirough the distributor into the goods contained in the other kier. When all the liquor has been transferred, both two-way taps are reversed, steam enters the second kier, and drives the liquor through the goods in the same manner back into the first kier. Tliis alternating process is continued usually for about seven hours. The essential action of boiling with lime is to decom- pose the fatty, resinous, and waxy impurities present in the fabric. They are not removed, but remain attached to the fibre as insoluble lime soaps, which can, however, be readily removed by the subsequent processes. The colouring matter of the fibre is modified, and any alumina present is also attacked. Xo doubt, caustic alkalis would also decompose and at once render soluble the fatty impurities, but lime is cheaper, and is said to attack the resinous matters more energetically. Care must always be taken that a sufficiency of water is present in the kier, otherwise the cloth, esi)ecially that at the top or the bottom, is liable to be tendered Too much liquor is almost equally objection- able, since the pieces are then apt to become entangled and damaged by tremulous boiling. 3. Lime-sour. — This operation, also called the •' gi*ey sour," is immediately preceded by a washing of the pieces as they come out of the lime-boiL It consists in washing the pieces with dilute hydrochloric acid in a machine identical with that illustrated in Fiir, 60. During this process the insoluble lime-soaps, resulting from the lime-boil, are decomposed and the lime is removed ; any other metallic oxides present are also dissolved out, and the brown colouring matter is loosened. Hydrochloric acid is prefen'ed to sulphuric acid because it forms a more soluble compound with the lime. Care must be taken to maintain the strength of the dilute acid as uniform as possible, both by having a regular Chap, v.] CALICO BLEACHIXa 81 flow of fresh acid from a stock cistei'n, and by making occasionally rapid acidimetrical tests. After souring, it is advisable not to leave the pieces long in their acid state^ for fear of the exposed portions becoming tender, but to wash them as soon as convenient. It is very essential, too, that this washing be as complete as possible, other- wise a tendering action may take place during the follow- ing process. 4. Ley- or Lye-boil. — The object of this operation is to remove the fatty matters still remaining on the cloth. The fatty matters having been decomposed during the lime-boil, and the lime having been removed from the lime-soaps by the souring, the fatty acids remaining on the cloth are readily dissolved off by boiling with alkaline solutions. The brown colouring matters are also chiefly removed at this stage. The boiling takes place in exactly the same kind of kiers as those used for the lime-boil. Other kiers besides Barlow's, however, are frequently used for both operations. In the so-called "vacuum kiers," perfect penetration of the cloth by the liquors is obtained by first pumping out the air from the kier before admitting the liquors. Fig. 27 gives the section of a modern "injector" kier a, filled with cloth ; b b are the steam pipes, c is the injector, and d the circulating pipe ; F is the liquor pipe, by wliich water or other liquid may be admitted ; E E the draw-ofi" valve and waste pipe. The kier being suitably filled with cloth and liquor, whenever the steam is turned on, the vacuum produced by its condensation in c withdraws the liquor from the kier and causes it to ascend the pipe d, to be at once showered over the pieces at g. A portion of the liquid may tem- porarily collect at H, but it soon percolates or is drawn through the cloth to the bottom, again to enter the injector. A continual circulation of the liquid is thus maintained. If open or low-pressure kiers are used, similar to that referred to in cotton-yam bleaching, the boiling is o 82 DYEING OF TEXTILE FABRICS. [Chap. V ^WM Fi^. 27. — Section of Injector Kiec. Chap, v.] CALICO BLEACHING. 83 continued for ten to twelve hours ; with the injector kier and steam at fifty pounds pressure, three to four hours' boiling may be sufficient. Some bleachers, as indicated on page 77, boil 1 — 3 hours with soda-ash alone, both before and after the resin boil, using 1 — 2 kilos, soda-ash per 100 kilos, calico. The first soda-ash boil, though not absolutely necessary, is advisable, in order to neutralise any traces of acid accidentally left in the cloth from the souring. Another plan to avoid tendering, is to let the goods steep in a weak soda-ash solution for a short time, and then to draw it off again before commencing the boiling operation with " resin-soap " This is termed " sweeten- ing " the goods. The boiling with resin-soap is a very special feature in the madder-bleach. Experiment has shown that resin-soap removes, better than any other substance which has been tried, certain matters, which would subsequently attract colouring matter in the dye-bath. What these particular substances are, and in what special manner resin-soap acts upon them, is at present unknown, or, at most, only conjectured. The boiling with soda-ash solution after the "resin boil " is useful, in order to ensure the complete removal of fatty matters and undissolved resin. Since the cloth is very liable to contract iron stains if left in the kier too long after the alkaline liquor has teen drained away, it is well to wash immediately after the ley-boils. 5. Chemicking . — After all the previous operations the cloth still retains a faint yellowish or creamy tint, and the object of this operation is to destroy the traces of colouring matter from which it arises. The pieces are passed through a very dilute solution of chloride of lime or "bleaching-powder," in a "chemicking" machine, which is exactly similar to that employed for washing (Eig. 60), and are then allowed, while still moist, to remain in pile and exposed to the air 84 DYEIXG OF TEXTILE FABRICS. [Chap. V for a few hours or over-night. The bleaching action, which must be considered as one of oxidation, takes place largely during this exposure, hypochlorous acid being then liberated by the action of the carbonic acid of the air. It is essential that the bleach i n g-powder solution should not be too strong, otherwise the cloth may be tendered or be partially changed, into oxycellulose, and thereby be apt to attract certain colouring matters in the dye-batli, or to contract brown stains during subsequent steaming processes. For the same reason the solution of bleach in g-powder shonld be entirely free fix)m undissolved particles. The bleaching power of the liquor should be main- tained as constant as possible by having a continual flow of fresh bleachin g-powder solution into the machine, and by occasionally testing how much of the liquor is required to decolorise a specially prepared standard solution of ai-senat^ of soda, tinted with indigo extract or cochineal decoction. 6. W7iits-sour. — This operation does not differ irom the lime-sour already described Its object is to com- plete the bleaching action by decomposing any " chloride of lime '' still in the cloth, also to remove the lime, the oxidised colouring matter, and any traces of iron present. The cloth usually remains saturated with the acid a few hours. 7. The ^71^ washijig must be as thorough as possible. It 18 usually performed by the square beater machine, illustrated in Fig. 62. The squeezing is done by the machine shown in Fig. 65. After squeezing, the cloth is again opened out to the foil width, previous to drying. This is effected by allowing a lengthened portion of the chain of cloth to hang loosely and horizontally, and in this position to pass between a pair of rapidly revolving double-armed scutchers, which shake out the twists from the horizontal length of cloth. On leaving the scutchers, the piece passes in a state of tension ovct C^P- V.J TURKEY-RED-BLEACH. 85 one or more rollers provided with spiral projections, which tend to open out the cloth still more thoroughly • in this state it passes round the steam cylinders of the' drying machine illustrated in Fig. 79. The average length of time required for the madder- bleach is four to five days. TuRKEY-EED-BLEACH.— When calico is intended to be dyed Turkey-red it is not necessary to give it the madder- bleach, since no white gi^ound has to be preserved. Certain modifications, too, are introduced ; it is found, for example, that singeing, and the application of bleach- mg-powder which causes the formation of oxycellulose interfere with the production of the most brilliant colour' ihe apparatus employed being similar to that already described, it is only necessary to give the followincr summary of the operations usually earned out : ° 1. Wash. 2. Boil in water for two hours and wash. 3. Ley-boils: 1st, 90 litres caustic soda, 70° Tw. (Sp. Gr. 1-35), boil ten bours and wash. 2nd, 70 htres, ditto, ditto.' 4. Sour; sulphuric acid, 2« Tw. (Sp. Gr. 1-01) steep two hours. 5. Wash well and dry. The above quantities of materials are intended for 2,000 kilos, cloth, with low-pressure kier. Market-bleach.— In market-bleaching the essen- tial difference consists in the absence of the boiling with resin-soap, and the introduction of tinting the cloth with some blue colouring matter previous to drying. With many bleachers, the operation of chemicking comes be- tween the two ley-boils, and not after them, as is usually the case. Other bleaching agents than chloride of lime have been proposed for cotton, and even partially adopted— e.g., hydrogen peroxide, permanganate of soda, X-c— but none liave yet been able to supplant it, principally 86 DYEING OP TEXTILE FABRICS. [t^hap. VL because of their greater cost. The same may be said regarding the mode of bleaching by means of the electro lysis of alkali chlorides CHAPTER VI. LINEN BLEACHING. 58. The bleaching of linen is more or less similar to that of cotton, although it is decidedly more tedious, owing to the larger proportion of natural impurities present in the flax fibre, and the greater difficulty of removing or decolorising them. These impurities consist principally of the brown insoluble pectic acid, which remains on the fibre after the retting process, to the extent of 25 — 30 per cent. Linen is bleached in the form of yarn, thread, and cloth. 59. Bleaching of Linen Yarn and Thread. — Linen yarn is frequently only partially bleached, and one distinguishes yarns which are " half white " (cream), "three-quarters white," and "full white." The followinsj is an outline of the oreneral method of bleaching linen yarn as at present adopted in Ireland. The percentages relate to the weight of yarn under treatment : — 1. Boil: 10 i>er cent, soda-ash, boil 3 — 4 hours; wash and squeeze. 2. Eeel : bleaching powder solution, ^° Tw. ; reel 1 hour ; wash. 3. Sour: sulphuric acid, 1° Tw., steep 1 hour; wash. 4. Scald : 2 — 5 per cent, soda-ash, boil 1 hour ; wash. 5. Reel : as No. 2 ; wash. 6. Sour : as No. 3 ; wash well and dry. At this stage the yarn should be "half white." If it is requii'ed " three-quarters white," the drying Chap. VI.] LINEN YARN BLEACHING. 87 is omitted, and operations 4, 5, and 6, are repeated with the following slight modifications : {a) after the " scald " the yarn is "grassed," i.e., spread on the grass in a field for about a week ; (6) instead of reeling the yarn in the solu- tion of bleaching-powder, it is simply steeped in it for 10 — 12 hours, an operation which is analogous to the chemicking of cotton yarn (p. 72), and usually called the « dip." If the yarns should be "full white" the same operations are again repeated once or twice, the duration of grassing being varied according to necessity and the weather. In each succeeding operation the concentration of the solutions employed is diminished. The operation of boiling takes place in ordinary open or low-pressure kiers, while those of dipping, sour- ing, and washing, are best performed in the apparatus illustrated in Fig. 24. In many establishments, however, the dipping and souring are effected by simply steeping the yarn in stone tanks filled with the necessary liquids, but owing to the absence of all circulation of the latter, this plan cannot be so eflective. The washing is fre- quently done in wash-stocks, or dash-wheels, but this also is not good, because it tends to make the yarn rough. The mode of applying the bleaching-powder solution in the earlier stages by " reeling," is peculiar to linen yarn bleaching. Its primary object has probably been to ensure regularity of bleach, but since the carbonic acid of the air decomposes the calcium hypochlorite more readily by this means, and liberates hypochlorous acid within the fibre, as it were, the bleaching must be more thorough and greatly accelerated. The reeling machine consists of a large shallow scone cistern holding the solution of bleaching-powder, and provided with a movable framework supporting a number of reels. On these are suspended the hanks of yarn in such a manner that only their lower ends dip into the liquid. Each single reel can be readily detached if 88 DYEING OF TEXTILE FABRICS. [Chap. Vt necessary, or, by means of a hydraulic lift, the whole framework with reels and yarn can be raised and withdrawn from the liquid, and at once transferred to another and similar cistern for the purpose of washing, erly managed the process is almost continuous. Care must be taken in admitting new liquid from h into the red-hot chamber c, since it froths up very considerably. The pipe connecting h and c is so arranged that it can be readily re- moved and cleaned. Comparatively little coal is required, since it is largely economised through the burning of the oi^ganic matter of the yolk itself. It has been found in Chap. Vn.1 WOOL-SCOURING. 99 practice, that to evaporate 12 kilos, of Water in such a furnace 1 kilo, of coal is required. Yolk-ash is recovered in JRoubaix, Antwerp, Yerviers, Louvain, Brugge, Hanover, Dohren, and Bremen. Scouring and Washing. — In small establishments the wool is thrown (and, indeed, without previous steeping) into a large tank filled with the scouring liquid, and worked about by hand for a short time with poles. It is then lifted out with a fork, drained on a wooden screen, and well washed several times in a cistern having a perforated false bottom. Wheti soap is used, the excess of liquid is removed by a paiv of squeezing rollers before washing. Obviously, by this method the wool is only in- completely or irregularly scoured, hence in large and well-equipped establis? /lents, after "steeping," it is passed through the wool-scouring machine. There are many varieties, e.g., those of Petrie, M'Naught, Crabtree, Sirtaine and Melon, &c., but it is beyond the province of this work to discuss their different points of merit. As a typical representative, the rake-machine (Fig. 31) of M'Naught may be described. It consists of a large cast-iron trough, provided with an ingenious arrangement of forks or rakes. The wool is introduced at one end of the trough and evenly spread on an endless apron or feeder situated at a. It is immediately pressed beneath the surface of the scouring solution by the rotating immerser 6, and then gradually passed forward by the to-and-fro digging motion of the reciprocating rakes f, c. At e there is suspended a stationary oblique rake or grating, which the recipro- cating rakes intersect ; its purpose is to prevent a too rapid forward progression of the wool. By the move- ment of the rakes, the wool is well worked in the scouring liquid and carried gradually to the other end of the trough. It is there lifted out by a swing rake c and the special mechanism /, then passed through a pair of squeezing rollers and thrown ofl" by a fan ^ in a loose, open condition. The wool is afterwards washed 100 DYEING OF TEXTILE FABRICS. ICLap. VXr, with water in a similar machine. A really effective scouring arrangement consists of at least three such machines, placed in line, so that the wool may be passed automatically from one to the other. The operation of scouring and washing thus becomes continuous, regular, and complete. The first machine into which the wool is intro- duced contains more or less soiled scouring liquor, which has aheady been used in the second trough ; the latter contains fresh scouring liquor, and the third a continual flow of clean, cold, or preferably tepid, water. Each trough is fitted with a perforated false bottom, beneath which dirt may collect, and each pair of machines is connected with an in- jector pipe, for the pur- pose of transferring the liquor from one to the other, as occasion requii'es, in a direction opposed to that of the movement of the wooL The great object of the wool-scouier should be, to Chap. VII.] WOOL-gCOURINQ. 101 maintain the composition of the second bath as constant as possible, or at least not to allow it to become too much soiled. This is effected partly by the squeezing rollers between the first and second machines, and partly by emptying the first bath the moment it gets charged with fatty matter, transferring to it the slightly-soiled liquor of the second bath, and refilling the latter with fresh scouring solution. No doubt a still more regular and complete scour would be obtained by having a range of four troughs instead of three. If the amount of fatty matter remainincj in the wool after scourinsf exceeds 1 per cent., the operation must be regarded as having been inefficiently performed. MagmaProcess. — The waste scouring liquor ought to be collected in stone lined pits, and there neutralised or acidi- fied with sulphuric acid. The magma of fatty matter which rises to the surface is collected, drained in filter bags, and sold to oil dealers. If soap has been the scouring agent employed, the fatty acids thus recovered are all the more valuable, but in any case the spent scouring liquors should never be allowed to pollute the neighbouring stream. h. Scouring ivith Volatile Liquids. — This is more advantageous than the alkaline method, because it de- prives the wool more completely of its wool-fat, and the injurious effect of the alkalis is entirely removed. On the other hand, the method is more costly, and by the use of some extracting liquids the wool may certainly be modified. Some consider that since oil must be added to the wool before spinning, it is not necessary to remove the whole of the natural fatty matters from raw wool. Whether this view be correct or not as far as spinning is concerned, it is certainly not to be entertained if the loose wool has to be dyed Up to the present time, wool scouring with volatile liquids has not met with general acceptance, pai-tly because of the attendant danger if not employed with 102 DYEING OP TEXTILE FABRICS. [Chap. Vn. great care and with suitable appliances. The difficulties, however, are not insuperable, and have, indeed, been more or less overcome by Da Heyl, Van Haecht, and others. One method recently proposed is that of T. J. Mullings. The wool is placed in an enclosed centrifugal machine, and submitted to the action of disulphide of carbon. When this liquid is saturated with yolk, the machine is set in mo- tion to remove the bulk of it, the remaining portion being 3xpelled by admission of water. The wool is afterwards washed with water in the usual washing machines. The novel feature in the process is the expulsion of the carbon disulphide by displacing it with water, by which means the wool does not acquire the yellow tint it invai-iably assumes when heat is employed for this purpose. The mixture of carbon disulphide and water is collected in a tank ; after settling, the former is di-awTi off from below and recovered for subsequent use by distillation. Exf»eri- ments are said to have shown that wool cleansed in this way is stronger, and will spin finer yarn, and with less waste, than if scoured by the ordinary method with soap, and this is done at one-eighth of the visual cost This process has been recently tried on a large scale with a certain degi*ee of success. 65. Yarn Scouring. — The scouring of woollen yam is more readily effected than that of raw wool if the oil with which it has been impregnated by the spinner has been of good quality (e.g.^ olive oil). It has always been considered that the difficulty is increased if cheap oils have been used which contained an appreciable amount of mineral oil, since this, being a hydro-carbon and not a glyceride, is unsaponifiable. Experiments by C. Roth seem to show, however, that this view is eiToneous. a. StretcJting of Yarn. — Those yams which are hard twisted requii-e this preliminary pix)cess in order to remove their curly appearance and to prevent them from ^blinking during the subsequent scouring operation. Chap. VII.] WOOLLEN YARN STRETCHING. 103 For this purpose the '•' yani-stretching " machine (Fig, 32) Li employed. It consists of two vertical iron screws d, connecting Fig. 32.— Yam-stretchiDg Machine. two horizontal bars A, b, one above the other, each fitted ^vith a series of metal pegs or arms c, on which the hanks are suspended. The lower bar b is fixed, while the upper one a is capable of being moA'ed up 104 DTEIXG OF TEXTILE FABRICS. [Chau TIL lili Chap. Vn. I WOOLLEN YARN SCOURING. 105 or down by turning the vertical iron screws, and fixed at any point. After filling the arms c with yarn, as indicated in the figure, the bar a is screwed up until the yarn is suit- ably stretched. In this condition the whole apparatus is immersed in a bath of boiling water, and after a few minutes removed. Those portions of the hanks imme- diately in contact with the pegs are still unaffected and Fig. 34.— Continuous Woollen Yarn-scouriug Machiae. look curly. Hence after relaxing the tension of the hanks, their positions on the pegs are changed, they are again screwed up, and the immersion in boiling water is repeated. When taken out and allowed to cool, the yarn is taken off ready for scouring. The principle of the operation has been referred to in speaking of the hygroscopic and elastic nature of the wool fibre (see p. 28). b. Scouring of Yarn. — Yarn scouring is generally done by hand in an ordinary rectangular wooden tank, the liquor being heated by means of a perforated copper steam- pipe. The hanks are suspended on smooth wooden rods placed across the tank, on each side of which stands a workman {see Figs. 45, 70). One by one the rods full of yarn are taken up, once or twice swayed to and fro, and 106 DYEING OF TEXTILE FABRICS. [Cliap. VIL then each hank is carefully lifted up and turned, so that the exposed portion resting on the rod may l>ecome im- mersed. This is frequently facilitated by means of a second and thinner rod, which is inserted in the loop of the hunks, immediately beneath the suspending rod_, so that the whole rod full of hanks may be turned at once, and Fig. 35.— Woollen Cloth-scouriug Macliine. without scalding the hands. Tlie whole operation is systematically repeated during fifteen to twenty minutes, after which the yarn is transferred to a second tank containing cleaner scouring liquid. Here the process of turning is repeated, after w4iich the yarn is washed, either by the same method or by placing the rods full of hanks on a pair of horizontal bars, situated beneath a perforated wooden tray, on wdiich water is flowing ; the yarn thus receives an efficient shower bath, Chap. Vn.] WOOLLEN CLOTH SCOURING. 107 Scouiing partly by hand and partly by maclii-ne ia effected by the apparatus represented in Fig. 33, and made by Thos. Aimers and Sons, Galashiels. The yarn is suspended on reels projecting from one side of the scouring box, and caused by steam-power to revolve in the scouring solution alternately in each direc- tion for a short time. The hanks are then taken off the Pig. 36. — Sectaoii of Machine shown in Fig. 35. reels, placed on a moving endless band, and thus led through a paii' of squeezing rollers, to be washed with water in a similar machine. In some machines the reels are omitted, and the hanks worked in the liquid by hand. A perfectly continuous method of scouring by machinery alone, is that in which the loose hanks of yarn are placed on a feeding apron, and borne along between two broad endless bands, through a succession of scouring baths fitted with a series of squeezing rollers. Another continuous method is that carried out by means of the machine represented in Fig. Si. 108 DYEING OP TEXTILE FABRICS. (Chap. \T:I. The hanks are linked together by means of a small knotted and twisted loop of cord. The chain of yarn thus formed is then passed continuously through a series of three machines, similar to the one represented, c. The squeezing rollers A and b are thickly covered with some .soft, durable material, e.g., silk noils. 66. Cloth Ssouring. — AYoollen cloth is either scoured in the " chain " form or in the open width, the latter being the preferable mode, since the operation cannot but be thus more evenly performed, and does not tend to produce creases in the material. Figs. 35 and 36 represent (in perspective and in section) the common chain-scouring machine, usually termed a "^ dolly." It consists essentially of a pair of heavy wooden squeezing rollers A b, placed over a box or trough c containing the scouring solution. The pieces are stitched end to end, to form an endless band, and this is made to pass continuously for tw^enty minutes or so between the rollers, the lower one of which, since it is partially immersed, carries the solution to the cloth. D is a steam pipe for heating the scouring solution, E an empty wooden box, F and G are guiding rollers. The operation is repeated with fresh solution in another similar machine, and the pieces are afterwards washed with clean w^ater. The machine employed for scouring cloth in the open width is shown in Fig. 37. It is much broader than the one just described, in order to suit the width of the cloth, and certain straining bars F are required for the purpose of keeping the cloth opened out and free from creases previous to its passage between the squeezing rollers A, B, which are preferably of iron, in order to give a more equal pressure across the whole width of the cloth. Immediately below these rollers is the trough c containing the scouring solution. The perforated water- pipe H is used when the pieces are washed in this machine after scouring. 67- Scouring of Union Goods. — The scouring of thin Chap. VII.J WOOLLEN CLOTH SCOURING. 109 materials with cotton warp and woollen weft presents certain difficulties. The different liygroscopic, elastic, Fig. 37.— Woollen Cloth open- width ScouriDg Machine. and other physical properties of cotton and wool, cause such materials, if simply scoured in the ordinary way, to contract or shrink irregularly over the whole surface of the fabric, so that they assume, when dried, a rough. g t) Em •l^'M -"V "^r^TLi Chap. Vll.] CRABBING. 1 1 1 shrivelled appearance which renders them quite unsale- able. Special appliances and methods are in consequence required. The scouring of thin union goods comprises the operations of Crabbing y Steaming^ and Scoui'ing. (a) Crabbing or Fixing. — The object of this and the following operation is to prevent the material from ac- quiring the " cockled," " curled," or shrivelled appearance above alluded to. It also imparts a permanent and inde- structible lustre and finish of a peculiar quality, which is not removed or affected by any subsequent operation. Fig. 38 shows the arrangement of a treble crabbing machine. The cloth a wrapped on the roller or beam b is passed in the open width, and in a state of tension, below the roller d and through boiling water contained in the vessel c, then immediately between the pair of heavy iron rollers b and E, under great pressure. It is at once tightly wrapped or beamed on the lower roller b, there- fore, while still revolving in the hot water. The process is repeated with boiling water in the second trough, and again with cold water in the third trough. The tension of the cloth and the pressure of the rollers are varied according to the quality of the goods, and the particular feel^ lustre, and finish ultimately required. With such goods as must have subsequently a soft feel or "handle " ' — e.g., Cashmeres, Coburgs, drc, — no pressure at all is employed, the pieces being simply beamed tightly on the bottom roller. (6) Steaming. — The pieces are unwrapped from the last crabbing roller {i.e., from the cold water), and tightly N\Tapped on the perforated revolving iron cylinder g. Steam is admitted through the axis of this cylinder for the space of about ten minutes, or until it passes freely througli the cloth. In order to submit every portion of the piece to an equal action of the steam, the process is repeated with the cloth tightly beamed on a second and similarly perforated roller g', so that those portions of the cloth which were on the outside are now in the interior. 112 DYEING OP TEXtlLfi FABRtCfe. (Chap. Vtl These perforated steam-cylinders are frequently quite separated from the ci-abbing machine, and then usually rest on a steam nozzle in a vertical or horizontal position. (c) Scou7'ing. — The cloth, being now " set," as it is technically termed, is scoured for half-an-hour or more, with soap solution at 40° — 50° C. in the " Dolly " or " open width " machine, above described. The sequence of operations as here given, although frequently employed, is not altogether rational. The best results are obtained by crabbing and scouring simultaneously, and then steaming. To accomplish this, the boiling water in the crabbing troughs is merely re- placed by a solution of soap, sodium carbonate, or other scouring agent. It is found that to steam the cloth in its oily state exercises some injurious action, and renders it liable to contract dark stains during mordanting, espe- cially if stannous mordants are employed. It is possible that the oil is more or less decomposed, and a portion becomes fixed on the fibre. 68. Bleaching of Wool. — Wool is generally bleached either in the form of yarn or cloth, but only when it is intended to remain white, or if it has to be dyed in very light delicate colours. The bleaching agent universally adopted is sulphur dioxide. According to the state in which it is applied, either in the form of gas or dissolved in water, one may distinguish between " gas bleaching " and ''liquid bleaching," and of these the former is more generally employed. In recent years that excellent bleaching agent, hydrogen dioxide, has become an article of commerce, and no doubt would be more largely used in woollen bleaching than it is at present, if only it were less costly. Gas Bleaching^ Stoving, or Sulphuring. — Yarn is first scoured and well washed, then suspended on poles and placed in the sulphur stove — a spacious brick chamber which can be charged with sulphur dioxide. The necessary amount of sulphur (in the proportion of 6 — 8 per cent, of the wool to be bleached) is placed in an iron pot in one corner of the Chap. VII.] WOOLLEN CLOTH BLEACHING. 113 chamber, and ignited by inserting a hot iron ; the chamber is then closed, and the moist yarn is left exposed to the action of the gas for six to eight hours, or even over- night. Afterwards the chamber is thoroughly ventilated; the yarn is removed and well washed in water. Heavy woollen cloth, such as blanketing, is treated in exactly the same manner as yarn, but with thin Fig. 39.— Sulpliur Stove for Woolleu Cloth Bleaching. material — e.g., merino, ifec. — the operation is preferably made continuous, by adopting the arrangement of stove shown in Fig. 39. It is provided internally with a wooden frame, having rollers above and below. The roof should be lined with lead, and heated with steam pipes, in order to prevent condensation. The stove is charged with sulphur dioxide as already described, or, preferably, the sulphur is burnt in a separate furnace, and the gaseous product is led underneath the perforated tile floor of the stove. The cloth is introduced through a narrow slit in the wall ; it then passes, as indicated 114 DYEIXG OP TEXTILE FABRICS. IChap. VII. under and over the rollers, and passes out again by the same opening. The number of times the cloth is passed through the stove varies according to the appearance of the clotL In liquid hUaching, the woollen material is worked and steeped for several houre either in a solution of sulphurous acid or in a solution containing sodium bi- sulphite (5 — 50 grams per litre), to which an equivalent amount of hjdix>chloric acid has been added ; it is after- wards thoroughly washed. A better method, however, is that in which the wool is treated with sodium bisulphite and hydrochloric acid in separate baths, whereby the sul- phurous acid is generated within the fibre, and, being in the nascent state, acts more powerfully upon the colouring matter of the wool Goods which have to remain white are tinted with some blue or bluish-violet colouring matter (e.^., ground indigo, indigo-extract, aniline blue, kc ), either before or after the bleaching operation, in order to counteract the yellow colour of the wool which is so apt to returiL The principle here applied is that of the complementary colours, which when mixed in due proportion produce white light. Blue is complementary to yellow. The bleaching action of sulphur dioxide is most probably due to its reducing action ujx)n the natural yellow colouring matter of the wool ; another explanation, however, is that it combiaes with the latter to form a colourless compound. Certain it is that the effect is by no means permanent ; frequent washing of bleached wool in alkaline solutions always tends to restore the yellow appearance of the fibre. Either oxidation is thus in- duced, or the colourless sulphite is decomposed, and the original colouring matter is precipitated on the libre. The agent par excellence for liquid bleachiug is hydro- gen dioxide (H^Oj). Even yellow - coloured wool is bleached by it to a white, possessing a biilliancy and purity miattainable by the ordinary methods. The woollen material is steeped for several hours in. a dilute Chap. Vni.] UNGUMMING OF SILK. 115 and slightly alkaline solution of commercial hydrogen dioxide and afterwards well washed, first with water acidulated with sulphuric acid, and afterwards with water only. - CHAPTER yill. SILK SCOURING AND BLEACHING. 69. Object of Scouring Silk— The object of scouring silk is to remove from the raw fibre a greater or less proportion of the silk-glue which envelops it, and thus to render it lustrous and soft, and better fitted for the operation of dyeing. According to the amount of silk- glue removed, the product of the scouring operation may be either hoiled-qf silk, souple silk, or ecru, for each of which, indeed, a difierent treatment is necessary. 70. Boiled-off Silk is the name given to silk from which practically the whole of the silk-glue has been removed. It exhibits most fidly the valued properties of lustre, softness, &c. Two operations are necessary for its production, namely, "stripping" and " boiliug-off." (a) Strippiiig or Ungumming (Fr., degommage). — The object of this operation is to soften the silk, and to re- move the great bulk of the silk-glue and also the colouring matter. The hanks of raw silk are suspended on smooth wooden rods, and worked by hand in rectangular copper troughs, in a solution of 30—35 per cent, soap, heated to 90^ — 95° C. When the water is very calcareous, the silk is first rinsed in a weak, tepid solution of sodium carbonate. The best plan is to correct the water pre- viously. Rinsing in dilute tepid hydrochloric acid before ungumming is also good, since it removes calcareous and other mineral matters from the silk, and prevents their action in the soap batli. Weighted ecru silks cause great inconvenience in the ungumming : the soap bath ia 116 DYEING OF TEXTILE FABRICS. [Chap. THL precipitated, the fibre becomes tarnished and sticky, and the iingummiDg is rendered difficult and incomplete. Daring the stripping operation the silk at first swells up and becomes glutinous, but, afttr a short time, when the silk-glue dissolres off*, it becomes fine and silky. It is best, especially when the silk is intended for whites or delicate colours, to work it successively in two or three separate baths, for about twenty to twenty-five minutes in each, and to pass fresh lots of silk through in regular order. When the first bath becomes charged with silk- glue it is renewed, and then employed as the last bath. Each soap bath should be utilised to the fullest extent compatible with excellence of result. It is well to bear in mind that too prolonged contact with boiling soap solution is not good, since a little of the colouring matter of the glue is apt to be attracted by the fibre, and the silk loses substance, strength, and purity of white. The waste soapy and glutinous liquid obtained is called "boiled-off" liquor, and serves as a useful addition to the dye-bath when dyeing with the coal-tar colours. After *• stripping," the hanks are rinsed in water, in which a small quantity of soap and sodium carbonate has been dissolved. (6) Boiling-off (Fr., la cuite). — For the purpose of remo\-ing the last portions of silk-glue, 0. Calcium Calcium Calcium bi-carboiiate. hydrate. carbonate. In carrying out the method here expressed, many practical difficulties are met with, and constant skilled oversight is necessary to insure success. Only the temporary hardness is removed, and not even this completely. A small residuum of chalk always remains in solution. It is quite possible, however, to remove 10-llthsof the whole temporary hardness, as well as iron salts and much organic matter. Experiments on a large scale have proved that, by the lime process, water of 23*^ hardness can be reduced to 7^, of 15^ to 3° or 4^, and so on. It is best to employ clear lime-water for correction, since this possesses a known constant composition. The amount of such lime-water which it is necessary to employ may be calculated after making an analysis of the water, or may be determined by actual experiment. If the number of degrees' hardness (Clark's scale) is divided into 130 or 150, the number obtained will approximately represent as a rule the number of litres of water which can be softened by the addition of one litre of lime-water. Clear lime-water may be replaced by milk-of-lime, if 132 DYEIXG OF TEXTILE FABRICS. [Chap. rX- the latter is carefully applied. Excess of lime in the cori^ctetl water is i-eadily detected by adding a little of it to a filtered decoction of cochineal. Such excess changes the yellowish-red colour of the solution to a violet. Other delicate alkali-indicators may also be adopted. In working Clark's process as originally devised, large tanks or reservoirs are resijuisite. It is best to have at C least three — one into B wliich to run the water and lime and to allow the pre- cijntated chalk to settle for about 16 hours ; another fix)m Mhich clear and pre- vionsly corrected watei' can be drawn ; and a third as a re- serve during cleans- ing operations. Each reservoir sliculd hold at least a day's sup- ply. 86. Purification with Caustic Soda. — For purwses of scouring, or where a slightly alkaline water is not prejudicial, caustic soda may l3e conveniently substituted for quicklime, since its solution can so readily be made of a standard sti*ength and added in the requisite amount to the water to l>e corrected : — CaH^CCO,,), + 2 XaHO = CaCOs + NasCOg + 2 H.O. In this ease, of course, exactly the same amount of sodium carbonate remains in the corrected water as if the purifying agent used had been soap. It is well to heat the mixture to 50 '^ C. in order to cause more mpid Fig. 40.— Plau of Porter-Clark's Apparatus for Softening Water. Chap. IX.] PURIFICATION OF WATER. 133 settling of the precipitate. Mechanical impurities, also iron, aluminium, and earthy phosphates are completely thrown down. Permanent as well as temporary hardness is removed by the use of caustic soda, since the calcium and magnesium sul- phates present 1 A Jl ^ are decomposed by the sodium carbonate pro- duced in the above reaction. Should the water corrected in this manner be required for purposes where alkalinity is to be avoided, it can be readily neutralised be- fore use. 87. Porter- Clark Process. — The essential improvement effected by this process is a saving of space, time, and la- bour, through the application of machinery to the ordi- nary Clark's process. Figs. 40 and 41 give plan and elevation of an arrange- ment for supplying over 6,000 litres of softened water per hour, but there is practically no limit to the amount which may be supplied if the apparatus is made large enough. The lime-water is prepared in the small horizontal Fis 41. — Pcrter-Clark's Apparatus for Softening Water (elevation). 134 DYEING OP TEXTILE FABRICS. [Chap. IX. cvlinder A, by constantly chuming up slaked lime with wat^r admitted under pressure direct from the reservoir or main. By a pipe midway in the height of the chum, the more or less saturated lime-water (a saturated solution contains about 1-4 gi-ams of lime per litre), and with some lime in suspension, is led into the large cylindrical vessel B, where the lime and water are kept in slight agitation, to assist in completing the saturation. As the lime-water ascends, the particles of lime in suspension ^adually settle out, and tolerably clear lime-water passes out at the top into the cylinder c, where it is continuously mixed with the water to be purified, in accurately deter- mined proportions. The supply of each is regulated by valves furnished with dial plate and index. A brisV Agitation is maintained in the mixing cylinder c, in order to facilitate the chemical reaction takincr place. When this is completed, the chalky water is forced through the filter-press D, wherein the carljonate of lime acts as a medium of filtration, and the clear water thus obtained is at once fit for use. If it be desired to remove both permanent and tempo- rai"y hardness by means of the above apparattts, carbonate of soda, or caustic soda, must be used in addition to the lime. 88. G-aillet and Huet's Process. — The agents of purification here adopted are lime and caustic soda, and the cost does not exceed, say, one farthing per 1,000 litres of softened water. This apparatus differs essentially fix)m all others by the simple but effective means adopted for separating and removing the precipitated impurities without in any way choking the purifier or retarding the delivery of water. Fig. 42 gives a perspective view of a complete appa- ratus capable of purifying about 200,000 litres of water per day. The purification takes place in the large square clarifying, or precipitating, tank a, which forms the l»ody of the apparatus, and which is shown separately in Fig. 43, a poilion of the casing being there removed 135 Fig. 42.— Graillet and Huet's Apparatus lor Softening Wattr. 136 DYEING OF TEXTILE FABRICS. [Chap. IX F-- Fig. -^S.-Gailiet and Huet's Precipitating Tank. to show the in- terior armnge- ment. Instead of passing down- wards throuijh filtering screens, wliich would soon become clogged and retard the flow, the water, after having l^een mixed with the pi-ecipitating re- agents, entei-s at the bottom of the tank, A, and rises slowly towards the top, follo\^-ing a zig-zag course in the shallow spaces between a numl>er of Y- shaped dia- phragms, inclined at an angle of 45°, and riveted alternately to op- ix)site faces of the tank as also to the two adjacent sides. All the dia- phragms shelve at the same angle towards the same face of the tank, where they lead to a series of mud cocks, F. Chap. IX.l PURIFICATION OF WATEU. 137 Above the clarifying tank are situated smaller tanks, in which the precipitating reagents are dissolved. Tank B contains the solution of caustic soda, of which the required quantity is run off into one of the tanks, c, in which lime has been dissolved in water. The liquid is allowed the requisite length of time to settle, the other tank, c, being meanwliile in use. The clear soda-lime solution thus obtained is run off at a regulated rate, and mixes with the water to be purified entering at D, in a special tank situated above the clarifying tank, A, and immediately below the raised platform. The turbid water falls through the pipe e, enters the clarifying tank at the bottom, and at once assumes an upward motion. As the section of the tank, a, is very large, and that of the supply pipe, D, very small, the water naturally rises very slowly and gently, allowing the precipitate to settle almost as if the water were at rest. The purpose of the V-shaped diaphragms will now be apparent. The water has to pass slowly between them in sliallow layers, and as the solid particles have but a few inches to fall, they readily settle upon the diaphragms, which represent, in- deed, a very large precipitating area in a limited space. As the latter are V-shaped, the deposit slides down into the angle towards the mud cocks, f, through which it is dis- charged when necessary. The water meanwhile becomes gradually clearer as it rises, and is ultimately drawn off at the top, G, perfectly soft and limpid. The process of purification is can-ied on automatically without the necessity of constant attendance or motive power. It need scarcely be added that the amount of soda- lime solution to be mixed with the water is determined according to the results of a careful analysis, previously made, of the water. Other modifications of Clark's process are in vogue, differing chiefly by the mode of effecting the clarification of the water after mixing with the precipitating reagents, but the two processes described may be considered typical of the rest. 138 DYEING OF TEXTILE FABRICS. LChap. IX. 89. Purification of Water discharged from Dye- honaes. — If it is necessary that the dyer should have pure water for the successful prosecution of his business, he ought to feel it his duty not to pollute the river, from which he possibly receives his supply, with injurious discharges, to the annoyance and loss of his less-favoured neighbours lower down the stream. Not only are the waste liquids from dye-works for the most pai-t highly coloured, but they contain large qnantities (over 1 -5 grams per litre) of organic and in- organic matter, both suspended and dissolved. Should the dye-works situated on the banks of a small stream be numerous, the latter generally assumes a turbid, inky appearance ; its bed is gradually impregnated with decom- ]>osing organic matter, putrescent odours are given off, the water is poisoned, and the stream becomes practically a large open drain, disagreeable to the sight and more or less noxious to health. One of the simplest mode^ of mitigating this evil is to conduct all the refuse waters resulting from the various operations of the works into two or more re- servoirs, where they mix together and precipitate each other. The whole must be allowed ample time to settle, and only the clear water permitted to flow into the river. Where space is limited, filtering beds of coke, sand, (tc., may take the place of settling reservoirs. The purifica- tion is rendered more complete, however, if additional precipitating agents are employed, e.g., magnesium and calcium chloride, lime, est and the most generally efficacious ; it neu- tralises acids, precipitates colouring matters, mordants, Boapy liquids, albuminous matter, ed into the iiigh level magma tanks, c (each of about 20,000 litres capacity-), where it is thoroughly well mixed, by means of an air-pump, p, with a calculated quantity of sulphuric acid- After being allowed to settle, the supernatant acid liquid is run off into the tank, e, for further treatment. The precipitated magma of fatty matter is allowed to flow into the pit, d, the bottom of which is a di-ainer made up of ashes, spent dyewood chips, and sawdust. Here it is allowed to drain for about a week, the acid filtrate being also led Chap K.] PURIFICATION OF REFUSE WATER. 141 into the tank, E. The pasty magma is sold to oil extractors and soap-makers. The highly-coloured discharge from the dye-house passes through a sieve into the settling tank, f, whence it ovei-flows into the large reservoir, G. In this reservoir the colouring matter of the spent dye-liquor, and the unexhausted mordants, partially combine and precipitate each other. Tank H contains slaked lime, well mixed with some dye-house liquor from tank G. By means of the pump, p, definite proportions of acid magma water, from E (about one part), spent dye-liquor, from G (about three parts), and lime-water from h (about one part), are forced into the high level purification tanks, K, and there thoroughly well mixed. By this means the whole of the colouring matter is thi'own down as a fine, flocculent precipitate. After being allowed to settle, the almost colourless supernatant water flows into the tank m, and the deposit is run oflf at intervals into the pit L, and there allowed to drain until it acquirer such a consistency that it can be dug out and con- veyed to the refuse heap. The water from the purification tanks, K, is slightly alkaline from excess of lime, but in the tank m it is neutralised by allowing it to mix with the slightly acid rinsing- water coming from the dye- house. ° Thus purified, the water overflows into the tank N, and passes through a filter into the river o, clear, neutral, and free from objectionable colour. The following is an analysis of the effluent water by Crum Brown : — Total solids in grams i)er litre 1 s H 1 u o c 3 Ammonia in grams per litre Analysis of inorganic solids in grams per litre Organic 0-13 Inorganic 0-78 Saline 0-003 Albumin- oid 0-002 KoCroOy . . 0-006 CaSOi . .0-11 CaCOa . . 0-32 NaoS04 . . 0-29 Na'Cl . . 006 142 DYEING OF TEXTILE FABRICS. fChap. EL The turbidity is represented by the quantity of china clay (stated in grams per seventy litres), which, when added to pure water, gives a turbidity equal to that of the sample. The colour is represented by the quantity of ammonia (stated in hundredths of a gram per seventy litres), which, when added to pure water, gives, with Nessler's reagent, a colour as nearly as possible agreeing with that of the sample. The colour of the elfluent water is a faint browTiish-yellow. This analysis shows that, with the exception of the small quantity of potassium dichromate, the substances remaining in solution in the water discharged into the river, are the usual substances found in ordinary spring and river water. In explanation of the above process, it may be stated that pai't of the lime used serves the purpose of neutral- ising the acid magma liquor, while the excess precipitates, from the waste mordant liquor, the hydi-ated metallic oxides, which at once combine with and precipitate any colouring matter present. It will be observed that^ as far as possible, the waste materials from the various pi\>- cesses of manufacture are caused to aid in their mutual purification and removal from the water discharged into the river. In the works of E. Schwamborn at Aachen, the re- fuse water from the washing of i-aw wool, and the milling and washing of cloth, is precipitated by lime. The com position of the air- dried precipitate is as follows : — Water 3-11 per cent. Lime and ferric oxide lS-47 Fatty niatt'Cr 71-96 Wool fibre, &c. 6-46 Mixed with coal, this precipitate serves for the manufac- ture of illuminating gas. Although in this metliod the potash salts of the raw wool are lost, it is estimated that, after deducting the working expenses, there is a net Chap. IX,J PURIFICATION OF REFUSE WATER. 143 recovery of 30 per cent, of the value of the soap used in milling. In other works the precipitate is treated for the recovery of fat. The economy which can be effected by the general adoption of some such methods as these, may be calculated from the statistics which give the weight of cloth milled each year in Europe as 500 million kilos., corresponding to about 100 million kilos, of lime-soap of the above composition. 144 THEOEIES OF DYEING. CHAPTER X ABOUT DYEING. 90. Materials and Colouring^ Matters. — The two most essential elements with which the dyer has to deal, are the material to be dyed and the colouring matter to be applied. With regard to the former, our attention is confined to the textile fibres, and it has already been shown that great differences exist between them, both as to their physical and their chemical properties. Not un- naturally, therefore, they might be expected to behave differently towards colouring matters. That such is really the case is readily shown by making the following simple dyeing experiment. Three pieces of clean white textile material — wool, silk, and cotton — are immersed in a moderately strong aqueous solution of acid Indigo Extract, and are kept in continual movement by stirring, while the liquid is gradually heated to the boiling point. If the pieces are then taken out and well washed with water they present a remarkably different aspect ; the wool and silk have become dyed, and appear pale or deep blue according to the amount of colouring matter employed, while the cotton is not dyed, or, at most, becomes slightly stained. If the experiment is repeated with many other colouring matters — e.g., Magenta, Methyl Violet, &c. — similar differences are noticed. The real cause of this striking difference in behaviour towards colouring matters exhibited by the different ciiap. x.i 'Theories of dyeing. l45 textile fibres is still a matter of discussion. Several theories have been propounded, but none have gained general acceptance. It is maintained by some that the animal fibres attract certain colouring matters by reason of chemical affinity, and that in the process of dyeing they actually combine with the soluble colouring matter to produce an insoluble coloured compound. Cotton, they say, does not become dyed because it has no affinity for such colour- ing matters. Such is the purely chemical theory oj dyeing. The opponents of this theory very properly urge as a vital objection to it, that two fundamental signs of chemical combination having taken place are entirely wanting, namely, the union of the fibre and colouring matter according to chemical equivalents, and the disap- pearance of the special properties of each. Experiment proves that the animal fibres may attract either large or small amounts of Indigo Extract, and be properly dyed in both cases, the difference being simply one of intensity of colour. There is not the slightest appearance of a combination according to molecular proportions, as in the formation of Prussian Blue by the mutual reaction of ferric chloride and yellow prussiate of potash. As to the second point of the objection, no doubt the soluble Indigo Extract attracted by the fibre has appa- rently become more or less insoluble in water, but it can be readily removed — e.g., by heating v/itli a dilute solution of carbonate of soda — with all its proiDcrties imchanged, and the decolorised fibre is also exactly the same as before. Those who adhere to the mechanical theory of dyeing explain the foregoing facts, by stating that the animal fibres have become dyed by reason of a purely physical attraction exerted between the Indigo Extract and the said fibres. The latter, they say, are very porous or absorbent bodies, the colouring matter has penetrated the K '146 DYEING OP TEXTILE FABRICS. [CW. i. substance of the iibre, and is there retained in an un- changed condition. By this theory the whole question is resolved into one of surface attraction, and the action is said to be identical with that which takes place when a weak solution of the same colouring matter is decolorised by filtering through animal charcoal. On the whole, the mechanical theory of dyeing seems to have most points in its favour, although it cannot be denied that an alteration in the chemical composition of a fibre may materially alter its behaviour towards cer- tain colouring matters. The most striking example of this kind is that exhibited by cotton, when changed into oxycellulose through the action of hypochlorous acid {see p. 11). 91. Pigments and Colouring Principles. — To return now to the second of the two essential elements dealt with by the dyer, namely, the colouring matter ; so excessively varied are the bodies belonging to this class, both in physical and chemical properties, that it is again not at all surprising that they should behave differently, even towards the same fibre. If two pieces of wool are treated in separate vessels, the one with a solution of Magenta and the other with Alizarin, the former will soon be dyed red, while the latter only assumes a brownish-yellow stain of no practical use. If a third piece of wool is first heated in a solution containing a suitable amount of aluminium sulphate and cream of tartar, and, after washing well, is then boiled with Alizarin and water (preferably somewhat calcareous), it acquires a bright red colour. When other metallic salts — e.p',, potassium dichromate, stannous chloride, ferrous sulphate, &c. — are substituted for the aluminium sulphate, the wool becomes dyed other colours, namely, claret-brown, orange, purple, &c. If similar experiments are made with Magenta, the wool always assumes a more or less similar magenta-red tint. Chap. X.1 CLASSES OF COLOURING 5IATTERS. 14? It is quite evident from these experiments that Magenta and Alizarin have totally different dyeing pro- perties; they are indeed typical representatives of two distinct classes of colouring matters. The members of the one class are coloured bodies or jmpnents in which the colour is fully developed, and they require simply to be fixed on the textile fibre, more or less in their unchanged state, to cause the latter to become dyed. Such colouring matters may be conveni- ently termed monogenetic, since they are only capable of yielding, at most, various shades of one colour. To this class belong Magenta, Indigo, Orcein (orchil), Picric Acid, Methyl Green, &c. The members of this class may be soluble (Magenta), or insoluble (Aniline Black), organic (Indigo), or inorganic (Ultramarine Blue). As to the members of the other class of colouring matters, although they are generally possessed of some colour, this is not an essential feature, and even when present it generally lacks intensity, and does not necessa- rily bear the slightest relationship to the colours obtain- able _ from them in dyeing. As a rule, they are to be considered as colouring principles capable of yielding several colours, i.e., very distinct coloured bodies, accord* ing to the means employed for the production of the latter, and hence an appropriate name for them may be polygenetic colouring matters. To this class belong Hte- matein (logwood). Alizarin (madder), Gallein, &c. From what has just been stated, it will be understood that the general mode of applying the members of these two classes of colouring matters in dyeing is very dif- ferent. This is, however, only partially true, for the dis- tinction between monogenetic and polygenetic colouring matters in this respect is not sharply defined, since there are those which stand, as it were, on the border-land between the two. Some of the monogenetic colouring matters— e.^., Alizarin Blue, Coerulein, &c.— combine the properties of colouring principles and of veritable pig- ments. The method of applying them to the textile 148 DYEING OP TEXTILE FABRICS [Chap. X, fibres is that usual with the poly genetic class, but they are only capable of yielding various tones of one colour, and they can also be applied by special methods adopted with certain monogenetic colouring matters, for instance, Indigo. The presence of the fibre in the third experiment cited above, is not a condition essential to the develop- ment of the colour, as can be readily enough shown by the following experiment : — Make a dilute solution of aluminium sulphate, and render it somewhat basic and more sensitive by neutralising a portion of its sulphuric acid with sodium carbonate ; add now to the still clear solution a little alizarin, and shake the mixture vigor- ously, or heat it a little. A red-coloured body is very soon produced in the form of an insoluble precipi- tate, especially if a calcium salt be also present. It would appear in this case that the colouring matter enters into chemical combination with the aluminium, or with a very basic salt of the same. Analogous but variously- coloured precipitates are produced on substituting decoctions of Cochineal, Persian berries, Logwood, &c., for the Alizarin, or by replacing the aluminium sulphate with solutions of other metallic salts. Coloured precipitates produced in this manner are the rea,l colours or pigments which it is desired to obtain from the poly genetic colouring matters ; indeed, when dried, ground, and mixed, say, with boiled oil, they are used by the painter under the name of lakes. The object of the dyer, however, is not only to produce, but, at the same time, to fix these coloured precipitates or lakes on the material to be dyed, without the aid of such a vehicle as boiled oil. To effect this, two operations as a rule are necessary, namely, mordanting and dyeing. 92. The Mordanting Process. — The first has for its object, the precipitation and fixing upon the textile ma- terial as firmly and permanently as possible, of some sub- stance capable of combining with the colouring matter Chap. X.] THE MORDANTING PROCESS. 149 subsequently to be applied, and precipitating it in an in- soluble state upon the fibre. This operation or series of operations constitutes the mordanting process, and the metallic salts or other substances used for this purpose are termed mordants. This name is derived from the Latin, mordere^ to bite. It was originally introduced because the early French dyers considered that the utility of these metallic salts consisted in their corrosive nature ; the general opinion was that they sim})ly made the textile fibres rough, that they opened their pores, and thus ren- dered them more suitable for the entrance of the colouring matters. No doubt some slight corrosive action does take place here and there, in which case, of course, the surface of the fibres will be increased, entailing, probably, a slight increase of physical attraction of the fibre for colouring matters, but the essential action of mordants is undoubt- edly chemical. As to the mamier of applying these mordants, it varies with the different oriofin and state of manufacture of the textile fibres, the nature of the mor- dants and colouring matters employed, the particular effects to be obtained, and so on. The method generally adopted in the case of the woollen fibre is to boil it with dilute solutions of the metallic salts, frequently with the addition of acid salts, e.g.^ cream of tartar, &c. A partial dissociation of the metallic salts takes place, induced and augmented both by the dilution and heating of the solution and the ad- dition of assistant acids and salts, and partly by the presence of the fibre itself. What actually becomes fixed upon the fibre during this process is in most cases more or less a matter of conjecture, the chemistry of the pro- cess having been as yet only imperfectly studied. Although the term mordant is generally applied only to the metallic salts used, a mordant in the Avidest sense of the term is that body, whatever it may be, which is fixed on the fibre in combination with any given colouring matter. In the case cited of dyeing wool alizarin-red, it is cons\dered that during the boiling of the wool with creaju 150 DYEING OF TEXTILE FABRICS. [Chap. r. of tartar and aluminium sulphate, this latter salt is de- composed, and the mordant precipitated on the fibre is insoluble a]umina, or a basic aluminium sulphate ; in the subsequent dye-bath this combines with the alizarin to produce the red-coloured compound, or lake. Silk and wool have many analogous properties and hence the silk jihre is frequently mordanted in a manner similar to that employed for wool, but as a rule high tempei^tures are avoided, and mere immei*sion in a cold concentrated metallic salt solution, with a subsequent washing with water, is all that is necessaiy. During the immei'^ion the silk absorbs the metallic salt more or less unchanged, but in the subsequent washing, this absorbed salt is dissociated by the mere dilution with water, and an insoluble basic salt is precipitated within the substance of the fibre. Cei-tain soluble basic ferric sulphates, basic aluminium sulphates, and stannic chloride, behave in this manner. As to the methods employed for mordanting cotton^ they are usually more complex, since this fibre has not the property, like silk and wool, of decomposing metallic salts by such a simple method as boiling in their solu- tions, nor is it so porous as these fibres. In some cases, metallic salts are chosen whose component parts are, under certain conditions, readily separable from each other, such as acetates of iron and aluminium, and with these, after immersing the cotton in their solutions, and removing the excess, it may suffice to dry the cotton and then to expose it for some time to air rendered suitably warm and moist (*' ageing *'). Ferrous acetate absorbs oxygen from the air most energeticallv, and forms already in this way a difficultly soluble basic salt. 2[Fe(aH302^2] + + H,0 = Fe2(aH30.)4(OH), Ferrous acetate. Basic ferric acetate. In most cases of moitianting, however, whether the material be silk, wool, or cotton, there is precipitated upon the fibre a metallic oxide, or a basic metallic salt^ with a Chap. X.J THE MORDANTING PROCESS. 151 con-esponfling liberation of acid, or formation of an acid salt, and the mordanting process continues only as long as the constantly increasing acid allows, i.e., until a state of equilibrium proper to the new conditions has become established. The advantage of using the metallic acetates as mordants for cotton is, that the liberated acid does not injure or tender the fibre, which is readily the case with other salts ; further, owing to its volatility, the acetic acid is quickly removed, under suitable conditions of heat and moisture, from the field of action, and a more perfect precipitation of the real mordanting body on the fibre takes place. In some cases of mordanting cotton, the use of acetates, and the simple exposure or " ageing " referred to, are avoided, either from motives of economy or because certain practical difliculties arise. With cotton yarn, for example, the drying is apt not to be uniform, and irregular colours result from unequal decomposition of the acetate. Even where acetates are both applicable and preferable, it is not always the case that the " age- ing" process causes the maximum amount of mordant to be fixed upon the fibre. In such cases, other modes of getting rid of the acid are adopted, and other mor- danting salts even are employed. The mordanting base may be fixed upon the fibre by using a weak alkaline bath of ammonia, chalk, sodium carbonate, &c., cr by using such alkaline salts as not only remove the acid, but also produce insoluble compounds with the base, e.g., sodium silicate, phosphate, arsenate, &c. This method is adopted by the calico-printer in the operation of " cleans- ing" or "dunging," which succeeds the "ageing" and precedes the dyeing operations. When the mordanting body is applied in alkaline solution, e.g. , stannic oxide, as stannate of soda, ^ a slightly acid bath (sulphuric acid) is required for its precipitation upon the fibre. This is a method also frequently used by the calico-printer. 152 DYEIXG OF TEXTILE FABRIC5S. [Chap. X Still another method of fixing the mordant on textile fabrics is that of steaming ^ a process adopted for certain styles of work by the printer of cotton, wool, and silk mateiials. In the calico styles referred to, a mixture of poly- genetic colouring matter (e.g., Alizarin) and metallic salt (e.g., aluminium acetate) is printed upon the fabric, which is then dried and submitted to the action of steam in a closed box. During this steaming process, the metallic salt employed as mordant is decomposed, a greater or less proportion of its acid is driven off, and the remaining oxide or basic salt is fixed upon the fibre. Not only so, however, but, at the high temperature employed, com- bination between the colouring matter and mordant takes place, coloured pigment is produced, and is at the same time firmly fixed upon the fibre. The mordanting and dyeing operations are combined in an analogous manner when applying certain colouring matters to wool by dyeing, since this fibre f>ossesse5 the property of decomposing acid solutions of colour-lakes, and even of attracting and mechanically fixing the latter when undissolved, if sufficiently fijiely divided. 93. Colour-Acids and Colour-Bases. — In the above cases, where polygenetic colom^ing matters are employed, the actual mordants fixed on the textile fibre have more or less a basic character; as already stated, they are metallic oxides or basic metaUic salts, and although these colouring matters ai-e not really acids, but rather bodies of an alcoholic or phenolic natm*e, they possess so much of the acid chai-acter, that they combine with these and other bases ; it is not at all improbable indeed that the colouring matter and the mordant (when this is neces- sary) must always Ixrar some such definite relationship towards each other. All polygenetic colouring matters known hitherto possess the acid character referred to. It has been stated that cotton does not become per- manently dyed when immersed in a hot solution of Indigo Exti-act or of Magenta. In so far as this latter colouring Chap. X] COLOUR- ACIDS AND COLOUR-BASES. 153 matter is a red-coloured body, altliougli soluble, it may be considered analogous to the alizarin-red pigment pro- duced by the combination of alumina and Alizarin. The question arises, is it similarly constituted ? is it produced by the combination of a basic body with one of an acid character 1 Experiment answers yes, and shows it to be a chemical compound of a colourless base rosaniline with hydrochloric acid It does seem, therefore, to ha\'e a con- stitution somewhat analogous to that of alizariii-red, but of a reverse character. In Magenta, the colouring power resides in the basic part of the compound (rosaniline), whereas in the alizarin-red it is to be found in the acid portion (Alizarin), although in ejich case the other constituent is equally necessary to the production of a coloured body. Such considerations lead one to distin- guish colour-acids and colour-bases, and we may infer that if the former, as we have seen, require basic mor dants, the latter will probably require acid mordants. Among the numerous monogenetic colouring matters, there is an extensive class of colour-acids which differ conijiderably in chemical constitution from those which possess an alcoholic or phenolic character like Alizarin. They contain the atomic group (HSO3), are analogous more or less to acid sulphites, and have been termed 'sulphonic acids." To this class belong Indigo Extract, Crocein Scarlet, (fee. Some colouring matters, e.g., lu- digotiu, may be regarded as of a neutral or indifferent character. In endeavouring to fix Magenta upon cotton, the question arises, will the colourless rosaniline combine with any other acid than hydrochloric acid to form an insoluble red or otherwise coloured compound 1 Is it capable of forming a lake ? If so, the next question is, is the requisite acid capable of being fixed upon cotton in such a manner that it can still combine with the rosaniline? Experiment shows that there are such acids, e.g., tannic acid. If a solution of Magenta is mixed with a solution of tannic acid (either free or 154 DYEING OF TEXTILE FABRICS. [CLar.. X. neutralised with an alkali), an insoluble red-coloured tannate of rosaniline will be precipitated. Cotton has a natural atti-action for tannic acid, so that when once steeped in its solutions it is not readily removed by washing. In order to dye cotton, therefore, with Magenta, it suffices to immei'se it for some time in a solution of tannic acid, and after drying, to pass it into a solution of Magenta. The red tannate of rosaniline thus produced upon the fibre does not, however, possess the chai-acter of absolute insolubility, especially in alka- line and soapy liquids, so that the dye cannot be con- sidered entirely satisfactory. But, just as it has been seen that certain alkali salts can be used for the better fixing of the basic mordants on cotton, by reason of their acidj so here certain metallic salts can be used to fix such acid mordants as tannic acid, but in this case by reason of their base. In applying Magenta to cotton, for example, a dye much faster to boiling soap solutions is obtained, if the tannic acid prepared cotton is passed into a solu- tion of an antimony or tin salt — e.g.y tartar emetic, or stannic chloride — previous to its immersion in the solu- tion of Magenta. By this means the tannic acid is fixed upon the cotton in a very insoluble form, as tannate of antimony or tin. Acid mordants, which act in the same manner as tannic acid, and fix the basic colouring matters upon cotton, are not numerous, but oleic acid and other fatty acids mav be mentioned as such. It is interestinsc to note that colouring matters of an acid chai*acter {e.g.. Alizarin) when fixed on cotton, may also behave as mor- dants towards basic colouring matters. Alizarin pui'ples and alizarin reds on cotton can be readily dyed \s'ith Methyl Violet, Magenta, kc. Hitherto, all the acid mordants employed to fix any particular basic colouring matter on textile fabrics have produced only similar shades of colour. Basic colouring matters are hen^e ^1.1 monogenetic. Chap. X.] COLOUR-ACIDS AND COLOUR-BASES. 155 Since, however, both oleic and tannic acid can combine not only with organic colour-bases in the manner just described, but also with certain metallic oxides {inorganic bases), to produce insoluble compounds, they may be, and are, indeed, employed as fixing agents for the latter in the same way as the alkaline phosphates, arsenates, &c. A usual method of dyeing cotton black, for example, is first to impregnate the cotton with a solution of tannic acid (decoction of sumach, (kc), and afterwards with a solution of a ferric salt (nitrate of iron). The mordant (ferric oxide) is in this way fixed on the cotton by means of the tannic acid. Thus mordanted, the cotton is ready to be dyed in a decoction of logwood. Another notable example of the same kind is afforded by the method employed in dyeing Turkey-red. Here the cotton is first impregnated with oleic acid, or other oil compound of similar character, and is afterwards immersed in a solution of an aluminium salt. The mordant alumina is fixed on the cotton by means of the oil compound, and yet it combines with the alizarin in the subsequent dye-bath, to produce the red pigment. Apart from this preliminary precipitation and fixing of the basic or acid mordant on the cotton previous to the application of a colour-acid or colour-base, the fixing of all colouring matters upon cotton seems to depend largely on their capability of forming insoluble precipitates or lakes. Colouring matters, like Indigo Extract, Crocein Scar- let, &c., which do not form any sufficiently insoluble com- pound with bases, are not suitable for dyeing cotton. In dyeing with Indigo and Safflower, the colouring matters are themselves readily precipitated from their solutions, either by oxidising or acid influences. With Turmeric, and some few other dye-stuffs, precipi- tation is not necessary, since cotton is dyed with these by merely steeping it in their decoctions, and the case seems to be analogous to the dyeing of wool with Magenta. 156 MOEDANTS. CHAPTER XL USE OF MORDANTS. - 94. Application of Mordants. — In the opening words of the preceding chapter it was stated that the two most essential elements in the operations of the dyer are, the material to be dyed, and the colouring matter to be ap- plied; but from what has been said, it is e\adent that the mordant plays an almost equally important part, according to the particular colouring matter and tibre dealt with. Whenever mordants are necessary, the method of ap- plication should not perceptibly affect the physical charac- teristics of the fibre — for example, its strength, elasticity, feel, lustre, cetate. + .3PbS04 + 27H2O Lead Water, sulphate. On carefully evaporating a solution of the normal acetate (which always smells of acetic acid), to dryness at a low temperature, a gummy mass having the com- position AL^(C2H302;4(OHj2 is obtained. This does not Fmell of acetic acid, and it has hence been considered by Crum as the normal salt, and that in the solution there is free acetic acid present. By adding to a solution of the normal salt increasing amounts of an alkaline carbonate, solutions of various basic aluminium acetates are formed, as shown by the following equations : — Al,:CWi02)« + NaHCO^ = Al^{C^li,O.MOn) + NoiBnl MonoBodioiD Basic aeet&te. carbonate. aiaminiiim acetate. -f XalCaHjOj) + CO2 Sodium Cartonic acetate. acid. Cliap. XL] ALUMINIUM MORDANTS. 1G5 Ala(C,n302)8 + 2NaHC03 = Alo(02H302)4(OH)2 + B:isic alaminium acetate. + 2Na(an302) -I- 2('U, A1.(0,H3<)2), -f aNuHCO, = Al,(C2HA)3(OH)3 -f Basic aluminium acetate. + 3Na(C2H302) + 3CO2 Al,(C2H302)e + 4NaHC03 = Al2(C2H302)2(OH)4 -|- Basic aluminium acetate. + 4Xa(C2H302) + 4C0., Solutions of these various basic acetates containing sodium acetate are precipitated on heating, and the more basic they are the lower is the temperature at which dis- sociation (precipitation) takes place, but, strange to say, the more dilute the solution the higher the temperature of dissociation. By mere dilution with water they are not precipitated (Liechti and Suida.) Solutions of freshly prepared pure normal aluminium acetate (equivalent to 200 grams per litre of the normal sulphate) are not precipitated either by heating or by dilution, but on standing for a length of time, they de- compose spontaneously with deposition of alumina, es- pecially, it is .said, when exposed to light. Solutions of all aluminium acetates (normal and basic) are precipitated both by heating and by dilution, if they contain sulphates, e.g., K,SO^ AL(S0/)3, itc, and this is always the case with those basic acetates manufactured from aluminium sulphate when a poi*tion of the lead acetate has been replaced by alkaline carbonates, thus : — Al2(S04)3- I8H0O -}- NaoCOs -f H.O + 2[Pb(aH30o)2-3H.O] = Aluminium Disodium Water. Lead acetate, sulphate. carbonate. = Al3(C2H302)4(OH)2 + XaoSO^ + 2PbS04 -f CO2 + 24H2O Basic Souium Lead Carbonic Water, aluminium acetate. suljiliate. sulphate. acid. It matters not whether the sodium carbonate is added before or after the lead acetate, the final result is the samo. 166 DYKING OF TEXTILE FABRICS, [Chap. XI It also matters little at wLat stasre the alkaline car- bonate be added for the production of a basic acetate, whenever the amount of lead acetate employed is suffi- cient to precipitate the whole of the sulphuric acid of the aluminium sulphate, but in this case there is not alkali sidplvate, but always acetate in the solution, thus : — ALfSO^I/lSH^O -f ya2(X)3 4- 3[Pb (CgHgOak-SHaO] = AlrnniTili^m I>isodium Lead acetate. BXLlphate. carbonate. Als(C2Hs02}/PH)a + 2Na(C2HsOi) -\- SPbSO^ + CO2 + 27H2O Basic Soditun Lead Carbonic Water. ■hmrintnin acetate. acetat-e. sulphate. acid. When a solution of normal aluminium acetatij con- taining sulphates is precipitat€?d by heating, the pre- cipitate re-dissolves on cooKng, but this does not take place with the basic acetates under any circumstance ;s. The precipitate thus produced in the presence of sulphates has been c-onsidered by some to h)e simply aluminium hydrate, but careful analysis has shown that it contains a small amount of sulphuric acid ; in other words, it is an exceedingly basic aluminium sulphate. Experiments by Liechti and Suida have shown that if cotton be impregnated wdth a solution of nonnal aluminium acetate (equivalent to 200 grams of normal sulphate per litre), then dried at a low temperature, about 50 per cent, of the available alumina is fixed on the fibre, whereas an equivalent solution of the basic salt Al2(G2Hj.02)^(OH)2 containing Na^SO^ yields, under the same conditions, nearly the whole of ite alumina to the fibre. Aluminium acetates (especially the normal salt) pre- pared by means of lead acetate, are liable to contain a oeitain amount of lead sulphate, since this is soluble in aluminium acetate; hence, in cases where such contami- nation would be injurious — e.g.^ in steam-alizarin-reds for calico-printing — the lea-d acetate may be advantageously replacred by an equivalent amount of calcium or bariimi acetate. The solubility of lead sulphate is lessened, how- Chap. XI.1 ALUMINIUM MORDANTS. 167 ever, by the presence of soluble sulphates, so that where a large excess of aluminium sulphate is present through a limited use of lead acetate, only traces of lead sulphate- are found in the solution, and solutions of basic acetates, in the preparation of which a suitable amount of sodium carbonate has replaced some of the lead acetate, may l)e entirely free from lead. 101. Aluminium Sulphate- Acetates. — It has long been known that there is no practical advantage in employing an amount of lead acetate sufficient to decom- pose the whole of the aluminium sulphate. D. Kochlin explains this by stating that the real mordanting body fixed on the fibre is not necessarily pure aluminium hydrate, but may be, and in most cases probably is, an insoluble basic aluminium sulphate. He finds it pos- sible, indeed, to prepare an excellent mordanting solution by dissolving insoluble basic aluminium sulphate in warm acetic acid. A precipitate of the necessary basic sulphate is obtained by carefully neutralising a solution of alum with sodium carbonate until the precipitate at first formed just ceases to re-dissolve, and then boiling the solution. D. Kochlin's solution and those prepared from aluminium sulphate by using a deficiency of lead acetate, contain so-called aluminium sulphate acetates. Theii* mode of formation is illustrated by the following equations : — Al2(S04)3'l8H20 + 2[Pb!C2H302)2-3HoO] = Aluminiuin Lead acetate, sulphate. = Al2S04(CoH302)4 + 2PbS04 + 24H2O Aluminium Lead Water, sulphate-acetate. sulphate. 2[Al2(S04)3-18H20] + 3[Pb(C,H30o)2-3H20] + 2XaHC03 = Monosodium carbouate. = 2[Al2S04(C2H30o)30H] -f 3PbS04 + Na.SO, -f 2CO2 + iSHaO Basic aluminium Lead Sodium Carbonic Water sulphate-acetate sulphate. sulphate. acid, IC8 DYEING OF TEXTILE FABRICS. [Chap. XI. AL(S04)3-18H20 + Pb(aH302)2'3H20 + 2NaHC03 = =:: Al2S04(C2H30,)2(OH)2 + PbS04 + NaaSOi -\- 2CO2 -f 2in20 Basic aliiminiiiui suliiliate-acetate. Al2(S04)3-18H20 + C2EI4O2 -f 4NaHC03 = Acetic acid. = Al2S04(C2H302)(OH)3 -f 2Na2S04 -\- 400^ + IQUgO Basic aluminium sulphate-acetate. Experiments by Liechti and Siiida have shown that increase of basicity in the aluminium sulphate-acetates lowers their dissociation point, both on heating and dilut- ing with water, i.e., the sensibility of their solutions is increased. In all cases, the precipitate produced by heating is gelatinous, and if the sulphate-acetate is not more basic than Al2S04(C2H302)3(OH), the precipit-ate in almost entirely re-dissolved on cooling. The aluminium sulphate-acetates yield nearly the whole of their alumina to the cotton fibre during im- pregnation and drying, and act, therefore, in this respect much stronger than the aluminium sulphates, and about the same as the basic aluminium acetate AL(C2H30.)4(OH)2. The technical name given to solutions of the various aluminium acetates and sulphate-acetates used in practice, is red liquor, because they are universally employed by the calico-printer and cotton-dyer as the mordant for producing alizarin reds. Considerable licence is apparently taken in practice in the manufacture of " red liquors " required for different purposes and styles of work, both with regard to the particular ingredients used, and their relative proj^ortions. Apart from the fact that their real value is determined by practical results, the above considerations show that numerous variations in composition are possible, which cause them to behave very differently. The following may be taken as representative of the Chap. XT.] ALUMINIUM MORDANTS. 1C9 innumerable recipes adopted in the manufacture of various red liquors : — gms. gms. gms. gms. gins. gins. gms. gms. gma. gma. Water ... 250 300 400 200 400 400 403 495 — — Alum . . .100 1(30 100 103 100 100 — — — 100 Alumiuium sulphate — — — _ — — 120 120 68 — Lead acetate . . 100 75 666 80 90 100 KX) 1:!2:. — Sodium carbonate ) ,,, ,,, ,.^ cryst. (10 aq.)( lu lU 10 --_-__ _ Chalk ...- — __«._ 8-5 7-9 8 C Calcium acetate") 24°Tw.{Sp.Gr. [■ -_ — — __ __ 252 2^0 112J . . ) The red liquors of commerce are prepared by the double decomposition of normal aluminium sulphate and commercial acetate of lime. The so-called common red liquor contains a certain proportion of undecomposed aluminium sulphate, and is a crude sulphate-acetate, while iu that known as tin red liquor, the decomposition has been made as complete as possible, so that it represents a crude normal aluminium acetate. These red liquors always possess a brownish appearance, from the presence of empyreumatic matter. Application of the Aluminium Acetates and Sulphate-Acetates to the several Fibres. 102. Ajiplication to Cotton. — These are the alumi- nium mordants j^^^^-t^ excellence of the calico-printer. Their solutions are suitably thickened by means of flour, starch, or dextrin, and printed upon the calico and dried. Excessive heat in the drying must be carefully avoided {e.g., by substituting hot ]Aaies, hot air, ifec, for steam-heated cylinders), especially in the case of those mordants which are most readily dissociated (basic salts), otherwise poor and irregular colours are subsequently obtained. When this happens, it is said that tlie printed mordants have been " burned " ; the mordant fixed upon the fibre has probably been dehydrated, or has undergone some physical change, which renders it less capable of attracting colouring matter in the subsequent dye- bath. 170 DTBING OF TEXTILE FABRICS. (Chap. XL After ** printmg " and ** drying " follows the so-called " ageing " process, which consists in exposing the printed goods in a more or less open or loose condition to an atmosphere of suitable temperature and hygroscopic state. The process has been made continuous by using the so-called "ageing machine," which is in resdity a large chamber specially heated to 32* — 38^ C, and into which steam is admitted, so that a wet-bulb thermometer roisters 4° — 6** C. lower. The printed calico is drawn through this chamber, under and over a system of hori- zontal rollers situated at the top and bottom, at such a rate that the calico is exposed to the moist warm atmosphere for about twenty to thirty minutes. Diinng this operation the starch, or other thickening, is more or less softened by the moisture, and the mordant permeates the fibres more thoroughly ; large quantities of acetic acid are driven oi^ and a considerable amount of insoluble basic salt is fixed upon the cotton. Immediately on leaving this chamber the pieces are rolled up into loose bundles, and are allowed to remain for some time (tweuty-four to forty-eight hours) in a warm room (32* C, dry bulb, 28^ C, wet bulb) for the completion of the ageing process. The next operation is that of "cleansing,'' or " dunging," in which the pieces are passed in the <^n width, for two minutes, through hot solutions con- taining one or more of the following ingredients : cow- dung, arsenate of soda, phosphate of soda, silicate of soda^ chalk, er- formed in a separate bath. 114. Application to Silk. — Ferrous sulphate, as such, is not much used in mordanting silk. In the dyeing of EngKsh black {noir Angluis), the silk is mordanted by nrorkinoj it at 60° C. in a bath containins; a solution of 50 per cent. Logwood, 50 per cent. Old Fustic, 5 — 6 per cent, ferrous sulphate, and 2 — 3 per cent, acetate of copper. It is afterwards dyed in a bath of Logwood and soap. (See also p. 333.) 115. Ferrous Acetate. — This mordant may be pre- pared by the double decomposition of ferrous sulphate and lead or calcium acetate. The solution thus obtained does not keep well; it rapidly becomes oxidised, basic ferric acetate being deposited. FeS04 + CalCoHsOs). = Fe'aHsO.Os + CaSO^. Ferrous Calcium Ferrous Calcium sulpliate. acetate. acetate. sulplLat^e. A much more generally useful mordant, and one which is manufactured on an extensive scale, is the so-caMed pyroli-gnite of iron, Iron liquor, or black liquor. It is prepared by satui-ating crude acetic acid, 4o_8o Xw. (Sp. Gr. 1-02— 1-04), (pyroligneous acid), with iron tiu-nings, until the dark olive liquid stands at about 20^^ Tw. (Sp. Gr. 1*1.); sometimes it is concentrated to 30° Tw. This mordant is generally understood to be a crude ferrous acetate, containing a certain amount of tarry matter, which prevents it from oxidising rapidly. According to Moyret, however, it is a mixture of the ferrous salt with a salt of FcaO^ (magnetic oxide), and he considers that to the presence of this latter its good qualities are due. Moyret further maintains that it does not necessarily contain tarry matter, but pyrocatechin, Cj;H^(OH)j, the Chap, il.l IRON MORDANTS. 179 iion salt of which is dark green, and he attributes the islowuess of oxidation of the mordant to tlie presence of this reducing ao:ent. 116. Application to Cotton. — Pyrolignite of iron is the iron mordant most largely used by the calico-printer for dyeing blacks, purples, chocolates, (ire. The mode of fixing by "ageing " and " cleansing " in identical with that employed with the aluminium acetates {see p. 169). To obtai-a the best results, the mordant must be applied to the calico as much as possible in the ferrous state. During the ageing process, a variable proportion of acetic acid escapes, but it is accompa^ded by oxidation of the remaining compound, and care must be taken that this latter does not proceed too rapidly or continue too long. If the oxidation were effected rapidly — e.g., by steaming, or by passing through solutions of potassium dichromate or bloaching-po^vder — the results would be unsatisfactory. According ijO Schlumberger, the normal state of oxidation for gooci results is that intermediate between ferrous and ferric oxide. Various additions have been made to this iron mordant, with a view to retard and render incomplete, or to make more regular, its oxidation during " ageing " ; that which has found most favour is arsenious acid, either dissolved in a mixture of acetic acid and common salt or ammonium chloride, or in the form of sodium arsenite. Since glyce- rme acts in the same way, a solution of arsenious acid in glycerine would probably be an excellent addition. Such solutions have received the name of "purple fixing liquors," or simply "fixing liquors," since they are almost invariably mixed with the mordant by the calico-printer for the production of dyed alizarm-purples. Iron liquor at about 6° Tav. (Sp. Gr. 103), properly applied to calico gives a black on dyeing Avith Alizarin ; from 4° Tw. (Sp. Gr. 1-02) downwards to a very diluted state, it yields various shades of purple or lilac ; mixed flrith red liquor, and dyed subsequently with Garancine 180 DYEING OF TEXTILE FABRICS. iChap. Ti. or Alizarin, with the addition of Sumach and Quercitron Bark, it gives chocolate colours. Pyrolignite of iron is not extensively used by the general cotton-dyer, principally because it is more ex- pensive than the "nitrate of iron " usually employed, and because in many cases it yields only slightly better results. It is best applied by impregnating the cotton with a solution of tannin matter of suitable concentration ; after removing excess of liquid by squeezing, the cotton is worked and steeped in a cold solution of the iron mor- dant at 2°— 6° Tw. (Sp. Gr. 1-01— 1-03) for one hour or more, and finally washed. The concentration of the tannin bath determines the amount of iron fixed on the cotton. Since iron mordants are invariably used for the production of dark, dull, or sad colours, this method of fixing them by means of tannin tends to save colouring matter, because the dark colour of the tannate of iron is added to that of the colour subsequently imparted. 117. Ajyplication to Wool. — Pyrolignite of iron is not employed in wool dyeing, though it might possibly be used with advantage in some cases — e.g., in tlu.^ l)lack dyeing of skin mats, ifec. — where only lov7 temperatures in the baths are admissible. A mixture of ferrous sul- phate and sodium acetate might be used instead of the pyrolignite. 118. Applicatioji to Silk. — Pyrolignite of iron is largely employed in the black dyeing and weighting of raw-silk fringes, &c. ; its application is always preceded by a tannm bath. The silk is first imj^regnated at 40® — 45° C, with an infusion of tannin mattei-, 100 per cent, (preferably chestnut extract), then worked at 50^ — 60^0. in a bath of pyrolignite of iron (Fr. jned defer) 12° — 14°Tav. (Sp. Gr. 1"06 — 1"07), and finally exposed to the air. These opera- tions may be repeated from two to fifteen times, both to give body of colour and to add weight, which latter may vary from 30 to 400 per cent, of the weight of the silk. The mordanting bath is maintained at tlie requisite degi-ee Chap. XI. J IRON MORDANTS. 181 of concentration by fresh additions of pyrolignite of iron ; its acidity, which increases with use, is neutralised by occasionally adding iron turnings, and heating the bath to near the boiling point. Too frequent use of the bath must be avoided, in order to give the added iron time to dissolve. The scum produced in heating must be removed. Pyrolignite of iron gives a bluish-black difficult to obtain by using other iron salts. The blue tone seems to be acquired through oxidation, and since the rate at which this proceeds depends upon many factors, the colour is very liable to be irregular. Although pyrolignite of iron has been employed in the above manner for boiled-off silk, it is now entirely replaced for this, by basic ferric sulphate (nitrate of iron). Sometimes a weak pyrolignite of iron bath is em- ployed in black silk dyeing, between two catechu baths, in order to alter the tone of colour. 119. FerrousNitrate and Ferrous Chloride do not seem to have been generally adopted as mordants. The latter is used under the name of " muriate of iron," in the pre- paration of a logwood black printing colour for woollens. 120. Ferrous Thiosulphate (Hyposulphite) has been recommended as a good iron mordant for cotton, but it has not been adopted in practice. It is produced by the double decomposition of ferrous sulphate and calcium thiosulphate. When dried on the fibre, it decomposes with final i^roduction of basic ferric sulphate. 121. Ferric Sulphate. "Nitrate of iron." — A solu- tion of normal ferric sulphate Fog (804)3 ^^^7 ^^ prepared according to the following equation : — 6FeS04-7H,(,> + 3H2SO4 -f- 2HN0, = 3Feo(S04)3 + 2N0 -f 46H2O Ferrous Sulphuric Nitric Ferric Nitrogen Water, sulphate. acid. acid. sulphate. dioxide. The ferrous sulphate is dissolved in water containing the calculated amount of sulphuric acid, the solution is gently heated and the necessary quantity of nitric acid ia added gradually. If the solution is sufficiently concen- trated it may be boiled in order to complete the reaction. 182 DYEING OF TEXTILE FABRICS. IChap. XI. The iiitric acid merely acts as an oxuiisLng ageDt, thus :- •2HXO3 = ^aO + 2X0 -f O3 hence the usual name given to this prepai-ation, " niti^ate of ii'on," is a misnomer. By adding an alkaline carbonate to solutions of the normal salt of suitable concentration, it is possible to ob- tain solutions of basic ferric sulphates, e.g., YeJ^^0^.{OH.)^ and Fe^ (80^)3 ( OH )6, both of which, however, readily decompose on standing for a few hours. A soluble basic sulphate of gi-eater stability is pre- pared by adding a suitable amount of hydrated ferric oxide to a solution of the normal salt. It is, however, more economical to adojjt the method described for the normal salt, but using only half the amount of sulphuric acid, thus : — 12FeS04-7a,0 + SR.SO^ + 4HXO3 = ^^04(804^ ( OH ^. + Ferrous SrJpliiiric Iiitric Bisic ferric sulphate. acid. acid. sulphate. -f 86H2O 4- 4X0 Water. Nitrosren dioxide. In making this preparation on a small scale, it will be noticed that at lii'st, even after the whole of the requisite nitric acid has been added, the solution has a dirty olive-brown coloui*, which is indicative of the presence of ferrous salt. When, however, the boiling liquid has attained a certain degree of concentration, complete oxidation suddenly takes place, thei'e is a copious evolu- tion of red fumes, and the liquid at once assumes the normal orange yellow colour of the feme salt solution. This basic ferric siilphate (Fr. rouille) is sold very largelv to black silk-dyers, as a deep red liquid of alxmt 70°— 85° Tw. (Sp. Gr/l-35— 1-4). It is made in large covered stone vats provided with a wide tube for the dis- engagement of the nitrous fumes, a small tul>e for the introduction of the acids, and a large opening for intro- Chap. X1.J IRON MORDANTS. 183 ducing the ferrous sulphate, and stirring the mixture. For every 100 kilos, of basic sulphate at 84° Tw. (Sp. Gr. 1*42) required, 80 kilos, of ferrous sulphate are era})loyed ; these are put into the vat, and a mixture, slightly diluted with water, containing 10 — 15 per cent, of nitric acid 72° Tw., and 6 — 7 per cent, of sulphuric acid 168° Tw., is run in gradually. The whole is well stirred, and the reaction is allowed to proceed in the cold ; whei. this primary reaction has subsided it is completed by blow- ing in steam. The nitrous fumes, which are given off ir. large quantities, are condensed and collected. When no more are evolved, the reaction is complete, and the liquid is transferred to large tanks to cool and settle. It was formerly thought that the presence of small proportions of ferrous sulphate and nitric acid were bene- ficial in the production of the best black on silk, but this was a mistake. A good sample of this mordant should not be precipitated by silver nitrate. Potassium ferricyanide should, with a dilute solution, give at most a blue colora- tion, but no precipitate. Submitted to desiccation and calcining, it should leave about 17 per cent, ferric oxide. It is dissociated by diluting with water, an insoluble and still more basic ferric sulphate being precipitated, wliile a more acid salt remains in solution. Since it sometimes happens that two preparations having the same chemical composition give dififerent results in dyeing, it is supposed that there are isomeric compounds due to the different temperatures at which the oxidation may take place. Great care is required in its manufacture, since if it is too basic it tarnishes the lustre of the silk, and if too acid it does not give up its oxide to the fibre in sufficient quantity. 122. Application to Cotton. — The normal ferric sul- phate is seldom used. The above-mentioned soluble basic ferric sulphate, or even a slightly more acid compound, is used in dyeing cotton black. Tlie cotton is first impregnated with an 184 DYEING OF TEXTILE FABRICS. [CliftD XI. infusion of tannin matter, and either at once, or after pass- ing through lime- water, it is worked and steeped for about one hour in a solution of the mordant, at a strength of 2°— 4°Tw. (Sp. Gr. 1-01— 1-02). It is finally washed, either in water only, or in such as contains a small addi- tion of ground chalk, for the purpose of completing the precipitation of basic salt on the fibre, and to remove all acidity. The cotton is subsequently dyed in a logwood bath. In this process the tannic acid, which is absorbed and attracted by the cotton, serves principally to fix the iron mordant, although it incidentally produces a bluish black colour by combining with the ferric oxide or basic ferric salt. The passing through lime-water after the tannin bath evidently forms a calcium tannate. and the decomposition of the ferric salt is thereby facilitated, since the lime combines with its sulphuric acid. This mordant may also be used for dyeing iron bufls in the same way as ferric nitrate (see p. 191). 123. Application to Wool. — The ferric sulphates do not appear to have been utilised hitherto in the mordant- ing of wool, although it seems possible that they might be useful if properly applied. 124. Application to Silk. — The soluble basic ferric sulphate re4(S04)5(OH)j, is the iron mordant par excel- Unce of the black-silk dyer. In mordanting raw silk, the latter is first worked in a tepid bath (40" — bO" C.) of sodium carbonate, washed and well w-rung out, and then worked in a cold solu- tion of the mordant at 15' Tw. (Sp. Gr. 1075) for ^ — 1 hour. The silk is then drained, wrung out, well washed, wrung out again, and worked for about half an hour in a tepid (40° — SG^C.) solution of sodium carbonate. It is finally MTung out and well washed. These several operations may be repeated three or four times, according to the colour and weight required In mordanting boiled-off silk, the material is worked for ^ — 1 hour in a cold solution of the basic ferric Chap. Xtl IRON MORDANTS. 185 sulphate at about 50° Tw. (Sp. Gr. 1-25), excess of liquid is then removed by squeezing and wringing, and the silk is well washed — first with cold water, and finally with tepid water. These operations may be repeated as many as seven or eight times, after which the silk is worked at 100° C, in an old soap-bath, or one containing "boiled-off" liquor, to which about 12 per cent, (of the weight of silk) of ole'in soap and 2 per cent, of sodium carbonate crystals are added. A final washing completes the mordanting process. The iron and soap baths are permanent, care being taken, by making fresh additions of mordant, to maintain regularly the concentration of the former, and to boil up the latter before mordanting each lot of silk, in order to bring to the surface and then skim off the iron soap which has been formed during a previous operation. It is essential that silk mordanted in basic ferric suljjhate should not be allowed to dry in the mordanted state. It should either be left steeping in the strong mordant, or left, after washing, well covered up with wet sheets. Silk strongly impregnated with ferric oxide is gradually destroyed on keeping, slow combustion or oxi- dation of the fibre being induced. The theory relative to the above methods of mordant- ing is as follows : — In the case of raw silk, where a comparatively weak solution of the ferric sulphate is employed, apart from general absorption of the liquid, the silk-gum itself causes decomposition and precipitation of an insoluble basic salt throughout its mass during the steeping operation. The washing in water, and rinsing in sodium carbonate, complete the decomposition, and remove the necessarily liberated acid salt. In the case of boiled-off silk, the fibre simply ab- sorbs the liquid during the steeping in the concentrated solution of mordant, decomposition and precipitation of basic salt only taking place during the washing process. 186 w Chap. XI.] IRON MORDANTS. 187 M hicli, of course, also removes the acid salt formed. The employment of water containing bicarbonate of hme is exceedingly advantageous for the washing, since it greatly facilitates the decomposition of the absorbed mordant. The boiling in soap solution is necessary to complete the decomposition of the absorbed mordant, and the Fig. 46.- Squeezing Machine used in the Mordanting of Silk. temperature employed, 100° C, is said to modify the pre- cipitated ferric oxide and render it less liable to dissolve in the successive iron baths. According to jMoyret, no iron soap is precipitated on the silk in this operation. Previous impregnation of the silk with tannin matter does not tend to cause a larger precipitation of mordant on the fibre, but rather the reverse ; indeed, the silk loses weicdit throufrh the oxidation and destruction ot the absorbed tannic acid. 188 DYEING OF TEXTILE P.ABRICS. [Chap. Xl By one complete mordanting oj>eration the silk gains about 4 per cent in weight. If the operations are repeated six times, it gains about 25 per cent, or has about made up the loss sustained in boiling-off. If repeated seven to eight times, there is a gain of about 8 per cent, of the original weight of the raw silk. Thus moixianted, the silk possesses a deep orange brown colour, and still retains its lustre. Fig. 45 represents the mordanting bath in general use with black silk dyers. It consists of a rectangular wooden vat, for holding the ii"on mordant. The silk, properly suspended on smooth wooden rods {e.g., hickory sticks with the bark peeled off), is tun:eil in the solution by hand After draining, the excess of liquid is removed by passing the hanks singly through a squeezing machine (Fig. 46), provided with an inclined, broad, endless band of india- rubber, A, which carries the hanks laid thereon through the india-iTibber rollei"S. By means of the screws at B the endless band, a, can always be kept in a state of proper tension. A more complete expression of the liquid is effected afterwards by twisting the hanks vigorously by hand. The washing machine employed is illustrated in Fig. 47, which represents one constructed by Gebriider Wansleben, of Crefeld. It consists of a double row of glazed, fluted, porcelain reels, on which the hanks of silk are suspended and made to revolve. The reels are geared together by a series of cog-wheels, one of which, on each side, is driven by a cog-wheel attached to a central fiiction disc. The washing is effected by water-pipes, situated below the reels, and perforated on both sides horizontally. A similar water-pipe is situated between each pair of hanks, so that each one during its revolution has a continuous and uninterrupted stream of v.ater-jets playing upon it, both internally and extemally. In order to prevent the fibres from becoming en- 189 1 ill ? W i 190 DYEING OF TEXTILE FABRICb. (Chap. XL tangled, the reels are automatii;ally caused to i-evolve alternately to the right and left. The movement of a single lever sets the reels in motion, and turns on the water. The i*eels on each side can be worked indepen- dently of each other, so that while one set are in action and NN'ashing, the other can be emj)tied of hanks and refilled. After washing with cold w^ater in the above manner, an additional washing or rinsing with warm water is effected in a wooden trough, situated between and below the two sets of reels. By means of a counter- poise, it can be readily brought below either set of hanks, so that they may then revolve in the warm water. The trough is fed from a tank placed at a higher level, where the water is specially heated by steam to the requisite tempei^ture. 125. Ferric Nitrate-sulphates. — Several of these ai-o made and employed in practice under the name of nitrate of iron. They are produced whenever ferrous sulphaie is oxidised by means of nitric acid, after the manner ah'eady described for the production of ferric sulphates {see pp. 181, 182), but the sulphuric acid which w^as there added is here entii^ly or paitially replaced by nitric acid, thus : — 6FeS04-7H20 + 6HXO3 + 2HXO2 = ZYe4iiOi)-,{SO^\i -f Ferroxxs sulphat-e. Xitric acid. Ferric-uitrate-snlpliate. + 2X0 -f 46H2O Nitrc^en dioxide 12FeS04-7H20 + GHXO3 + 4HN03= 3Fe^'SOJ)^fX03)^;OH^2 + Basic-ferric-nitTate-sulpliat*. -f 4X0 -f 86ILO The composition of those used in practice is very variable. Compounds of definite composition are not generally intended to be made, and their value as mor- dants is entirely determined by the results they yield in dyeing. They are deep broTs^nish-red solutions, and contain Cliap. XI. I IRON MORDANTS. 191 frequently some ferrous salt which has escaped oxidation, and whicli, in many cases, is nob considered injurious. In conjunction with Logwood, for example, jmre ferric salts tend to give brownish-blacks, while the ferrous salts give bluish-blacks. A mixture of the two is there- fore considered to give a more pleasing jet-black. Excess of acid should be avoided when these mor- dants are applied to cotton, especially in printing colours which require steaming. If used for purposes of "saddening," a slight acidity may, on the other hand, be beneficial, since the mordant is then more slowly decomposed, and more likely to penetrate the fibre and to give a regular mordanting. If too basic, on tlie contrary, the mordant is too sensitive, decomposes spontaneously, and gives irregular Av^ork. 126. Ajyplication. — The principal application of the nitrate-sulphates of iron is in the black dyeing of cotton. The mode of application is identical with that given for the ferric sulphates. {See p. 183.) In wool dyeing, the above mordants are not used, and in silk dyeing they have been supplanted by the soluble basic ferric sulphate. 127. Ferric Nitrate^ — This mordant constitutes the true nitrate of iron of the dyer, and is prepared by dissolving scrap-iron slowly in nitric acid. As soon as there is a sensible deposit of insoluble basic ferric nitrate the addition of iron is discontinued, and the liquid is allowed to settle. According to the proportion of nitric acid used, and the care taken in the preparation, the composition will be very variable. It finds a comparatively limited use now, being em- ployed only in cotton dyeing, e.g., in the production of buff shades. The cotton is impregnated with a solution of nitrate of iron, and, after removing excess, is passed through a cold solution of sodium carbonate, whereby ferric oxide is precipitated. It is also used occasionally for blacks. 128. Ferric Acetate.— Thenormal acetate, Fe2(C2H302)c, 192 DYEING OP TEXTILE FABRICS. [Chap Xx is prepared by the double decomposition of ferric sul- phate and lead acetate, in suitable proportions. On neutralisincj a solution of the normal acetate with increasing amounts of an alkaline carbonate, solu- tions of various basic acetates are obtained, e.*/., Fe,(aH30.4(0H), Fe,(aH30,)4(OHX, Fe,(aH30,)3(OH)3; Feo(CoH.Oo).(OH)4. A solution of the normal salt is not dissociated either by heating or diluting with wat^r; solutions of the basic salts ai'e, however, dissociated on heating, but not by dilution. Increase of basicity lowera the dissociation temperature. It is remarkable, however, that when the solutions are diluted, the point of disso- ciation by heating is raised in the least basic mordant, Fe2(C..H30o)5(OH), remains michanged in the case of Feo(C2H302)4(OH)^„ and is lowered only in the more basic mordants. (Liechti and Suida.) 129. Application. — The ferric acetates seem to tuid, at present, little or no use as mordants, although some were formerly employed rather largely in black silk dyeing. 130. Ferric sulphate-acetates have occasionally \^een used, having been incidentally prepared through the desire of reducing the excessive acidity of ferric sulphates by the addition of lead acetate. 131. Ferric Acetate-Nitrat€, or/^r?-/.- p.ilmte-acetate, — This mordant has also been incidentally prepared by adding a certain propoi-tion of lead acetate to solutions of certain feri'ic nitrate-sulphates with a view to reduce their acidity. A product of this nature has, however, been much used in silk dyeing, and is still employed in the dyeiug of black f:ilk intended for plush (e.g., for hats), since tlie colour which it yields is not affected by hot- pressing or ironing. Its mode of prepaiution, for a long time kept secret, is as follows : iron turnings are dissolved Lq nitric acid, as in the manufactm-e of ferric nitrate, but the addition of iron is continued until the whole becomes a pasty mass of insoluble basic ferric nitrate. This basic precipitate is collected and dissolved in hot acetic acid, taking cai*e to leave a slight excess of the (?l3ai>. Xt] IRON MORDANTS. l93 precipitate. The deep red solution thus obtained is allowed to cool and settle. 132. Ferric Chloride. — The normal compound, FcaOlg, is not used as a mordant. Basic salts may be produced by dissolving hydrated ferric oxide in solutions of the normal salt, but these, too, have as yet found no use in practice. 133. Alkaline Iron Mordants. — Although hydrated ferric oxide is not soluble in caustic alkalis, the addition of certain organic substances (tartaric acid, glucose, glycerine, &c.) to the solution of a ferric salt, prevents the precipitation of the ferric oxide by alkali^ and hence an alkaline solution of iron can be thus obtained. Take, for example, 2^ litres of ferric sulphate solution, equiva- lent to 1,250 grams of ferrous sulphate, add 1 litre of glycerine and 10 litres of caustic soda, 70^ Tw. (Sp. Gr. 1 '35) ; the solution has a deep reddish-brown colour. An alkaline ferric solution is also obtained by adding an excess of a concentrated potassium carbonate solu- tion to a concentrated solution of ferric sulphate or nitrate. The precipitate which at first forms is re-dis- solved under the above conditions. Pyrophosphate of iron, (Fe2)2(P2^7)3) is soluble in ammonia. Cotton mordanted by means of this alkaline solution is said to give good purples when dyed with Madder or Alizarin. It has been noticed by Burgemeister that an addition of glycerine to a solution of ferrous sulphate prevents the precipitation of oxide by alkali, and that this alka- line solution is capable of mordanting cotton. Mix, for example, 1 kilo of ferrous sulphate, 2 Litres of glycerine, and 60 litres of caustic soda, 70^ Tw. Notwithstanding the above facts, alkaline iron mor- dants have as yet received no practical application by the dyer, no doubt because of their excessive alkalinity and cost. 134. Iron Alum.— This salt, ^^ I {^0,),'2iB:,0, is exactly analogous to ordinary alum, and may be applied 194 DYEING OF TEXTILE FABRICS. [Chap. XL in the same way. Its use liitlierto has been limited, havini; been confined to mordantins: wool for dyeing with alizarin colours. There is no reason, however, why it should not find a more extended use. TIN MORDANTS. <. 135. Tin. — Tin may occur in two states of oxidation — as stannous oxide, SnO, and as stannic oxide, SnO^. These oxides, in their hydrated state, Sn(OH)o and Sn(0H.)4, are soluble either in acids or in caustic alkalis, and thus give rise to corresponding stannous and stannic salts, either of an acid or of an alkaline nature. Apart from their character as mordants, the stannous salts act as powerful reducing agents ; they have a great avidity for oxygen, and tend to change into stannic compounds. This fact should always be borne in mind by the textile colourist, since it sometimes excludes them from being used in conjunction with other mordants of an oxidising character, or with such colouring matt-ers as are decolorised by a reducing action. In particular cases, however, this characteristic may be made to serve a useful purpose, for example, in the reduction of indigo-blue to indigo-white, the discharging of iron bufife, manganese browns, itc, in calico-printing. As a general rule, the stannous salts are employed for wool, and the stannic salts for cotton ; the colours they yield with polygenetic colouring matters are usually remarkable for their brilliancy. Solutions of the stannous and stannic salts are colour- less. Many of the tin solutions, however, which the dyer prepares by means of nitric acid, with or without the addition of hj'drochloric acid or alkali chlorides, possess a very decided yellow colour, and they seem to be of a more unstable character than the ordinary compounds. Hence some consider that these represent solutions of tin in an intermediate state of oxidation, namely, as sesquioxide, SujO^. It is, however, more probable that this coloration and sensibility are due to Chap. SM TIN MORDANTS. 195 the presence of a peculiar modification of stannic oxide called metastannic acid. L 136. Stannous Chloride. — This mordant is sold in the crystalline form (SnCl/2 H2O) under the name of "tin crystals" or "tin salt." A good sample should contain 52 per cent, of tin. It is prepared by dissolving granulated tin in hydrochloric acid with the aid of heat, and allowing the concentrated liquid to crystallise. Sn + 2Ha + 2H.0 = SnCl2-2H20 + H2 Access of air is said to facilitate solution, so that it may also be effected without heat if the acid is poured successively on exposed heaps of feathered tin. Sn + 2HC1 + 2H2O + O = SnCl2-2H20 4- H^O Very frequently the solution is not crystallised ; it is then sold under the names of "single muriate of tin" and "double muriate of tin," accordi^ as the Specific Gravity is 1-3 or 1-6 (60° Tw. or 120°Tw.). These "muriates of tin" differ frequently, however, in concentration, from the standards here given ; the amounts of tin, and the free acid which they always contain, vary considerably, and can only be determined by analysis. They are occasionally subjected to adul- teration. " Tin crystals " dissolve in a small quantity of water without undergoing decomposition, and a clear solution is obtained ; on further dilution, however, this becomes turbid through the formation of an insoluble basic chloride or oxychloride [2Sn(OH)Cl-H20J which is pre- cipitated. 3SnCLj -f 2H2O -f O z=2Sn(OH;Cl-H20 + S11CI4 Basic stannous chloride. The precipitate re-dissolves on the addition of hydro- chloric acid. A similar oxidation takes place when " tin crystals " are kept for a lengthened period, especially if exposed to aii- and light. Owing to the presence 196 DtfilXG OP tEXTILE FABRICS. [Chav.TL of excess of acid, the " muriates of tin " are less readily decompoised by dilatioii with water. 137. AppliaUwn to Cotton. — " Tiu crystals " arc largely used by the calico-printer for mixing with thickened alnniininm mordants. When used in small amount, this addition pre^ ents, probably by reason of its reducing action, the fi Yi' ng of iron accidentally present in the printing colour, or acquired during the processes of printing, &c. It thus preserves the purity and bril- liancy of dyed alizarin-reds, Tw. (Sp. Gr. 1-32). 150—600 grams of hydrochloric acid 32«> Tw. (tip. Gr. 1-16). 6 — 12 per cent, of the weight of mixed acids of tin. In some cases even 30 — 40 per cent, of tin has been used- h. 100 grams of nitric acid 64'' Tw. (Sp. Gr. 1-32). 12-5 gi-ams of ammonium chloride (or 5 grams NaCl). 12 — 16 per cent, (of the weight of nitric acid) of tin. The solutions are frequently diluted with water to a moderate degree. Oxymuriate of ^Hn and Pink Cutting Liquor are names given to a preparation belonging to the same class, and made by adding gradually and with continual stirring 125—150 grams of nitric acid 62° Tw. (Sp Gr. 1-31) to 100 grams of stannous chloride crystals, and diluting slightly with water. It is a white, somewhat milky solution. According to the proportions of the different in- gredients, the temperature, and the method of procedure adopted in making the above mordants, their composition will vary exceedingly, not only as to acidity and per- centage of tin, but also as to the state of oxidation in which the tin is present. Much ditficulty is experienced in the manufacture of tin mordants by the dyer, because of the fact .already alluded to, that two stannic oxides exist, 208 DYEING OF TEXTILE FABBICS. [Cliap. XL namely, stannic ax?id and metastannic acid ; the formei is solable in nitric acid ; the latter is insoluble. Metastannic acid is invariably formed wheneAer tin is violently acted upon by nitric acid, either because the latter is too concentrated, or the temperature employed is too high. The formation of this body as an insoluble precipitate constitutes the so-called " filing " daring the preparation of some of the al30ve mordants, and most be rigorously avoided by adding the tin slowly in the form of rods, keeping the acids cool, and preventing the evolution of nitrogen dioxide, since it means a loss of tin and a diminution of the mordanting power of the solution. But even when this violent oxidation does not take place, solable metastannic chloride or complex oxychlorides are frequently formed, and the presence or absence of th^e in any solution of stannous or stannic salts influences very ma^ its behaviour in mordanting. Applicatioii of Stannic Salts to tlie various Textile Fibres. 145. Application to Cotton. — In ordinary yam and piece dyeing stannic chloride finds only a limited use. As barwood-spirit and red-cotton-sf)iiit, it is used in dyeing reds with Barwood and Peachwood, The cotton is first well impregnated with a decoction ermit. The mixture becomes much heated, and care should always be taken not to allow it to cool, otherwise there is a possibility of the reaction ceasing; and external heat would then have to be applied. The following proportions of ingredients are employed by calico-printers : 100 (ri-ams of K..Cr.,0-, 220 gi^ms of water, 123 grams of H.SO^, 168^ Tw' (Sp. Gr. 1-8-1), 24 grams of starch. When properly made, the solution should ha^e a bluish-green colour; if olive-green, it stiU contains undecomposed bichromate of potasL Since the liquid has been heated, crystallisation takes place Ns-ith difficulty ; but, as a rule, after standing for a lengthened period, it deposits dark purple crystals. These dissolve in cold water, with a dii*ty bluish-violet colour, but if the solution be heated above 70^ C, it acquires a green colour. On long standing the original colour returns. The violet solution contains the normal salt, whereas the green solution is said to contain a mixture of basic and acid salts. This explanation is simpler and better Chap. XI.] CHROMIUM MORDANTS. 213 than that which supposes the existence of two modifica- tions of chromium liydrate. These violet and green solutions differ from each other in many of their reactions, e.g., barium chloride does not precipitate the whole of the sulphuric acid from the green solution at the ordinary temperature, whereas with the violet solution the decomposition is normal ; ammonia precipitates hydrated chromic oxide, Cr2(0H)(;, from both solutions, but only that obtained from the violet solution is soluble in excess of ammonia. Similar differences are shown by other chromic salts. A normal chrome-alum solution is not decomposed either by heating or by dilution. By adding calculated amounts of an alkaline car- bonate or chromium hydrate to a solution of the normal chrome-alum, solutions containing basic chromium sul- phates are obtained, for example, such as are represented by the following formulae : — 0r„(SO4)2(OH)2, Cr4(S04)3(OH)e, Cv^{^0,){OB.),. Such solutions will, of course, contain also potassium and sodium sulphate. Unlike those of the corresponding aluminium compounds, they show no sign of dissociation on heating (Liechti and Suida). Dissociation by dilution is accelerated the more basic the salt is, e.g., a solution containing Cro(SO,j)o(OH)o must be diluted 85-fold before precipitation ensues, whereas Cr2(S04) (OH)^ requires only 1-5-fold dilution; but in all cases the precipitation is not complete. The presence of sodium sulphate makes the solution less sensitive to dis- sociation by dilution. Parallel with these facts are those which refer to the behaviour of chrome-alum solutions to the fibre ; with increase of basicity a larger amount of chromic oxide is deposited on the fibre by the operations of impregnation, drying, and ageing. A solution of normal clirome-alum containing 224:"6 grams per litre {i.e., an amount equivalent to 150 grams of aluminium sulphate per litre) deposits on the cotton fibre 2l4 DYEING OF TEXTILE FABRICS. (Chap. Xt 1'8 per cent, of the chromic oxide presented to it, an equivalent solution of the basihate. sulphate. + 3C0a. With the use of chromic hydrate, the most basic salt obtainable is Cro(SO^)2(OH)2, thus : 2Cr.,(S04)3 + Cro(OH)g = BCralSOJaCOH,). Chromic Basic hydrate. chromium sulphate. In the first case the neutralising can be pushed to a further limit because thei^e the presence of the sodium sulphate tends to retard the dissociation of the basic salt. Neither of these is so basic as the solutions similarly obtained from cJirome-alum. Both the normal and the basic chromium sulphates behave in respect of dissociation by heating and by dilution, like the corresponding chrome- alum solutions ; the same may be said of their behaviour with sodium hydrate, ammonia, sodium carbonate, phos- phate, and silicate. A solution of normal chromium sulphate (equivalent to 224*6 grams of chrome-alum per litre) deposits 12 '8 per cent, of the available CroO.^ on the cotton fibre by the operations of impregnation, drying, and ageing ; an equi- valent solution of the basic salt Cr^(S0^)3(0H)g made from chromium sulphate and sodium carbonate yields to the fibre 86*4 per cent, of the available chromic oxide. Although these solutions of pure chromium sulphate cannot be made as basic as those of chrome-alum, they give up practically the same amount of chromium oxide to the fibre under the above conditions?, because they are more sensitive (Liechti and Suida). 162. Chromium Acetate. — A solution of the normal Bait [Cr2(C2H30.,)n] may be prepared by mixing, in suitable proportions, solutions of lead acetate and chromium 216 DYEING or TEXTILE FABRICS. [Chap. XL suliiliate or chrome-alum ; in the latter case, of course, potassium sulphate is present. [^' ! (S04)4-24H20] + 3[PL(CoH302)2'3H20] = Cr,(aH302)e 2 ) Lead acetate. Chromium Chrome alum, acetate. -\- 3PbS04 + K2SO4 + 33H2O. It is both interesting and remarkable that a solution of normal chromium acetate, prepared as above indicated, is not dissociated pn boiling, however much diluted the solution may be. It is not precipitated in the cold by caustic alkalis, alkaline carbonates, phosphates, and sili- cates, ammoniacal soap, or sulphated-oil solutions, but on hoiling with these additions, complete precipitation is effected. The duration of the boilinsr necessarv to cause decomposition varies with the amount of dilution, and if the addition made be phosphate of soda, very long boiling is required (Liechti and Suida). A solution of pure chromium acetate can be evapo- rated to dryness, and be even heated to 2.30'' C, it is said, without losing its solubility. If a freshly prepared violet solution of normal chro- mium acetate be boiled, it becomes greenish-violet, and if basic salts are made from this by the addition of sodium carbonate, they soon decompose. A similar change takes place if a solution of the normal salt is kept for a long time ; it loses its violet colour, and is then readily precipi- tated by sodium carbonate on heating. Somewhat less sensitive basic mordants are obtained, if the sodium car- bonate is added in two portions, and the liquid is gently heated after the first addition. On the contrary, if from a freshly prepared violet solution of normal chromium acetate, basic solutions are made by adding sodium carbonate, such solutions retain the violet colour ; they may be kept for a long time, and may even be heated gradually to the boiling point with- out undergoing decomposition. If, however, after long keeping, a very slight further addition of sodium carbon- Chap. XI. CHROMIUM MORDANTS. 217 ate is made, complete decomposition takes place at once on boiling the solution. Solutions of basic acetates may be obtained by making suitable additions of an alkaline carbonate to solutions of the normal salt, or by adding lead acetate to solutions of basic chromium sulphates. It is possible even to make a solution so basic that it contains three molecules of sodium carbonate to one of chromium acetate. It is an interestincr fact that the more basic a chro- mium acetate is, the more lead sulphate it can hold in solution. On the addition of acetic acid it is precipitated. The presence of sodium acetate also causes lead sulphate to be dissolved, but in this case an addition of acetic acid does not precipitate it (Liechti and Suida). The basic chromium acetates are not dissociated by RUution, and only the most basic dissociate on heating ; a solution, for example, of the basic salt Cro(C^H30n)^(OH)2 (made from basic chromium sulphate and lead acetate, and equivalent to 224*6 gi-ams of chrome-alum per litre) is not dissociated on heating, unless it be diluted 75-fold. It yields to the cotton fibre by the operations of impregna- tion, drying and ageing, 29 '5 per cent, of the available chromic oxide. The more basic salt Crr,(C2ll30o)3(OH).3 made in the same way, dissociates when heated to 80^ — 90° C, and gives up to the cotton fibre 66 per cent, of the chromic oxide presented to it. An equivalent solution of normal chromium acetate yields only 8'4 per cent, of the available chromic oxide to the fibre when similarly applied. 163. Chromium Sulphate -Acetate. — Solutions of these are prepared by adding to a solution of chrome- alum such amounts of lead acetate as are insufiicient to cause complete decomposition. They bear, to a certain extent, the cliaracter of solutions of chromium acetate, not being affected in the cold by the ordinary precipi- tants, but only on heating. Basic salts are made in the same way, substituting basic chromium sulj^hates for chrome-alum. Only the most basic show signs of disso- ciation on heating or diluting. 218 DYEING OP TEXTILE FABRICS. [Chap. XL 164. Chromium Nitrate and Chromium Chloride are prepared by the double decomposition of solutions of chrome-alum with lead niti*ate and barium chloride re- spectively. Solutions of basic salts are prepared by making suitable additions of an alkaline carbonate. These solutions, on diluting and heating, behave very similarly to the corresponding solutions of chromium sulphate, t.c, they ai'e not readily dissociated. The nitrate seems to be the most susceptible, and the sulphate the least, while the chloride holds an intermediate place. 165. Chromium Nitrate-Acetate. — Solutions of this salt mav be made bv mixinof together solutions of chrome- alum or chromium sulphate, lead nitrate, and lead acetate. Cr2{S04)3 -f Pb(N03)2 + 2[Pb(C2H30o)o-3H20] = Lead nitrate. Lead, acetate. = Cr2(^'03\(CoH302)4 -i- 3PbS04 -f GILO. Normal chromium nitrate-acetate. Basic salts are prepared by adding sodium carbonate to solutions of the normal salt. A very suitable method of preparing solutions of basic salt is to reduce bichromate of potash with glycerine, the requisite amounts of nitric and acetic acid being also added, thus : 2K2Cr.207 + 6HXO3 + ian^Oo -f 6H2 =r 4KXO3 + Aceric acid. + 202(^03) (aHgOs): (OH}34- SH,0. Basic chromixim nitrate-acetate. Dissolve 100 grams of bichromate of potash in 150 gleams of warm water, then add 131 gi-ams of nitric acid, 64° Tw. (Sp. Gr. 1 -32) ; cool the solution a little, and add gradually a mixture of 29 gi^ams of glycerine and 134 grams of acetic acid, 10^ Tw. (Sp. Gr. I'Oo). The solu- tion obtained may be evaporated a little and cooled, in order to allow the potassium nitrate to crystallise out 166. Chromium Thiocyanate. — A solution of the Chap. Xl.l OfiROMlUM MORDANTS, 21 J> normal salt Cro(CNS)g is prepared by mixing together solutions of normal chromium sulphate and barium thiocyanate. With solutions of sodium hydrate, am- monia, sodium carbonate, and phosphate, it behaves very like a chrome-alum solution. Basic salts are prepared by adding sodium carbonate to a solution of the normal salt. The most basic salt Cr2(CNS)(OH)5 decomposes after a few hours' standing, but the rest are quite stable. The chromium thiocyanate solutions are not dis- sociated either by boiling or by dilution ; if, however, di- luted excessively, and then boiled or allowed to stand for a long time, some of the more basic salts dissociate. A solution of the basic salt Cr2(CNS)2(OH)^ (equiva- lent to 224-6 grams of chrome-alum per litre) gives up 33*6 per cent, of the available chromic oxide to the cotton fibre by the operations of impregnation, drying, and ageing. In this respect chromium thiocyanate is much behind chrome-alum and chromium sulphate. 167. Alkaline Chromium Mordants. — In considering the previous mordants, it has been stated that sodium hydrate, and ammonia precipitate their solutions, and that an excess of the precipitant redissolves in the cold the precipitate at first formed. Chromium hydrate may also be precipitated from a solution of chrome alum by sodium carbonate, then washed and dissolved in a cold concentrated solution of caustic soda. Such alkaline solutions of chromic hydrate are prone to decompose spontaneously, but the more alkaline the solutions, the less liable they are to do this, and it is quite possible to use them for the purpose of mordanting cotton. 168. Application of the Chromium Salts to Cotton. — The great importance of chromic oxide as a mordant for cotton, and the stability of its lakes, have long been recognised, but until recently no very satisfactory methods of fixing it simply, and in suflicient quantity upon the fibre, were recognised. Chromium nitrate, sulphate, nitrate-acetate, and ace- tate have been much used by the calico-printer for steam- 220 DYEING OP TEXTILE FABRICS. [Chap. Xt colours, e.g. J for blacks, browns, olives, &c., the colour- ing matters used in conjunction with them being, as a rule, decoctions of Logwood, Quercitron Bark, Sapan- wood. Alizarin, &c. The method of impregnating the cotton with the chromium solution and steaming seemed indeed as if it might be the only method of fixing an adequate amount of mordant on the fibre for purposes of dyeing, since the ordi- nary methods of precipitation employed with the aluminium and iron mordants give only very indifferent results. Satisfactory results are, however, obtained by adopt- ing the method proposed by H. Kochlin. The cotton is impregnated with the chromium solution, dried, and then passed through a boiling solution of carbonate of soda (100 grams per litre). Solutions of the basic sulphate, Cr4(S04)3(OB[)6, and the basic nitrate, Cr2(NOo)3(OH)3,give the best result; then follows the basic nitrate-acetate, Cr2N03(C2H302)2(OH)3 ; but all the chromium salts, even the normal ones, allow a satisfactory amount of mordant to be precipitated upon the fibre by this method. If the temperature of the soda solution is below the boiling point, or if phospliate of soda, &c., be substituted for the carbonate, the results obtained on dyeing are not so good. With regard to this last point, it is quite possible that the difference may be caused through the precipitated chromic phosphate not possessing such a power of attract- ing colouring matter as hydrated chromic oxide. If the cotton before being impregnated with the chromium solution is prepared with anmioniacal sul- phated oil (100 grams per litre), the results obtained on dyeing are still further improved. In this case ground chalk suspended in water may be substituted for the soda solution, and with equally good results. Liechti and Schur have shown that a solution of chromium acetate or nitrate-acetate, is not precipitated by addition of an alkali in the cold, but only on heating, and point out that this fact is capable of being applied by the calico-printer for steam-colours. The printing- colour Chap. XI.] CHROMIUM MORDANTS. 221 may be made by mixing in the cold, suitable proportions of chromium nitrate-acetate, sodium carbonate, and colouring matter. Good results are obtained, for example, with such colouring matters as Logwood extract and Alizarin, the chief difficulty being apparently, that the mixture is apt to decompose and become gelatinous on standing. The following are the proportions of ingredients of a steam-alizarin-chocolate mixture given by Liechti and Schur : — 100 cubic centimetres of basic chroiniuin-mtrate-acetate*o8° Tw. (Sp. Gr. 1-29). 250 grams of alizarin (10 per cent, paste). 25 „ ammonia (20 per cent.). 11 „ sodium carbonate crystals. Make up to one litre with water. More recently H. KDchlin has observed that cellulose possesses the property of attracting chromic oxide by mere steeping for several hours in an alkaline solution of chromium acetate. The following is the solution recommended : 100 grams of chromium acetate, 23" Tw. (Sp. Gr. M15), lOU grams of caustic soda, 66'" Tw. (Sp. Gr. r33), 50 grams of water. Cotton may be mor- danted by steeping in this solution for twelve hours ; after washing it is ready for dyeing. In practice, how- ever, the method of drying, quick steaming, and washing, is preferred. The chromic oxide fixed on the cotton is .said to be still combined with sotla, forming, as it were, an acid chromite of soda. Another method adopted by the calico-printer, but capable of wider apj^lication, is to print or pad the calico in a solution containing potassium dichromate, sodium thiosulphate, and magnesium acetate. At the ordinary temperature, and without access of light, these various salts do not react upon each other, but if the printed or padded cloth, after drying, is steamed, under the influence of tlie magnesium acetate, reduction of the potassium dichromate by the thiosulphate takes place, and chromic oxide is deposited upon the fibre. 222 PYEIXa OF TEXHLE FABRICS. [Chap. XL 169. Application to Wool. — ^The only chromium salt (other than bichromate of potash) which seems to have been used as a mordant for wool is chrome-alum. It is capable of giving good results, but it requires the addition of somewhat large amounts of cream of rartar to the moidanting bath, in order to render the latter properly eflectiva In any case its mordanting power is by no means equal to that of an equivalent quantity of bichromate of potivsh. In those cases where the oxidising action of bichro- mate of potash acts injuriously upon the colouring matter employed, the use of chrome-alum in its stead might cer- tainly be recommended, but for the gi-eat majoiity of cases it has no advantages over its more successful rival. It is possible that some of the basic salts of chromium may mordant wool better than the normal ones, but it will be difficult for them to supplant bichromate of potash. 170. Application to tSilk. — The chromium salts in which the chromium acts as a base have hitherto found little or no use in silk dyeing. They are, however, well worth the attention of the dyer. COPPER MORDA>'TS. The use of copper salts as mordants is unimportant ; in most of the cases whei*e they are employed by the textile colourist, they serve principally as oxidising agents. ^ 171. Copper Sulphate (CuS0^-5H;0) is manufac- tured in large quantities by roasting copper pyrites or other ores containing copper, and subsequently heating them with snlpliuric acid. Purification fi'om iron is generally effected by fii-st precipitating the whole of the copper from the impure solutions by means of iron, and then re-dissolving it in dilute sulphuric acid. To the dyer, copper sulphate is well known under the names " blue- vitriol, '" " blue-stone." »ta Sevei-al insoluble basic sulphates are known. Chap. XI.] COPPER MORDANTS. 223 172. Copper Nitrate [Cu(]Sr03)2'3H20] is obtained in solution by dissolving copper or copper oxide in nitric acid, or by tbe double decomposition of solutions of copper sulphate and lead nitrate. On evaporating the solution deliquescent crystals are obtained. In the dry state it is of a very unstable nature, and possesses strong oxidising properties. 173. Cupric Chloride (CuCl2-2H20) is obtained in solution by dissolving copper oxide or carbonate in hy- drochloric acid. In the crystalline state it is very deli- quescent. Insoluble basic cupric chlorides are known. 174. Copper Acetate. — The normal salt having the formula [Cu(C2ll302)2.Il20] is obtained in solution by dis- solving hydrated copper oxide or carbonate in acetic acid, or by the double decomposition of copper sulphate and lead acetate solutions. In the crystalline state it effloresces when exposed to the air. It is very soluble in water. Of basic copper acetates the best known is " blue verdigris " [Cu20(C2H302)2-6H20]. 175. Copper Sulphide (CuS) is obtained as a black precipitate by the double decomposition of copper sul- phate and sodium sulphide solutions. 176. Application of the Copper Salts to Cotton. — All the above copper salts are used on account of their oxidising properties. In this respect the nitrate is the most energetic. They enter, for example, into the com- position of several calico-printing colours containing Catechu, e.g., madder browns; also in steam-colours con- taining colouring principles whose colouring power is developed by oxidation, e.g., decoctions of Logwood, Sapanwood, &,c. Copper sulphate and nitrate have also been used in printing-colours intended to resist the fixing of indigo-vat-blue on calico, in which case tlioy oxidise and precipitate the indigo before the reduced indigo solution can reach the fibre. The cotton dyer frequently adds copper sulphate in small quantity to the catechu decoction used for pro- ducing catechu browns (see p. 369), and it is occasionally 224 DYEING OF TEXTILE FABRICS. (Chap. II. employed as an oxidising agent in the production of certain logwood blacks. Copi^er sulphide forms a usual constituent of the aniline black printing -colour of the calico -pidnter. During the ageing process it is changed into copper sulphate, which assists in the oxidation of the aniline salt. L 177. AppUcafion to Wool — Copper sulphate may be used as a veritable mordant in wool-dyeing, and be applied after the boiKng of the wool with the colouring matter as a so-called " saddening '" agent. Very often it is used in this manner along with ferrous sulphata In conjunction with cream of tartar, it may cii-tainly be applied in the ordinary manner, i.e., previous to boiling with the solu- tion of colourmg matter, but the colours thus produced possess no superiority over those obtained by the use of Qther cheaper mordants, e.g., bichromate of potash. 178. Application to Silk. — Copper salts wei'e for- merly used in conjunction \vith Logwood for obtaining imitation indigo blues. At present they are occasionally used as " saddening '' agents, and to give a particular tone of colour to certain blacks. LEAD MORDANTS. 179. Lead Acetate [Pb(C,H30,),-3H,0], known also as " white sugar of lead," is prepared by dissolving the requisite amount of litharge (PbO) in acetic acid, and evaporating the solution to crystallisation. "Brown sugar of lead " is prepared in the same way, substituting crude acetic acid or pyroligneous acid for the purer acid. A solution of the basic lead acetate, ( C£H30.^)^Pb.,0 "H.^O, is obtained by dissolving the calculated amount of litharge in a solution of the normal acetate. By using excess of litharge, a still more ba,sic solution is obtained. Both solutions soon become milky through absorption of carbonic acid from the air. 180. Lead Nitrate [Pb(N03),] is prepared in a similar manner by dissolving litharge in hot dilute nitric acid. It frequently contains coj:>per as an impurity. A solution Chap. Xt] MANGANESE M0RDANT3. 22.') of basic nitrate of lead [Pb(ISr03)(0H)] is obtained by boilins: a solution of the normal salt with the calculated amount of litharge. Application of lead salts to the fibres. — The above salts are used both by the calico-printer and the cotton-dyer for the production of orange and yellow colours. The cotton is printed or impregnated with a solution of the lead salt, and afterwards passed into a solution of bichromate of potash. With the calico- printer, steaming of the dried printed fabric and fixing of the lead as lead sulphate, by means of sodium sulphate, may intervene; with the cotton-dyer these operations are replaced by passing the cotton impregnated ^vith lead salt into a bath containing milk of lime or ammonia. In the colour produced, the lead oxide fixed on the fibre may fairly be considered to act as the mor- dant, and the bichromate of potash, or chromic acid, as the colouring matter. Basic lead acetate is used for the weightiug of white silk. The great defect of lead colours is that they are poisonous, and are blackened when exposed to the action of sulphuretted hydrogen. MANGANESE MORDANTS. Although hydrated manganese oxides may act as mordants, manganese salts have not hitherto been em- ployed by the dyer for this purpose. 181. Manganous Chloride [MnClo'^HoO,] obtained as a by-product when dissolving manganese dioxide in hydrochloric acid for the production of chlorine, is used in dyeing cotton manganese brown or bronze. The cotton is impregnated with a solution of manganous chloride, then submitted to the action of ammonia or passed through a boiling solution of caustic soda, and the manganous hydrate thus precipitat€d is oxidised to form brown manganic hydrate either by exposing the cotton to air or by passing it through a dilute solution of bleach- p 226 DYEING OF TEXTILE FABRICS. [Chap. Xl. ing -powder. Cotton thus dyed brown may be further treated with solutions of various aromatic amines, e.g.^ sulphates of aniline, naphthylamine, kc, for the pro- duction of fast aniline black, naphthylamine brown, (to. In this case the manganic oxide acts, not as a mordant, but as an oxidisinor assent towards the orcranic salts. 182. Potassium Permanganate [KMnO^] is pre- pai'ed by heating a mixture of manganese dioxide, potassium chlorate and caustic potash, and extracting the sintered mass with water. On account of its power- ful oxidising properties, it has been proposed as a bleach- ing-agent for cotton, wool, and silk. Its application in this dii'ection has, however, met with little success. SULPHUR AS A MORDANT. 183. It has been observed by Lauth that when wool is boiled with a solution of thiosulphate of soda (Na^^SoOg'SHoO) (generally called hyposulphite of soda), to which a mineral acid has been added, the fibre undergoes a peculiar change. It loses its elasticity, and becomes soft and contracted. Amorphous sulphur is, indeed, precipitated upon the fibre, and thus imparts to it a special attraction for certain basic coal-tar colouring matters. This property has been made use of in practice in dyeing with Methyl and Malachite Greens, for which (more particularly the former) wool has little affinity. Experiment proves that only that modification of sulphur which is insoluble in carbon disulphide can act as a mordant in this way. SILICA AS A MORDANT. 184. It has been observed that if cotton or wool be impregnated with a solution of silicate of soda, and then passed into dilute mineral acid, so as to precipitate sdica upon the fibre, tliey dye up very well in solutions of certain coal-tar colouring matters, for which they have naturally little or no attraction. It has been found, too, that precipitated silica has the power of attracting Chap. XL] TANNIC ACID. 227 alumina and other mordants, and can then be dyed much in the same way as mordanted cotton can. TANNIC ACID AS A MORDANT AND AS A FIXING-AGENT FOR MORDANTS. 185. Tannic Acid is the name given to a certain astringent principle found in Gall - nuts, Sumach, Myrabolams, and other vegetable products, which are largely used by the textile colourist. It is readily extracted from the above substances by means of a mixture of alcohol and ether. In its pure state, it appears as an amorphous, colourless powder, very soluble in water, and possessing a strong astringent taste and an acid character. Its employment by the dyer depends upon the fol- lowing properties : — 1. Towards colouring matters of a basic character — e.g., Magenta, Malachite Green, &c. — tannic acid acts the part of a mordant, as truly as alumina does towards such phenolic colouring matters as Alizarin, since it combines with the colourless base they contain, to produce an insoluble coloured lake or pigment. During the precipi- tation of the solution of a basic colouring matter by tannic acid, there is always a liberation of the hydro- chloric acid or other acid in combination with the colour- base. J. Kochlin has noticed, for example, that the addition of an alkali — e.g., carbonate of soda — to the mixture, facilitates the precipitation and renders it more complete. For the production of a tannic acid lake, it is not at all essential that the tannic acid should be in the free state. Insoluble metallic tannates possess an equal, if not greater, attraction for basic colouring matters. The presence of the metallic oxide facilitates the decom- position by reason of a portion neutralising the liberated acid of the colouring matter, and it is probable that a very insoluble dibasic compound (tannate of antimony and colour-base) is produced. The use of an insoluble metallic tannate prevents the colour-lake formed on the 228 DYEING OF TEXTILE FABRICS. [Chap. XI fibre fi'om being re-dissolved during the process of dyeing or of final washing, either by excess of tannic acid or colour- ing matter. It is well known that excess of tannic acid gives soluble compounds with bcisic colouring matters, a fact which makes it necessary to apply to the cotton fibre, first the exact amount of tannic acid requisite, and then the colouring matter. 2. Just as tannic acid can produce insoluble com- poiuids with organic colour-bases, so it does with inorganic bases, e.g., alumina, ferric oxide, stannic oxide, soiling of the printing-colours by ii'on. 232 DTEiyO OF TEXTTLK FABBIC& [Chap. Xi. In its capadtj as a fixing -agent for aluminiam mordants, tai^Tiir! acid, in the form of Snmach, lias long been used bj the Torkey-red dyer. Its mode of applica- tion is given on page 432. 187. Application to SUk. — Tannin matters are largely employed by the silk-dyer, partly for the purpose of adding weight to the silk, and partly as the basis of certain black dyesi Silk is able to absorb as mnch as 15 per cent, of its weight from a cold solution of tannic aod without its bnliiancy or feel being injuriously affected ; it seems, indeed, to gain slightly in strength. From a hot solution silk will gain as much as 2-5 per cent, of its weight, and this more rapidly even then from a cold solution. At TCP C the action is already nearly complete, the maximum effect being readied a litde bdow the boiling point. Although the tannic acid seems to be well fixed, and resists washing witli water, a solution of soap, especially if warm, is able to remove the whole of the taxmic acid, leaving the silk slightly tinted, and with its onginal properties more or less modified. The action of tannic add on silk is regarded by some as a diemical one ; it seems, at any rate, to be similar to that which it has upon animal skins^ Tanned silk does not allow endosmose and exosmose to take place through- out its substanca This is well seen by the fact that, whereas raw and boiled -off silk absorb considerable quantities of basic ferric sulphate (gee p. 185), tanned silk has to a large extent lost this property. When tannic add is applied to silk fen* the purpose of yidding a black dye, the silk is repeatedly steeped in tepid solutions of tannic acid (chestnut extract) and pyrolignite of iron. OIL AS A MOROAST AND AS A FIXIXG AGENT FOB MORDAXTS. 188. Use of Oils in Dyeing. — The fact that fatty matters can be advantageously employed by the dyer has br«n i-ecognised from very early timesi The Chap. XI.] OIL AS A MORDANT. 233 ancient Hinp^H'.nH Chap. XI. I SULPHATRD OIL. 235 When boiled with dilute caustic alkali, it decomposes with the production of insoluble oxyolei'c acid, glycerine, and sulphuric acid. Its alkaline compound is soluble, but those of the alkaline earths and heavy metals are inso- luble ; they are readily obtained by mixing its aqueous or alkalir.e solutions with solutions of the metallic salts. The aluminium compound [Al4(Cj2H740iaS)3j is a white or slightly yellowish body. The substance which is insoluble in water but soluble in ether is oxyoleic acid (OigHo^Oa). It is readily soluble in alkaline water, forming a soapy liquid, which produces with solutions the salts of the alkaline earths, earths, and heavy metals, tarry or flocculent precipitates very soluble in ether. A secondary reaction seems also to take place, probably giving rise to the production of an intermediate and unstable ether derivative of oxystearic acid. This is decomposed during the washing with water, and produces sulphuric acid, and oxysteaTic-glycerine-sulphuric-ether (C42lIg20i2S) and oxystearic acid (OigHggOg). 2(Ci8H3302)3C3H5-f 7H2S04-t- 8H2O = C42H80O12S + 4C18H36O3 + Tn-olein, Oxystearic - Oxystearic g]ycerine-sul- acid, phuric ether. + 6H0SO4. Castor oil consists essentially of the glycerine com- pound of ricinoleic acid, CigHasOg'OH, and has the composi- tion C3H,(O-0,8H33O2)3. If in the above reaction castor oil be substituted for olive oil, similar substances to those just mentioned are pro- duced, namely, trioxyoleic-glycerine-sidphuric-eiJier ; — C^sH^sO^eS, or SO^^^g^^g 33^5 ' and trioxy oleic acid (C18H34O5). The castor oil product is now a commercial article, and is sold, more or less diluted with water a^d neutralised 23G DYEING OF TEXTILE FABRICS. [Cbap. XL with caustic soda or ammonia, under the following names, Turhey-red oil, alizarin oil, sulpliated oil, soluble oil, »tc. When properly made and perfectly neutralised or rendered slightly alkaline, it dissolves in distilled water, giving a perfectly clear solution. If the water contains Ume, (fcc., the solution is more or less milky, from the formation of the lime compound. Some commercial "soluljle oils " are merely solutions of a castor oil soda- soap. These are readily made by boiling castor oil with the requisite amount of dilute caustic alkali ; saponification takes place with the greatest ease. 190. Application to Cotton. — As a fixing-agent for aluminium or iron mordants, the method of applying oil in its se%eral forms to cotton is given under the head of *• Application of Alizaiiru" (See pp. 428, 438, 443.) As a mordant for the basic coal-tar colours, oil i« generally applied in the form of sulphated castor oil, castor oil soap, or even ordinary oil soap. For mordanting yarn or calico, the fii^st, second, third, and fourth operations, given on pp. 427, 438, 442, may be employed, but frequently only the first, second, and fourth are adopted, i.e., the bleached material is first impregnated with the alkaline solution of sulphated oil or soap, then immei'sed in a solution of aluminium salt, and finally washed previous to dyeing ; if dried and steamed before dyeing, the colour is faster to washing and soap- ing. Since in this application the modified fatty acid is the real mordanting body, the aluminium salt must be considered as only employed for the purpose of fixing it. The fact is that the metallic comf>ounds of these modified oils are dupUx mordants, either the basic or acid con- stituent of the compound may act in the capacity of mofdant, according as the colouring matter employed is of the opjxjsite character. The metallic compounds of tannic acid are in exactly the same position. Dyed aniline colours fixed by means of oil mordants are brighter than those fixed with tannic acid, but they are not so fast to boiling soap solutions. Clmp.XI.J ALBUMEN, CASEIN, AND GLUE. 237 The calico-printer makes considerable use of siilphated oil as a general prepare for steam-alizarin and steam- aniline colours containing tannic acid, since the presence of the oil in the fibre intensifies and brightens the majority of these colours very considerably, and makes them faster to boiling soap solution. The cloth is simply padded in a neutral or slightly ammoniacal solu- tion, more or less dilute, and dried previous to printing. Apart from their use as mordants, sulphated castor oil and castor oil soap are largely used in finishing for the purpose of softening heavily-starched goods, or dyed cloth or yarn, whicli would otherwise have an unpleasant harsh "feel." The principal objection to their use for this purpose, and one which is sometimes brought against their use as mordynts, is that, after a lengthened period, the goods contract an unpleasant rancid odour. i91. Application to Wool and Silk. — Oil mordants have not yet found any use as such for wool and silk. Certain preparations made by mixing olive oil and sulphuric acid have hitherto been used only for softening purposes. ALBUMEN, CASEIN, GLUE, ETC., AS MORDANTS. 192. Albumen is a nitrogenous animal substance soluble in cold or tepid water. Its solutions are co- agulated by the addition of mineral acids and solutions of various metallic salts, and also if heated to about 70^ C, in both cases the albumen being rendered in- soluble. In chemical comDosition it is allied to wool and silk, and when coagulated it behaves towards colouring matters like these fibres. It is because of the above properties that albumen is of use to the textile colon rist. Egg alhv/nien is represented in its purest form by the white of e^g. This is evaporated to dryness at a low temperature, and the dry soluble product thus obtained in the form of light yellow horny flakes is an article of commerce. 238 DYEING OP TEXTILE FABRICS. [Chap. XL If kept dry, it can be stored for a considerable time without being injuriously affected ; but, if damp, putre- faction sets in, and it becomes more or less rasoluble in water. Blood albumen very closely resembles egg albumen in its composition and properties. The chief difference is that it is somewhat darker in colour. It is obtained by evaporating at a low temperature the serum of the blood of oxen, &c The commercial product has the appearance of dark brownish-olive scales. Solutions of albumen readily putrefy, especially in warm weather ; this may be retarded, or even prevented, by slight addi- tions of borax or sodium bisulphite. 193. Ajyplication to Cotton. — Albumen is of great use to the calico-piinter for the purpose of fixing in- soluble pigments — e.g., ultramarine blue, chrome green, aniline-colour lakes, er cent sodium arsenate. As a fixing accent for moi-dants it behaves very like sodium phosphate. It is extensively used by the calico-printer as a substitute for cow-dung in the so-'^lled operation of "dunging " or ** cleansing." The use of sucli a poisonous salt for this purpose is not followed by the injurious consequences one might at first sight expect, since it is either washed out of the cloth subsequently, or is fixed thereupon in an insoluble and innocuous form. To the cotton-yarn-dyer who works his material in the solution by hand, this salt is not to be i-ecommended as a fixing- agent, since it readily causes ulcerated sores on the hands of the workmen. It must be borne in raind, too, that its employment may entail contamination of the neighbouring stream with a poisonous salt. Chap. XI.] FIXING-AGENTS FOR MORDANTS. 241 200. Sodium Tetrasilicate or Silicate of Soda, NaoSi^Og. — Under the name " soluble glass," this com- pound is met with in commerce in the solid form. In solution, it can be used as a fixing- agent for aluminium and other mordants on cotton. It has, however, not found very general employment in England for this purpose, since there is always the risk that excess of caustic or carbonated alkali may be present, in which case alumina, more or less fixed on the fibre by drying or ageing, would be partly dissolved off again, and lead to unsatis- factory results. Well-made silicate of soda is, however, free from defects of this kind, except through the tendency of its solutions to dissociate and form a mixture of acid and basic silicate. Mordants not soluble in alkali — e.g., those of iron and chromium — are not injuriously affected by sodium silicate. Aluminium mordants fixed by means of silicate of soda do not attract colouring matter so readily in the dye-bath as if fixed by sodium arsenate, nor are the colours produced so bright. 201. Sodium Carbonate (Na.COg-lOHoO).— This salt constitutes the " soda crystals " or " washing soda " of commerce. Tlie salt NagCOa-HoO, is sold in an almost chemically pure state under the name of " crystal car- bonate." It is largely used for purposes of neutralising acid liquids, and in a crude calcined form as soda-ash in bleachin^r cotton. It serves as the most useful fixinar agent for ferric and chromic oxides on cotton ; in the former case its solution is used cold ; in the latter boiling hot. 202. Ammonia (NH3). — This gas, dissolved in water, serves for general purposes of neutralising. It serves as a fixing-agent for lead acetate, but for fixing aluminium and ii'on mordants on cotton it is unsuitable, not only on account of its volatility, but because it does not give such good results as sodium phosphate and arsenate. 203. Ammonium Carbonate [H ( NH^) C0 3-|- NH4C02NH2]. — This commercial salt forms a white, semi- 242 DYEING OF TEXTILE FABRICS. [Chap. XL transparent, fibrous mass. "When it is dissolved in water, the carbamate, KH^COoNH.,, is changed into the normal salt, (NH4)oC03. According to Liechti and Wolf, it U one of the best agents for fixing alumina upon cotton. Make a solution containing 40 grams of ammonium cai- bonate per litre, and use it cold, or at a t-emperature of 45°_50° C. 204. Calcium Carbonate (CaCOa). — As gi-ound chalk or "whitening," this substance is frequently employed for the purpose of neutralising acid liquids, and forms occa- sionally an excellent fixing-agent for alumina and other mordants upon cotton, e.g., upon oil-prepared calico. As an addition to the alizarin dye-bath, it has long rendered essential aid to the full development of the ultimate colour, though it is now advantageously replaced, in many instances, by calcium acetate. 205. Antimony Potassium Tartrate [K(SbO)C4H,OJ- — This salt, better known as " tartar- emetic," is only slightly soluble in water. It precipitates a solution of tannic acid, especially if neutral salts are present, e.g., NaCl, NH^Cl, itc. Tartar- emetic, employed for fixing tannic acid in its capacity as a cotton mordant for basic coal-tar colours, gives most satisfactory results. One important point to be remembered is that, with continued use, a tartar-emetic bath becomes ineffective and even iujurious before it is quite exhausted. Through the abstraction of antimony there is a gi*adual accumula- tion of acid potassium tartrate in the bath, wliich tends to dissolve the antimony tamiate or colour-lake from the fibre. A good substitute for tartar-emetic is the cheaper antimony potassium oxalate [K3Sb(CoO^)3*6H^O]. It is more sensitive and gives up its antimony more readily than the tartrate, hence the bath becomes sooner charged with Mcid-potassium-oxalate ; the duration of the fixing process should therefore not be prolonged beyond, say, one minute, and the solution should be weak. Antimony hydrate freshly precipitated from antimony chloride by means of sodium carbonate, then washed and Chap. XI.] ASSISTANTS. 243 suspended iu water, is eveu more economical as a fixing agent for tannic acid, and is said to possess the further advantage of not leaving the batli acid. 206. Potassium Ferrocyanide [K^(¥e-Cy)6-3H20]. ' — This salt and also 2^otassium ferricyanide K3(FeCj)g have long been used by the dyer and calico-printer iu conjunction with iron salts for the production of Prussian Bkie. With solutions of several of the basic coal-tar colours they produce precipitates, and hence may, in certain cases, be emploj^ed as mordants for cotton in place of tannic acid. ASSISTANTS. Under this head may be included all those substances of use to the dyer which cannot be classed as colouring matters, mordants, or fixing-agents. It is, however, only intended to enumerate here a few of those which ai-e more prominent, and to refer briefly to some of their applications. 207. Tartaric Acid [C^H404(OH)o].— This substance is sold in the form of hard, colourless crystals, readily soluble in water. It is used by the calico-printer in the production of steam-blue, steam- green, aniline-black, &c. ; also as a resist for aluminium and other mordants, and in the discharge colours for Turkey-red. It is occasionally used by the woollen dyer as an addition to the mordant- ing bath, e.g., in conjunction with potassium dicliromate, alum, stannous chloride, &c. The silk-dyer employs it as an agent for brightening colours after dyeing. In some cases tartaric acid may be advantageously replaced by OXClllC ClCZCf 208. Acid Potassium Tartrate [C4H^04(OH)(OK)]. •—This salt is better known as cream of tartar or tartar. It forms hard, colourless crystals, but is more usually sold as a white crystalline powder. In its crude state it is called red or white " argol," according as it has been deposited during the fermentation of red or white wine. It is extensively employed by the woollen-dyer as ao 244 DYEING OF TEXTILE FABRICS. [Chap. XL addition to the mordanting bath, e.g., in conjunction with alum, stannous chloride, &c. In such cases, double decomposition undoubtedly takes place, and the corre- sponding tartrates, or double salts, which are formed, seem to be more suitable as mordants than the original salts. Why this is so has not yet been determined, but probably the alumina is fixed upon the fibre in larger amount and in a more suitable form ; no doubt, too, if the liberated tartaric acid absorbed by the fibre is improperly washed out, it will be less injurious in the dye-bath than the sulphuric acid of the alum would be. Certain it is that the addition of tartar to the mordanting bath, in suitable amount, adds fulness and brilliancy to the ulti- mate colour. By mordanting wool with pure tartrates of aluminium, &c., excellent results are obtained. Owing to the comparatively high price of cream of tartar many substitutes for it have been proposed, and also employed. These bear such names as " tartar substitute," " pro- argol," &c., and generally consist of mixtures containing oxalic acid, bisulphate of potash, alum, common salt, &c. " Essence of tartar " is a solution of tartaric acid, fre- ({uently adulterated with sulphuric acid. " Super-argol " is said to be a mixture of white argol and sulphuric acid, the latter present in amount sufticient to combine with the potash. It may be confidently asserted that all these substi- tutes, if at all useful, can be made more cheaply by the dyer himself, and, as a general rule, the real value and economy of all articles bearing fancy names may be doubted. In those cases where the use of tartar or argol depends entirely or mainly upon their acid properties, cheaper acid salts may frequently replace them with advan- tage, but not where their action is due to the property they possess of forming double salts. 209. Acetic Acid [C2H30(OH)]. — This acid, also known in its dilute and less pure form as " vinegar," ia largely obtained as a product of the dry distillation of C^P. Xl.j ASSISTANTS. 245 wood, and by the oxidation of dilute alcoholic liquids. It is of very general use — e.g., as a solvent for colouring matter — to acidify dye-bath solutions, to neutralise calca- reous water, as an addition to printing colours, itc. 210. Acetate of Lime [Ca(CoH30,,)/2HoO].— This salt is prepared by dissolving chalk or calcium carbonate in acetic acid. It is used as a solution, and should be as free from iron as possible. The best commercial pro duct sold as a white powder contains about 90 per cent. CafCoHnOo)^. In a more or less crude fonn, namely, as pyrolignite of lime, it is largely employed for the pui-pose of making commercial aluminium acetate (red liquor). It is of very special value as an addition to the dye- bath when using non-calcareous waters in dyeing with several colouring matters, e.g., Alizarin, Logwood, Brazil- wood, Weld, (tc. The exact rOh of the lime-salt in such cases is, perhaps, not yet fully determined. The view which seems to explain known facts the best is that the calcium forms a necessary constituent of the coloured lake fixed on the fibre. In woollen dyeing, it will certainly have the primary effect of neutralising the acidity of the mordanted fibre. 211. Sulphuric Acid (HoSO^).— This acid is exten- sively employed as an assistant in the dye-bath by the wool- and silk-dyer when aj^plying those "acid colours," which consist of the alkali salts of sulphonic acids, e.g.^ Azo-scarlets, Indigo Carmine, &c. It is also frequently employed along with potassium dichromate in the mor- danting of wool (see p. 209). It serves generally for neutralising alkaline solutions. s^ 212. Sodium Sulphate (Na,SO,-10H,O).— This salt, also known as Glauber's salt, is extensively employed by the woollen-dyer as an aid to obtain even, regular, or level dyeing. Being very soluble, it raises the Specific Gravity and the boiling point of the dye-solution if used in large amount, and this fact alone may possibly be of some little 246 DYEIXG OF TEXTILE FABRICS. [Chap. It. service in cei'tain dyeing operations. .The shade of an aniline violet, for example, can be made reddish or bluish, according to the temperature of the dye-bath. When added to a woollen dye-bath as a " le veiling- agent," it tends to render the colouring matter less soluble, and the latter is then only attracted giadually by the wool, as it dissolves. Sometimes it may be necessary or convenient, in dyeing compound shades, to add to an acid dye-bath colouring matters wJiose dyeing power is actually di- minished by the presence of acid, e.g.^ Orchil, Magenta, redwoods, ^c. In such a case, the addition of sodium sulphate to the dye-bath causes them to dye better, since it tends to reduce the acidity of the bath by combining with the free sulphuric acid used to form sodium bisulphate. If the addition of the sodium sulphate is regulated, it is even possible to determine the rapidity vt-ith which the wool shall take up such colouring mattere, and a means of shading is thus afforded. In order to pre- vent excessive felting of woollen yarn it may sometimes be preferable indeed to shade in this manner, rather than to remove the textile material frequently from the dye-bath, for the pui*pose of adding fresh colouring mattei. If, by mistake, an excess of colouring matter should be added, a further addition of sulphuric acid will rectify the error. A similar example is afforded in the dyeing of red, brown, and grey shades on wool mordanted with potassium dichromate, where Logwood or Peach- wood are used in small amount. To prevent these dye- woods from giving up their colouring matter too rapiclly, and thus dyeing unevenly, one may either add a large amount of sodium sulphate from the beginnincr, or first a little svdphuric acid, and afterwards sodium sul- phate gradually. By the first plan, the colouring matter is made to dissolve irraduallv ; bv the second, its dveins power is diminished, and only developed on the addition of the sodium sulphate. The prevention of too rapid and consequently uneven CLap. XL] LEVELLING-AGENTS. 247 dyeing by the use of sodium sulphate is exemplified in dyeing with Indigo Carmine, Azo-scarlet, and other acid colours. 213. Boiled-off Liquor.— This is the soapy liquid which has been employed for the purpose of removing the silk-glue from raw-silk previous to dyeing. It is, hence, a slightly alkaline, more or less concentrated' solution of silk-glue. To the silk-dyer it serves much the same purpose as sodium sulphate does to the woollen- dyer, especially in the application of coal-tar colours. If added to the dye-bath in suitable amount, it causes the colouring matter to be attracted more slowly and evenly by the silk. It also preserves the lustre of the latter. If used in excess, it is very injurious, since it wastes colouring matter and destroys the lustre of the silk. As a suitable amount for most cases, 50 — 100 cubic centimetres of boiled-off liquor per litre of dye-bath solution may be employed. AVhen this liquor is not obtainable, it can be re- placed, with more or less success, by a solution of soap and gelatin. 248 METHODS AXD ]\IACHmERY USED IX DYEIXG. CHAPTER XII. yOTES ON COTTON, WOOL, AND SILK DYEING. 214. Methods of Cotton Dyeing. — Owing to the slight attraction which cellulose has for the great ma- ioritv of colouring matters, the method of dyeing cotton usually compi-ises the two operations of mordanting and dyeing. As a general rule, these operations are perfectly dis- tinct, and follow each other in the order given. This is decidedly the most rational plan; it yields the best results, both with respect to brilliancy and depth of colour, and to fastness against washing, soaping, ttc. In some cases the " one-dip " method — i.e., dyeing in a single bath containinc; both colourinsr matter and mordant C7 O O — is adopted, e.g., for logwood and copper sulphate blacks. This plan, however, is by no means of general application, and although saving time and labour, it never gives such good results as can be obtained by the first method. Of course where no mordant is required — e.g., in indigo- vat- blues, aniline black, &c — a single bath only is necessary. Another plan, frequently adopted, but by no means the most rational, is first to impregnate the cotton with a solution of colouring matter, and then in a separate bath to apply the mordant, as in certain logwood blacks. It invariably gives pale colours, because the absorbent power of cotton is too limited to take up the necessary amount of colounng matter; hence the operations require Chap. XII.] METHODS AKD MACHINERY. 249 to be repeated several times, or very concentrated colour solutions must he used, to obtain a satisfactory result. The principle of the process really consists in precipitating on the fibre successive layers of pigment (compound of colouring matter and mordant), and, indeed, in a most superficial manner, so that the dyes obtained by this method are never so fast to rubbing or washing as thoso produced by the first method alluded to. Sometimes, for example, in the production of catechu browns, the last-mentioned method is the best possible ; but in this case the cotton has a marked attraction for the active principle of the Catechu applied in the first bath, and absorbs large quantities of it. The potassium dichromate used in the second bath serves rather as an oxidising agent than as a mordant. 215. Operations, &c., in Cotton Dyeing. — Cotton is dyed in all stages of manufacture, namely, as loose cotton- wool, cotton yarn or thread, either in hank or " chain " (warps), and as cotton cloth (calico). It is mostly dyed in the form of yarn or cloth, but in recent years raw-cotton lias been extensively dyed for the purpose of mixing with dyed wool previous ro the "scribbling" process. Only in few cases can really satisfactory colours be obtained, able to withstand the subsequent scouring and milling processes of the woollen manufacturer {e.g., aniline blacks, catechu browns, kc). When light shades of colour are to be dyed, the cotton, in whatever state it may be, should be thoroughly bleached. For dark colours (in order to ensure even dyeing after- wards) it suffices to boil the cotton well with water, preferably with the addition of sodium carbonate. Baw-cotton is apt to become matted by such pre- liminary boiling, and the operation is usually omitted ; but it is invariably done with cotton yarn. As to calico, all sizing material, at least, should be removed, even if further bleaching be not attempted. There is a prevalent opinion that cotton should only 250 DYEISG OF TEXTILE FABRICS. fChap. XIL be dyed in the cold, but it is altogether a mistaken ona When, for example, it is possible to fix the necessary mordant on the fibre in a thoroughly insoluble state, cold dyeing is not to be recommended, except where a high temperature would destroy the brilliancy of the colour. Cold or tepid dyeing is employetl when the mordant applied is more or less soluble ; for example, if tannic acid only is used, or if the colour-lake is soluble in hot water, e.g., ordinary azo-scarlets on cotton. In some cases the employment of a high temperature is absolutely necessary, as, for instance, when the colouring matter used is not very soluble, e.g., Alizarin. The various de\^ces for ensuring " level " dyeing will be treated of in " Xotes on Wool-Dveing " (see p. 276.) 216. Unspun Cotton Wool. — Dyeing Machinery. — The dye- vessel employed for raw-cotton is similar to that described as being used for loose-wool [see p. 277). Direct lire heat is seldom or never adopted. In recent years various novel arrangements have been proposed and patented, but their practicability has yet to be proved, e.g.^ vacuum-dyeing machines. Washing Machinery. — The washing of raw cotton may be eftected by the raw-wool scouring machine {see p. 100). Excess of water is removed by passing it between a pair of squeezing rollers, or by means of the centiifugal machine (hydro-extractor). Drying Machinery. — Raw cotton may be dried on the machines described as being used for loose-wool {see p. S77). 217. Cotton Yarn. — Dyeing Machinery. — For hank- dyeing the simplest method is to work the hanks in the dye liquor by hand in the manner described for woollen yam scouring on p. 105. With large quantities of any single colour, e.g., Turkey-red, logwood-black, indigo-blue, kc, the employ- ment of dyeing machines becomes almost imperativa Chap, mt] MACHINERY FOR COTTON YARN. 251 Figs. 48 and 49 represent an excellent machine, de- signed by A. Wilson, of Paisley. It consists of an ordinary rectangular wooden dye- Fig. 48.— Hauk-Dyeing Machine. vat fitted with a four-armed skeleton-winch, upon which the rods, previously filled with yarn, can be readily suspended. In charging the ma- chine, the arm a is brought into the upright position, the movable portion B is lifted ofi" the cross piece, and the hinged portion at c is turned back. The hanks of yarn are hung on pairs of light wooden rods ; these are placed in Fig. 49. -Section of Fig. 48. the sockets at b and c, and then securely fastened down by re] facing the movable portions alluded to. The winch is then turned round, and the other half is filled with hanks in a similar 255 DYEING OF TEXTILE FABRICS, [Chap. Xit. uianner ; b represents the arrangement of sockets with movable caps in the central part of the winch, D that at the ends where there are no movable parts, the ends of the rods l>eing merely pushed into the sockets. When the dyeing is finished, the whole winch full of yarn can }3e raised with a ti^velling crane out of the dye- vat by the rings e, and lowered into another vat for washing, 67 The cloth is drawn from the machine by means of a roller or wincli actuated by the pulley m. The pressure of the brass disc B against the grooved roller a is regu- lated by the screw c connected with lever and spring ; N N are fast and loose driving pulleys. Dnjing Jfachinenj.—CaMco is frequently dned m Fig. 65.— Side View of Fig. 61. stoves heated with hot flues or steam pipes situated in the basement {fiee p. 441). The internal arrangement for suspending the pieces varies. In some the building is one- storey ed, and the pieces are suspended in zigzag fashion from wooden rails placed near the roof, so that the loose folds come within a few feet of the iron grating over the flues In 268 DYEIXG OF TEXTILE FABRICS. [Chap J.IL others, the stove is divided into several storeys, each with floors of iron grating, and furnished with wooden fi-ame- work having long parallel rows of upright wooden pegs. One selvedge of the pieces is passed alternately from right to left, and twisted over the j^egs. By this plan of Kg. 66. — Hot-air Drring Machine. hanging it is possible to pack a much larger quantity of cloth into a given space. Calico is also dried by means of the steam-cylinder drying machine described on p. 286. When it is not desirable that the cloth should come into actual contact with a heated metallic surface — e.g., in drying cloth after impregnating it with mordants which are injuriously affected by a high temperature — the pieces may be made to ti"avei-se a closed hot-air chamber fitted with wooden ix)llers at the top and bottom. Fig. 66 shows the arrangement used by the calico-printer for diying the pieces immediately after printing. The fan d drives a current of air in a zigzag course along the channels c sur- rounding the steam pi|)es b. The heated aii- passes into thiC upper drying chamber, there moves in a direction Cliap. Xn.J METHODS CF WOOL DYEING. 269 contrary to that of tlie pieces, and makes exit at tlie top. In this particular case three different pieces of cloth are dried simultaneously : the printed piece E, the back-cloth or grey G, and the endless blanket H. In some cases calico is dried on the so-called " tenter- m^r " machine, similar to those used for woollen cloth {see p. 287). NOTES ON WOOL DYEING. 219. Methods of Wool Dyeing.— The methods of dyeing wool differ considerably from those employed for cotton and other vegetable fibres. Wool has a much greater affinity than cotton for most of those colouring matters in which the colour is ready formed and does not require developing by the use of mor- dants. Such is the case, for example, with a number of the coal-tar colours. It is sufficient in many cases to add the solution of the colouring matters to the cold or tepid water contained in the dye-bath, and after introducing the woollen material, to raise the temperature of the solution. With such colouring matters as require a mordant to develop the colour they yield, e.g., Logwood, Camwood, Cochineal, (tc, the exact mode of dyeing varies according to the nature of the colouring principle and the mordant. The following three methods are employed in practice :— 1. The wool is first boiled in a solution of the metallic salt or mordant, and afterwards in a fresh bath con- taining the solution of the colouring matter or dyewood decoction. In other words, the wool is mordanted first and dyed afterwards. Dyers sometimes call the colours dyed by this method " prepared colours. " The mordanted cloth is said to be " prepared." 2. The wool is boiled in a solution of the colouring matter or dyewood decoction, and when, after some time, it has absorbed as much of the colouring principle as possible, the colour is developed and fixed on the wool by adding the mordant to the same bath. This method has been generally adopted with certain mordants which 270 DYEING OF TEXTILE FABRICS. [Chap. 111. produce dark or sombie shades of colour, and is called the " stuffing " and " saddening " method ; the " stuffing" being the boiling of the wool ■witli the dye-stuff, and the " saddening '"' the subsequent operation of developing the colour by adding the mordant 3. The wool is boiled in a solution containing both colourinsj matter and mordant from the besdnnins: of the operation. In this case the colouring matter and mordant combine with each other to form a coloui-ed body which an excess of the mordant dissolves ; fi'om the solution it is gradually absorbed by the wool. 4. Combination of 1 and 2. Mordant, dve, sadden. 220. The Mordanting and Dyeing Method.— The best example of the first method is afforded in the black dyeing of wool by means of potassium dichromate and Logwood. The method can be employed with most of the natural colouring mattere or dye woods in conjunction with the following mordants — alum, potassium dichix>- mate, chrome-alum, stannous chloride. AMien it is carried out in its entirety, the fabric should be well washed be- tween the mordanting and dyeing processes, in order to prevent any mordant which is not fixed on the wool fi-om being carried over into the dye-bath ; otherwise it would not only cause loss of coloiu'ing matter by precipitating it in the bath, but might also prevent the dye-stuff from yielding its colouring matter to the solution. One advantage of this method is, that the solutions used for mordanting and dyeing can be preserved for suc- cessive lots of material, and need only to be replenished occasionally. This implies that the mordant and colouring matter are better utilised. Another advantage is that the dyer can "match-off'' to any exact shade with very little trouble, since the mordant determines the tone of colour, and this being once fixed on the wool, the proportions of the various dyewoods required can be frequently altered until the de- sired shade is obtained. To ensure success in this matter it is only necessary to add in the beginning a slight Chap. Xll.i METHODS OF WOOL DYEING. 271 deficiency of each dyewood, since it is evident that no modification of the proportions wonld rectify the error caused by employing an excess of dyewood. As a nile, it may be said that from a given weight of dyewood and mordant, this method of dyeing produces colours which are deeper and richer in tone, and faster against milling than those obtained by any other method. Its only disadvantage is that it requires more time and labour, and, consequently, expense. 221. The Stuffing and Saddening Method. — The dyeing of a claret-brown by means of Camwood and ferrous sulphate is a good example of this method which is appli- cable with some of the natural matters. The mordants generally employed are ferrous sulphate, copper sulphate, or potassium dichromate, and occasionally alum . When Catechu is used as the dye-stuff, the saddening is preferably effected in a separate bath — e.(/., by means of potassium dichromate — since in this case both baths can be preserved and used continuously for successive lots of woollen material. The same may be said of dyeing the claret-brown just mentioned ; indeed, the use of two baths in this method miglit be adopted, whatever be the colouring matter or mordant employed, but this would in many cases possess no material advantage over the method of mordanting first and dyeing afterwards. The following are the advantages when the stuffing and saddening take place in one bath : — The time, labour, and expense are less. The desired tone of colour required may be some- times obtained more readily. The disadvantages are more numerous : — The colour is generally not so fast against milling and rubbing, from which it appears that it is fixed more superficially than by the first method. It is not very easy to dye to an exact shade ; indeed, this can be done only after long experience. The method demands that the correct proportions of dyewooda 272 DYEING OF TEXTILE FABRICS. [Chap. XIL required for any given shade be added to the bath before the saddening is effected, i.e., at a stage when the colour of the wool gives little or no indication of the ultimate colour produced by the action of the mordant. Any misjudged proportions would make little difference if, after saddening, one could add with effect fresh quantities of one or other of the dye woods still needed. This, however, is inadmissible, if economy of dye-stuffs is studied, because the mordant present in the bath not only prevents the extraction of colouring matter, but even tends to precipitate it within the dyewood itself, and in the liquor. It is e%'ident, therefore, that it would only yield a useful effect after a large excess of dyewood had been added, and after this a further quantity of mordant would requii'e to be added. As a rule, mis- takes in " shading " of the kind mentioned are rectilied, so far as new shades are concerned, by adding to the dye-bath SDiall quantities of some veiy soluble colouring matter requiring no mordant — c.^., Cudbear, Turmeric, or Indigo Exti-act — by which it is comparatively easy to ob- tain the exact tint required, since they at once dye the wool with their proper and only colour. With such dyestuffs, however, these last touches of colour put upon the wool do not generally possess the fastness against light, soap, and milling, of the fundamental colour. The method gives rise in most cases to much loss of dyestuff, since the wool never absorbs the whole of the colouring matter, however prolonged the lx)iling with the dyewood before saddening may be, and all the colouring matter still un absorbed is rendered insoluble and useless by the addition of the mordant or saddening agent. After saddening, the bath is thrown away, and the dense inky liquoi*s and precipi- tates increase the pollution of the river or stream. There are, indeed, many cases in which saddening in a sepai^te bath does not quite yield such full coloui-s as when a single bath is employed, since, even after the addition of the mordant or saddening agent, the dyeing still goes Chap. Xn.] METHODS OF WOOL DYEING. 273 on to some extent, the colour precipitated in the bath not being entirely insoluble, especially in the presence of a slight excess of the mordant Such is the case, e.^., witli Logwood and ferrous sulphate, Logwood and copper sul- phate. Madder and potassium dichromate^ Logwood and alum, (fee. 222. The Single Bath Method. — As an example of the third or "one-dip" method of dyeing, in which the wool is dyed from the beginning with a mixture of colouring matter and mordant, one may quote the dyeing of cochineal scarlet. This method can be carried out only with those colouring matters and mordants which, when used together, yield precipitates somewhat soluble in the acid liquid of the bath, e.g., Cochineal and stannous chloride, yellow dyewoods and alum or stannous chloride. Logwood and ferrous sulphate or copper sulphate. Madder and potassium dichromate, ttc. Although in all cases the colour is not quite so full and deep as that obtained by mordanting first and dyeing afterwards, it may still be sufficiently near the maximum intensity obtainable, to cause the process to be preferred in practice before any other, since it means, of course, a great saving in time, labour, and steam. In some cases, too, it gives a very much brighter colour than the other methods ; the presence of the mor- dant in the bath prevents the impure extractive matters, tannic acid, (fee, from becoming fixed on the wool. This action is very marked in the case of the yellow dye- woods when used with alum or stannous chloride. With Logwood and copper sulphate, ferrous sulphate, or alum, the full colouring power of the dyewood is not obtained, but, notwithstanding this, the method may be and is adopted in practice, the chief advantages gained being a saving of time and labour, and the requii-ement of less apparatus. The '^ stuffing and saddening " method, and the " one- dip " method, are useful and economical whenever light colours are required, since in such colours the time and labour expended cost far more than the matenals. 8 274 DYEiyC OP TEXTILE FABRICS. fChap XII. Sometimes, too, the light shades obtained bj these methods are more uniform. 223. The Mordanting, Dyeing, and Saddening Method. — Tlie fourth method mentioned, in which the wool is mordanted, dyed, and saddened, is adopted when it is desired to obtain the maximum fastness of colour, eg., in tweed-yarns. As an example of this method may be given, a fast black for the production of which the wool is first mordanted with potassium dichromate, then dyed in a fresh bath with Logwood, and finally saddened by passing through a fi-esh hot bath containing potassium dichromate. Another example is, the claret-brown pro- duced by mordanting with potassium dichromate, dyeing in a fi-esh bath with Camwood, and saddening in the same bath with ferrous sulphate, towards the end of the opera- tion. In these and similar cases, there is always a certain amount of the colouiing matter which is merely absorbed by the wool, and not in combination with the mordant, and it is this uncombined colouring matter which the additional saddening fijxes. Excess of mordant must be avoided, otherwise the colours on the wool are apt to have an unpleasant metallic lustre (they assume a bronzy, rusty appearance) ; especially is this the case with log- wood and iron blacks. Sometimes this additional mordanting operation has the object of modifying, and even brightening, the colour already on the wool In such case the term saddening is inappropriate, and the operation is called "brightening" or " blooming." The agents used for this purpose are solutions of tin or alum. 224. Operations, &c., in Wool Dyeing. — Wool is dyed in all the various stages of its manufacture, namely, as iinspun wool, slubbing {i.e., the product of a preparatory stage of the spinning process), yarn, cloth, worn clothing, i-ags, and shoddy {i.e., woollen rags torn up into flocks). When the dyer receives it in the form of raw-wool, his first duty is to >x ash it well with tepid water, and then to scour it {see Wool Scouring), in order to remove Chap. XII.J OPERATIONS IN WOOL DYEING. 275 all those natural impurities adhering to the fibre, which otherwise would seriously impede the entrance of the dye, and produce very unsatisfactory results. If the wool is in the form of sluhhing, or of yarn, the washing and scouring of the raw-wool have already been performed by the spinner, but in order to facilitate the spinning processes, and to prevent breaking of the fibre durins: the scribbling, kc, the scoured wool has been again impregnated w-ith oil. The dyer must therefore first remove this by a second scouring process, if he desires to obtain the best results in dyeing. From motives of economy, the scouring of slubbing and yarn is sometimes omitted, e.g., in the case of low- class, cheap, carpet yarns, ko. Only experiment can show with what dyes such liberty can be taken with impunity, but in any case it is very irmtional. Woollen Cloth is sometimes sent to the dyer still saturated wdth the oil used by the spinner; sometimes it is already in an advanced stage of manufacture, having gone through the operations of scouring, milling, raising, cropping, pressing, and boiling ; hence, a preliminary washing and scouring is or is not necessary, according to the stage in which the dyer receives the material. Wetting-out. — In all cases, in whatever stage of manu- facture the wool may be, it is essential that, previous to being introduced into the dye-bath, it should be thoroughly well " w^etted-out " by a passage first through hot, then through cold water, and subsequent squeezing, in order to ensure ultimately an even or level dye, i.e., that the colour shall penetrate each fibre regularly, and be uni- formly diffiised over the whole fabric. If wool were placed in the colour or mordant solution in the diy condition, the large quantity of mechanically-enclosed air would, for a time at least, prevent a proper and regular contact between the solution and the fibre, and an uneven, ii-regular dye would inevitably result. Temperature of Dye-hath. — Generally speaking, the mordant or dye bath is heated to the boiling point 276 DTIXSG OF TEXTILE FABEICS. IChap. HX GreaJter intensitj of ooloar is tlnis obtained, owing to the aaAening of tibe subslaiice of the tihjne, the expansion of the external scales, and a laare eampLete expulsion of air, all oiwhieh pamit a readier aitrance oi the solution to the hnmst portioos ove which the wool is spread out on a large surface of galvanised wire netting h. Beneath, in a box-like space, two ventilating fans a drive the heated air through the layer of damp wool. Tliis ma^" also he effected by means of a centrifugal fan. Steam is supplied b}- the pipe e ; d is a tube for convevinsj oil to the bearings of the fans. Loose-wool may also be dried in a continuous manner by Nor- ton's machine, shown in Fig. 69. The damp wool is placed on the feeding-apixjn a, and passed continuously, in zigzag fashion, thix)ugh a hot - air chaml>er, by means of the endless bands B. c, D, E. The dry wool leaves the chamber at i. The fan F drives the external air, heated by the steam-tubes h, into the space J, and thence into the chaml>er ; the moist air escai>es by k ; m and l are the inlet and outlet tubes connected with the steam-pii>es h. 379 Chap. XII.J MACHINERY FOR WOOLLEN YARN. 226. Woollen Ysun.—Di/eiiig Machinery. For yarn dyeiiK^, tlie simplest apparatus is a substantially made, -FL ;\N-\i-^S.^-;>- FiK- 69.— Cv^ntiuuGHS Wool-Dryiug MachiTie. rectangular, wooden box A, about J — 1 metre wide, and varying in length and depth to suit different quantities of material {see Fig. 70), also Fig. 45, p. 186. The water is heated by means of a perforated copper steam-pipe D, running centrally along the bottom. In Fig. 70.— Woollen Yaru Dyeiug Machine. the most complete arrangement, there is also a closed copper worm-pipe, so that the dyer may employ either 280 DYEING OF TEXTILE FABRICS. [Chap. XIL the one or the other in order to maintain the liquid at a constant level. Gold water taps for tilling, and draw-off plugs, are conveniently situated. The hanks of yarn b are hung on square wooden Fig. 71.— Pitt's Woollen Yam Dyeing Machine. rods c, placed across the tank, and turned by hand, as described on p. 105 for yarn-scouring. An excellent example of a macliine specially adapted for dyeing irooVen yarn is that of Messrs. Pitt Bros., and illustrated in Fig. 71. The ^at, which is of the ordinary kind, is provided with a light iron frame A resting upon the edges of three of its sides and beneath the ends of the rods of yarn. This frame can be moved up or down by means of the chains B, and thus the Chap. XII.] MACHINERY FOR WOOLLEN YARN. 281 whole of the wooden rollers holding the yarn can be im- mei-sed in or removed from the vat liquor simultaneously. When the frame is lowered, the ends of the axes of tlie rollers rest iii the sockets c fixed on each side of the vat. The turning of the hanks is effected by loose wooden blades, which are inserted within the loop of the hanks, and close to the supporting roller. The ends of these blades project and rest in a series of forks or notches fixed on Fig. 72.— Hydro-extractor. horizontal rails d, situated on both sides of the vat. By means of a complicated system of levers e, actuated by a pair of cams, the rails D are moved both vertically and horizontally in such a manner that a small circle is de- scribed by the wooden blades which they su))port. Each blade is raised above the roller on which the yarn is suspended, then moves away from it, and then falls; the point of suspension of the yarn is thus being continually altered, and the yarn is drawn intermittently across the rollers. The movement of the yarn is indeed very similar to that which it receives when worked by hand, the difference being simply one of degree and not of kind. Washing Machinery. — Woollen yarn is washed by 282 DYEING OF TEXTILE FABRICS. [Chap. XIL Fig. 73. — Arrangement for Drying Yam in the open air. hand in a rectangular wooden box, identical \vitb that used for dyeing, or the rods full of yarn are placed under a per- forated wooden drainer, where they i-eceive a shower bath. Pig. 74 — Pair of Winch Dyeing Machines for Cloth. 283 O d '•'l 1— .- -e- |ii j"~ , ■- -1 -J i<: i- J ^. o d io 'S Q a o •a t3 to 284 DYEING OF TEXTILE FABRICS. [Chap, XII. Excess of water is removed from woollen yam by means of the hydro -extractor (Fig. 72). That made by T. Broadbent & Sons consists of a drum or cage of galvanised or copper wire-work a a', so supported that it can be made to revolve, by means of an engine, very rapidly {e.g., 1,500 revolutions per g}=»= Fig. 77. — "Woollen Cloth-Squeeziiig Machine. minute), with a per- fectly smooth move- ment. The cage is enclosed in a suitable cast-iron ca-sing b. The wet yarn is placed as evenly as possible in the cage to balance it. The water is expressed by the powerful centri- fugal force developed during the revolution of the cage, and makes its exit by the pipe c. Drying.— Woollen yarn is dried in stoves, or in the open air, as shown in Fig. 73. 227. Woollen Cloth. — Dyeing Ma- chinery. Woollen cloth, like yam, is vat. In the better wooden partition dyed in a rectangular wooden forms of apparatus, a perforated divides off a small portion in fi-ont, into which dye- wares, ttc, can be added without necessitating the re- moval of the goods from the dye-liquor ; the perforated steam-pipe for heating is also situated at the bottom of this compartment. After introducing the pieces, they Cliap. XII.l MACHINERY FOR WOOLLEN CLOTH. 285 are stitched end to end, to form an endless band ; this is supported, and drawn continuously through the liquor by means of reels or winches placed above, and driven by power. Fig. 74 gives a perspective view of an arrangement by W. Kemp, of Ijeeds. During the movement of the pieces, it is the special duty of an attendant to see that any knots which may be formed are as speedily as possible un- loosed. Each dye-vat usually contains several pieces of cloth. Figures 75 and 76 represent the dye-vat usually employed for dyeing unions (cotton and wool). The vat is made of iron, and divided across into several compartments by means of perforated plates. This arrange- ment prevents inter- mingling and entangle- ment of the several pieces, of which there may be from forty to eighty, each about forty-five metres long, and so stitched as to form six or eight endless bands. The winch of each dye-vat is driven by means of a small engine attached to the machine. Washing Macliinery. — The machine generally used for washing woollen cloth is the " dolly " {see p. lOG). Tn some cases the wash-stocks (Fig. 52) may bo Fig. 78.— Side View of Fig. 77. 286 DYEING OF TEXTILE FABRICS. [Chap. XIL «5^ M m i^K;=c=!c: -i bo used with advantage, e.g., when the material is very thick and he^vj. Washing in the open width may be done by the oj^en-scour- ing machine (Fig. 37, p. 109). Figs. 77 and 78 represent a woollen cloth-squeezing machine in which the water is expressed by a brass roller b, in the groove of which a disc roller a is pressed by a strong spring c. Drying Ma chinery. — Dryiu g is effected by means of the drying machine shown in Fig. 79. This machine consists of a number of hollow copper or galvanised iron cylinders a b, heated by steam and driven by bevelled gearing and an engine at D. The axes of the cylinders are hollow, the steam enter- ing at one end, the condensed water escaping by the other. A folding ari-angement c is attached at the end of the ma- chine. Another mode of drj^ing is by means of the " tenteiing " machine, of which there are several varieties. Fig. 80 shows one of the most generally used arrange- ments, by W. Kemp & Co., Leeds. It consists of a series of hori- zontal steam-pipes c c, supported by iron framing, between which Chap. XII.] MACHINERY FOR WOOLLEN CLOTH. 287 the cloth is led in a ziojzacf course and stretclied con- dition. The clotli is introduced at a, and guided by means of two end- less chains bb, fur- nished throughout their length with pins, on which the selvedges of the cloth are pushed down by revolving bruslies as it en- ters the machine. As the dried cloth leaves the machine it is folded down mechanically at e 228. Irregular Dyeing. — A very marked feature in the dyeing of woollen materials, and one to be well borne in mind, is, that after they are removed frojn the dye-bath, and so long as they con- tain the hot liquor of the bath, the dyeing process still continues. The wool, or the mor- dant in union with it, continues slowly 288 DYEIXG OF TEXTILE FABRICS. [Chap. XlL to attract such colouiing matter as remains dissolved in the absorbed dye liquor, and the material )>ecomes some- what darker in colour. It seems as though the wool had an insatiable appetite for the colouiing matter, and the material is said to " feed." If due care is not taken, this tendency may lead to an uneven shade in the ultimate colour of the material, however well the operation of dyeing piv)per may have been done. If, for example, the woollen cloth, yam, or fibre is removed from the dye-bath and at once thrown on the floor to form there an iiTegular heap, this residual dyeing or " feeding " goes on in an irregular manner. The same takes place in recently dyed yams or pieces which ai*e hung on poles or over rails ; the hot dye- liquor drains to the lowest portion, and there causes a darker shade of colour to result. The best mode of obviating this |X)ssible defect, is to remove the source of heat, and allow the material to cool slowly in the dye-bath, at the same time continuing the regular movement of the mateiial. In this manner the " feeding " is made to proceed in a regular manner. In practice this takes too long, and hence it is customary to cool the dye liquor more i-apidly by running into it the necessary amount of cold water, in which case the dee|)ening of colour is also somewhat diminished. Another method of preventing iri^gular dyeing ai-ising from this cause, is to wash the materials immediately after they have been withdrawn from the dye-bath. This of course prevents all danger of "feeding," and possible irregularity in c-olour, but the shades obtained when this method is adopted are not usually so full and rich as in the first method. They look paler, and the nap or loose fibres may, in some cases, l>e almost entirely devoid of colour, gi^'ing the material a very unsatisfactory grey appearance, as if it were insutficiently dyed. 229. Dyeing in the Wool, Yarn, and Piece. — The quality of the wool has considerable influence upon the depth and l>eauty of colour ultimately obtained CTiap. XII.] WOOL-, YARN-, AND PIECE-DYEING. 289 Coarse, hard wool, and sucli as possesses more the character of hair — e.g., worsted, alpaca, mohair, &c. — dyes less readily than fine wool having the merino character. The finer the wool the greater will be the quantity of colouring matter which it will take up, and the richer and more brilliant will be the colour one is able to impart to it. No doubt this is owing to its greater porosity, its softer and more absorbent character, and the less horny character of its scales. If in any dyed woollen fabric the colour has been imparted to it while it was yet in the state of unspun wool, it is said to be loool-dyed, or to have been dyed in the wool. When the dyeing took place while it was in the state of thread or yarn, it is said to be yarn-dyed, and when it was not dyed until it had become woven cloth, it is said to be piece-dyed. Wool-dyed cloth is generally the most esteemed, because the dye chosen must be fast, since it has to withstand all the subsequent manufacturing operations. Then, again, each individual fibre being, as it were, separately dyed, the material is uniformly dyed through- out, however thick it may be ; and if the colouring matter is of a permanent character, the cloth will preserve its colour in spite of wear and tear. Wool-dyeing is preferred for dark-coloured goods, and such as have to bear much friction. It is rarely used for light colours, since these would be soiled during the sub- sequent manufacturing operations. When the fabric is not of one uniform colour, but is composed of threads of different colours — e.g., in Tweeds, Kidderminster carpets, shawls, &c. — either wool-dyeing or yarn-dyeing, of course, becomes a necessity. In such cases, where the great desideratum is to have large quan- tities of yarn of a very uniform shade, wool-dyeing or slubbing-dyeing is preferred to yarn- dyeing, for even if the loose-wool or slubbing be somewhat unevenly dyed, the subsequent operations of scribbling, carding, &c., equalise most thoroughly any irregularity of colour. T 290 DYEING OF TEXTILE FABRICS. [Chap. XIL Wool-dyeing mubt also be adopted in the manufacture of " mixed yarDs," such yams, namely, as are spun with a mixtare of Tariously-coloured wools. Wool-dyeing is generally adopted by those yam or cloth manufacturers who wish to do their own dveing:. Piece-dyeing is preferred for light colours and such as are of a fugitive character, though it by no means follows that all piece-dyed goods are dyed with loose or fugitive oolounDg matters. Such a fast and permanent colour as vat-indigo-blue is as frequently applied by piece-dyeing as ^y wool-dyeing. Piece-dyed goods, especially such as are made of hard- K|iTin yams, or are closely woven, thick, or well-milled, mre sometimes apt to become grey with wear and tear, even if the colouring matter applied has all the requisite permanency desirable. This arises fix)m the fact that the central part of the fabric has remained more or less un- dyed, and through wear l>ecomes partially exposed. Piece-dyeing may often be detected by tearing the fabric and aseertaining whether the centre is fully dyed or not. In some cases, particularly ■v^dth light, blight colours — e.g.j scarlets on hunting-cloths — an increased brilliancy of the adonr is produced by piece-dyeing, since the central white shines through the surface colour. In such cases there is eondderabie economy in colouring matter by piece- dyeing. The same remarks apply in a lesser degree to yam- dyed goods. Yam-dyeing and pieoe-dyeing form, generally, distinct branches of trade For the production of a given shade, the laigest amount of colouring matter is required in wool-dyeing ; SNKiie^Kiiat smaller amounts may be taken in yam-dyeing, and in piece-dyeing, less still. Piece-dyed goods, if composed of one kind of fibre only, are necessarily of one uniform colour. When, how- ever, the fabric ooiuststs of two fibres — e.g., of cotton warp and woollen weft — although the goods may be pi( co-dyed, Chap. Xn.] DYEING TO SHADE. 291 they may have every appearance of having been yarn- dyed, since each fibre having a different power of attract- ing the colouring matter, has acquired a different tint. In some cases one fibre may remain altogether undyed, this is so, for example, with the cotton when such a mixed fabric has been dyed in an acid bath with Cochineal, Indigo Carmine, &c. In other cases the difference in colour between the two fibres is still further increased by submitting the fabric to two distinct processes of dyeing, the one being intended for the wool, the other for the cotton ; the fabric may, indeed, be doubly piece-dyed, and yet contain two such distinct colours as, say, black and red. This method of dyeing is, however, frequently em- ployed when mixed fabrics of cotton and wool are dyed one uniform shade if it is not possible by a single dyeing operation to give exactly the same tint to the two fibres. 230. Matching-Off. — The immediate object which the dyer has in view, is to dye a quantity of textile material so that the whole of it shall have a definite shade of a given colour, similar, it may be, to that of a pattern supplied by the merchant, or otherwise presented to him. His skill consists in knowing exactly which mordants and dye-stuffs to employ, also their relative and absolute proportions, and to determine the temperature and dura- tion of the mordanting and dyeing processes, in order to ensure the result aimed at. Even though the pattern- colour may have been originated by the dyer himself at some previous period, he dare not implicitly rely on obtaining exactly the same result by simply repeating his former trial in every detail. The reason of this lies in the fact that the quality of the dye- wares and of tlie fabric may have varied meanwhile. It is also a fact well known to practical dyers, that different qualities of wool — e.g., merino and English wools — have different powers of attraction for colouring matter, so that, when dyed under exactly the same conditions, marked differences in colour result. Even in wools which are more closely related to 292 DYKING OP TEXTILE FABRICS. {Chap. XU each other than the two just mentioned, similar differences are observed {see p. 289). With regard to the irregularity occurring in dye-wares, it is Tery marked in the natur^ colouring matters or djewoods. Their colouring power may, indeed, vary eac-h year, unless they are mixed and made equal to a standard sample by the merchant or dyewood cutter. For such reasons, therefore, and perhaps because of others of a more subtle nature, it is necessary, in order to judge of the progn^s of the dyeing, that the dyer should occasion- ally compare, with the sample pattern, small portions of the wool, yam, or cloth, taken from the bulk in the dye-bath. In the case of cloth, these small portions are either cut from the ends of the pieces themselves, or from some small odd bits of the same kind of material which have been specially attached for the purpose. Before making the comparison, the " swatch, " " fent," or '' trial-bit " taken from the dye-bath must be dried, by which it assumes a much lighter or paler appearance ; it is then placed by the side of the sample pattern, and the two are examined and compared by reflected light, being held at some little distance from the eye, and with the back of the observer to the light. They are then compared " overhand." To this end the two samples are placed between the light and the ob- server, who then glances along the surface, in order to catch the light transmitted through the projecting fibres. A judgment must be formed immediately, otherwise the eye soon becomes fatigued, and incapable of discerning nice differences of shade. Sometimes the eye becomes tired through comjmring or "matching off" a large number of different swatches of the same bright colour, in which case relief and in- creased power of discernment are most rapidly gained by occasionally gazing steadily for a few seconds at a piece of cardboard or other material possessing the complementary colour of the samples under com- parison. In comparing reds, for example, the eye is Chap. Xn.1 DYEING TO SHADE. 293 relieved hj looking at green, if blue5? by looking at orange, and vice versd. Having made the comparison of trial-bit with sample- pattern, the dyer judges whether the desired colour has been arrived at or not. In the latter case, if the tone of the colour is right, but it lacks intensity, the dyeing is either simply prolonged, or a further addition is made, of each colouring matter in the relative proportions already employed. If the colour lacks the proper tone the dyer then adds one or other of the dye-stuffs already employed, in such amount as he considers necessary to correct the error. Sometimes a difficulty is found in obtaining the exact tint or brilliancy required by simply using the dyewares decided upon in the first instance, and it may be ne- cessary to make some slight addition of other colouring matters, which it was not originally intended to use. This is frequently a sign of want of experience, but it may also arise from some unexpected change in the quality of the dyewares or the textile material, or from some other cause. In dyeing to shade, the young dyer is recommended to err on the side of employing a deficiency of colouring matter rather than the reverse, since he can readily make further additions, but cannot very well correct the defect arising from the use of an excess of dye ware. It is well to bear in mind, too, particularly with the polygenetic colouring matters, that the affinity which any given mordant has for colouring matter varies with the different colouring matters. When, for example, a dyeing operation is nearly completed, but it has been found necessary to add a further quantity of some one particular dyewood, the change in shade thus produced is not always simply due to the addition of the colour proper to the dyewood, but also to a partial displacement of some one or other colour already on the wool. The yellow colour of aluminium-mordanted calico, dyed with Quercitron Bark, is displaced by dyeing with 294 DYEING OF TEXTILE FABRICS. [Chap. XIL Tx)gwood, and the purple colour thus produced is again dispLiced, and chauged to red by dyeing with Madder. In matching-off, care should be taken to have, if possible, a north light, not only because it is steadier, but ]>ecause there is an absence of that excess of yellow light always present in the more direct rays of the sun ; these greatly modify the aspect of colours, and render comparison more difficult. For the same reason it is ira}X)ssible to judge accurately of the tnie shade of a colour by gas-light. This defect is partly overcome by using spectacles of plain glass tinted slightly blue. Many practical dyers have long been in the habit of matching-off at night by me^ns of the magnesium light, and in recent years the electric arc light has been used for the same purpose. Although colours more nearly assume their normal tint under these lights, they are by no means identical in character with those exhibited under ordinary sunlight. There is, indeed, in both these artificial lights an excess of blue or purple rajs, and for accurate colour-matching the light should be screened with globes of tinted glass. The correct tint to employ may be determined by a spectroscopic examination of the light. NOTES ON SILK-DYEING. 231. With few exceptions, the general method of dye- ing silk is similar to that employed for wool. By far the largest amount of silk is dyed with coal-tar colouring matters, which do not require the aid of a mordant ; at most, some assistant — e.g., acid, soap, kc. — is needed, and the dyeing usually takes place in a single bath. Some- times, however — specially in the case of black dyeing — two or more baths are employed, and, indeed, the whole process becomes more complicated than most methods of dyeing employed for any fibre. The silk-dyer uses comparatively little machinery, and being most of it intimately connected with special operations, allusion is made to it when referring to these. 296 APPLICATION OF THE NATUEAL COLOUEINa MATTEES. CHAPTER XTII. BLUE COLOURING MATTERS. INDIGO. 232. Theory of Indigo Dyeing. — This valuable colouring matter is obtained from the leaves of various species of Indigofera (/. tinctoria, I. disperma, <&;c.\ which are cultivated largely in India. The method par excellence employed in dyeing with Indigo is founded on the property it possesses of being converted under the influence of reducing agents {i.e., bodies capable of yield- ing nascent hydrogen) into indigo- white which is soluble in alkaline solutions. When textile materials are steeped for a short time in such solutions, and then exposed to the air, they become dyed blue in consequence of the re-oxidation of the indigo-white absorbed by the fibres, and the precipitation of insoluble indigotin thereupon, and, indeed, in such a manner as to be indelibly fixed. This "indigo- vat" method is applicable to all textile fibres, and gives permanent colours. Another method of dyeing with Indigo, but one which yields fugitive colours, and is applicable only to the animal fibres, depends on the fact that Indigo treated with strong sulphuric acid becomes changed into sohible indigotin- di-sulphonic acid (Indigo Extract). Animal fibres attract and are dyed with this compound when they are simply steeped in its hot and slightly acidified solutions. Vat-blue is largely employed, particularly in woollen 296 DYEING OF TEXTILE FABRICS. [Cbap XIII. dyeing, as the blue part of compound shades, e.g., browns, drabs, itc. The. same may be said of Indigo Extract or Indigo Carmine blue, with regard to wool and silk dyeing. Indeed, this colouring matter possesses c^iiain advantages over the majority of blue colouring mattere. It can be associated with other acid colouring mattei^, and it dyes verj^ level shades. Its only drawback is its extremely fugitive character. 233. Indigo Grinding Mills. — One of the first necessities in employing Indigo in dyeing is to have it Fig. 81. — Indigo Grinding Mill. thoroughly well ground. "When required for making In- digo Carmine it must be ground in the dry state, but for the indigo-vat it may be mixed with water, by which means the grinding is considerably facilitated. The oldest form of gi'inding machine is the stamping mill, provided with an arrangement for passing the ground Indigo through fine sieves. At jiresent the mills generally employed consist of cast-iron vessels, in which the Indigo is ground either by the rolling of heavy cannon balls, or of iron cylinders. The ball mills are said to give the finest powder ; the cylinder mills the greatest yield within a given period. Fig. 81 represents a section Chap. Xm.] INDIGO. 297 of one of tlie best forms of ball mills. It consists of a strong iron box enclosing several heavy cannon balls, which are pushed round by means of a pair of revolving arms. Sometimes the bottom of the box is flat, and heavy blocks of sand-stone are substituted for balls. 234. Application to Cotton. — The fermentation vats so much used in dyeing wool with Indigo, are never em- ployed for cotton, since it is essential that it should be dyed in the cold to obtain the best colour ; and, further, it permits the use of vats, in which the reduction of the indigo is eflfected in a manner more under control. Ac- cording to the reducing agents employed, the indigo-vats used for cotton may be named as follows : the ferrous sulphate vat, the zinc powder vat, the hydrosulphite vat. 235. Ferrous Sulphate Vat. — This vat, usually known by the name of the lime and copperas vat, is the oldest, and perhaps the one still most commonly employed. The vats or dye-vessels are rectangular tanks of wood, stone, or cast-iron. The size varies according to the material to be dyed ; for calico they are generally two metres (6J ft.) deep, two metres long, and about one metre broad, while for yarn-dyeing they are somewhat smaller. In order to economise the Indigo as much as possible, the vats are generally worked in sets of ten. The materials used in preparing this vat are : — Cloth. Yam. Water .... 4,000 Hires or 750 litres. Indigo .... 40 kilos. ,, 4 kilos. Ferrous sulphate , . 60—80 ,, „ 6-8 ,, Slaked Ume (dry) . . 50-100 „ „ 5-10 „ The chemical changes which take place during the "setting" or preparation of the vat may be briefly summed up as follows. The lime decomposes the ferrous sulphate, and jiroduces ferrous hydrate, which in the presence of the indigo rapidly decomposes the water, and becomes changed into ferric hydrate, while the liberated hydrogen at once combines with the indigotin to form 298 DYEING OF TEXTILE FABRICS, fChap. XIJL indigo- white. This last substance combines with the excess of lime present, and at once enters into sohition. These reactions may be expressed by the following chemical formulae : — FeS04 + Ca(0H)2 = CaSOi 4- Fe(0H)2. Ferrous sulphate. Lime. Calcium sulphate. Ferrous hydrate. 2[Fc(OH)2] + 2H2O = Fe2(0H)s + H^. Ferrous hydrate. Ferric hydrate. CisHjoN^Oa + H. = C,,:R^,^^0.,. Indigotiu. Indigo-white. The order in which the ingredients are added is of comparatively little moment, and varies with different dyers. The most rational method, however, is to fill the vat with water and add first the ground Indigo and milk of lime ; after raking up well, a solution of ferrous sulphate is added, and the whole mixture is systematically raked up at frequent intervals during twenty-four hours, until the Indigo is thoroughly reduced. With this plan, the actual reducing agent, ferrous hydrate, is always in the presence of an excess of Indigo, and the indigo-white the moment it is produced is dissolved in the excess of lime. Owing to the mixture becoming rapidly thick and difficult to stir well, the more usual plan adopted is to put in the Indigo and ferrous sulphate first, and to add the milk of lime gradually. Lime is used in preference to caustic soda because the vat thus produced dyes the cotton more readilv ; and owins: to the film of calcium carbonate which forms on its surface, the indigo-white in the liquor beneath is less liable to become oxidised. The ferrous sulphate employed should be as pure as possible. Any admixture of copi>er sulphate is injurious because of its oxidising influence, while the presence of aluminium sulphate and basic ferric sulphate, since these are quite inert as reducing agents, causes loss of so much lime as is required for their decomposition, besides a useless increase of sediment. The use of a large excess of ferrous sulphate and lime should also be avoided Chap. Xin.j INDIGO. 299 for this last reason. Ferrous sulphate, containing copper sulphate and ferric sulphate, is readily purified by boilinc its solution with iron turnings, whereby the copper is pre- cipitated, and the ferric sulphate is partly reduced to ferrous sulphate, or fully decomposed and precipitated. A freshly made-up vat is in good condition when numerous thick dark-blue veins appear on raking up the liquor, and the surface becomes rapidly covered with a substantial blue scum or " flurry." The liquid should be clear, and of a brownish-amber colour ; if greenish, it shows the presence of unt-educed Indigo, and requires a further addition of ferrous sulphate. If the colour is very dark, more lime is required. At the end of every day's work the vats should be well raked up, and, according to their appearance, " fed " or replenished with small additions of lime and ferrous sulphate. The rake used for this purpose consists of a rectangular iron plate, with long wooden handle attached. Before dyeing, the flurry should be carefully removed with an iron scoop or "skimmer," otherwise it attaches itself to the cotton, and causes it to look uneven or spotted. Cotton yarn should be previously well boiled with water, in order to make it dye evenly. When dyeing light shades of blue, only a few hanks are dyed at once, the dipping, turning, and squeezing being performed with the utmost regularity. According to the dej^th of blue required, the duration of each immersion may vary from one to five minutes or more, and after wringing, the hanks are thrown aside, and allowed to oxidise completely. The amount of indigotin which is precipitated on the cotton is said to vary with the duration of the im- mersion ; if this be true it would appear that the cotton really attracts indigo-white from the vat solution, and is not dyed merely by reason of the indigotin precipitated from the portion of liquid absorbed by the fibre. The most economical method is to dye the cotton first in the 300 DYEING OP TEXTILE FABRICS. [Chap. XHL weaker vats, and then to pass it through each succeeding stroiio-er vat until the desired shade is obtained. For a dark shade, the cotton should not be put at once into a strong vat, because it vrould be difficult in this way to obtain even colours ; and in the long run, the method would not be so economical. For light shades of blue, only a few of the weaker vats are needed. By this plan of always using the weakest vat first, so long as it yields any colour, each vat in turn becomes thoroughly exhausted. After dyeing, the carbonate of lime which is deposited on the fibre is removed by rinsing in sulphuric acid, 2°_4° Tw. (Sp. Gr. 1-01— 1-02). This operation removes the grey tint, and brightens the colour considerably. The cotton is finally dyed in a moderately strong vat^ wrung out and dried at 60° C This imparts to it the coppery lustre so much admired. It is, however, entirely super- ficial, and may be removed by simply washing in water. As a rule, however, washing is avoided, since the indigo is apt to rub off, and the colour may look bare and wanting in body and intensity. Vat blues are improved in colour by passing the goods through lime-water or a hot soap bath, probably because of the removal thereby of some yellow colouring matters. When dyeing cotton cloth or calicoes, the dry pieces are fastened by the selvedges on a rectangular wooden frame, having small brass hooks at the top and bottom ; chey are stretched moderately tight, and each fold is per- fectly free. When filled the frame is alternately dipped beneath the surface of the vat liquor for fifteen to twenty minutes, and then raised above the vat by means of ropes and pulleys, in order to expose the calico to the air, so that indigotin may be regenerated and precipitated on the fibre. During the immersion it is customary to stir the liquor gently by means of a "muddler," i.e., a short- handled rake having a wooden head. Another method of dyeing calico, sometimes called •* skying," because used for light blues, is shown in Fig. 82. Chap. XIII.J INDIGO. 301 The pieces are passed through a series of rollers, arranged on a wooden frame immersed in tlie vat a. At tlie point of exit they pass through a pair of squeezing rollers, and are then led over a similar system of rollers b, outside the vat, for the purpose of oxidation. The whole process ^IVtZJfW'Sf^^ Fig. 82.— Continuous Indigo Dyeing Machine. may be repeated two or three times, according to the in- tensity of colour required. . After leaving the vat, the pieces are first rinsed in cold water, to remove the loose lime and Indigo adhering super- ficially, and then in dilute sulphuric acid, 4°— b iw. (Sp. Gr. 1-02— 1-04), to dissolve off" the calcium carbonate; they are finally washed and dried. All the indigo washed-ofi^ in the rinsing pits, as well as the sediment of the vats themselves, must be collected in special tanks, in order to recover the indigo. Accordmg to F. C. Calvert, the vat sediments consist 302 DYEIXG OF TEXTILE FABRICS. [Char- XUL largely of an insoluble compound of indigotin and ferrous oxide, forming a bulky flocculent green precipitate. From this the indigotin can be recovered by decomposing it in the cold with strong hydrochloric acid. Another method is to mix the vat sediments with water, and boil with some cheap, energetic reducing agent, e.g., with caustic soda and orpiment. After settling, the clear liquid is drawn off, and oxidised by pumping it into a trough which stands at a high level, and allowing it to flow into a large tank ; here the pre- cipitated indigotin is washed and collected. By adoptiDg such methods of recovery, the total loss of Indigo may be voduced to 2 — 3 per cent, of the original weight employed It is sometimes the custom to dye the cotton or " bottom " it with catechu brown, manganese bronze or brown, or a blue shade of aniline black, previous to introducing it into the indigo vat. By this means, very deep blue shades can be obtained with less indigo than would otherwise be required. It is well to remember that when aniline black is used the colour may be liable to become green on exposure. In order to add a fictitious purple bloom or rich effect to the colour, vat blues are sometimes dyed afterwards or "topj^ed" in a dilute solution of Methyl Violet or Methylene Blue, and dried without washing; less fre- quently, they are dyed a logwood blue. 236. Zinc Powder Vat. — This vat is frequently used on the Continent, and also in Great Britain. It is founded on the fact that zinc in the presence of lime and Indigo readily decomposes water, and combines with its oxygen, whilst the liberated hydrogen reduces the indigotin to indigo-white, which is at once dissolved by the excess of lime present. Zn + H.0 = ZnO -\- H.. The relative proiwrtions used of the several ingredients vary according to their quality, especially as regards the Indigo employed. Chap. Xni.] INDIGO. 303 The following may be considered as average amounts ; Water 4,000 litres Indigo 40 kilos. Zinc powder 20 „ Slaked lime 20 „ The whole is well stirred occasionally during eighteen to twenty-four hours, when it is ready for use. Lime and zinc ix)wder are added as occasion requires. It is an extremely simple vat, easy to work, and possesses even certain advantages over the " lime and copperas " vat. In the first place, the sediment is reduced to about one- seventh of that in the vat referred to. Then the absence of ferrous sulphate removes the possibility of the forma- tion of the insoluble compound of indigotin with ferrous oxide referred to on the previous page. Hence this vat can be used for a much longer time without emptying, than the " lime and copperas " vat, and there is little or no loss of Indigo. Its chief defect is that it is liable to be muddy and frothy, from a continuous slight disengagement of hydro- gen gas. No hydrogen is given off, however, until the whole of the indigo is reduced, so that much froth denotes the presence of excess of zinc. If there be only little froth, it is removed by vigorously stirring up the vat several times, and then allowing it to settle, but with a large excess, a further addition of Indigo should be made before stirring. After settling for an hour, the vat should be sufficiently clear for dyeing. If the vat is muddy, the same remedy must be applied, since the cause is the same. It is of no use to let it stand for a long time in the hope that it will settle ; the hydrogen simply accumulates, and the liquid becomes more muddy still. The liquid must be vigorously stirred up, in order to liberate the hydrogen from the sediment. The dyeing should be completed before the liquid has had time to become muddy again. Experience alone can teach the exact amount of zinc powder which should be 304 DYEIN'G OF TEXTILE FABRICS. [Chap. XIIL used, SO that the vat may be maintained in an effective condition, vet free from the defects mentioned- Some dyers find it an advantage to add alx)ut 12 — 20 kilos, of iron boiings. These act mechanically, by present- ing a large and rough surface, from which the hydrogen gas is more easily liberated, and thus a clear vat is more readily obtained. 237. Hydrosulphite Vat. — This vat is prepared for cotton exactly in the same way as for wool (see p. 308). The cotton, however, should be dyed in a cold solution. 238. Applicatwn to Wool. — In order to utilise the Indigo to the fullest extent, it is previously ground with the addition of water, and added to the dye-vessel in the form of a fi.ne smooth paste. The *'' vat '' or dye-vessel in which the reduction of the indigo and the dyeing takes place, is a large tank, generally made of cast-iron (about 2 metres wide and 2 metres deep). For dyeing unspun wool it is generally round, for piece-dyeing, square. The whole is enclosed in brickwork, so arranged that the upper portion of the vat is sun-ounded by a chamber or canal, into which steam can be admitted. By this means the liquid of the vat is heated from the outside, and a regular temperature can always be maintained, without any danger of disturbing the sediment. During the " setting " of the vat the contents are stirred up, either by hand, by means of a rake, or by a mechanical an-angement fixed in the bottom of the vat, and driven by machinery. Before dyeing, the contents are allowed to settle, since the textile material must always be dyed in the clear liquid- The disturbing of the sediment is prevented as much as possible by sus- pending in the vat, 1 metre below the surface, a so- called *' trammel," i.c., an iron ring or frame, across which coarse rope network is stretch e^i Tlie accompanying figure (Fig. 83) gives the section of a well-arranged round indigo-vat for wool dyeing, with mechanical stirrer, ed on its surface. Pre- vious to fulling, it is well to boil the goods with a solution of alum or bichromate of potash and tartaric acid This operation makes the colour much faster against light and rubbing. As a rule, the loose indigo removed during the fulling operation is allowed to run to waste, but it is probable that much of it might be profitably regained fi'om the sediment of the ftdling mills, by a system of washing biised on the diSerence of Specific Gravitv between the fuller's eanh and indigotin : or one might mix the sediment with ferrous sulphate solution, let settle, draw otf tlie clear solution of reduced indigo, oxidise it, and collect the regenerated and pre- cipitated indigo. By boiling the cloth (after dyeing and washing) with Barwood, Sanderswood, or Camwood, the blue is said to be better fixed and faster against light than without this treatment. It is not so liable to bleach at the cut edges, «tc. Steaming the goods for half an hour makes the blue a little more violet, but faster n gainst, liorht. Vat-blues, which have been boiled with alum and tartar after dyeing, become slightly paler by the o})eration, but are rendered much more stable against light; the ultimate gain being much greater than the primary loss. Exposure to light gives vat-blue a violet tint By boiling with alum and tai-tar, after dyeing and washing, ikc, and steaming half an hour in addition, the colour is only Chap. XIII.] INDIGO EXTRACT. 817 slightly weaker, and the greatest fastness against light is obtained. If treated in this way, the colour becomes darker during the first five months of exposure to light and air, and at the end of the year possesses the same depth of shade as at first. From these facts it may be inferred that in the case of woaded browns, greens, er cent, of Logwood, a dark shade of blue is obtained ; the addition of too much Logwood decoction, however, must be avoided, otherwise the colour is apt to become dull The most rational method of adding the colour yielded by Logwood to that of the Indigo Carmine, is to dye with the two colouring mattere in separate baths. Chap. XIII.] DYEING WITH LOGWOOD. 319 LOGWOOD. 251. This dyewood consists of the heart wood of Hcematoxylon camj^iechianwm, growing in Central America. 252. Ajyi^lication to Cotton. — Tiie principal use of Logwood in cotton-dyeing is for the production of blacks and greys ; it may, however, also serve for purples, blues, and numerous composite colours. In conjunction with other colouring matters, it is employed for the production of numerous compound shades, its use being, in such cases, to make the colour darker, or of a bluer tone. 253. Logwood Blacks. — The method of obtaining a logwood black consists essentially in mordanting the cotton with a salt of iron, and then dyeing with a decoc- tion of Logwood. Numerous modes of applying this simple process are in general use, but the principle is always the same. • In order to mordant the cotton, it may be worked in a cold solution of pyrolignite or nitrate of iron, at about 5° Tw. (Sp. Gr. 1-025) till' thoroughly saturated; after squeezing, the iron is fixed by working in a cold weak bath of sodium carbonate, or milk of lime; the cotton is finally well washed in water. Another method of mordanting, and one which gives faster blacks, is to fix on the fibre a tannate of iron instead of ferric oxide, as in the last case. Work the cotton in a cold infusion of about 30 — 40 per cent, of Sumach, or its equivalent of other tannin matter (ground Gall-nuts, Myrabolams, &c.), and allow it to steep for several hours, or even over-night; remove the excess, and, without washing, work for about half an hour, in a cold solution of pyrolignite or nitrate of iron at 2° — 4° Tw. (Sp. Gr. rOl — 1'02), and wash well. In order to remove all traces of acid, and to fix more completely on the fibre a basic salt of iron, it is advisable before washing to work the cotton in a cold bath of chalk- water, or in weak milk-of-lime. Not unfrequently a lime bath is applied immediately after sumachiiig and before passing into tho 320 DYEING OP TEXTILE FABRICS. [Chap. XIII. iron bath. In this case a ta.nnate of lime will be formed upon the libre, and the double decomposition with the iron salt is facilitated, since the lime at once takes up the acid liberated. In warp dyeing the whole process is continuous, and the cotton, after being steeped in a decoction of myrabo- lams is passed successively through baths containing lime-water, nitrate of iron, logwood liquor, dilute iron solution, and water. For low-class goods, many dj^ers substitute ferrous sulphate for the pyrolignite and nitrate of iron. The pyrolignite of iron may also be mixed with an equal or somewhat smaller amount of aluminium acetate (red liquor) at 5° Tw. (Sp. Gr. 1-025), in which case it may be better to fix the mordants by working the cotton for a quarter of an hour at 50° — 60° C, in a dilute solution of phosphate or arsenate of soda. An aluminium mordant alone would give a dull lilac shade, but along with an iron mordant it helps to re- move the unpleasant reddish or rusty appearance of the blacks otherwise obtained. When Catechu is the tannin matter employed, the cotton should be worked in a boiling decoction of it, and allowed to steep till cold, in order to effect the precipita- tion on the fibre of the maximum amount of catechin. The cotton may afterwards be worked 5 — 15 minutes in a boiling solution of bichromate of potash (five grams per litre), before passing it into the bath of pyrolignite of iron, though this is not absolutely necessary. By whichever method the mordanting is effected, the dyeing takes place in a separate bath containing a suitable amount of freshly-made Logwood decoction, to- gether with a small quantity of extract of Old Fustic, or of Quercitron Bark. If an iron mordant only has been employed, it is beneficial to add also a small quantity of copper sulphate to the dye-bath, in order to prevent the cotton from acquiring the rusty appearance already referred to. Cliap. XIII.] LOGWOOD. 32] The cotton is introduced into the cold dye liquor, and the temperature is gradually raised to the boiling point After dyeing, the cotton may be passed through a 'fff^Z of bichromate of potash, 0.5 grams per litre, at OU O Ihis operation gives intensity and fastness to tlie b ack, since any excess of colouring matter is fixed as a chromic oxide lake. The dyed cotton is washed and worked in a solution ot soap, hve grams per litre, at a moderate temperature then squeezed and dried. This final soaping removes any bronze appearance, and imparts to the colour a bi^^er softeiTeel ^^^^^^^^^ *^''^- ^^^ ^^*^^"^ ^^^o acquires^ a The following is a method by which a chrome black on cotton can be obtained in a single bath : Dissolve 1-5 kilos, of bichromate of iiotash in a small quantity of water, mix the solution with 500 litres of Locr. wood decoction at 3° Tw. (Sp. Gr. 1-015), and add S% kilos, of hydrochloric acid, 34° Tw. (Sp. Gr M7) The cotton is introduced into the cold solution, and the tempe- rature is very gradually raised to the boiling ooint The cotton acquires at first a deep indigo-blue shade, which clianges to a blue-black on washing with a calcareous water. A slight modification of this process which may be adopted, IS to work the cotton in a solution contaiiiin- at^ first only the bichromate of potash and hydrochloriS acid and to add the decoction of Logwood to the bath in small portions from time to time, gradually raisino- the temperature as before. ° Another method of producing a Logwood black, is to clye m a bath containing Logwood extract, and copper acetate, entermg the cotton cold, raising the tempera- ture gradually to 50'^ a, and dyeing at that temperature until the colour is sufficiently developed. Copper sulphate, to the amount of about 4 per cent ot the weight of cotton, is frequently used instead of acetate, and an addition of 4 per cent, of soda-ash is made 322 DYEING OF TEXTILE FABRICS. TChap. XnX to the bath along witli 20 per cent, of solid Logwood, extract. The cotton is passed rapidly through this mixtiire;j heated to 60° — 80° C, and then allowed to oxidise or " smothec " for 5 — 6 hours. This pix)cess requires to be repeated several times l.>efore a full black is obtained. Tlie method is not economical for ordinarT use, but it is said to yield a black which withstands milling with soap very well. Carbonate of copper may also be applied in the above process, instead of copper sulphate and soda-ash. The methods already given may be adapted to the dyeing of unspun cotton. The following method of dyeing a chrome black is said to be specially applicable to such as must withstand the operation of fulling. Wet out the cotton well in boiling water, then boil in a strong solution of about 30 per cent, of solid Logwood-extract, drain, and allow it to lie exposed to the air for some time ; complete the oxidation thus begun, by working it one hour in a cold solution of 8 per cent, of bichromate of potash and 6 per cent, of copper sulphate, wash and complete the dyeing in a bath containing 10 per cent, of Logwood extract; enter the cotton cold, and raise the temperature gradually to the boiling point. Wash, soap, and dry. In the first bath the cotton simply absorbs the colouring matter of the Logwood ; in the second this is oxidised, and at the same time combined with a sufficient amount of mordant, copper and chromic oxide, to enable it to take up still more colouring matter in the third bath. The first Logwood bath is analogous to the tannin bath alluded tc in a previous process (p. 319). 254. LogwoDd Greys are obtained by -working the cotton for a short time at 40^ — 50° C. in a weak decoction of Logwood (1 — 5 per cent.), then in a separate bath con- taining a weak solution of ferrous sulphate or potassium dichromate, and washing. Many dyers adopt the aj>- parently irrational method of mixing the ferrous sulphate and Logwood solutions, and dye at once in the inky liquid thus obtained. Comparatively little precipitate, Chap. XIII.] LOGWOOD. 323 however, is produced in the dye-bath in this case, and the colour is for the most part developed on tlie cloth itself during the subsequent oxidation by exposure and wash- ing. The shade of grey may be modified ad libitum, by adding to the Logwood bath a small proportion of decoc- tions or extracts of tannin matter, Old Fustic, Peach- wood, &c. 255. Logwood Purples are obtained by mordanting the cotton in a weak solution of stannou-s chloride, then washing and dyeing in a separate Logwood bath. The colour is tolerably fast to soap, but not to light. 256. Logwood Blues on cotton are now seldom dyed, because of their fugitive character. To obtain them, work the cotton in a bath containing a decoction of Log- wood and a small proportion of copper acetate or sulphate, raising the temperature gradually to 50° C. The tone of colour has great similarity with that of an indigo- vat blue. 257. Application to Wool. — Logwood is the essential basis of all good blacks on wool, although other colouring matters are frequently used along with it, either to niodify the particular shade of black, or to add to its intensity and permanence. _ According to the materials employed, we may distin- guish the following kinds. Chrome black, copperas black, and woaded black. 258. Chrome Blacks are produced by first mordantinj^ the wool for 1— l^ hour at 100° C, with 3 per cent, of bichromate of potash and 1 percent, of sulphuric acid, 168° Tw. (Sp. Gr. 1 -84), then washing and dyeing in a sej^rate bath for 1— li hour at 100° C, with 35—50 per cent, of Logwood. This represents the simplest form of dyeing a chrome black, but in practice numerous slight modifica- tions are introduced, in order to obtain various shades of black. The following, which arc typical, may be men- tioned. The mode just given yields a blue-black, or, as it is sometimes called, a black with blue reflection. By the addition of a suitable amount of some yellow colouring matter to the dye-bath — e.g.^ 5 per cent. Old Fustic— a S24 DYEING OF TEXTILE FABRICS. [Chap. XHX dead-hJack is obtained, i.e., a neutral black, which possesses no decided tint of blue, green, violet, «i:c. By inci-easing the amount of Old Fustic to 10 per cent., a p-e-en-black is obtained, and the greenish shade becomes still more pro- nounced, if 3 — 4 per cent of alum is added to tlie mor- danting bath along with the bichromate of potash. A viohtrhlack is produced bv dyeing exactly as for blue black, but after the dye-bath has been exhausted, a dilute solution of about 2 per cent, of stannous cliloiide (tin crystals), or its equivalent of commercial muriate of tin containing no free acid, is added to the dye-bath, and the boilins: is continued 15 — 20 minutes lonirer. In the case of dead-blacks, it is the custom with some dyers to " sadden " in a similar way with 3 — 4 per cent, of ferrous sulphate: or instead of this, the goods are passed, after dyeing, through a warm bath containing about 0*5 per cent, of bichromate of potash. The object of these last modifications is to precipitate and fix more completely on the wool any colouring matter, perchance not combined "vvith the mordant, but simply absorbed by the wooL With black yarn, which will eventually appear in a woven fabric, in close proximity to white or delicately- coloured yams, this fixing of the dye is very necessary, otherwise the light-coloured or white yarns become stained during the operations of milling, ttc, and the finished fabric has a soiled appearance. It is always the case that some black comes oft" during these operations, but if the colouring matter of the Logwood is thoroughly com- bined with its own mordant, it will not readily combine with the mordant of any neighbouring fibre, but be simply ntbbed or washed out as an insoluble powder. Chrome blacks may also be dyed in a single bath, as follows : A mixture of Logwood liquor and bichromate of potash solution in suitable proportions is boiled. The precipitate thus produced is collected, and may then be employed as a " direct black," or a " one-dip dye." It is, indeed, the actual coloured body or pigment one wishes to fix upon the wool, and this is rendered possible, becatise Chap. XIII.] LOGWOOD. 325 not only is the precipitate soluble in an acid solution, but tLe wool is capable of attracting it from the solution. The precipitate is added to the dye-bath, along with just suffi- cient oxalic acid to dissolve it, and the wool is dyed in the solution at 100° C, for one and a half hour. Good results are, however, not so readily obtained as when iron and copper mordants are used {see Bonsor's black, p. 329). 259. Indigo Substitute. — This product, at present sold in the form of a purplish-blue liquid, is said to be pro- duced by boiling together Logwood extract and chromium acetate. Cotton is dyed by simply working it in a hot solution of the mixture. Of all the blacks derived from Logwood, the chrome black is the one least affected by acids. If tested by spotting with strong sulphuric acid, it becomes a dark olive colour. It also resists the action of scouring and fulling very well. On the other hand, however, chrome blacks are not altogether satisfactory as regards their behaviour on exposure to light. They gradually assume a greenish hue, although otherwise they are tolerably fast. The greening of a chrome black is most apparent when Logwood, or Logwood and Old Fustic, have been employed in dyeing. Its bad effect may be counteracted by the addition of a suitable red colouring matter to the dye-bath — e.g. Alizarin — or by dyeing the wool a reddish- brown colour before dyeing with Logwood. This is very conveniently carried out in practice by boiling the wool with 6 — 8 per cent, of Camwood for an hour, then adding to the exhausted bath the bichromate of potash (generally with the addition of a small percentage of alum and tartar), and mordanting, &c., as already given. Owing to the comparatively small proportion of bichromate of potash required to produce the fullest blacks, there is evidently a minimum quantity of lake precipitated on the fibre, so that the latter retains very much its prLstine elasticity and softness. Excess of bichromate of potash should always be 326 DYEING OF TEXTILE FABRICS. fCliap. XHL avoided, since the colour is then more liable to become green, or to fade, on exposure to light. 260. The use of Bichromate of Potash.— The fol- lowing results of experiments on the use of chromium mordants will be of interest. By mordanting the wool with 3 per cent, of bichro- mate of potash, a full and bright shade is obtained. The use of more than this amount causes the colour to become dull and grey (over-chroming, see p. 209). The employment of sulphuric acid along with the bi- chromate of potash is advantageous when the proportion does not exceed one molecule of sulphuric acid to one molecule of bichromate of potash, i.e., 1 per cent, of sul- phuric acid 168° Tw. to 3 per cent, of bichromate of potash. When used in this proportion it gives a brighter and somewhat deeper shade than can be obtained from bi- chromate alone ; but should the above-mentioned amount be exceeded, a dull grey appearance results, which becomes more apparent as the amount of sulphuric acid increases. If the bichromate of potash be increased along with the sulphuric acid, the injurious effects of " over- chroming " are intensified. The addition of tartar or tartaric acid to the mor- danting bath, along with bichromate of potash, is bene- iicial, the shades being much more brilliant, though somewhat lighter, than when sulphuric acid is used. Tartaric acid gives decidedly brighter and more purple shades than tartar. The best results are obtained b}' using 6 per cent, of tartaric acid or 8 per cent, of tartar to 3 per cent, of bichromate of potash. Oxalic acid is also beneficial in the mordanting bath, and in this case, 4 per cent, of oxalic acid to 3 per cent, of bichromate of potash yields the best results. On comparing the shades obtained by using these acids in the mordanting bath, it is seen that they are all better than can be obtained by bichromate of potash alone. The addition of sulphuric acid produces a deep, dead- locking blue-black ; tai-tar or tartaric acid yields a bright Chap. XIII.] LOGWOOD. 327 bloomy bluisli-black ; oxalic acid a black which is darker, duller, and slightly greener than can be obtained with tartar or tartaric acid, but not so dark as with sulphuric acid. Whenever bichromate of potash alone is employed, the mordanted cloth has a dull yellow colour, but if tartar or tartaric acid has been added to the bath, it is a pale bluish-green. From these results it would appear that the best shade is obtained w^hen the chromium mordant is fixed on the cloth in the state of chromic oxide previous to the application of the Logwood. The substitution of chrome alum as a mordant in place of bichromate of potash does not give good results, the ultimate colour obtained having an irregular speckled appearance, evidently owing to the unequal deposition of the chromic oxide ; besides a very large proportion of tartar must be used to obtain a full shade. When the cloth has been mordanted with bichromate of potash alone, or with bichromate of potash and sul- phuric acid, the presence of chalk or calcium acetate in the dye-bath is decidedly injurious. The acetate seems to be least hurtful, although, even with this, the addition of more than 2 per cent, gives the colour a greyish ap- pecirance. If tartar has been employed along with the bichromate of potash, the presence of calcium acetate is decidedly beneficial, the shade being intensified from a pale blue when no calcium acetate is used, to a deep indigo-blue when 30 per cent, is employed. The best amount to use appears to be 30 per cent., but even 80 per cent, may be added to the dye-bath without any gTeat detriment, the colour merely losing a little brilliancy and purple tone, and becoming blacker. 261. Copperas or Ferrous Sulphate Black. — This black was formerly the one in general use, but since the introduction of the chrome black, it has been more or less discontinued. It is often used for low-class carpet, varns, &c 328 DYEING OF TEXTILE FABRICS. [Cbap. XIII. Two metliods may be employed, namely, that of mor- danting the wool tii-st and dyeing afterwards, or that in which the wool is first boiled with Logwood and after- wards saddened. It is usual to add along with the ferrous sulphate a small proportion of copper sulphate, and when tlie first method is employed, argol, and frequently also alum, is added. Example of first method. — Mordant the wool for ]| — 2 hours with 4 — 6 per cent, of ferrous sulphate, 2 per cent, of copper sulphate, 2 per cent, of alum, 8 — 12 per cent, of argol ; take out, squeeze, and let lie overnight. Dye for 1^ hour with 40 — 50 per cent, of Logwood. Example of second method. — Boil the wool for one hour with a decoction of 40 — 50 per cent, of Logwood, and 5 — 10 percent, of Old Fustic ; lift, cool the bath, add 4 — 6 per cent, of ferrous sulphate, and 2 per cent, of copper sulphate, re-enter the wool, raise the temperature to 1 00° C. in three-quarters of an hour, and boil half an hour. The first method is the more economical. The amount of tartar or ars^ol used alona: with the ferrous sulphate in the first method has considerable influence on the beauty of the colour ; with too little it is grey and dull ; an excess is less hurtful. Experiment shows that the relative proportions should be — 1 molecule of ferrous sulphate, 2 — 3 molecules of cream of tai-tar. There is no advantage in using more than 6 per cent, of ferrous sulphate. Wool mordanted Avith ferrous sulphate alone is bufi-coloured from deposition of ferric oxide ; when tartar is used its colour remains almost unchanijed. If the water employed is not calcareous, the addition of 3 per cent of chalk, or preferably calcium acetate, to the dye- bath increases the intensity of the colour. The use of a lime salt here does not appear to be so effective as with chromium or aluminium mordants. As with the chrome black, so here the addition of a yellow colouring matter to the dye-batli is necessary in order to obtain a dead-black ; withoiit such addition a ferrous sulphate black possesses Cliap. Xni.] LOGWOOD. 329 a bluish- viol etliue. The addition of relatively small pro- portions of Madder, Sumach, (kc., aids in giving a fuller and faster black. Sumach, or other tannin matter, when used alone, is incapable of giving a black on wool with ferrous sulphate. When dyeing unspun wool or yarn it is preferable to use a freshly-made decoction of Logwood, or a good com- mercial Logwood Extract, in order to keep the material clean and free from ground dye wood, since this would interfere in the carding. The ferrous sulphate blacks become red if spotted with strong mineral acid, and are thus readily dis- tinguished from chrome blacks. They bear the action of scouring and milling satisfactorily, and withstand the action of light better than the chrome blacks. . Experi- ment proves that with regard to fastness against light a simple copper sulphate black is the best, so that the use of copper sulphate along with the ferrous sulphate or potassium dichromate is distinctly beneficial. The use of alum is, on the contrary, detrimental in this respect. The copper sulphate will probably also aid in developing a fuller black by reason of its oxidising action upon the hgematoxylin. When employed alone, copper sulphate gives greenish shades of blue, having a slightly speckled appearance. The best proportions to employ appear to be 5 per cent, of copper sulphate, and 5-5 per cent, of tartar. An excess of tartar causes the shade to become much lighter. With these amounts, and varying the quantity of Logwood, a series of shades, ranging from pale blue to black, may be obtained, but the lighter shades have a distinct greenish appearance when examined overhand not ob- servable in the darker shades. The mordanting and dyeing method yields the deepest and most useful shades. The addition of lime salts to the dye-bath is only slightly beneficial. 232. Bonsor's Black. — This "direct black," originated by P. Watinne-Delespierre of Lille, consists of a black 330 DYEING OF TEXTILE FABRICS. [Chap. XIIL paste, produced by precipitating a decoction of Tx)gwood with a mixture of ferrous and copper sulpliate. It is applied in the same way as the direct chrome black already referred to. Add to the dye-bath 25 — 30 per cent, of the black paste, and about 2 — 3 per cent, of oxalic acid. The wool is dyed at 100° C. for 1—2 hours. It is essential that the solution shoidd not be too acid, or it will not yield its full colouring power. The normal colour cf the solution is dark-brown; if blue or green in tint, it is a sign of the presence of undissolved precipitate, and a further slight addition of acid must be made. As the dyeing proceeds, the solution necessarily becomes more and more acid, and it is well before taking out tlie wool to add a small quantity of sodium carbonate, to neutralise the excess. If a deeper shade is wanted, one may add along with the black paste some extract or decoction of Logwood. For a jet-black or dead-black some suitable yellow colour- ing matter may be added in small quantity, e.g.. Old Fustic Exti^act, «tc. Such additions, however, alter the normal colour of the solution, and a little experience in their use is required. The spent dye liquor should be kept, and may serve again if replenished with fui-ther quantities of black paste and oxaHc acid. It is possible to use this black along with other so- called acid-colours for the purpose of obtaining composite colours, e.g., in the dyeing of unions. 263. Woaded Blacks are obtaiued by first dyeing the wool in the indigo-vat to a light or medium shade of blue, then washing well, and dyeing as for chrome or ferrous sulj^hate blacks. If the chrome-black method is selected, it is ad^^.sabIe to make the addition of tartaric acid to the mordanting bath, in order to reduce to a minimum the oxidising action of the bichromate of potash, and the consequent deterioration of the indigo blue. Chap. XIIT] LOGWOOD. 331 264. Logwood Blues (Wool). — Tliese are much em. ployed bv dyers, in order to imitate an indigo-vat blue. They are often combined \vith the latter by first dyeing the wool a comparatively light blue in the indigo- vat, and then intensifying it by one or other of the methoda now to be described. Logwood blues are best dyed in two baths, the mor- dants employed varying in composition and in amount according to the particular tint of blue which it is desired to obtain. One method is as follows : mordant the wool foi l_li hours at 100° C. with 4 per cent, of aluminium sulphate, 4 — 5 per cent, of cream of tartar; wash well, and dye in a separate bath for 1 — IJ hour, at 100° C, with 15 — 30 per cent, of Logwood, and 2 — 3 per cent, of chalk. By increasing the amount of alum and tartar the shade is made redder. The addition of the chalk, or preferably calcium acetate, to the dye-bath is very beneficial if the water employed is not calcareous, since it tends to make the colour level, and gives richness and considerable intensity to the blue. When calcium acetate is employed, the best result is obtained by using 30 per cent, of the weight of wool. Some dyers imagine that the use of lime salts in dyeing has only a temporary effect, but this is entirely a mistake ; indeed, if distilled water and Logvi^ood liquor be employed, the addition of calcium acetate to the dye-bath becomes just as absolute a necessity for the production of a good full colour as it is for alizarin-red. The colour produced with aluminium mordants is not fast to acids or to light. This difference in respect of fastness to light with the different mor- dants is somewhat remarkable. A somewhat faster colour is obtained by using along with the alum and tartar 0-5 — 3 per cent, of bichromate of potash ; or, better still, one may mordant entirely with 3 per cent, of bichromate of potash and 1 percent, of sulphuric acid, 16S° Tw. (Sp. Gr. 1-84). If it is desired to imitate the purplish tint of a v-at indigo blue, one may then add to the dye-bath, along 332 DYEIxVG OF TEXTILE FABRICS. [Cbap. XIIL with the Logwood, a small proportion of Gallein, Alizarin, Gallocyanin, ttc. Another method of imparting this purplish ^' bloom " is to add 0-5 — 1 per cent, of tin crystals (SnClj'SHoO) at the end of the dyeing operation. The brightest Logwood blues are obtained by dyeing at a temperature somewhat below the boil (90° C). Pro- longed boiling tends to dull the colour. 265. Logwood Purples (Wool). — These are now seldom used. They may be obtained by mordanting the wool with 6 per cent, of tin crystals (SnCl2*2H20), or its equivalent of muriate of tin, with the addition of 9 per cent, of cream of tartar, and dyeing in a separate bath, with 30 per cent, of Logwood. The addition of chalk or calcium acetate to the dye-bath in this case is injurious, since it makes the colour greyer and less intense. 266. Ajyplication to Silk. — The black dyeing of silk has increased to such an enormous extent, that some, and even very large, establishments are exclusively devoted to it. Judged from the technical standpoint, it must be admitted that this branch has reached a high standard of excellence, although, on the other hand, it is to be regretted that the practice of weighting silk, which, in the case of black, may reach as high as 400 per cent., has been so much developed. From 100 kilos, of raw-silk the dyer produces 500 kilos, of black silk ! The primary object is to increase the volume of the silk fibre, which swells up very considerably, losing, of course, its strength proportionally. The other valuable properties of silk are also more or less deteriorated, and the illusory gain of the buyer is that he requires to pay less for one and the same surface of silk material This is not the place to combat the ai'guments brought forward by the manufac- turer in favour of weighting silk, but it may be fairly maintained that the advantages gained are bought too dearly, and the durability of weighted silk is certainly too much diminished. The production of black on silk consists in alter- Clmp. XIII.] LOGWOOD. 333 nating treatments svitli iron mordant and tannin matters, with or without a Prussian Blue basis. According to Messrs. Gillet and Son, the present methods of dyeing Wack silk may bo classilied as follows : — A. Black on boiled-off Siik, 5—15 per cent. loss. I.— Black for Hat Flush. 1. INIordant in cold nitrate-acetate of iron, and 2 Dye in a decoction of Logwood and a sufficiency of Old Fustic Extract. As a rule, 1—2 per cent, of copper acetate, and 5—10 per cent, of ferrous s.^lphate, are added to this bath. 3. Dye again in a decoction of Logwood and soap. 4 Brighten in a bath containing a little oil. ll.—Massons Black for Hat Trimmings.— Thani^, arc exclusively Parisian goods, and of limited use. The silk is boiled-off in soap containing Logwood decoction, by which means it is rendered less liable to felt. It i:i mordanted in a solution of partially oxidised ferrous sul- phate, with addition of a little copper acetate, and after- wards dyed with Logwood and soap. III.— English Black— Formerly in great demand, this black is now of minor importance. 1 INIordant with basic ferric sulphate, and, atter allowing the silk to lie for some time, wash well and soap at 85°— 90° C. . ,^ 2 Dye with 50 per cent, of Old Fustic, 10 per cent, of ferrous sulphate, and 2 per cent, of copper acetate. 3. Dye with Logwood and soap. 4. Brighten lY —Black for Vehefs.—The same method as for En-lish black is used, but dye a lighter-coloured black. The tone of colour is frequently modified by givmg tne silk previously a dark ground of aniline violet or blue. Great care is required in order not to strip off the amlme blue. 334: DYEING OF TEXTILE FABRICS. [Chap. XHL B. Black on boilei>-ofp Silk, original weight or weighted 10 per cent. V. — Lyons Black (dating from 1860), for expensive articles, 1. Mordant in a cold strong hath of hasic ferric sul- phate, 50° Tw. (Sp. Gr. 1'25), once only, and wash, 2. Soap at 85°— 90° C. 3. Dye blue with 15 — 20 per cent of pota^nm ferro- cyaiiide and an equal weight of hydrochloric acid- 30° Tw. (Sp. Gr. 115). Add the hydrochloric acid in two separate portions. 4. Mordant with basic feiric sidphate, and wash. 5. Give a Catechu bath, 50 — 100 per cent, at 60^—80= C. 6. Mordant in a cold solution of alum or aluminium sulphate, and wash. The object of using aluminium mordant is to impart ultimately to the silk a violet or blue-black shade. 7. Dye with Logwood and soap. If the shade is too Wolet, a little Old Fustic is added. 8. Brighten. Yl.—M'uieral Black (dating from 1840).— This is a light black, not so fine as the last, and is used for " linings." Mordant with basic ferric acetate, and wash; dye Prussian Blue : repeat the mordanting with iron- Prepare with Catechu (100 per cent) at 80° C. Dye with Logwood and soap. Brighten. C. Black on boiled-off Silk, weighted 20 — 100 per cent. (hea\'y black). YTL. — This black is dyed on organzine and tram for satin s, sarcenets, taffetas, tte, 1. JSIordant with basic ferric sulphate, then soai>. Kepeat these operations 1 — 8 times, according to the amount of weighting necessary. %. Dye blue ; the proportions of potassium ferro- /Jliap. XIII.1 LOGWOOD. 335 cyanide and liydrocliloric acid vary according to the amount of ferric oxide fixed on the silk. 3. Give a Catechu bath (100 — 150 per cent.), with the addition of 10 — 15 per cent, stannous cliloride, at 60°— SO'' C. The employment of stannous chloride in weighted black-silk dyeing has been of the greatest impor- tance, since it facilitates the fixing of the Catechu to a surprising degree, through the formation of a tannate cf tin. 4. Give a second bath of Catechu (100 — 200 per cent.). This is fixed on the silk only by the action of the tin mordant present. 5. Mordant with pyrolignite of iron. 6. Dye wdth Logwood and soap. 7. Brighten. Blue shades of black are obtained by repeating operations 5, 4, G, in the order given, four times. The only factors which affect tiie limitation of weighting are the strength, elasticity, and lustre of the silk itself. As a rule, boiled-off organzine is w^eighted to 60 — 70 per cent., and boiled-off" tram to 100 per cent. D. Heavy Black, weighted to 400 per cent. VIII. — This is used for fringes and the fancy articles of Paris and Lyons ; also for the tram silk for satin, cheap ribbons, &lc. The raw-silk is dyed by working it alternately in chestnut extract and pyrolignite of iron. By repeating these operations fifteen times, the silk is weighted to about 400 per cent. The final processes consist of brightening operations with 10 — 20 per cent, of olive-oil. In the first chestnut extract bath, tram is soupled by raising the tem])erature of the bath sufficiently to soften the silk- glue. I)iff"erent qualities of silk require slightly different treatment. Bengal silk souples easily ; Chinese silk less readily than European silk. 336 DYEING OF TEXTILE FABRICS. IChap. XIH. E. Fine Black Souples. IX. — The finest souples are always obtained bj using water as soft as possible, like that of the Gier at Saint-Chamond. 1. Mordant with basic ferric sulphate. 2. Give a soda bath at 30°— 40° 0. Use 50 per cent, of carbonate of soda crystals. 3. Dye blue with potassium, ferrocyanide. 4. Souple by working in a bath of gall-nuts, dividivi, or other similar tannin matter. Heat the bath to 90° — 95° C, for 1 — 3 hours, according to the kind of silk. Experience alone enables the workman to judge when the softening or soupling is sufficient. 5. Leave the silk in No. 4 bath until cold, and then add 5 — 15 per cent, of stannous chloride crystals. 6. Give a soap bath at 30°— 35° C., with 60 — 80 per cent, of soap. 7. Brighten with 5 — 15 per cent, of oil. A single iron bath gives 40 — 50 per cent, of weighting (light souple) ; two baths give 60 — 70 per cent. ; three give 80 per cent. ; four give 80 — 100 per cent. F. Black on Raw-Silk. X. — This is seldom dyed In order to retain the stiff- ness of the silk, the silk-glue is not softened, the number of operations is as limited as possible, and the various baths are used at a low temperature. The process consists of working the silk in baths of ferric salt, then in decoctions of Logwood, and Old Fustic. The mode of fixing iron mordants on silk has been already explained {see p. 184). For boiled-off silk the potassium ferrocyanide baths are employed at a temperature of 55° — 60° C., because the formation of Prussian Blue would otherwise proceed only very slowly, creeping, as it were, from the periphery to the centre of the fibre. For souple silks, however, it Chap. Xni J LOGWOOD. 337 is necessary to use cold baths. Only a portion of the requisite hydrochloric acid is at first added, in order to avoid dissolvijig off any basic ferric sulphate. The relative proportions of Logwood decoction and soap employed, vary according to the black which it is desired to obtain. The usual quantities may be taken as 50 per cent, of soaj) and 100 per cent, of Logwood ; the mixture is employed as a rule only for boiled-ofF silk. The temperature of the dye-bath varies from 50" — 90° C. The operation of brightening is intended to restore the soft feel and lustre, which have been greatly de- stroyed by reason of the large amount of foreign matter with which the silk has become encrusted. For boiled- off silk there is used about 1 — 2 per cent, of olive oil ; for souples 5 — 15 per cent. ; and for fringes, &c., 5 — 20 per cent. The oil is made into an emulsion with carbonate of soda at 60° — 70° C, or with caustic potash or soda in the cold, and then immediately mixed in the bath with water. The silk must be worked in the mixture at once, i.e., before any separation of the oil can take place. Very often an addition is made of 40 — 60 per cent, of citric, tartaric, or acetic acid ; seldom hydrochloric acid. The bath should taste slightly sour. After each mordanting or dyeing operation, the general rule is to wash thoroughly, and then to remove the excess of v/ater in a hydro-extractor, in order not to dilute the succeeding baths. The usual duration of each operation varies from one to two hours, but in the tannin baths the silk should remain longer; it is frequently left steeping in thera over-night. The black dyeing of Tussur silk is a difficulty not yet completely overcome. The shades are not satisfactory, and the fibre becomes covered with metallic-looking sjjots. Tussur silk is not readily weighted, and does not absorb the iron mordants well. According to Moyret, the follow- ing process gives good results : — 1. Boil-off with dilute caustic soda. w 338 DYEING OP TEXTILE FABRICS. [Chap. XI7. 2. Mordant once or twice in basic ferric sulphate, and fix by means of a bath of weak caustic soda. 3. Dye with potassium ferrocyanide. 4. Prepare -svith a weak chestnut extract bath. 5. Mordant with pyi'olignrte of iron, and repeat operations 4 and 5. 6. Brighten with 6 — 8 per cent, olive-oil CHAPTER XIY. RED COLOURING MATTERS. BRAZILWOOD, PEACHWOOD, LIMAWOOE. 267. These dyewoods are obtained from various species of CcBsalpinia. Their dyeing properties are similar, and owing to the fugitive character of the colours they yield, they are now employed in dyeing, only to a compara- tively limited extent, chiefly for the purpose of modi- fying the shade of colours mainly derived from other sources. 268. Application to Cotton. — With aluminium mor- dants comparatively dull bluish-red colours are obtained. Work the cotton in a decoction of tannin matter, then in a cold solution of more or less basic aluminium sulphate. Wash and dye in a fresh bath at a low temperature, with a decoction of the dyewood. The stannic mordants yield brighter and more orange- toned reds. Scarlet may be obtained by mordanting with aluminium and stannic salts, and dyeing afterwards with the addition of some yellow colouring matter to the dye-bath, e.g., Old Fustic. With iron mordants these dyewoods give violet-grey colours. By using a mixture of aluminium and iron mordants, and by adding a small proportion of Logwood to the dye-bath, dark purple or "plum" colours are obtained. Chap. XIV.] BRAZILWOOD AND PEACHWOOD. 339 The colours are not fast to soap. The fastest are tliose in which the mordant is fixed by the aid of tannic acid. 239. Application to Wool. — In wool dyeing these dyewoods are generally emplo3'ed along with other dye- woods, for producing brown colours, which cannot, how- ever, be regarded as fast or permanent. The most useful mordant for wool is bichromate oj potash. By mordanting with 3 per cent, of bichromate of potash, then wa.shing, and dyeing in a .separate bath, with small amounts of dyewood, a purplish slate colour is obtained ; with large amounts a claret-brown is pro- duced. The addition of sulphuric or tartaric acid to the mordanting bath is not beneficial ; it makes the colour redder. The addition of 3 — 5 per cent, chalk or calcium acetate to the dye-bath makes the shade bluer. A bluish-red colour is obtained by mordanting the wool with 6 per cent, of aluminium sulphate and 5 per cent, of cream of tartar, then washins:, and dyeing in a separate bath for f — 1 hour at 80°-^100" C. with 40— 60 per cent, of dyewood. Still bluer shades are pro- duced by adding to the dye-bath towards the end of the dyeing operation a little ammonia. The addition of 2 — 6 per cent, chalk or 6 — 12 per cent, calcium acetate to the dye-bath is very beneficial ; it makes the shade bluer and more intense. Brighter shades of red are obtained by adding to the mordanting bath 1 per cent, of stannous chloride, and a small percentage of some yellow coloni-ing matter, e.g., Old Fustic, Flavin, »fcc. The addition to the dye-bath of skimmed milk or a .solution of gelatin in moderate quantity is beneficial ; it combines with and renders insoluble and inert the tannin matters present in the wood, thus enabling one to obtain some- what brighter shades. The single bath method gives fairly satisfactory results, the colour being paler, but more brilliant than by the mordanting and dyeing method. Use 4 per cent, of aluminium sulphate, with addition of 2 per cent, potassium oxalate. 5i0 DYEIXG OF TEXTILE FABRICS. [Chap. XIV. Although the employment of stanroous cidoride as the mordant yields bright reds when it is used in small proportioii (say 2 — 4 per cent, of stannous cliloride with 4 po" cmt. of tartar), it requires the addition of too much tartar (30 — 40 per oeat.) to give a leaBv good colour. Stcaude ekhride also gives bright reds, but here, too, the amount of tartar leauired is abnormally large — use, say, stannic chlcMide eqfoivalent to 4 per cent SnCU'2H.-,0 and 32 per cent, ai taitar. With tin mordants the addi tion of lime salts to the dye-bath is injurious. Ccjipar sulfhaie as the mordant gives drab or clai^et- txTQwn shadea^ aooording to the amount of colouring matter ^nployed. Use 4 per cent, of copper sulphate. Tbe addition of tajrtajc is not beneficial. The addition of calcinm acetate or dialk to the dye-bath is beneficial. Ferroug gulphiaU as tiie mordant gives dark slate and daretb Use 2 — 5 per ooit. ferrous sulphate, and 4 — 8 per cent tartar. Tlie addition to the dje-bath of 8 per cent, or mc»e calcium aoetate or cdialk is essential 270. AppUoation, to Silk. — ^These dyewoods are now no longer used by the silk-dyer, having been entirely dis- placed by the coal-tar ooloursL Hieiy were fannexij used for obtaining crimson shade& Hie oidinaxy method was to mordant the silk with alum, and dye in a separate bath at a low temperature in a decoction of Peacliwood, with the addition of a little soap. Sranewhai brighter and faster shades were obtained by workiiig the alk afterwards in a bath containing nitzo-muziate of tin, and finally washing. 'Bn^t crimsons were also obtained by mordanting the silk with stannous chloride and tartar, and dyeing after- wards with a decoction <^ Peachwood. CAmrOOD, BABWOOD, SJLKDEBSWOOD. 271. These dyewoods are obtained from certain species of PUroearpug amd Baphia ; but although the origin of esdi is distinct^ and the colours they yield vary some- Chap. XIV.] CAMWOOD AND BARWOOD. 341 what in tone, their general dyeing properties are so similar that it will be most convenient to consider their applica- tion in dyeing, together. They are principally used in wool-dyeing, in conjunc- tion wdth other dyewoods — e.g., Logwood, Old Fustic, &c. — for the purpose of obtaining various shades of brown, olive, drab, &c. In cotton-dyeing their use is more limited, while in silk-dyeing, owing to the gi-eat insolubility of their colouring principles and the essential exclusion of all ground wood from the dye-bath, they are not used. at all. 272. AjyplicatioJi to Cotton. — The colours produced on cotton are moderately fast to soap and weak acids, but not to light. They are destroyed by hypochlorites, and boiling alkaline solutions rapidly impoverish them. With aluminium and tin mordants (especially the latter) fairly good reds can be obtained. These are rendered bluer by the action of soap and alkalis. With iron mordants they yield dull violet colours. Barwood is chiefly used by the cotton-dyer for the purpose of obtaining '^ Barwood red," sometimes called ** mock Turkey -red." The cotton is worked in a cold solution of stannate of soda, 4° — 6° Tw., till thoroughly saturated, wrung out, and then worked rapidly and for a short time in dilute sulphuric acid, J° Tw. Wash well, and dye with about 200 per cent, of Barwood. The cotton is introduced into the dye-bath cold, the temperature is then gradually raised to 100° C, which is maintained for an hour or more. By adding a small quantity of sodium carbonate to the dye-bath (about 6 per cent, of the weight of Barwood) the colouring matter is somewhat more readily extracted, and a fuller but slightly duller red is obtained. The cotton may also be mordanted by working either in stannic chloride or nitro-muriate of tin, 4° — 8" Tw., wringing out and passing afterwards into a cold solution of sodium carbonate, 4° Tw., and washing. Yery good results are obtained by fixing the stannic mordant on the fibre by means of tannin matters. 342 DYEING OF TEXTILE FABRICS. [Chap. XIV. If it is desLi'ed to mordant with aluminium, work the cotton in cold basic aluminium sulphate, 4° — 6° Tw., and fix by means of phosphate or silicate of soda. Good chocolate or violet brown shades are obtained by mordanting the cotton with pyrolignite of iron, 4p — 6'' Tw., then passing into a cold dilute solution of ammonia, and afterwards dyeing with Camwood instead of Barwood, because of its greater solubility and colouring power. By using a small proportion of "red liquor" with the iron mordant nice reddish-brown colours are obtained. 273. Application to Wool. — Rich claret-bro\vTi shades are obtained if wool is mordanted with 0*5 — 2 per cent. hichromate of potash, and then dyed, in a separate bath with 40 — 80 per cent, of dyewood. Camwood gives the bluest and Sanderswood the yellowest shades, Barwood holding an intermediate place in this respect. The colouring power of Camwood is about three or four times stronger than that of the other woods. Owing to the sliglit solubility of the colouring matter of these dyewoods, they are extremely well adapted for the " stuffing and saddening " method of dyeing, with this and other mordants. The wool is boiled for 1 — 2 hours with 40 — 80 per cent, of dyewood, by which it acquires a veiy full brownish-red colour. It is then boiled either in the same or preferably in a separate bath, with 2 per cent, of bichromate of potash for half an hour. The shades thus produced are all deeper and bluer than those obtained by the mordanting and dyeing method ; especially is this the case with Camwood, which yields quite a purplish colour. By whichever method Camwood is applied, the addition of sulphuric acid either to the mordant or dye-bath is injurious. In practice it is certainly added to the stuffing bath, but its office is probably to neutralise the alkalinity of the scoured woo? or of the calareous water. With aluminium moo^dant and employing the " mor- Chap.XlV.1 CAMWOOD AS0 BARWOOD. 343 danting and dyeing" method a dull brownish-red, very similar to a Madder red, is obtained. ^ , , . . Mordant the wool with 1-6 per cent, of alum nmm suli-hate with 2-8 per cent, of tartar; wash and dye m separate bath for 1^-2 hours at 100» G with 40-GO per cent, of Camwood. With the smaller amounts of mordant indicated, the red produced approaches m tone of colour that given by boiling the wool -^t^ Camwood without any previous mordantmg, being only shghtly bluer. By using the larger amounts of mordant the colour is lighter and yellower. The best method, however, of applying the alunu- nium mordant is that of " stuffing and saddening ; firs , boil the wool with Camwood (20-80 per cent and afterwards with 10 per cent, of aluminium ^^'I'l^^^f " * separate bath. The reds thus produced are bng^'tei, blue foller, and more level than those obtained by the "'monlanting and dyeing" method. Even when such a small amount as 10 per cent, of Camwood is employed, the Dink produced is perfectly level. , ^ n ^ cLwU gives the deepest and bluest shade of red Barwood and Sanderswood give yellower ami bni^^e, reds those of Sanderswood possessmg the yellowest tonu "\mewhat brighter and more_bluish ^>>ades of red a e obtained by mordanting with O-o-l Pf ■?«'"• f '^^4' cJdoride and 2-16 per cent, tartar, "^^t?-/ °J ^ '^'^ ^;^. :irruir r*=5 -Br'""" * in order to give the best result is too large to <^ 1^!^ ;* in oruei tug uefiifftncr and saddening its adoption m practice. The ^^^°^^;- ^^^ j>^il ^Uh method, however, gives even bettei results r.o the requisite amount of dyevvood and madden ma sepa. rate Lath with 1-4 per cent, stannous chloude. i e addition of tartar in this case is not benefacial The coloui' obtained are fuller, bluer, and more level than those given by the first method. Z4:i DYEING OP TEXTILE FABRICS. [Chap. XIV. By far the brightest and richest reds obtainable from these dyewoods are those produced when a stannic salt is employed as the mordant, but the amount of tartar which must also be added in order to mordant the wool sufficiently is so excessive as to exclude its being adopted in practice. By mordanting wool for 11 — 2 hours at 100'' C. with 4—8 per cent, of stannic chloride solution (Sp. Gr., 1-6°) and 40 — 160 per cent, of tartar, then washing and boiling 1 — 2 hours with 40 — SO per cent, of bar wood, one obtains a bluish-red or crimson, very similar in shade to a peach wood and alum red, and certainly very much brighter and bluer than a madder and alum red. By reducing the amount of tartar the colour becomes yellower and lacks brilliancy and intensity. With this mordant Camwood gives a more intense red^ having a purplish shade ; Sanderswood gives a yellower red. Unfortunately none of the reds obtainable from these dyewoods withstand the action of light well ; a year's exposure suffices to bleach them entirely. Cop-per sulphate is frequently used as a saddening airent with these dvewoods. The best results are obtained by saddening with 8 per cent, of copper sulphate. The colour given with 40 — 80 per cent, of Camwood is a good claret-brown. Very different in colour are the bluish-reds obtained by mordauting with 2 per cent, of copper sulphate and 7 — 8 per cent, of tartar, and dyeing in a separate bath. When ferrous sulphate is used as the mordant the best results are also obtained by the " stuffing and sad- dening " method. Sadden with 5 per cent, of ferrous sul- phate. Good full puq^lish shades are produced similar to those obtained by using bichromate of potash. Bjr mordanting \s-ith 5 per cent, of ferrous sulj^hate and — 12 per cent, of tartar, good claret>-browns are obtained. MADDER. 274. This dye-stuff, which consists of the ground dried i-oots of Huhia thictorum^ was formerly one of the most Chap. XIV.] MADDER. 345 valued and most largely employed. It lias now been more or less entirely displaced by the coal-tar derivative Alizarin and allied colouring matters. 276. Application to Cotton. — Madder and its commer- cial preparation Garancine, were formerly used by the cotton dyer for the purpose of obtaining the red colour so well known as Tuikey-red, a colour remarkable for its great brilliancy and fastness both to light and to boil- ing alkaline solutions. The chief interest attaching to Turkey-red is the characteristic preparing of the cotton with oil previous to mordanting and dyeing, and to this, indeed, it owes its special qualities. The displacement of Madder by Alizarin in Turkey-red dyeing has not necessarily brought about any material changes in the mode of cariying out this preliminary oiling process, so that the Emulsion and Steiner's processes {see pp. 427, 438) may be taken as representmg essentially the method of dyeing Turkey-red adopted in the days when Madder was employed, substituting merely an equivalent amount of ground Madder for the Alizarin. 276. Application to Wool. — When wool is boiled with Madder it acquires a pale brown or drab colour, and although this can only be considered a stain, this simple method of application has been adopted in practice. By mordanting the wool previously with 3 per cent, of bichromate of potash, good reddish-browns are obtained. The addition of 1 per cent, of sulphuric acid, or 9 per cent, of tartaric acid, gives a darker colour. By the "single- bath method " fairly good colours are obtained ; they are, however, yellower and not so deep as those yielded by the ordinary method. For red, the wool is mordanted with aluminium sul- phate and tartar, and dyed with Madder in a separate bath. Mordant the wool with 6 — 10 per cent, of aluminium sulphate and 5 — 8 i)er cent, of tai-tar. Dye with 60 — 80 per cent of Madder. Begin the dyeing at 40° C, and raise the temperature of the bath gradually S46 DYEING OF TEXTILE FABRICS. [Cha-». XIV to 80° — 100° 0. in the course of one hour, and continue the dyeing about one hour longer. Wash and dry. The shade thus produced is a brownish-red. It may be made considerably brighter, and of an orange tone, by adding a small proportion of stannous chloride solution along with the aluminium sulphate and tartar ; or instead of tliis^ the stannous chloride may be added to the dye- bath towards the end of the operation. The gradual raising of the temperature of the dye- bath is essential in order to develop the full colouring power of the Madder. If the bath is allowed to cool considerably or frequently during the progress of the dyeing, even though the correct temperature is con- tinually re-established, there is a loss of colouring })ower. If the water or Madder used;, is deficient in lime, brighter and fuller shades are obtained by an addition to the dye-bath of 1 — 2 per cent, (of the weight of Madder employed) of ground chalk, or acetate of lime. This addition is useful with Dutch and Alsatian madders, since these are naturally deficient in lime. The addition too of a small proportion of tannin matter along with the Madder serves to exhaust the bath more fully and to give deeper shades. Add Sumach, say, to the amount of one-tenth of the weight of Madder employed. Avoid an excess, since it gives a poor weak colour. Brighter shades are obtained by employing the lower temperature given (80° C.) and prolonging the dyeing process, because in this case the yellow and fawn-coloured principles of the Madder are not so readily fixed. After dyeing and washing, the coloiu* ma}' be made somewhat brighter by working the wool for a short time at 70° C. in a bath containing either a small proportion of soap solution, or of a decoction of bran. With thick woollen materials it happens sometimes that the colour does not penetrate sufliciently. To over- come this defect it is usual to add a small portion of Madder to the mordanting bath, so that at least some of the colouring matter of the Madder may penetrate to the Chap. XIV.] MADDER. 347 centre of the fabric before it is precipitated and fixed V)y tJie mordant. It is quite possible, indeed, to dye light shades with the Madcler and mordant in the same bath, but this method is not applicable if the fullest and richest colours are required. Under the most favourable conditions a Madder red on wool is by no means brilliant, and not to be compared in this respect with Cochineal scarlet. It is, however, a fast and permanent colour, and withstands the action of light and milling with soap extremely well. Since the introduction of artificial Alizarin, fast reds should be dyed with this colouring matter in preference to Madder, since brighter colours are obtained at a less cost Wool mordanted with 8 per cent, of stannous chloride and 4 per cent, of tartar, and dyed in a separate bath, acquires a fine orange colour. In single-bath use 4 per cent. SaCl"2HoO and 2 per cent, tartaric acid. With copper sulphate and tartar, brown-colours are ob- tained ; with ferrous sulphate and tartar, darker browns. Use two-bath method ; single-bath method is also applicable. 277. Application to Silk. — Notwithstanding the gene- ral fastness of the colours produced by Madder, owing to their want of brilliancy this dye-stuff is comparatively little used in silk-dyeing. For red the silk is mordanted as usual with alum by steeping over-night in a cold concentrated solution. Wash well and dye in a separate bath with 50 per cent, of finely ground Madder. Begin dyeing at a low tempera- ture and raise it gi-adually to 100° C. The addition of bran to the bath tends to give brighter colours. For the purpose of obtaining a fuller colour one may also add to the dye-bath a small percentage of Sumach. After dyeing, wash, then brighten in a boiling solution of soap to which a small percentage of stannous chloride has been added, and wash well. By mordanting with fet'rous sulphate, either alone or after a pre\dous mordanting with alum, violet and brown shades may be obtained. 348 DYEING OF TEXTILE FABRICS. [Chap. XIV COCHINEAL. 278. This colouring matter consists of the dried insect Coccus cacti, largely cultivated in Mexico. It is little used in cotton-dyeing, except by the calico- printer. Formerly much employed in silk-dyeing, it has now been almost entirely replaced by the use of various aniline-reds, while in wool-dyeing since the introduction of tlje azo-reds its use has become more and more limited. 279. Ajyjylication to wool. — Wool mordanted with 2 per cent, of bichromate of potash, and dyed in a separate bath with Oochineal, gives a good purple colour. The ad- dition of sulphuric acid to the mordanting bath, even to the extent of 3 per cent, of H2SO4 168° Tw., makes the colour darker. Two different shades of red are obtained from Cochi- neal, namely, a bluish red, called crimson, and a yellowish or fiery red, called scarlet. 280. Cochineal Crimson is obtained by mordanting the wool with 4 — 8 per cent, aluminium suljyhate and 5 per cent, of tartar, and dyeing in a separate bath with 8 — 15 per cent, of Cochineal. The addition of lime salts to the dye-bath is not benefi.cial. Fairly good shades are obtained in a single bath by using 6 per cent, of alumi- nium sulphate and 4 per cent, of oxalic acid or 6 per cent, of potassium oxalate. Cochineal crimson can, how- ever, be obtained in a variety of ways. One method is to dissolve about 5 per cent, of alum, and 2|^ per cent, of tartar in an old Cochineal-scarlet bath, and boil the wool about one hour in it ; then dye at the boil for half an hour in a separate bath, with 10 — 15 j^er cent, of Cochineal. The following table gives the proportions of other materials which may be employed : SnCl2 SnCl4 Alum, Tartar. (crystals) (crystals) sulphate Cochineal, per cent, per cent, per cent. i)er cent. per cent. Wool, No. 1. 6 3 3 10 8 to 15 100 „ 2. 4 2 1-5 .. 3. 1 1 6 « Chap. XIV.] COCHINEAL. 349 Boil 1— U hour with the mordants, and dye in a separate bathVith the Cochineal for 20-40 minutes at 100^ C. . , . 1 n 1 Good crimsons may also be obtamed in one bath by boiling the wool for i- j of an hour with the alummium sulphate and tartar, then removing it temporarily to add the ground Cochineal, boiling a few minutes, and finally re-entering the wool and boiling 1— i of an hour longer. A certain proportion of the colouring matter always re- mains precipitated in the bath and is lost by this method. In order to modify the shade of crimson and make it still bluer, a small amount of carbonate of Foda or liquidammonia is sometimes added to the dye-bath towards the end of the dyeing operation, or the goods are washed in water and made slightly alkaline by the addition of a little lime-water. Other modifications of shade are obtained by adding to the dye-bath varied proportions of Ammoniacal Cochineal, Orchil, or Cudbear; these, how- ever, produce a colour which is not so fast towards light. Ammoniacal Cochineal is frequently used along with ordinary Cochineal for the production of rose-pmks, i.e., bluish shades of pinks. ^ -, • • Cochineal crimson obtained by usmg aluminium mor- dant is tolerably fast to light, and also to milling with soap and weak alkaline carbonates. . 281 Cochineal Scarlet.— The ingredients generally used in' obtaining this colour are Cochineal a stannous salt, and cream of tartar, or oxalic acid. Two distinc methods for its production maybe adopted, (1) the wool is first mordanted with the stannous salt and tartar and then dyed in a separate bath with Cochineal ; (2) the mordanting and dyeing are performed simultaneously in one and the same bath. , r i 1 1 u^,,.. First J/e^Aorf.— Mordant the wool for l^U hour, with 6 per cent, of stannous chloride (crystals) and 5 per cent, of cream of tartar, and wash. Dye with 5-12 y^x cent, of ground Cochineal for 1-U hour. In order to obtain level shades, enter the wool both in the mor- 3^ DYEIXG OF TEXTILE FABRICS. [Chap. XIV. dantms- and dTe-l»ath at about 50*^ C. and raise the tern- peratare gradual! y to the boiling jwint. If 3 per cent, of the stannaos chloride is rei)laced by its equivalent of stannic diloride, tlie colour is yellower and more brilliant (Liecliti). Hie addition of lime salts to the dye-bath is injurious. Second Method. — Fill the dye-bath half full of water, add 6 — 8 per c^nt of oxalic acid, 6 per cent, of stannous chloride, and 5 — 12 [>er cent, of ground Cochineal ; boil up for 5 — 10 minuteiS, then fill up the dye-bath with cold waAea". Intaxjduce the woollen material, heat up the bath to the boiling point in the course of | — 1 hour, and boil I" hom: Potassium oxalate may replace oxalic acid : or one may use with advantage the mixture of stannous and stannic chloride with tartar as given above. By this " single-bath method " the dye-bath is not ex- hausted as in the first method ; a portion of the colouring matter always remains in the bath in combination 'with the mordant as a yellowish flocculent precipitate. The nnexljausted bath may, however, be utilised for one or two succeedino: lots of material, bv merely re- plenishiDg it with further quantities of the several in- gredients. In practice many modifications have at one time or another been introduced into both the above methods. In the first, for example, the mordant has been divided, adding a portion only, to the actual mordanting bath, and the remainder to the dye-bath along with the CochineaL This division has extended either to both tartar and stan- nous chloride or \o one of these only. Sometimes, too, the Cochineal has been divided, a small proportion being added already to the mordanting-bath. Washing between mordanting and dyeing, not being absolut-ely essential. has been omitted. The temperature and duration of m<»dantiDg and dyeing have varied greatly ; and other stannous and .stannic salts, with the addition of other assistants than tartar, have been employed. The changes rang on the Tariations j^Kssiljle in the second method have been almost equally numerous. Chap. XI7.1 COCHINEAL. 351 Comparing the two methods, experiment shows tliat, with an equal expend itnre of ingredients, the lirst method gives a blue shade of red possessing both purity and intensity of colour. The single-bath method gives a yellower and more brilliant scarlet. This method is on the whole the more advantageous, and is the one gene- rally adopted. When the single-bath method is employed, compara- tively little difference is produced by dividing the mordant and reserving a portion to be added along with the Cochi- neal during the second period of the process. If the addition is mainly or entirely confined to the first or mordanting period, the scarlet obtained is slightly more intense and yellower. Without the use of tartar a poor bluish shade of red would be obtained. Addition of tartar up to 8 per cent, increases the intensity and yellowness of the colour. A deficiency of tin mordant gives also a dull bluish- red, while an excess makes the scarlet paler. As a rule, stannous chloride is not employed in the crystalline state — i.e., as " tin-crystals " — but in the form of an acid solution, namely, as " double or single muriate of tin." The presence of a moderate excess of free hydrochloric acid in these solutions has the following advantages : — 1. The mordant is thereby rendered less sensitive to decomposition, and is better able to penetrate thick, closely- woven or hard-spun material before any deposition of mordant takes place. The material thus becomes more thoroughly mordanted throughout its mass, the ultimate colour is not so much confined to the surface, and the material appeai-s dyed through. 2. Tlie free acid present, acts beneficially by retaining the coloured lake already alluded to longer in solution, so that the wool acquires a deeper shade than it would otherwise. 3. The presence of free acid in the dye-bath is abso- lutely essential, when a calcareous or otherwise alkaline 352 DYEIXO OF TEXTILE FABRIC3. [Chap. XIT. water is employed, anless the latter is previously neu- tralised ; or when after scouring the wool with weak alka- line solutions the washing has been insufficient. Without the free acid, the mordant would be precipitated in the bath to a greater or less degree, aocoidiDg to the alkalinity of the water, and the scarlet would either be of a weak, dull-bluish shade, or might not even be produced at alL In dyeing Cochineal scarlet, therefore, an acid condition of the bath is essential to the production of a satisfactory colour. A large excess of free acid, however, must be avoided, otho^inse the colour lacks intensity. Other salts of tin, known as Tin Spirits, Scarlet Spirits, &&, are often used instead of those already given. The firstrmentioned solution, or "nitrate of tin," is much used by dyers. The scarlet it yields has a decided yellow shade, owing probably to the action of the nitric acid liberated during the mordanting process. In this respect, therefore, it is equivalent to an extra addition of tartar. Although stannic chloride, when used in conjunction with tartar and Cochineal, yields fairly good scarlets, these cannot compare in bnlliancj with those obtained by the use of a mixture of stannous and stannic chloride. The pr&nsDce of a certain amount of stannic salt along with stannous chloride is said to be beneficial in preventing the production of so-called " tin spots," i*.e., dark-looking or almost black spots, which sometimes occur ini^ularly throughout the scarlet-dyed i^bric These sjxjts consist of anhydrous stannic oxide, produced from the hydrate stannous oxide during the boiling. The use of oxalic acid acts beneficially in the same direction. In order to obtain bright yellow shades of scarlet, it is usual to add a small proportion of some yellow colour- ing matter alon^ with the cochineal. Flavin, or Young Fustic, are generally used for this purpose. Persian Berries are occasionally used, but they are more expen- siva Cochineal red on wool must be considered as very Chap. XIV.J COCHINEAL. 353 fairly fast to light. Its principal defect is that by the action of weak alkalis, soap, (fee, it acquires a duller and more bluish shade of colour. Excessive milling must therefore be avoided whenever cochineal red is present in the goods. By rinsing the goods afterwards in water acidified with acetic acid, the bright tone is more or less restored. Cochineal is always preferable to an Azo Red for dyeing yam intended to be woven along with other white or delicately-coloured yarns in goods which require to be scoured or milled. Cochineal red does not "bleed " and stain the neighbouring fibres like the Azo reds. The dye-baths used for Cochineal scarlets should be either of wood, stone, or block-tin. Iron and copper ones should be rigorously avoided, since the acidity of the bath causes a small quantity of these metals to be dissolved, and the colour produced is dull. A piece of clean block-tin placed in a copper dye-bath obviates this defect, no copper being then dissolved. Wool mordanted with 10 per cent, of copper sulphate, and dyed in a separate bath with Cochineal, gives a red- dish-purple or claret colour. The addition of tartar to the mordanting bath is not beneficial. With ferrous sulphate as the mordant, very good pur- plish-slate or lilac colours can be obtained. Mordant with 8 per cent, ferrous sulphate, and 20 per cent, tartar, and dye in separate bath. In single bath use 4 per cent, fer- rous sulphate and 4 per cent, potassium oxalate. 282. Application to Silk. — Crimson. Mordant the silk by working for half an hour, then steeping over-night in a concentrated solution of alum. Wash well, and dye in a fresh bath containing a decoction of 40 per cent, of Cochineal Enter the silk at a low temperature, and heat gradually to 100° C. Scarlet. After boiling-off and washing, the silk is fii*st slightly dyed or grounded with yellow, by working it for a quarter of an hour at 50° C. in a weak soap bath contain- ing about 10 per cent, of Annatto, it is then well washed. For darker shades of yellow use no soap, and dye at 90** C. X 354 DYEIX'G OF TEXTILE FABRICS. [Char. XIV. Mordant the silk by working it for half an hour and then steeping it over-night in a cold solution of 40 per cent, of nitro-muriate of tin. Wash and dye in a fresh bath, with a decoction of 20 — 40 per cent, of Cochineal, and 5 — 10 per cent, of cream of tartar. Enter the silk at a low temperature, and heat gi*adually to lOO"" C. Bricjhten in a fre.sh bath of cold water, slisrhtlv acidified with tartaric acid. Very good results ai-e obtained by adopting the method found most advantacreous in wool- dveing, namely, dyeing in a single bath with Cochineal, stannous and stannic cliloride, with addition ot tartar. "With the use of iron mordants very fine shades of liJac may be obtained on silk, with CochineaL 283. Lac-dye Red (Wool). — Lac-dye is used for ob- taining reds similar to those yielded by Cochineal, and the methods adopted are essentially the same as those already described. Owing to the presence of a large excess of mineral and resinous impurities, Lac-dye yields its colour- ing matter to water less readily than Cochineal ; hence, twelve hours or so before it is added to the dye-bath, it should be ground and made into a paste with the tin solution to be employed, sometimes with the addition of a little fi'ee hydrochloric acid. This preliminary treat- ment softens the Lac-dye, dissolves part of the mineral matter with which the colouring matter mav be com- bined in the form of a lake, and thus i-enders it more soluble in the dye-bath. With the exception of this slight deviation, the dyeing is performed in exactly the same manner as with CochineaL Lac-dye reds are less brilliant than Cochineal reds, but possess greater intensity. They are also considered to }ye somewhat faster to light and wear, and to the action of milling with weak alkalis. Hence Lac-dye is frequently used in conjunction with Cochineal, in order to take advantage of the good qualities of both, and thus obtain a colour which combines fastness and brilliancy. To this end the two dye-stufls may be added to the same dye-bath ; or bet ter still, the material is fii-st dyed with Chap. XIV.l ORCHIL AND ANNATTO. 355 Lac-dye and afterwards with Cochineal, in a separate bath. ORCHIL. 284. — Orchil paste, Orchil extract, and Cudbear aie prepared from certain lichens by submitting them to a process of oxidation in the presence of ammonia. They are still much used in the dyeing of compound shades on wool and silk. Their colouring matter (Orcein) dyes best in a neutral bath, but it possesses the very useful pro- perty of dyeing either in a neutral, slightly alkaline, or slightly acid bath, and the colours have an intensity or body not readily obtainable by means of its rivals among the coal-tar colours, chief among which is Fast Red or Roccelline. The colour is not fast to light. Orchil is not applicable in cotton-dyeing, and for wool and silk no mordants are required. Application to Wool. — Dye in a neutral bath, or with a slight addition of sulphuric acid, or of soap solution. Application to Silk. — Dye in a bath containing soaj) solution, or boiled-ofF liquor, with or without the addition of acetic or sulphuric acid. The colour produced is a bright bluish-red or magenta. ANNATTO. 285. — This colouring matter is obtained from the pulp surrounding the seeds of Bixa orellana. Owing to the fugitive character of the red or orange colour which it yields, its employment is very limited, and is chiefly confined to silk-dyeing. A short time before it is re- quired for use, it must be dissolved by boiling it with a solution of carbonate of soda. Application to Cotton. — Work the cotton in a hot solution of Annatto, containing soap or carbonate of soda. Pale colours are dried direct from the dye-bath ; dark colours should be rinsed slightly in a cold soap solution to remove excess of alkali from the fibre. By passing the dyed cotton through water slightly acidulated with sulphuric acid or alum, the colour assumes a redder tint. 356 DYEING OF TEXTILE FABRICS. [Chap. IV Application to Wool and Silk. — Pale shades are dyed at 50"^ Q., with the addition of soap to the bath : dark shades are dyed at 80° — 100° C, without any addition. SAFFLOWER. 286. — This dyestnff consists of the dried florets of the composite flower of Carthamus tinctorius. Previous to being used by the dyer the commercial product should be well washed with cold water to remove the worthless yellow colouring matter present. It is best to use the so-called Safflower-ex tract. Safflower finds a veiy limited use in the dyeing of cotton yaro, thread, and tape. The bright pink colour obtained is extremely fugitive. Application to Cotton. — To ensure even dyeing the cotton is first worked for some time in a cold carbonate of soda solution of the . colouring matter ; it is then removed from the bath, and the solution is slightly acidi- fied with sulphuric, acetic, or tartaric acid. The cotton is asrain introduced, and worked about until the bath is exhausted. The real dyeing only takes place in the acid bath. The dyed cotton is afterwards rinsed in water slightly acidified with acetic acid or cream of tartar, and dried in a cool, dark place. Silk may be dyed in a similar manner. CHAPTER XV. YELLOW COLOURING MATTERS. WELD. 287. — Weld consists of the plant Reseda luteola. It is principally used in wool- and silk-dyeing, for producing yellow and olive colours. 288. Apjylicatioji to Cotton. — The yellow colours ob- tained on cotton fi-om this dyestufl* are of little or no importance, since they are not fast to soap. Ci.ap XV. 1 WELD. 357 Chromium mordants yield yeJlowisli olives, very fast to soap and light. The addition of calcium acetate to the dye-bath is beneficial. With aluminium mordants yellows are obtaiaed, but they possess no particular brilliancy. Work the cotton in aluminium acetate 4° — 6° Tw. (8p. Gr. 1-02 — 1-03), and fix in a separate bath with phosphate or silicate of soda ; wash and dye for i | of an hour at 60" C. A slight addition of acetate of" copper to the dye-bath makes the shade more orange. With stannic mordants the yellows produced are slightly faster to soap, and somewhat more orange in tone. Pyrolignite of iron as the mordant, with or without the additional use of aluminium acetate^ and fixed by means of silicate of soda^ gives various shades of olive. Greens are obtained by mordanting with aluminium, and dyeing with a mixture of Weld and Logwood, or by first dyeing the cotton an indigo- vat blue, afterw^ards mordanting with aluminium acetate, or a stannic salt, and dyeing with Weld. 289. AppUcatio7i to Wool — The use of Weld in woollen- dyeing is limited, because it is of low colouring power and requires two baths, and because the fastness and purity of the yellow colour are not generally recognised. Wool mordanted with 2 per cent, of bichromate of jjotash, and dyed in a separate bath with 60 per cent, of Weld, gives an olive-yellow or old-gold shade. The addi- tion of sulphuric acid to the mordanting bath is not beneficial. The addition of 3 per cent, chalk to the dye- bath adds intensity to the colour. To produce Weld yellow, mordant the wool by boiling it 1 — 2 hours with 4 per cent, of aluminium sulphate, wash and dye in a separate bath with a decoction of 50 — 100 per cent, of Weld, for 20—60 minutes, at 80°— 90° C. The dye-bath is prepared immediately before intro- ducing the mordanted wool, the chopped Weld being en- closed in weighted bags, and boiled with soft water onlj^ for i — 1 hour, then add 4 per cent. chaJk before dyeing. 358 DYEIXG OF TEXTILE FABRIC;-. fChap. X7. The colour thus obtained is a yellow comparatively free from any tinge of redness. Its fastness to light and to milling with soap and weak alkalis is very satisfac- tory; indeed, it must be considered as superior to all other natural yellow colouring matters in these respects. The addition of 5 per cent, tartar to the mordanting bath is beneficial, but excess makes the colour dull. The addition of 2 per cent, of stannous chloride gives bril- liancy and fastness to the colour produced. The addition of 4 per cent, of chalk to the dye-bath gives a yellow, which possesses greater intensity but less purity. The addition of calcium acetate has the same effect as that of chalk, but in a less degree. Brighter yellows are obtained by mordanting with 8 per cent, of stannous chloride instead of with alumi- nium sulphate. By adopting the " single-bath " method similar to that given for Cochineal scarlet, very good bright yellows are obtained. Wool mordanted with 6 per cent, of copper sulphate, and dyed in a separate bath with Weld, gives a yellowish olive colour. The addition of tartar to the mordanting bath is not beneficial. Add 2 — 8 per cent, chalk to the dye-bath. Wool mordanted with 4 per cent, of ferrous sulphate and 3 per cent, of tartar, and dyed in a separate bath with the addition of chalk, gives good olive colours. 290. Ap)plication to Silk. — Of all the natural yellow colouring matters. Weld is the most important to the sUk- dyer, since the colours it yields are relatively fast to light and slight soapiug. It is principally used for dye- ing yellow, olive, and green. For yellow, the silk is mordanted in the usual manner with alum, washed and dyed in a separate bath at 50° — 60° C. with a decoction of 20 — 40 per cent, of Weld. A small quantity of soap solution is added to the dye- bath, in order to ensure even dyeing. The amount to be added increases with the degi^ee of hardness of the water, Ctap. XV.l OLD FUSTIC. 359 and the percentage of weld employed ; in any case, the addition of too much should be avoided. It is, of course, better to correct the water previously. After dyeing, the colour is brightened by working the silk for ten minutes in a fresh soap bath to which, in order not to im- poverish the colour, a little decoction of Weld has been added. Wring out without washing. If scroop is re- quired, the silk is washed, and then worked for ten minutes in water slightly acidulated ^dth acetic acid. It is essential to the production of bright yellows that the aluminium salt used be absolutely free from iron. The best Weld to employ is the short French Weld from Cette, and the purest yellows are obtained from the first and second decoctions of the flower portion of the stem. The root portion contains a little tannin matter, which tends to dull the colour. Dark shades of yellow are dyed in the same way, using proportionately more Weld (50 — 70 per cent.). The addition of soap to the bath is not necessary, but it is advisable to keep the temperature somewhat lower. For very dark shades it may be necessary to dye in two Weld baths. Very often, before wringing, the silk is worked at 60° C. in a strong soap bath, containing a little Annatto, in order to give a slightly more orange tint, as well as additional brilliancy. Full orangt colours are produced by first grounding with Annatto, aftei-wards mordanting with alum, and dyeing with Weld. OLD FUSTIC. 291. This dyestuff consists of the wood of Morus tinctoria. It is principally used in woollen- dyeing, also to a limited extent in silk-dyeing. 292. Application to Cotton.— Old Fustic is but little used by the cotton dyer, the colours it produces on cotton not being fast to soap. The same methods of application as for Weld may be employed. ^93. AppUcation to Wool — In the heavy woollen trado 3G0 DYEING OF TEXTILE FABRICS. [Chap. XV. this is perhaps the most largely used of all the natural yellow colouring matters, but principally along with other dyewoods for the production of various compound shades, e.g., browns, olives, drabs, &c. With bichromate of potash as the mordant, it gives a pleasing brownish or olive-yellow colour (old gold). Boil the wool for 1 — 1| hour with 3 — 4 per cent, of bichromate of potash, wash, and dye in a separate bath for 1—1 J hour at 100° C. with 20—80 percent, of ground Old Fustic. By increasing the amount of m.ordant deeper colours are obtained, but it is not advisable to use more than that indicated. The addition of tartar or sulphuric acid to the mor- danting bath is not beneficial. With aluininium mordant Old Fustic gives yellow colours, which differ in brightness, according as the dyeing is done in one or two baths. The " single-bath " method gives the brightest shades. Dye for 1 — IJ hour with 4 per cent, of aluminium sulphate, 2 per cent, of oxalic acid, and 20—40 per cent, of Old Fustic, at S0°— 100° 0. The addition of tartar intensifies but dulls the colour. When two baths are employed, mordant the wool for 1 — 1|- hour with 8 per cent, of aluminium sulphate, wash, and dye in a separate bath for | — J hour, at 80° — 90° C, with 20—40 per cent, of Old Fustic. Here, too, the addition of tartar to the bath is not beneficial. By using 2 — 3 per cent, of stannous chloride along with the aluminium sulphate, much brighter colours are obtained. The brightest and fastest yellows obtainable from Old Fustic are produced with the use of a stannous mor- dant. Mordant the wool 1 — 1| hour with 8 per cent, of stannous chloride (crystals), and 8 per cent, of tartar ; wash, and dye in a separate bath for 30 — 40 minutes, at 80—100° C, with 20—40 per cent, of Old Fustic. Yery bright yellows are better obtained by adopting the " single-bath " method given for Cochineal scarlet, possibly because then the lime compound of the colour- ing principle " morin " is decomposed. Use 40 per cent. Chap. XV.] OLD FUSTIC. 361 of Old Fustic, 8 per cent, of stannous chloride, 4 per cent, of tartar, and 2 per cent, of oxalic acid. By using less mordant fuller colours are obtained, but they are not so bright. Prolonged dyeing must always be avoided, especially when dyeing at 100" C, or when two baths are employed, otherwise the yellows become dull and brownish, owing to the presence in Old Fustic of a considerable amount of tannin matter. This effect can be obviated to a large extent by adding a solution of glue to the dye- bath, in the proportion of 4 — 8 per cent, of the weight of Old Fustic employed. Stannic chloride, in conjunction with Old Fustic, gives light-brown or fawn colours, and is not a suitable mordant. All the yellows obtained from Old Fustic change to a dull brownish colour after one month's exposure to sun- light, but they bear milling with soap and weak alkalis fairly well. With copper sulphate mordant Old Fustic yields olive colours. Either the " mordanting and dyeing " method, or the " single-bath " method may be adopted. Use 4 — 6 per cent, of copper sulphate and — 4 per cent, of tartar. With 8 per cent, ferrous sulphate and 3 per cent, tartar, darker olives are obtained. The "single-bath' method gives good and level colours. Use 4 — 8 per cent, ferrous sulphate, without the addition of tartar. 294. Application to Silk. — Old Fustic is still used in silk-dyeing for the purpose of obtaining various shades in green and olive. It is now seldom or never used for dyeing yellows, since they cannot compare in brightness with those derived from Weld, or from some of the coal- tar colouring matters. It is occasionally used in conjunction with other colouring matters for obtaining compound colours, or for modifying the shade of certain blacks. If required for a light yellow, the silk is worked for ^ — ^ hour, at 50° — Q0° C, in a bath containing 16 per 362 DTEIXG OF TEXTILE FABRICS. [Chap. XV cent of alum, and a decoction of 8 — 16 per cent, of Old Fustic. For dyeing a darker yellow — requii*ed, e.g.^ when pro- ducing in conjunction with indigo-vat blue the so-called '• fast-green" — the silk is mordanted with alum, washed, and dyed for about an hour, at 50° — 60^ with a decoction of 50 — 100 per cent, of Old Fustic, and then washed. The colour may be rendered brighter and faster by working the silk afterwards in a cold solution of nitro- muriate of tin, at 4° Tw., for an hour, and then washing. QUERCITRON BARK. 295. — This dyestuff consists of the inner bark of Quercus tinctoria. Its dyeing properties are so similar to those of Old Fustic that the same methods of applica- tion may be used for both. 296. Application to Cotton. — The colours produced on cotton by means of this dyewood are very similar to those obtained from ^Veld, and the same methods of application may be adopted. Quercitron yellow on cotton when dyed with Mjilachite Green gives very good yellowish-green shades. 297. Application to Wool. — With bichromate of potash mordant. Quercitron Bark gives somewhat redder olive- yellows than those yielded by Old Fustic. Mordant with three per cent, of hichromate of potash, xs-ithout the addi- tion of sulphuric acid or tartar, and dye in a separate bath. The aluminium yellows are paler, while those produced by stannous chloride are very much brighter and more orange in shade than the corresponding Old Fustic colonic. With stannic chloride^ Quercitron Bark gives a very pale buff colour. In all cases prolonged dyeing is injurious, and gives dull shades. The addition of glue solution to the dye- bath is beneficial, since it precipitates the tannin matter invariably present. The resistance of Quercitron Bark colours to light Chap. XV. I QUERCITRON BARK. 3(53 and milling is about the same as that of those yielded hy Old Fustic. It is not extensively used in woollen dyeino-, having been largely supplanted by Flavin. *' 298. Application to Silk.— Quevcitron Bark is seldom used alone in silk-dyeing. If required, it may be applied in the same manner as Weld or Old Fustic. Its principal use is for obtaining a dead-black, a small quantity of its decoction being added to the Lo^^wood dye-bath. ° FLAVIX. 299. — This dyestuff is a preparation of Quercitron Bark, and consists es.sentially of '* quercetin." '• Quer- citrin " may also be present in some products. It has occasionally been sold under the name "Auran- tine." The advantages which Flavin has over Quercitron Bark are, that it is very much stronger in colouring power, and being free from tannin matter it pelds brighter shades. A good quality of Flavin may possess sixteen times the colouring power of Quercitron Bark, but very inferior qualities are frequently met with. So- called "Patent Bark," prepared by boiling ground Quercitron Bark with sulphuric acid, is an excellent substitute for Flavin in wool-dyeing. Fldvin is not used in cotton-dyeing. 300. Application to Wool. — When employed for yellow, tin mordants, wdth or without the addition of aluminium' sulphate, are used. With aluminium mordants alone comparatively pale yellows are produced. With stan- nous mordants the yellows are verv much richer, and of a more orange tone. With stannic mordant pale yel- lowish buffs are produced. In dyeing Fhnin yellows it is most advantageous to mordant and dye in one bath, after the manner recom- mended for dyeing Cochineal scarlet. Bv this means, bnghter colours are obtained. Boil the wool for J | of an hour with 4—8 per cent, of stannous chloride (crystals), and 0—4 per cent, of tartar ; take out the v.ool temporarily ; add 1—8 per cent, of Flavin ; boil five 364 DYEING OF TEXTILE FABRICS. [Chap. XV. to ten minutes ; re-enter the wool, and continue boiling for half to one hour. It is well to mix up the Flavin with a little hot water to form a smooth paste, before adding it to the dye-bath, since it tends to form lumps not readily wetted and dissolved, if thrown into the bath in the dry state. Increase of stannous chloride adds intensity and redness to the colour. Acid solutions of stannous chloride or nitrate of tin may be used instead of stannous chloride crystals. Increase of tartar reduces the intensity, brilliancy, and redness. The tartar may be partly or entirely replaced by 2 — 4 per cent, of oxalic or tartaric acid, when, indeed, brighter shades result. Increase of Flavin adds intensity and redness. With 1 per cent, of Flavin the shade produced is a bright canary-yellow ; with 8 per cent, it is a bright orange. Flavin yellows aiid oranges on wool, obtained by means of stannous mordants, are among the brightest that can be produced from either natural or artificial colouring matters. With regard to their fastness to light and milling with soap and dilute alkalis, they behave the same as those of Quercitron Bark and Old Fustic, becoming brownish. Flavin is much used along with Cochineal for dyeing scarlet. 301. Application to Silk. — Flavin is not generally used in silk-dyeing. It may, however, be applied in the same manner as Weld. YOUNG FUSTIC. 302. — This colouring matter consists of the wood of the sumach tree (Rhus cotinus). Owing to the fugitive character of all the colours produced by this dyestufF, it is of little or no use to the cotton and silk dyer_, and it would be no great loss if it disappeared from the market altogether. It was, Chuy. XV.] YOUNG FUSTIC. 365 however, much used formerly in dyeing brown colours on silk, the yarn being mordanted with alum and after- wards dyed with a decoction of Young Fustic, Peach- wood, and Loofwood. It still finds a limited use in wool-dyeing for the production of orange or scarlet. 303. Application to Wool. — Wool mordanted with bi- chromate of potash and dyed in a separate bath with Young Fustic, gives a reddish brown. The colour is much redder than that obtained in a similar manner from any other of the yellow dyewoods, with the exception of Persian Berries. Very large amounts of bichromate of potash may be used, and with good effect, but it is not advisable to employ more than 3 per cent. The addition of sulphuric acid is not beneficial. With an aluminium mordant it produces a yellowish buff colour. The brightest yellows yielded by Young Fustic are those obtained when it is used in conjunction with stannous mordants. With stannous chloride (or nitrate of tin) and tartar, and with a good quality of Young Fustic, bright orange yellows are obtained, not unlike those given by Quercitron Bark or Flavin. The same methods of dyeing and proportions of mordants employed in the case of Flavin may be adopted here, using only larger amounts of dyewood, say 20 — 40 per cent, of Young Fustic. With a stannic salt as mordant it yields a tolerably good full orange yellow, but only when prohibitory amounts of tartar are employed. The colours yielded by the use of copper and iron mordants are olives similar to those obtained from the other yellow dyewoods. The yellows and oranges obtained from Young Fustic are not fast to light, two or three months' exposure being sufiicient to bleach the colour entirely. All except the aluminium colour withstand milling with soap and weak alkalis moderately well. In these respects Young Fustic is not so good as any of the other natural yellow colouring matters. 366 DYEING OF TEXTILE FABRICS. [Char. XV. .PERSIAN BERRIES. 304. This colouring matter consists of the dried un- ripe fruit of various species of BJmmnus ; it is not used in cotton- and rarely in silk-dyeing, although very largely in calico-printing for st^am-orange, olive, gi'een, kc. Application to Wool. — Persian Berries are seldom used in woollen-dyeing. They seem to be excluded en- tirely from the hea^■y woollen trade, and find only a limited use in dveincr lis^ht materials for ladies' wear. The chief objection is their high price, but they are also very variable in quality. In general dyeing properties Persian Berries greatly resemble Young Fustic, but the colours produced are very much faster. With hiihromate of potash mordant very good red- dish browns are obtained. With aluminium and stannic mordants only pale, un- satisfactory dull yellows are obtained. With stannous mordants rich yellows and oranges are obtained, which, when a good quality of Persian Berries has been em- ployed, are equal if not superior in brilliancy to those obtained from Flavin. Use the same methods and pro- portions of mordants employed in the case of Flavin, but with 10 — 40 per cent, of Persian Berries. When exposed to light, Persian Berry yellows gradu- ally become brownish, but in this respect they are not different from those obtained from Old Fustic and Quercitron Bark and Flavin, and are decidedly superior to those obtained from Young Fustic. They also bear milling with soap and weak alkalis very fairly. The action of light on the olive obtained by the use of copper sulpJuLte mordant is very characteristic. The olive gradually becomes greener and increases in inten- sity. Even after an exposure of twelve months no fading action seems to take place. This olive is probably as fast to light as any known, and may be classed in this respect along with ^at-indigo blue, kc. Chap. XV.J PERSIAN BERRIES AND TUUMERia 367 TURMERIC. 305. This dyestutf is the tuber of Curcuma iinctoria. Notwithstanding the very fugitive character of the colour it yields, it is still much used, especially by the wool- and silk-dyer for the production of compound shades — olives, bro^vns, &c. It gives a bright yellow colour without the aid of a mordant, but when mordants are used with it it yields other colours not unlike those obtainable from the yellow dyewoods. 306. Application to Cotton. — The colouring matter of Tiu'meric is one of the few for which cotton has naturally a strong attraction. Cotton is dyed by simply working it in a Turmeric bath heated to about 60'' 0.. for about half an hour. The colour is not fast either to light or to alkalis ; even very slightly alkaline solutions — e.g.., soap — change it to a reddish brown. 307. Ajyplication to Wool. — Dye at 60° C. without any addition. Boiling should be avoided, since the bright yellow then becomes soiled by reason of impure extrac- tive matters entering into solution. If the wool is mor- danted with aluminium or tin the colour is somewhat brighter, and in the latter case more orange. With the use of potassium dichromate and ferrous sulphate as the mordant, the colours produced are olive and brown. iSilk is dyed in the same manner as wool. BARBERRY. 308. This yellow dyestuff is the root, sometimes the bark, of Berheris vulgaris; it is also sold in form of an extract. It is principally used in the dyeing of leather, but still finds a limited application in silk-dyeing. Apjylication to Silk. — Work the silk at 50^ — 60^ C. in the dyewood decoction, slightly acidified with sulphuric, acetic, or tartaric acid. For dark shades the silk may be previously mordanted with stannous chloride. 368 DYEING OF TEXTILE FABRICS. [Cb&j,. XV. CATECHU. 309. This valuable dyestuff is obtained from cei-tain species of Acacm, Areca, and Uncaria, growing in India. It is largely used by the cotton-dyer for the purpose of obtaJniTig vaiious shades of brown, olive, drab, grey, and black. It is also extensively employed in black silk dyeing. In woollen dyeing it is little used. 310. Application to Cotton. — The brown colour pro- duced on cotton by Catechu is remarkable for its fastness to lig^t, soap, alkaline and acid solutions, and even to solutions of bleaching-powder. For the production of Catechu brown, the cotton is worked for | — 1 hour at 80° — 100" C. in a solution of 10 — 20 per cent, of Catechu, or, say, one containing 10 — 20 grams of Catechu per litre. After squeezing the cotton and allowing it to cool, it is worked for half an hour at 60° C. in a fresh bath containi n g 1 — 2 grams of bichromate of potash per litre, and is finally well washed- For very deep and full shades, the cotton is allowed to steep in the hot Catechu decoction till the latter becomes cold, before passing it into the bichromate of potash bath. The deepest shades are produced by drying the cotton after the Catechu bath. Veryfirequently — e.p'., in warp dyeing — the cottonis passed rapidly through a succession of Catechu and bichromate baths. In this process it simply becomes impregnated in the first bath with catechin ; this in its pure state would be quite white, but in the second bath it is imme- diately and completely oxidised, and is said to form in- soluble brown japonic acid within and upon the fibre. Previous mordanting of the cotton is not necessary, since the shade would be only slightly modified thereby. Mor- dants, however, are used when other colouring matters in the form of extract are added to the catechu bath — e.g.^ Logwood, Alizarin, Old Fustic, e colouring matter. Alkali Blue may be employed for the purpose of obtaining compound colours, by using it in conjunction with various acid-colours, e.g., Crocein Scarlet or Orange, &c. In these cases the acid bath is dispensed with, and after dyeing with Alkali Blue and washing, the wool is at once worked in the dye-bath of the acid-colour, with the necessary additions. The development of the blue, and the dyeing of the scarlet, orange, &c., thus take place simultaneously. Ajyplication to Silk. — Silk is dyed like wool, but it is preferable to use borax in the dye-bath instead of carbonate of soda or ammonia. ( C6H4-NH(CeH5) 321. Rosaniline Violets. C ] c^I^chJ^'^'^ These violets, also called by such names as Phenyl Violet, Spirit Violet, Parma Violet, Imperial Violet, (fcc, are hydrochlorides of mono- and di-phenyl-rosaniline. They find now only a limited use, being less bright than the Methyl Violets ; they are, however, said to be somewhat faster to light and to milling, and may be used with advantage when a dull, moderately fast violet is required, g.^., in felt-hat dyeing. Closely related to Rosaniline Violet is the so-called Regina Purple (Brook, Simpson, and Spiller). 382 DYEING OF TEXTILE FABRICS. LCliap. XVI. Application to Cotton. — Prepare the cotton with tannic acid and tartar emetic, and dye in a bath slightly acidulated with sulphuric acid or alum. Application to Wool. — Dye at 60° — 80° C. in a colour solution acidulated with 4 per cent, of sulphuric acid, 168° Tw. (Sp. Gr. 1"84). Since these are basic colouring matters, the need of acidulating the bath is noteworthy. Application to Silk. — Dye at 60° — 80° C. in a bath containing boiled-off liquor, slightly acidulated with sul- phuric acid. 322. Hofmann's Violet. \ n^H^rn "^^' ( NHCHs-Cl This colouring matter, also called Dahlia, Primula, &c., is considered as the hydrochloride of the base trimethyl- rosaniline ; it is only used for red shades of violet, the bluish violets beiug better obtained from the Methyl Violets. The colour it yields is not fast to light. Application to Cotton. — Prepare the cotton with tannic acid and tartar emetic, or with sulphated oil and alu- minium acetate; wash and dye at 45° — 50° C. in a neutral bath. Application to Wool. — Dye at 60° — 80° C. in a neutral bath, or with the addition of 2 — 4 per cent, of soap. Application to Silk. — Dye at 50° — 60° C. in a bath con- taining soap or "boiled-off" liquor, with or without the addition of a little sulphuric acid. Wash and brighten in a bath slightly acidulated with acetic or tartaric acid. { OeH4-N(CH3)2 323. Methyl Violet. C ] c'Sf^^^^'^' This colouring matter, also called Paris Violet, is con- sidered as the hydrochloride of penta-methyl-para-ros-^ aniline. Various brands are sold — e.g., Methyl Violet E,, B, 3 B, tfec. — according as they yield red or blue shades of violet. Some of the Methyl Violets are zinc double salts, and Chap. XVI.] ROSANILINE COLOURS. 383 are then sold in the crystalline state; with these the addition of soap to the dje-bath must be strictly avoided The methods of applying them to the textile fibres are identical with those employed for Hofmann's Violet. 324. Benzylrosaniline Violet. — This colouring matter is the benzyl (C^H-) derivative of Methyl Violet. The most highly benzylated product is generally sold as Methyl Violet 6B, and by mixing this in different proportions with Methyl Violet B, the various marks of Methyl Violet 2B, 3B, 4:B, 5B are obtained. Benzyl Violet yields much bluer shades of violet than Methyl Violet, although the method of its application to the various fibres is very similar. It bears the addition of a little sulphuric acid to the dye-bath better than Methyl Violet. Alkali Violet (Meister, Lucius, & Briining) is applied in the same manner as Alkali Blue. 325. Acid Violet 4 RS. p ) C6H3-XH(CH3)S03Na (BASF). ^ ) C6H3S03Na (XH This colouring matter is the sodium salt of di-methyl- rosaniline-tri-sul phonic acid. Acid Violet 5 RS (basf) is the corresponding mono- methyl compound. Acid Violet 6 B (basf) is the corresponding benzyl- methyl compound. These colouring matters, sold by several manufac- turers with different brands, are adapted only for wool and silk, and are apjjlied in the same manner as Acid Magenta. They are useful, in conjunction with other acid colouring matters, for producing compound shades. ( CeH,-N(CH3)2 326. Methyl Green, c ^ ^6H4-N(CH3)2-CH3-ci ( NH-CH3-C1 This colouring matter may be regarded as the methyl chloride compound of Methyl Violet. It occurs in commerce in the ciystalline state as a zinc double salt 384 DYEING OF TEXTILE FABRICS. [Chap. XVI. Although still used, it has been very largely supplanted by the Acid and Benzaldehyde Greens, since these are much cheaper, and offer certain advantages in point of application and stability. Application to Cotton. — Dye in the same manner as with Benzaldehyde Green. Aj)pUcation to Wool. — Owing to the weak attraction which wool has for Methyl Green, it is necessary that it should be mordanted previous to being dyed with this colouring matter. The ordinary mordants, however, are of no use, and recourse is had to the singular and strong affinity which amorphous sulphur has for Methyl Green. The wool is mordanted in a bath containing 10 — 20 per cent, of thiosulphate of soda (usually called hyposul- phite of soda) and acidified with 5 — 10 per cent, of sul- phuric acid, 168° Tw. (Sp. Gr. 1"84), or hydrochloric acid, 32° Tw. (Sp. Gr. M6). Introduce the wool into the milky liquid at 40° C., raise the temperature gradually to S0° C. in the course of an hour, then wash well. Dye at oO° — 60° C. in a separate bath containing Methyl Green and 2 — 4 per cent, of borax or acetate of soda. The addition of these latter salts to the dye-bath has the effect of neutralisinof the acid remaininof in the wool after washing ; if, however, previous to dyeing, the wool is worked for about a quarter of an hour at 70^ C. in a weak solution of carbonate of soda or ammonia, their ad- dition to the dye-bath is unnecessary. The shade produced by Methyl Green is always bluish, and if the temperature of the dye-bath is raised to 100° C. it becomes still bluer, owing to a portion of the colouring matter decomposing at this temperature with elimination of methyl chloride and the production of Methyl Yiolet ; the effect obtained is that of a mixture of green and A*iolet, namely, blue {Peacock blue). If it is desired to obtain yel- lower shades of gi'een, Picric Acid may be added to the dye- bath, but since this only dyes in an acid-bath (a condition which is prejudicial to the dyeing property of ]SIethyl Green) one must add also a small proportion of acetate of Chap.XVI.l ROSANILINE COLOURS. 385 zinc. This salt is gradually decomposed by the sulphur already fixed on the wool, and the liberated acetic acid causes the Picric Acid to dye, while it does not prevent the Methyl Green from doing so. The zinc sulphide pro- duced, acts as a mordant for the Methyl Green in the same manner as the sulphur. Should, however, the Methyl Green dye slowly, from over- acidity of the bath, the addition of a little acetate of soda is necessary. It is essential that in the operations of mordanting and dyeing, the use of metal, either in the dye-vessels themselves or in the utensils employed, should be strictly avoided, otherwise the wool may acquire a dark colour, or be spotted, by the production of metallic sul- phides. Application to Silk. — Dye exactly as in the case of Benzaldehyde Green. 327. Auramine (basf) (Soc. of Chem. Ind., Basle). [CgH^N(CH3)o]2 -C-lNH-HCl.— This yellow colouring matter is the hydrochloride of tetra-methyl-diamido- benzo-phenon-iraide. It is particularly useful to the cotton-dyer, and is said to resist the action of light and soap solutions fairly well, but is readily affected by chlorine. It should be dissolved in hot water, but the solution should not be boiled, since the colouring matter is thereby decomposed. It is useful for producing com- pound shades in conjunction with other basic colouring matters, e.g., Safranine, Benzaldehyde Green, etc. Application to Cotton. — Mordant the cotton with tannic acid and tartar emetic, and dye in a separate bath. Introduce the cotton into the cold colour solution, and raise the temperature of the bath to 40° — 50° C. Application to Wool. — Dye in a neutral bath. Enter cold and heat gradually to 70° C. Better colours are said to be obtained if the wool is previously mordanted with sulphur, after the manner in ^'Dgue for Methyl Green. ApjAication to Silk. — Dye in the same manner as with Mak'enta. 386 DYEING OP TEXTILE FABRICS. fChap. XVI. [ C6H4-N(CoH5)2 328. Ethyl Purple 6 B (base). ] q'^'^^^'^'^' (N(CH3)2C1 This colouring matter is the hydrochloride of hexa-ethyl- para-rosaniline. It is the bluest shade of violet at present known, and is applied to the various fibres in the same way as Hofmann's Yiolet. 329. Crystal Violet 5 BO (base). C ] §lj"^'^^^^^^' ( N(CH3)2C1 This colouring matter is the hydrochloride of hexa- methyl-para-rosaniline. It is applied to various fibres like Hofmann's Violet, over which it possesses the advantage of greater colouring power, of extreme solubility in water, and of having no tendency to produce a bronze scum on the surface of the dye liquor or on the dyed material. ( C6H4-N(CH3)2 330. Victoria Blue 4 R p, ) CioH6-N(CH3)(C6H5) (base). ^ ) C6H4 ( N(CH3)2 CI This colouring matter is the hydrochloride of penta- methyl-phenyl-triamido-diphenyl-a-naphthyl-carbinol. It is applied to the various fibres in the same manner as Hofmann's Violet. Wool and silk may be dyed with the addition of a little acetic or sulphuric acid to the bath, in the same manner as acid colours. The dyeing power is thereby somewhat lessened and the bath is not so well exhausted, but the colour obtained seems brighter. ( C6H,-N(CH3)2 331. Victoria Blue B (base). C \ ^lo^e^^'iOe^t) \ / 1 U6M4 ( ^(CHg)., CI This is the tetra-methyl compound corresponding to Victoria Blue 4 R, and may be applied in the same way. 332. Night Blue (base). This colouring matter is closely related to the last, and is applied to the textile fibres in a similar manner. It requires to be dissolved in dilute acetic acid to prevent decomposition on boiling. Cbap. XVI.l INDULINE COLOURS. 387 333. Phosphine [C.^Hi^Ng-HCl]. —This orange colour- ing matter (said to be a qumoline derivative) is the hydrochloride of the base chrysaniline. Its dyeing properties are simiJar to those of Magenta, and it is applied to the textile fibres in the same manner. It finds only a limited use in wool- and silk-dyeing because of its expense. 334. Rosolane [C2:Ho4N9-HCl].— This colouring mat- ter is the hydrochloride of the base mauveine ; it is, indeed, the original Perkin's Yiolet. It is sold at the present time in the form of a paste. Its method of application is similar to that of the Methyl Violets. Although itself not requiring a mordant, it may be used in conjunction with poly genetic colouring matters for the production of compound shades. It is used as a substitute for Orchil or Ammoniacal Cochi- neal in the production of bright greys. h. Induline and Safranine Group. 335. Indulines. — These comprise a number of colour- ing matters made by different processes, but all possessing somewhat similar dyeing properties. They are known by a variety of commercial names, e.g., Yiolaniline, Nigro- sine, Elberfeld Blue, Bengaline, Aniline Grey, Cou pier's Blue, Roubaix Blue, kc. Those used for cotton-dyeing are insoluble in water, and require to be dissolved in methylated spirit. These Spirit Indulines are hydrochlorides of a colour-base, e.g., violaniline, triphenyl-violaniline, &c. For wool- and silk- dyeing they are treated with strong sulphuric acid ; they are thus rendered soluble in water, and are sold as sodium salts of the corresponding sulphonic acids. They all yield dark dull blue colours, not unlike indigo- vat blues, to imitate which they are frequently employed. Application to Cotton. — Prepare the cotton with tannic acid and tartar emetic, wash, and dye in a separate bath containing the colour solution, acidified slightly with 388 DYEING OF TEXTILE FABRICS. [Chap. XVl. sulphuric acid or by the addition of alum (10 per cent.). Dye at a temperature of about 60*^ C. The bath is not exhausted, and must be preserved for succeeding lots of material. One may also employ the indigo-vat method. Application to Wool. — Owing to the precipitation of the free sulphonic acids of these colours on the addition of acid to their solutions, it is extremely difficult to dye light shades OA^enly with them. They are best adapted for dyeing dark shades. Add the requisite amount of colour-solution (5 — 15 per cent.) to the dye-bath, heat to 100° C. as rapidly as possible, enter the wool, and boil 1 — 1|- hour, without any other addition. Continue now to boil one hour longer, during which period add from time to time dilute sul- phuric acid in small portions. Use 5 — 15 per cent, of sulphuric acid, 168"^ Tw. (Sp. Gr. 1'84), according to the amount of colouring matter employed. The long boiling with colour solution alone, enables the wool to become thoroughly permeated with the colouring matter while still in the soluble state. An addition of 5 — 10 per cent, of borax, carbonate of soda, or strong ammonia solution at this stage is beneficial. The actual dyeing of the wool begins only when the bath is acidulated ; the addition of acid should always be made slowly, so that the wool may take up the gradually precipitated colouring matter as evenly as possible. Wool is said to dye much better with Induline if it has been previously rinsed in a weak solution of bleach- ing-powder and then in dilute hydrochloric acid. These colours have been frequently recommended as good substitutes for indigo-vat blues. Although fairly fast to light, they gradually lose their bluish tint and brilliancy on exposure, and assume a dull greyish tone. Towards weak alkalis they are moderately fast; the action of acids they withstand perfectly In conjunction with other acid-colours they are useful for producing a large variety of compound shades. Application to Silk. — Dye in a bath containing Chap. XVI.] SAFRANINT! COLOLRS. 389 " boiled-off " liquor, acidified slightly with sulphuric acid. Enter the silk at 60^ C, add the colour solution gradually, raise the temperature gradually to 100° C, and boil half an hour. Wash and brighten with dilute sulphuric acid. 336. Naphthalene Pink [C3oHoiN3-HCl + H,0].— This colouring matter, also called Magdala Red, and derived from amido-azo-naphthalene, is the hydrochloride of the base rosa-naphthylamine. It is but little used, namely, for the purpose of obtaining on silk blight pinks, which have a strong yellowish-red fluorescence. Application to Silk — Dye in a bath containing " boiled- off" liquor, with or without the addition of sulphuric acid. Brighten with dilute sulphuric or tartaric acid. The colour is faster than that given by Magenta, Eosin, or Safranine ; it is fast to dilute acids and alkalis, but not to light. " 337. Safranine [C.iHo^X/HCl]. — In chemieul consti- tution this red colouring matter is apparently allied to Magenta, and is the hydrochloride of a colour-base safra- nine. It is applied to the various fibres in the same manner as Magenta. On wool the colour is not fast to light. Strictly speaking, the name Safranine is given to several closely-allied products. Fuchsia (Soc. Ch. Ind., Basle) is dimethyl-aniline-safranine. Ajyplication to Cotton. — Prepare the cotton with tannic acid and tartar emetic, wash and dye in a neutral bath at 50^ C. One may also steep the cotton in a solution of lead acetate (with or without jjrevious impregnation with a solution of soap), dry, and dye in a neutral bath of the colouring matter; the colour thus obtained is oVjjectionable because of the lead it contains. Fixed with tannic acid and tartar emetic the colour is fairly fast to lisfht. AppIicatio7i to Wool and Silk. — Dye in the same manner as with Magenta. Neutral Red — (L. Cassella & Co.). — Qliis colouring matter and others called Keutral Blue and Neutral Violet being allied to Safranine. are all applied to the various 390 DYKING OF TEXTILE FABRICS. [Chap. XVI. textile fibres by similar methods. They yield dull shades of red, blue, and violet respectively, not fast to light on wool. They are of little use in wool- and silk- dyeing, but may be used with advantage by the cotton-dyer for producing compound shades. New Blue D (L. Cassella & Co.). — This colouring matter gives a colour closely resembling that of vat- indigo blue, which on cotton is extremely fast to light. Although affected by alkalis it is well adapted for cotton- dyeing, and may in many cases replace vat-indigo blue. New Blue D is frequently used in conjunction with Methylene Blue or other basic colouring matters. A2jplication to Cotton. — Mordant the cotton with tannic acid and tartar emetic, and dye in a neutral bath of the colour solution. (c) Aniline Black Group. 338. Aniline Black. — Unlike other colouring matters, Aniline Black is not a commercial article. For the pur- pose of the dyer it must be produced upon the fibre itself. Little or nothing is known of its chemical constitution. It is a product of the oxidation of a salt of aniline, generally aniline hydrochloride, and appears to exist in two states of oxidation. The less oxidised product is a blue-black, somewhat sensitive to the action of acids, particularly sulphurous acid, under the influence of which it acquires a greenish tint. The original colour can only be temporarily restored by treatment with an alkaline solution. The more highly oxidised product is a violet- toned black, which is not turned green by acids. This is produced by submitting the former to a supplementary oxidation. It is remarkable for its extreme fastness to acids, alkalis, light, &c., and is indeed one of the most permanent dyes known. 339. Application to Cotton. — For dyeing cotton Aniline Black the most usual oxidising agent employed is bichromate of potash, or chromic acid. According to the temperature at which the dyeing is effected, two Clinp. XVI.] ANILINE BLACK. 391 methods may be distingiiishecl, namely, the warm method and the cold method. Warm Method. — For 100 kilos, of cotton the dye- bath contains the following ingredients : 1,600 litres of water, 40 kilos, of hydrochloric acid 34° Tw. (Sp. Gr. M7), 10 kilos, of aniline, 10 — 14 kilos, of bichromate of potash. These proportions may be varied according to the particular shade of black required. A portion of the hydrocliloric acid may also be replaced by an equivalent amount of sulphuric acid. Use, for example, 24 kilos, of hydrochloric acid, and 4 — 6 kilos, of sulphuric acid, 168° Tw. (Sp. Gr. 1-84). The intensity of the colour, however, is always regulated by the amount of aniline employed. The aniline and hydrochloric acid diluted slightly with water, are carefully mixed in a suitable glazed earthen- ware vessel, and the acid solution of aniline hydrochloride thus obtained is added to the dye-bath previously filled with cold water. The bichromate of potash is dissolved separately in a Httle warm water and added to the bath. The cotton is worked for an hour in the cold solution, until, indeed, it has acquired a considerable intensity of colour, after which the temperature is gi^adually raised to 50° — 60° C. The whole operation may last from 1 — 3 hours. Another method is as follows: Dye the cotton in the cold for one hour with only half the quantity of the several ingi-edients added to the bath, then add the re- mainder, and continue the dyeing in the cold for an hour longer; after this raise the temperature gradually to 50°— 60° C, and continue the dyeing for another hour. The more concentrated the solution, and the greater its acidity, the more rapidly does the dyeing take place. Excess of acid and prolonged heating tend to give bronze - coloured blacks, and much of the colouring matter is only superficially fixed. If, however, the heating has been of 392 DYEING OF TEXTILE FABRICS. [Chap. XVI. short duration, the black has a bluish tone, and is liable to become green under the influence of acids. It is essential that the temperature of the bath should be raised very gradually, otherwise there is a great loss of colouring matter, since much of it is then precipitated in the bath and not on the fibre. After dyeing, the cotton must be well washed with water, then boiled in a solution of soap containing 5 — 10 grams per litre, with or without the addition of a little carbonate of soda, and finally dried. 340. Cold Me- thod. — According to this method the dyeing oj^eration is conducted entirely in the cold, the proportions of the ingredients and the concentration of the bath being altered to render this pos- sible. For 100 kilograms of cotton use 16 — 20 kilograms of nydrochloric acid, 20 kilograms of sulphuric acid, 8—10 kilograms of aniline, U— 20 kilograms of bichromate of potash, 1 kilograms of ferrous sulphate. .The quantity of water should be very much smaller than in the warm method, otherwise the dyeing would either be incomplete, or would take too long. Fig. 85 represents an appa- ratus of MM. Tulpin freres for dyeing cotton yarn Fig. 8.5.— Anilice Black DveLng Machine. Clinp. XVI. J ANILINE BLACK. 393 Aniline Black. It is specially designed so that tlie hanks can be projierly - manipulated in as little liquid as possible. It consists of a strong wooden dye-bath, about two metres long, and longitudinally divided into two compartments, each wdth rounded bottom. Above are two corresponding square rollers, each capable of holding about five kilograms of cotton yarn ; there is also a sup- port with, two arms, on which the rollers can be placed either at the end of the dyeing process or for the purpose of filling them with yam before beginning. Several such dye-baths are arranged in line, the rollers being turned by power, alternately to right and left, in order to avoid entanglement of the hanks. The use of such a machine saves labour, prevents th^ corrosion of the workmen's hands by the chromic acid, and gives a more regularly oxidised black. It will be noticed that the proportions of bichromate of potash and acid employed in the cold method are larger than in the warm method ; this is in order to facilitate the oxidation of the aniline salt at the lower temperature. The addition of the sulphuric acid has a similar eflect, but it also tends to yield ultimately a more pleasing tone of black. The use of hydrochloric acid produces blue-blacks, while sulphuric acid alone gives such as are of a reddish hue. The addition of the ferrous sulphate is for the purpose of rendering the black less liable to turn gi-een ; of course in the bath it is changed to ferric sulphate, and this acts as an oxidising agent. The method of preparing the dye bath for the cold method is similar to that already described. The aniline hydrochloride is previously made by mixing the aniline and hydrochloric acid ; separate solutions of the ferrous sulphate, bichromate of potash, and sulphuric acid are also kept in readiness. The cotton is first worked for about an hour with only half the full amount of the several ingredients in the bath. At the end of this time, when the cotton has already acquired quite a black colour, it is lifted out, the other half of the ingredients is added. 394 DYEING OF TEXTILK FABRICS. [Chap. XVL the cotton is tlien re-entered, and the dyeing is continued 1 — 1^ hour longer. After dveinor, the cotton is well washed and boiled with a solution of soap and carbonate of soda, as pre- viously stated, and dried. The use of soap alone gives violet-toned blacks ; the addition of carbonate of soda makes the shade bluer. Although the black produced by either of the above methods, but especially by the cold method, is tolerably stable, it is necessary, in order to render it perfectly ungreenable, to submit the dyed cotton, after washing, to a supplementary oxidation. Several methods have been proposed for this purpose, but perhaps the following, in which ferric sulphate is the oxidising agent, is the most serviceable: Prepai'e a mixture of 20 kilograms of ferrous sulphate, 5 kilograms of bichromate of potash, 15 — 18 litres of sulphui'ic acid 168^ Tw., 60 — 70 litres of water. Add 5 litres of this mixture to 500 litres of water, and work the cotton in the solution for three-quarters of an hour at 75° C. ; then wash well, boil with soap, and dry. Another method, depending for its efficacy upon the optical eflect that a mixture of violet and green appe^irs blue, is to dye the black in a weak solution of Methyl Violet. This violet is tixed, it is supposed, by reason of the cotton itself havm.g oeen partially oxidised and changed into oxycellulose during the dyeing process. Two other methods of producing Aniline Black on cotton, though not practically employed, possess sutficient interest to deserve mention. One is that borrowed from the method so successful in the printing of calico with Aniline Black. It is based upon oxidising the aniline salt by means of potassium chlorate in the presence of vanadium. The coUon is impregnated with a somewhat concentrated solution containing 5 — 20 per cent, of aniline hydrochloride (according to the intensity and fastness of the black required), 2 — 10 per cent, of potassium chlorate, and a very minute quantity of vanadium chloride (not more than -j^ of the weight of aniline hydrochloride Chap. XVI.] ANILINE BLACK. 395 employed). After wringing out the excess of liquid, the colour is developed by hanging the cotton in an ageing stove heated to 25° — 30° C, and in which the air is kept slightly moist by admitting a little steam. The chief defect of this process is that an uneven colour is liable to be produced, since the oxidation will take place unequally if there is a partial drying of the fibres, or an unequal exposure of the fibres to the air. The other method referred to is that proposed by Gop- pelsroeder, in which a vat of reduced Aniline Blackis made, the cotton being then dyed in it just as in an indigo-vat. The Aniline Black is first prepared separately, namely, by heating a solution containing aniline hydrochloride, potassium chlorate, ammonium chloride, and copper sulphate. The black pigment thus produced is purified by boiling with water, and afterwards with alcohol. It is then heated with a solution of caustic potash, and the colour-base of the black thus liberated is washed, dried, and dissolved in fuming sulphuric acid. This solution is poured into cold water, and the greenish-black precipi- tate thus produced is dissolved in caustic alkali, and reduced by heating with the addition of glucose, hydrosulphite of soda, or zinc powder. Ferrous sulphate and lime are inoperative. If cotton be steeped in the brownish-yellow solution thus obtained, and then exposed to the air, it acquires gradually a blue colour. By submitting this colour to a supplementary oxidation (see p. 394) it changes to a light grey or deep black, according to the concentration of the vat. A judicious combination of the aniline black vat with an indio^o-vat may yield very fast deep blues. On account of its great fastness. Aniline Black is ex- tremely serviceable for dyeing unspun cotton, intended to be mixed with loose wool previous to spinning ; it may also be associated with Logwood black, since chromic oxide is precipitated on the fibre along with the Aniline Black, in sufficient quantity to serve as a mordant for dyeing subsequently in a I^ogwood bath. If necessary, 39G DYEING OF TEXTILE FABRICS. [Chap. XVL an additional saddening with acetate of iron may also take place. 341. Application to Wool and Silk — At the present time these fibres, especially the former, cannot be dyed satisfactorily with Aniline Black. It would appear as if the reducing action of the fibres themselves hindered the oxidation of the aniline salt. Better results are said to be obtained if the fibres are previously oxidised by im- mersing them for some time either in a weak solution of permanganate of potash, or in a dilute solution of bleach- ing powder to which hydrochloric acid has been "added. After this preliminaiy process, the wool or silk is washed and d}' ed by a process exactly analogous to the one de- scribed for dyeing cotton. 342. Naphthylamine Violet. — This colouring matter, derived from naphthylamine hydrochloride in a manner similar to that by which Aniline Black is obtained, must also be produced upon the fibre itself. It gives a dull gi-eyish- or brownish- violet on cotton, which is not quite so fast as Aniline Black. It does not appear to be used in pi-actice by the dyer. Reference has already been made to the dyeing of manganese-brown cotton T\ith naph- thylamine salt (see p. 226). (d) Anilim Colours containiny Sulphur. 343. Aldehyde Green [C^H,,X.S,0].— This colouring matter, now seldom used, is invariably prepared by the dyer himself, by the action of aldehyde upon a solution of Magenta dissolved in strong sulj)huiic acid ; the blue solution thus obtained is then poured into a boiling solu- tion of thiosulphate of soda. The acid solution is filtered, and should be at once used for dyeing silk or wool, since it decomposes on long standing. It is not applic- able to cotton. fCeH3N(CH3)8 344. Methylene Blue. N^ >s 1_ lCeH3-N(CH3)2Cl Methylene Blue, a derivative of dimethyl-aniline, is sold Chap. XVII.l QtJINOLiNE COLOURS. 397 as a zinc double salt in the form of powder. It is princi- pally used in cotton-dyeing, and gives a greenish blue, much valued on account of its great fastness to soap and also, it is said, to light. For silk- and wool-dyeing it has less importance : since on these fibres it is not fast to lio;ht nor is it so brii(ht as other blues. Application to Cotton. — The cotton is prepared with tannic acid and tartar emetic, then washed and dyed in a separate bath containing Methylene Blue solution. The addition to the dye-bath of a small quantity of carbonate of soda or ammonia is beneficial. Enter the cotton cold, and raise the temperature gradually to 100'"^ C. For dark indigo-blue shades the tartar emetic may be substituted by nitrate of iron. Application to Wool. — Add to the dye-bath the requisite amount of colour in solution (0-5 — 5 per cent.) and 1 — 2 per cent, of carbonate of soda (crystals) or ammonia. Enter the wool cold, and raise the temperature gradually to 100° C. in the course of half an hour, and boil half an hour longer. The dye-bath cannot be exhausted. Excess of sodium carbonate is injiuious. Ethylene Blue. — This colouring matter is applied like Methylene Bhie, and has similar properties. It is prepared from diethyl-aniliae. CHAPTER XYH. QUINOLIXE COLOURING MATTERS. 345. Flavaniline (Meister, Lucius, and Briining) [C9H,N(CH3)-CeH,(NH2)-Ha]. This basic yellow colouring matter, derived from acetanilide, is the hydrochloride of the quinoline base flavaniline. It is applied to cotton, wool, and silk, in the same manner as Magenta. On wool the colour is 398 DYEING OF TEXTILE FABRICS. fChap XTIIL developed a little by passing the dyed material through dilute sulphuiic acid. Brighter colours are obtained on wool mordanted with thiosulphate of soda according to the method employed when dyeing with Methyl Green. Flavaniline yellow is not fast to light Flavaniliiie S is an alkali salt of the sulphonic acid of the flavaniline base. It is applied to wool and silk in an acid bath. Qmnoline Blue [CVgHg-X^^]- — This disused colour- ing matter, also called Cyanine, is applied to cotton, wool, and silk in the same manner as ]5ilagenta. The colours it pelds are very fusitive towards light. Quinoline Yellow (Act. GeseU.FarbenFabrik, Berlin). — This colouring matter is the sodium salt of the sul- phonic acid of quinoline - phthalein. It gives a pure yellow colour, and is applied in an acid dye-bath in the same manner as other sulphonic acid colouring matters. CHAPTER XYIIL PHENOL COLOUEING MATTERS. (a) Nitro Com-pounds. S46. Picric Acid [CeH2(N0.)3-0H].— This colouring matter is tri-nitro-phenol ; it is used only in silk- and wool-dyeing. Cotton has no atti-action for it, and although it may be fixed on this fibre by means of albumen, the method has no practical value. The animal fibres, on the contrary, readily take up Picric Acid from an acid solution. It gives a clear bright yellow, free from any tinge of orange ; indeed, when compai-ed with most other yellows it appears to have a greenish hue. Application to Wool. — Dve for h — 1 hour at 60"— 100° C. with 1—4 per cent, of Picric Acid, with the addition of 2 — 4 per cent, of sulphuric acid, 168® Tw. Cliap. XVIIIJ PHENOL COLOURS. 399 (Sp. Gr. 1-84). The bath must be pi-eserved, since it cannot be exhausted. By repeated washing with water only, it is possible to remove nearly the whole of the colour from the dyed fibre. It does not stand milling well, both on this ac- count and because the colour becomes brownish under the influence of alkalis. It is also not a good dye for the woollen part of mixed goods (wool and cotton), since it comes off in the tannin bath used for preparing the cotton. It is fre- quently employed for the production of compound colours, e.g., with Methyl Green and with Indigo Carmine for yellowish greens, with Acid Violet for olive, IC6H4-CO-0 1 I This fine purple oolouiing matter, sometimes called Anthracene Violet, is derived from phthalic anhydride and pjrogalloL It is sold in the form of a reddish- brown powder or a 10 per cent, paste, not very soluble in cold water, but readily so in hot. It ought to be mach mofe used than it is, since it gives fine purple shades on cotton, wool, and silk, which are tolerably fast both to light and soap. Chap. XVIII.] PHTHALeTn COLOURS. 407 Apjylicatioii to Cotton. — Prepare the cotton with aluminium, chromium, or iron mordants in the usua] manner, and dye in a separate bath with Gallein. The whole process is identical with that used in dyeing with Alizarin, Logwood, or other polygenetic colouring matters. All the mordants yield purple colours, those obtained by the nse of chromium and iron being bluish, those of tin reddish, and those of aluminium intermediate in tone. All the colours may be regarded as fast to light and soap. Application to Wool. — Mordant the wool with 2 per cent, of bichromate of potash. The addition of sulphuric acid even to the extent of 1 per cent, is injurious, and dulls the colour. Dye in a separate bath with 10 — 20 per cent, of Gallein paste, containing 10 per cent, of solid matter. Enter the wool cold, and raise the temperature gradually to the boiling point. The shade thus produced is bluish-purple or violet. With aluminium mordant a much redder and brighter purple is given. Mordant with 6 — 8 per cent, of alumi- nium sulphate and 5 — 7 per cent, of cream of tartar. With the addition of 1 — 2 per cent, of acetate of lime (solid), the shade is somewhat more intense and slightly brighter. The addition of chalk to the dye-bath is not to be recommended, even with 2 per cent, the colour is much deteriorated. W^ith iron mordants Gallein gives a deep violet colour. Use 8 per cent, ferrous sulphate and 5 per cent, tartar. The single- bath method is also applicable. All the above Gallein colours are specially adapted for goods which have to be milled. The chromium mor- dant is the most generally useful of those mentioned. Silk is dyed in the same way as with Alizarin (p. 456). i COaHa —0 364. Coerulein C.HJ >o ( COCyH(OH)-0 This green colouiing matter, also called Anthracene Green, is derived from Gallein by the action of sulphuric acid at a high temperature. It is sold in t\A'0 forms, either as a thick black paste (Coerulein paste) containing 40S DYEING OF TEXTILE FA^EICS. [Chap. XVIH 10 — ^20 po" cent, of CoBmlein, or as a black powder. The £011110* is more or less insoluble in water, and re- quires in some cases the addition of bisulphite of soda to render it soluble. The latter, known as Coerulein S, is soluble in water, and is indeed a compound of CGerulein with bisulphite of soda [CgQHgOg-SXaHSOg] ; this form is Uie one most easily allied. At the ^%sent time CoBrulem is mostly employed in caKoopmiting for producing Tery fast olive-green shades. The ofdouis it jields both on cotton and on wool are re- mazkaUe for their &stness to li^ht, acids, alkalis, phenylene- diamine and a-naphthol, or by the action of nitroso- dimethyl-aniline on a-naphthol. It gives colours very similai- to vat-indigo blues, and which are said to be moderately fast to light They are, however, extremely sensitive to the action of acids ; even weak acids destroy the blue colour and change it to brown. Indophenol Blue X is better adapted for wooUen- and calico-printing than for dyeing. Under the influence of reducing agents — e.g.^ glucose and caustic soda, stannous chloride and carbonate of soda, vtc. — Indophenol Blue is changed into indophenol- white, which is soluble in pure or acidulated water. For the prepai-ation of indophenol-white, mix to- gether 10 kilos, of Indophenol Blue (paste) and CO litres of water; add 30 litres of a 10 per cent, solution of tin crystals (SnCl2'2H20), and heat to 25^0. until reduction tiikes place. Chap. XVT.II.] INDOPHENOL COLOURS. 4ll Application to Cotton. — Dye for ten minutes at 40° C. in a solution containing 5 — 10 grams, of indophenol-white per litre, then wring out and wash, and develop the colour by working the cotton for about two minutes at 50° C. in a dilute solution of bichromate of potash. Better colours are obtained if the cotton is previously prepared with sulphated oil. Ap2jlication to Wool. — Dye for fifteen minutes at 80° C. in a solution of indophenol-white, rendered either alkaline by the addition of sodium carbonate, or acid by means of acetic acid. Wring out, wash, and develop the colour by exposure to air, or by working the material for a few minutes in cold dilute solution of bichromate of potash, or an ammoniacal solution of sulphate of copper. For dark shades the solution of indophenol- white should be concentrated ; the dye-bath is not ex- hausted, and should always be preserved. 366. Gallocyanin (Durand and Huguenin). — This colouring matter, also called 'New Fast Yiolet, is obtained by the action of nitroso-dimethyl-aniline on tannic acid. In dyeing, it yields a bluish-violet colour possessing only moderate brilliancy, but tolerably fast to the action of acids, alkalis, and light. Applied in conjunc- tion with other colourincj matters, it is useful for obtainiii^j compound shades. Application to Cotton. — Mordant the cotton by means of an alkaline solution of chromium oxide, and wash well. Dye in a separate bath with Gallocyanin, at a tempera- ture of 80° C. for 1 — 1^ hour. If, after dyeing, the cotton is washed, dried, and steamed, the colour becomes some- what darker and faster. Application to Wool. — The wool may be dyed without any previous pieparation, or it may be first mordanted in the usual manner with bichromate of potash. Dye in a neutral bath. Introduce the wool into a cold solution, raise the temperature gradually to 70° C. in the course of one hour, and continue dyeing for -| — 1 hour longer. 4:12 DYEING OF TEXTILE FABRICS. [Chap. XIX. Ap2olicat{on to Silk. — Dye at 70° — 80° C. in a bath containing colour solution and " boiled-off " liquor. The silk may be previously mordanted with chrome alum, though this is not absolutely necessary. CHAPTER XIX. AZO COLOURING MATTERS. (a) Amido-azo-colours. 367. Aniline Yellow [C6H,N = N-C6H,-NH2HClJ. Diamido-azo-benzene-hydrocbloride. — This colouring matter is no longer used in dyeing, because the colour which it yields is volatile and not fast. Cotton has no attraction for it. Wool and silk may be dyed in a bath slightly acidified with acetic acid. 368. Chrysoidine [CeH5-N = N-C6H3(NH2)2-HCl].— Diamido-azo-benzene-hydrochloride. This colouring matter, much used in cotton-dyeing for producing various shades of orange, is prepared by the action of diazo-benzene-chloride on m-phenylene-diamine. It is well adapted for shading, and may be used as the yellow part in a number of compound shades, e.g., olive, brown, scarlet, &c. Chrysoidine FF (L. Cassella & Co.) is the corresponding toluene compound. Ap2ylication to Cotton. — Mordant the cotton with tannic acid and tartar emetic, and wash ; dye at 60° C. in a solution of the colouring matter, without any further addition. Avoid high temperatures, since the colour is thereby rendered duller. Sometimes the fixing of the tannic acid with tartar emetic may be omitted, and for very light shades it is not even necessary to prepare the cotton with tannic acid, since this fibre seems to possess naturally a certain attraction for Chrysoidine. Good shades are Chap.XTX.7 AMIDO-AZO COLOURS. 'ilS obtained by applying Chrysoidine to cotton previously dyed with Catechu, Sumach, &c. Application to Wool—DyQ at 60°— 70° C. in a neutral bath, or with the addition of 2—4 per cent, of soap, or one acidified with alum. These additions tend to brighten the colour. The addition of sulphuric acid to the dye- bath impoverishes the colour, but if, after dyeing accord- ing to the above method, the wool be worked for 10—15 minutes in cold water slightly acidified with sulphuric acid, the colour acquires a deeper and redder hue. Dyeing at 100° C. dulls the colour considerably. Application to Silk.— Dye at a temperature of 60° C, with or without the addition of a little soap to the dye-bath. Brighten in a bath very slightly acidified with sulphuric acid. 369. Phenylene Brown.— raH4-(NH2)-N = N-C6H3(NH2)2-2HCl] Triamido-azo-benzene-hydrocliloride. This colouring matter is prepared by the action of nitrous acid on m-phenylene-diamine, and dissolving the base thus produced in hydrochloric acid. It also bears the commercial names : Bismarck Brown, Vesuvine, Ca- nelle, Manchester Brown, Cinnamon Brown, &c. Bismarck Brown GG and EE (L. Cassella & Co.) are the pure products of toluylene-diamine and phenylene- diamine respectively. Application to Co^^on.— Prepare the cotton with tannic acid and tartar emetic ; wash and dye in a neutral- bath at 50°— 60° 0. Add the colour solution gradually. A. slicrht addition of alum to the dye-bath may sometimes be mtde to modify the shade. The shades given by Bismarck Brown are similar to those obtained from Catechu, but, as a rule, brighter. Light shades can be dyed without previous preparation of the cotton. Catechu browns are frequently dyed with it in order to brighten or modify the colour. A threat variety of compound colours are obtainable 414 DYEING OF TEXTILE FABRICS. [Chap. XIX. by using it along with other basic colouring matters, e.g.^ Magenta, Malachite Green, Methyl Violet, Methylene Blue, &c. Application to Wool. — Dye in a neutral bath. For a full shade, use 5 — 8 per cent, of colouring matter. The addition of 8 — 10 per cent, of alum to the bath makes the shade redder. Enter the wool at 45° C, and heat gradually to 100° C. Application to Silk. — Dye in a weak soap bath at 60° C, and brighten in a fresh bath slightly acidified with acetic or tartaric acid. (6) Amido-azo-sulphoniG Acids. 370. Fast Yellow.— [(SOgNa) CeH^-N = N •C6H4(NH2)] Amido-azo-benzene-sodium-p-sulplionate. This colouring matter is also called Acid Yellow; it cannot be used for dyeing cotton. It is well adapted for using along with other acid colouring matters to obtain com- pound shades on wool or silk. Employed alone it cannot compete with some other yellows in brilliancy. The above compound is sometimes distinguished as Fast Yellow G, while Fast Yellow H is given to the corre- sponding toluene compound. Ap2:>lication to Wool. — Dye in an acid bath. For 0*5 — 3 per cent, of colouring matter add 2 — 6 per cent, of sulphuric acid, 168° Tw. (Sp. Gr. 1 -84). Enter the wool at 40' C., and heat gradually to 100° C. in the course of f — 1 hour, and boil for | hour. If 5 — 10 per cent, of alum be used instead of sulphuric acid, the shade given is weaker and less orange. Application to Silk. — Dye at a temperature of 60° — 80° C, in a bath containing '*boiled-off" liquor and acidified with sulphuric acid. 371. Dimethylaniline Orange. — [(S03'NH4)C6H4-N = N-C6H4(N(CH3).,)] p-Dimethyl-amido-azo-benzene-ammonium-p-sulpiiouate. Chap. XIXl AMIDO-AZO ACID COLOURS. 415 Other commercial names of this colouring matter are: Helianthin, Gold Orange, Orange III., and Tropseolin D, &G. Application to Cotton. — Work the cotton in cold stannate of soda solution, 5^ Tw. (Sp. Gr. 1-025), till thoroughly saturated, and wring out; work for \ — J hour in a cold solution of alum (15 — 20 per cent.) and wring out ; dye in a concentrated solution of the colour- ing matter, with the addition of an equal percentage of alum. Enter cold, and heat gradually to 45° C., but not higher. Dry without previous washing. The colour is not fast to washing. Apptlication to Wool. — Dye exactly as with Fast Yellow. Somewhat brighter shades are obtained by using stannic chloride instead of sulphuric acid. With 2 per cent, of colouring matter a full reddish-orange is obtained. Application to Silk. — Dye exactly as with Fast Yellow. 372. Diphenylamine Orange — [(S03K)C6H4'N = N-C,H4(N-H-C6H5)] p-Phenyl-amido-azo-benzene-potassium-p-sulphonate. This colouring matter is also called Tropseolin 00, Orange lY., Orange N, Yellow N, &c. It is very sensitive to the action of an excess of free acid, which causes it to dye a more orange colour. Large excess of mineral acid causes its solution to become violet through liberation of the free colour acid. Closely allied to this colouriag matter are the three following : — 373. Metanil Yellow (basf).— [(S07Na)C6H4-N = N-CeH4(N-H-C«Hg)] p-Ph.enyl-amido-azo-'benzene-sodium-TU-.sulphonate. This colouring matter is also called Tropseolin Q (L. Cassella k Co.). 374. Brilliant Yellow (basf). — [(S03Na)C6H3(CH3)-N..N-C«H,(N-H-CeH5)] jj-Phenyi-amido-azo-toluene-sodium-p-sulplionate. 416 DYEING OF TEXTILE FABRICS. [Cbap. XIX. 375. Azoflavin 2 (base). — [(S03Na)C6H4-N = N-C6H4(N-H-C6H4(N02))]. p-Nitro-phenyl-amido-azo-benzene-sodiuiD-p-stilphonate. All these colouring matters are specially suitable for wool- and silk-dyeing, and give fine yellow or orange shades. They are applied in the same way as Fast Yellow and Dimethylaniline Orange. The colours on cotton are not fast to washing. If 10 per cent, of alum is added to the dye-bath instead of sulphuric acid, the colours on wool are rendered brighter. Indian Yellow (L. Cassella & Co.) is isomeric with Azoflavin. 376. Congo Red (Act. Gesell. Anilin. Fabrik, Berlin).— I ;06H4-N=N-OioH5(NH2)(S03Na) I ^C6H4-N=N-CioH5(NH2)(S03Na) Tetrazo-diphenyl-dinapMhylaiiuiie-sodivun-disulplionate. This colouring matter possesses the very interesting pro- perty of being readily applied to the vegetable fibres without the aid of a mordant. It may be used for dyeing mixed goods consisting of cotton and wool, and yields a bright scarlet colour, fairly fast to boiling soap solutions, but not to light. It is also extremely sensitive to the action of acids ; these change the colour to blue. Application to Cotton. — Dye at 100° C. in a neutral bath, or one rendered slightly alkaline by the addition of soap ; wash and dry. A much richer colour is got if the cotton is previously mordanted with stannic oxide, or, better still, with sulphated oil and aluminium sulphate. Application to Wool and Silk. — Dye in a neutral bath or with the addition of a little soap. 377. Benzopurpurin (F. Baeyer & Co.). — C CyHe-NnN-CioHslNHo) (SOgNa) C CyHg-N = N-CioH5(NH2) (SOgNa) Tetrazo-ditolyl-diphenylamine-soiMum-disulplionate. This colouring matter is applied to the various fibres in Chap. XIX.] OXY-AZO COLOURS. 417 the same manner as Congo Red, being closely allied to it in chemical constitution. It yields a bright scarlet colour, fairly fast to soap, and less sensitive to light and particularly to acids, than Congo Red. It is not affected by dilute acetic acid, or even by dilute mineral acids. The best addition to make to the dye-bath is phosphate of soda, though one may, if desirable, use soap or silicate of soda instead. (c) Oxy-azo Colouring Matters. 378. These include yellow, orange, red, crimson, and brown colours. Nearly all belong to the class of so-called acid-colours, and are specially suitable for wool- and silk- dyeing. When applied to cotton, most of the colours are not fast to washing with water. Many of the scarlets have largely displaced Cochineal in wool-dyeing. For plain scarlet dyes (e.g. on flannels, &c.) they are even preferable to Cochineal, since the colour does not become dull and bluish on washing with soap. They are, however, not suitable for yarn which has to be woven with other light-coloured yarns, if the material so produced must afterwards be washed with soap, scoured, or milled. During these processes the colour " bleeds," or comes off slightly and dyes very permanently the contiguous light- coloured fibres, thus spoiling the general appearance of the fabric. This defect is common, indeed, to all those coal-tar colouring matters which dye without mordant. For dark-coloured fabrics the defect is not noticeable. The dyeing properties of many of these colouring matters are very similar. The dyes they yield are very fairly fast to light, though they differ consideraljly in this respect. As a rule, the tetrazo compounds are faster to light than the diazo compounds. It is difficult to identify all the colourins: matters of this class met with in commerce, since each manufacturer gives a special name and mark to his own products. B B i)S DTEIXG OF TEXTILE FABRICS. [Chap, itt- The followiDg list, however, comprises the most im- poi-tant : — 379. Tropaeolin Y.— : ;S03Xa: CgH.-X = X-C6H4- (OH)] p-Phenol-azo-benzene-sodium-p-sulphonate. This colouiing matter has now little importance, having Leen replaced by other similar but superior colouring mattei-s. 380. Resorcinol Yellow. — Ee5orciiiol-a20-beiiz€iie-sodiuiii-j:>-sulp£oaat€, This colouring matter is also called Tropseolin 0, Tro- paeolin E, Chiysejlin, Chrysoin (Poirrier). It gives an orange dye of only moderate biilHancy, and is chiefly used along with other acid-colours to produce olives, maroons, ijcc. 381. Orchil Brown (F. Baeyer (fc Co.).— [(XHs: CiA-X = X-CeH/SOsXa)] This colouring matter is a-naphthylamine-azo-benzene- sodium-sulphonate. 382. Azarin S (m. l. it b.).— rOH _ CgEUCU ] ^'^^'CioH^lOH) ( SOsXH.H This colouring matter is suitable only for cotton. It yields a brilliant red said to be faii-ly fast to light The following method of applying it to calico is pro- posed by the manufacturers : — Pad the cloth with a solution of aluminium acetate to which a small proportion of stannous oxide has been added. After drying and ageing for 12 hours, work the cloth for half an hour in a cold solution containincr a c very small proportion of acetate of lime and sodium car • l>onate ; then wash well and dye in a solution of the colouring matter with the addition of a little sulphated Chap. XIX.] OXY-AZO COLOURS. 419 oil. After djeing, wash, dry, pad with a dilute solution of sulphated oil, dry and steam ; then wash in a cold weak soap solution and dry. The alkalinity of the soap gives the red a bluish tone, which may be removed by a final passage in very dilute acid. 383. Azo Blue (F. Baeyer c] a ^ :-z :.:hvlainuie-azo.a-iiaphthol-80diiiin-siilphoiiate. Crocein 3 BX (F. Baeyer & Co.).— jS03Xa)C,,H,-Xz:XC,,H3(OH)(SO,Xa)] Kapbrlialeiie-5odiuin-snlphoiiate-az«>^-iiaphthol-5od:uin-«-siilphonate. 393. Claret Red B (m. l. i- r).— [Ci„H7X=iX-Ci„tt.(0H)(S0,Xa)] ar-Naphthalene-azo-^-naphtliol-sodiiuii-a-disalphoiiate. This colouring matter is also called Bordeaux B. If alum is used in the dye-bath for wool, the colour is apt to be very uneven. Fast Red B (basf). — This colouring matter is iso- meric with the last, being the sodium salt of the corre- sponding 3-sulphonic acid Othe^ names which seem to be given to it are Clgiret Red R (iL k i r ) and Bor- deaux G. Crystal Scarlet 6 R ( L. Cassella i Co. ). — This colouring matter is also ii^.-meiic with Claret Bed B, being the sodium salt of the corresponding y-disulphonic acid. Amaranth (m. l. hoiMte^ Cliap. XIX.J OXY-AZO COLOURS. 423 394. Anisol Red (basf). — [CeH4(OCIl3)-X-X-C,oH5(OH)(S03Na)] Anisol-azo-ZS-naphtliol-sodium-sulphoiiate Phenetol Red (basf). — [C,1I,{0C,1I,) -N =N-CioH4(OH) (SoJ^a)^] Phenetol-azO'/S-naphtliol-Bodiuiii-a-disalphonate. This colouring matter is also called Coccinin (m. l. & B.). Coccinin B (m. l. eration : Steeping. — Steep the yarn during 20 — 24 hours in water heated to 55° C, wash well, and dry in the stove at about 60° C. If the yarn contains much unmodified oil, a solution of carbonate of soda at J° Tw. (Sp. Gr. 1-0025) may be used; in this case a second steeping for two hours in tepid water is requisite before washing, &c. 10th Operation: Sumaching. — A decoction of Sumach is made by boiling 60 kilos, of best leaf Sumach for about half an hour, with sufficient water to make the cold filtered solution stand at \^° Tw. (Sp. Gr. 1-0075). The stoved yarn, while still warm, is steeped in large vats in this decoction as hot (40° — 50*^ C.) as it can be borne by the boys who usually tramp it with bare feet beneath the surface of the solution. After steeping about 4 — 6 hours, the solution is drained off, and the excess is removed by a hydro-extractor. Wth Operation: Mordanting or Aluming. — A basic solution of alum is made by dissolving ordinary rock- alum in hot water, and when nearly cold, adding gradually a cold solution of one-fourth its weight of carbonate of soda crystals. The solution is made to stand at 8*^ Tw. (Sp. Gr. 1*04). Sometimes, though this is not essential, a further addition is made of about 150 — 200 cubic centimetres of "red liquor," 16° Tw. (Sp. Gr. 1-08), and 5 — 7 grams of tin-crystals (SnClg) per kilo, of alum. The sumached yarn while still damp is tramped in the aium solution at a temperature of 40° — 50° C., and left Chap. XX.] ALIZARIN. 433 to steep for twenty-four hours. It is then thoroughly washed and hydro-extracted. \2th Operation : Dyeing. — Dye with 150 — 180 grams of Alizarin (10 per cent.), 30 grams of ground Sumach, Fig. 88.— Clearing Boiler. and about 300 grams of bullock's blood, per kilo, of cotton yarn. If the water contains little or no lime, add also ground chalk in the proportion of 1 per cent, of the weight of Alizarin (10 per cent.) employed. The yarn is introduced into the cold solution of the dye-vessel, the temperature is gradually raised to 100° 0., in the course c c 434 DYEING OP TEXTILE FABRICS. [Chap. XX of one hour, and the boiling is continued for 4 — 1 hour, After dyeing, the yam is washed, although this is not absolutely necessary. 13th Operation: First Clearing. — Boil the yam for four hours at 3 — 4 pounds' pressure with about 30 gi-ams of carbonate of soda crystals, and 30 grams of palm-oil soap, dissolred in a sufficiency of water, per kilo, of yam. Wash afterwards. The "cleariug boiler" used, and shown in Fig. 88, and in plan in Fig. 89, is similar in construc- tion to an ordinary low-pressure bleach- ing kier; it is, how- ever, made of copper instead of iron, a represents the yam ; B the lid provided with safety valve and blow-off pipe ; c the perforated false bot- tom ; D the puffer- pil^ E the bonnet Rg. 99.— Plan of Fig. 88. for distributing the liquor over the yarn ; F the draw-off pipe. During the boiling, the Hquor which collects below the false bottom is forced by the steam up to the top of the puffer-pipe, there to l^e ejected and spread over the goods. This action is of an intermittent character, since, after each ejection of the liquor, the pressure of the steam must accumulate below the false bottom until it is again able to overcome the weight of the column of water in the puffer-pipe. \^th Operation: Second Cl-earing. — Boil the yarn for 1 — 2 hours at 3 — 4 pounds' pressure with a solution containing 25 grams of palm-oil soap and 1^^ grams of tin- crystals per kilo, of yarn. Wash well and dry in an open- air shed. Previous to drying, the large excess of water Chap, Xi.J ALIZARIN. 435 is removed by means of the liydraulic press represented in Fig. 90. It consists of a strong ii'on framework d d, with a strong, fixed, but adjustable head a above, and a^us^^g i - '^^ g yf,^ ^ m. \^-.... Fig. 90.— Hydraulic Press. a similar one b below, attached to the hydraulic piston C, and thus capable of being moved up or down. By means of this machine a very large quantity of wet yarn may be rapidly and efficiently squeezed. The above fairly represents the " Emulsion process " 436 DYEIXG OF TEXTILE FABRICS. [Chap. XX. of Turkey-red yam-dyeing as practised at tlie present time. It consists, therefore, of a somewhat numerous series of o]>erations, occupying usually about thi-ee ^^veeks' time, and although, hitherto, no absolutely satisfactory scientific explanation has been given of the exact nature of the chemical chacges effected by every deta.il of the whole process, still theii' general chai'^cter is tolerably well understood. The object of the frequent steeping in oil- emulsion, dr^TJig in the open air, and stoving, is to im- pregnate the fibre evenly and thoroughly with oil, and to modify it in such a maimer that it is not affected or remov€Mi by weak alkaline solutions, and that it will attract alumina from its solutions. Many kinds of oil have been employed, but long experience has proved that olive oil gives the best and most certain results. The particular quality of oil most suitable for the purpose is that obtained by a second pressing of the olives after they have somewhat fer- mented and Ijeen steeped in boiling water. (Fr., Jaiih tournante). It contains nitrogenous and extractive mat- ters, which cause it gi^adually to become rancid, particu- larly when exposed to the aii', i.e., it decomposes, ai>d a portion of the glycerine and fatty acids (margaric and oleic acids) is liberated One of the chief character- istics of a good olive oil suitable for Turkey-red, is, that when one measure of it is shaken up with about 16 measures of sodium or potassium carbonate solution at 3"^ Tw. (Sp. Gr. I'Olo), it forms a white milky liquid or emulsion, from which the oil does not readily separate even after standing for 12 — 18 hours. The oil which forms the most perfect and permanent emulsion \s'ith the least quantity of potash or soda is the best. This property of emulsifying, however, can be readily imparted to any oil by mixing it with 5 — 15 per cent, of oleic acid. The exact nature of the chemical cbanijes which the oil undergoes duiing exposure to the air and stoving is unknown. It is probable, however, that under the influence of the alkaline carbonate and heat, the oil Clhap. iX.i AtlZARiN. 43t IS decomposed and oxidised in such a manner that there remains on the fibre essentially an insoluble oxyoleic acid. Whatever may be the exact chemical composition of the modified oil, it has the property of fixing or com- bining with alumina, and the compound thus produced can further combine with Alizarin to form a red-lake. The effect which it has of gi\'ing brilliancy and fastness to the ultimate colour is probably, in part at least, due to its physical action of enveloping the coloured lake with a transparent oily varnish, which protects it more or less from external influences. All unchanged oil must be removed before mordanting {see Operation 9). The impregnation of the cotton with tannin matter fixes an additional amount of alumina on the fibre, and tends to give deeper and fuller shades. Its use is, how- ever, by no means absolutely essential, as seemed to be the case when Garancin or Madder w^as used, and by some dyers it is not used. During the steeping in alum solution an insoluble basic aluminium compound is formed with the modified oil and also with the tannic acid if present. The com- plex mordant thus fixed on the cloth at this stage combines with Alizarin in the subsequent dye-bath to form the Turkey-red lake. The bullock's blood used is said to prevent, by reason of the coagulation of its albu- men, certain impurities accompanying the Alizarin from being fixed on the cotton, but some practical Turkey-red dyers say that blood-albumen, glue, and other substitutes which have been tried, cannot entirely replace it. It certainly adds brilliancy and purity to the colour. The "First Clearing" operation is for the purpose of removing any rema,ining impurities which the mordant may have attracted in the dye-bath, but for which its affinity is far less than for Alizarin. The " Second Clearinc: " is said bv some to introduce into the already extremely complex coloured lake a small portion of stannous oxide. Others allege that there is simply a tin-oleate produced, \Yhich is melted and 43d DYEING OP TEXTILE FABRICS. [Chap. XX spread over the fibre, as it were, without entering into chemical combinatior with the red-lake. Liechti has proved analytically that as much as 60 per cent, of the fatty acid of the soap employed, may dis- appear and become fixed in this manner upon the fibre. The practical object of this operation is to give the colour the maximum purity and brilliancy of which it is capable. 401. Steiner's Process for Dyeing 500 kilos, of Turkey-red Cloth. — The main difference between this and the '' emulsion process " already described, resides in the mode of applying the oil. In the process now to be described the cloth is impregnated with the requisite amount of oil at one operation, namely, by padding it in clear hot oil instead of in an oil-emulsion, after which it receives several passages through weak solutions of alkaline carbonate. This method is capable of yielding a Turkey-red dye of exceptional brilliancy and intensity — better, in- deed, than it is possible to obtaiu by the "emulsion process." 1st Operation. Bleaching. — The pieces are well washed and boiled during 2 — 3 hours, with water only ; then boiled for 10 — 12 hours with 22 litres of caustic soda, 70° Tw. (Sp. Gr. 1*35), and washed : then boiled a .second time for 10 hours •vsdth 16 litres of caustic soda, 70° Tw., and washed; and finally steeped for two hours in sulphuric acid, 2° Tw. (Sp. Gr. I'Ol), well washed and dried. In order to avoid tenderinsr the fibre in the next operation by reason of traces of acid left in the cloth, it is padded Avith carbonate of soda solution at 4° Tw. (Sp. Gr. 1-02), and then dried. 2nd Operatioji. Oiling. — The cloth is padded in the open width in olive oil maintained at a constant temperature of 110° C. Fig. 91 represents a section of the oil- padding Chap. XX.] ALIZARIN. 439 machine of Messrs. Duncan Stewart and Co. It consists of a double-jacketed tank b (inside copper, outside iron) for containing the oil. It is heated by means of steam, and is provided with a series of rollers at the top and bottom. Above is a pair of heavy squeezing rollers c. The cloth is passed through as indicated in the figure, ? C^ b b b O b^^ l^x>':^^^v-: ".'^ - -^sgj^ >^^^^;;ys\^^^v>^xKXvV . aH Fig. 91.— Oil-padding Machine. being well opened out and made free from creases before entering the oil, by means of the straining bars AAA, and aftei'wards loosely plaited down by the folder d. After padding, the cloth is detached in ten-piece lengths, and hung in the drying stove, the temperature of which is raised as rapidly as possible to 70' C, and this is maintained for two hours. 3rd to 9th Operation. Lirjuoring. — Pad the cloth seven times in the open width through a solution of carbonate of soda at 4° Tw., and hang in the stove no DYEING OF TEXTILE FABRICS. CChaj- XX. after each j^adding operation, maintaixiing the tempera- ture in each case for two hours at 75° — 77° C. In "winter the padding liquors are made waiia (35° — 40° C), but in summer tliey are always cold, since if too hot, oil is stripped off the piece to an excessive and injurious degi'ee. In the course of regular working, the liquors soon become veritable oil-emulsions, and constant Fig. 92. — Section of Liquor-pad'iing MacMne. oversight is necessary in order to maintain their sj>ecific gravity as constant as possible, and thus ensure ulti- mately a regular and satisfoctory colour. A section of the liquor-padding machine of Messrs. Duncan St€\\ art and Co is shown in Fig. 92. It con- sists of a wooden box or tank A to hold the Hquor, provided with rollers above and below. Over this are supported two pairs of heavy squeezing rollers B c and D E. At F a few straining bars serve to open out and stretch the cloth ; g is t>^e"folder. The mode of passing the pieces through the machine is readily iindei-stood fix)m the diagram. Chap. XX.J ALIZARIN. 441 With regard to the stoviiig, it is well to bear in mind that during the first stages of drying much va- pour is given off, and special attention must be given to ensure adequate ventilation. Fig. 93 is the ground plan, showing heating flues, and sectional elevation of a modern four-storeyed Turkey- red stove. A A repre- sent ordinary coal fires situated in the base- ment ; the hot flue- gases pass first through channels made of fire- brick, then through iron pipes, and finally make their exit to the chimney at B. The upper part of the stove is divided, by floors of iron-grating, into several storeys c, D, E, F, each of which is furnished with wooden frame- work, supporting, one above the other, two pairs of horizontal rails provided with short, upright, wooden pegs. Over these pegs one selvedge of the be 442 DTEIXG OF TEXTILE FABRICS. [Chzp. XX. cloth is fiiTQly hooked alternately from right to left, while the other is allowed to hang down ; thus, when the stove is filled, each storey is closely packed with two tiers of cloth suspended in such a manner that the heated air from below can readily pass between each fold. A yam stove is similarly constructed, but in this case the ends of the rods holding the yam are supported on horizontal rails free from pegs. Another mode of hanging cloth, but one which is not so economical of space, is to Lave only one storey in the stove. Above, near the roof, are fixed a number of strong, smooth, wooden rails, on which the cloth is sus- pended in long folds, reaching down to ■ within one or two feet of the iron-grating immediately above the hot flues. In all cases efficient ventilation is secured by means of numerous side windows, which can be readily opened and closed at will 10 th Opera tioTi. Steeping. — Run the cloth in the open width through a machine consisting of a large vat divided into several compartments fitted with rollers above and below. The first compartments are filled with a solution of carbonate of soda at ^° Tw. (Sp. Gr. 1-0025), and heated to 40° C. The last is fiUed with wat«r only. The cloth is then well washed, and di'ied in the stove at about 65° C. Wih to \A:th Operation. — These operations, con- sisting of mordanting^ dyeing, and clearing, are precisely similar to those already described for yarn-dyeing. It may be well to state that the number of paddings in dilute soda solution (liquoring) varies according to the quantity of oil which it is desired to fix upon the cloth. Good Tui key-red contains about 10 per cent, of modified oil on the fibre. 402. "Sulphated Oil Process" for Dyeing 500 kilos, of Yarn or Cloth. — In this process the frequent repetitions of passing the fabric through oil-emulsions or Chap. XXl AtlZARIiJ. 443 sodium carbonate and then stoving are not used. The olive oil is replaced by an alkaline solution of sulphated olive or castor oil {see p. 234) with which only a single impregnation is necessary, followed by a steaming or stoving process. 1st Ojoeration. Bleaching or Boiling. — This is iden- tical with that already given in describing the previous processes for yarn and cloth. 2nd Operation. Preparing. — The dry cotton is thoroughly impregnated by "tramping" or "padding" with a cold or tepid solution of 10 — 15 kilos, of neutral- ised sulphated-oil (50 per cent.) per 100 litres of water. The excess is removed, and the cotton is merely dried in the stove, or it may be heated for 1 — 2 hours to 75° C. 3rc? Operation. Steaming. — The prepared and dried cotton is submitted to the action of steam, 2 — 5 lb. pressure, during 1 — \\ hour. 4ith Operation. Mordanting. — The cotton is worked and steeped for 2 — 4 hours in a tepid solution of com- mercial aluminium acetate (tin -red -liquor), or more economically in basic aluminium sulphate, Alo(S04),(OH).>, at 8°Tw. (Sp. Gr. 1-04). After mordanting, the excess of aluminium solution is removed by wringing or hydro-extracting, the cotton is dried and then either simply well washed in cold water, or first worked for half an hour at 40° — 50° C. in a chalk bath containincr 20 — 30 orams of cjround chalk o o o per litre. A solution of sodium phosphate may replace the chalk water. Alkaline fixincr-a£cents like ammonia and sodium carbonate are best avoided in case any of the oil-preparation should be stripped off. K»th Operation. Dyeing. — Dye with 15 — 20 per cent, of Alizarin (10 per cent.), with the addition of 1 per cent, of its weight, of chalk or acetate of lime. The cotton is dyed in the cold for half an hour to ensure regu larity of colour, the temperature is then gradually raised to 70° C. in the course of an hour, and the dyeing is con- tinued at this temperature till the bath is exhausted 444 DYEING OF TEXTILE FABRICS. [Chap. XXt The cotton is then well washed (although with highly calcareous water this is best omitted), hydro-extracted, and dried 6^/i Operation. Second Preparing. — The dyed and dried cotton is again impregnated with a dilute solu- tion of neutralised sulphated oil (namely, 50 — 60 grams of sulphated oil [50 per cent.] per litre), and then dried. This second preparing may also take place after the mordantincf, the oil beins: then fixed bv means of a second mordanting with a weak solution of basic aluminium sulphate, ttc. ~th Operation. Second Steaming. — The dried cotton is steamed as before, for one hour. Wi and 9th Operations. First and Second Clearing. — These may be identical with ojierations 13 and 14, described in the ''Emulsion process," although many chemists think that soap alone should be used here^ and consider that the addition of stannous chloride is altogether unnecessary if not iri-ational. The " sulphated-oil pix)cess " is compai'atively so new, that numerous slight modifications of the process as here given are natui^Uy tried and adopted by various dyers, and to some of these reference will now be made. The sulphated - oil used is invariably carefully neutralised, either with caustic soda or ammonia. As a rule, ammonia is prefeiTed, since even the addition of aii excess of ammonia would have little or no injurious efi'ect, owing to its volatility ; and further, the ammonia compound of sulphated-oil is more readily decomposed on steaming than the sodium compound, and a more com- plete fixing of the oil results. Either sulphated castor oil or olive oil may I e used. Very good results are even obtained bj* the simple use of a carefully made castor oil soap, which, being excessively soluble, and giving thin solutions, is well fitted to impregnate the fibre thoroughly. In the " preparing" process, the cotton does not at- tract or fix any of the oiL It simply absorbs a definite 445 bo 446 DYEING OP TEXTILE FABRICS. lChiLY>. XX. amount of the solution, and supposing sulphated olive oil to have been used, the prepared cotton contains the sodium or ammonium compounds of oxyoleic acid and of the glycerine-sulphuric-ethers of oxyoleic and oxystearic acids, these being its constituent elements. It is very important to know the exact percentage of sulphated-oil contained in the solution, since it is this which determines the amount of oil and alumina ulti- mately fixed on the cotton, and consequently the beauty, brilliancy, and fastness of the colour. According to Liechti and Suida, the action of the Jirst steaming process is, to decompose the ammonium or sodium compounds of the ether constituent of sul- phated-oil into ammonium or sodium sulphate, glycerine, oxyoleic and oxystearic or trioxyolei'c acid, according as olive or castor oil has been employed. The other con- stituent (oxyoleic or trioxy oleic acid) remains unchanged. At the same time the steaming causes a better penetra- tion of the fibre by these oxidised fatty acids. Some- times the steamins: at this staore is altoi^ether omitted. The decomposition of the compound ether referred to may also be eflected by heating the dye-bath to the boiling point instead of only to 70° C, the bath becomes acid, and the brilliancy of the colour is developed suddenly. Fig. 94 represents a steaming-chest for yam made by Messrs. Tulpin Freres, of Rouen. The hanks of cotton are suspended on square wooden rods resting on an iron skeleton-carriage or framework, and are capable of being turned duiing the steaming process to ensure every portion being efficiently steamed. The iron carriage is supported on wheels, so that it can be filled with yarn and then run into the chest. The steaming-chest itself consists of a wrought^iron horizontal boiler, with a mov- able door at one end provided with clamps. For the prevention of drops there is fijced internally and at the top a cover of sheet-copper, in such a manner as to leave a space between it and the boiler-plate. The chest is provided with a steam-gauge, safety-valve, and blow-off 447 Z>' 5^. 95.— F^au and Elevation of Continuous St earning- Chest- 448 DYEING OF TEXTILE FABRICS. [Chap. XX. pipe. The steam enters by a perforated pij^e ininning along the bottom of the boiler, and which is usujilly covered with a |>erforated iron plate. Cotton cloth may be reeled and suspended on rods in a similar way, or it may be steamed in the continuous steaming-chest of Messi'^. Duncan Stewart and Co., Glas- gow, represented in Fig. 95. It consists of an annular- .shaped iron cylinder or chamber a B, in the upper part of which a series of brass radial rods c are caused to circulate slowly by means of the endless screw e driven by the engine d. The cloth (in the open width) enters the annular space through a pair of squeezing rollers at F, By an ingenious arrangement the cloth is suspended in long, loosely-hanging folds on the radial rods, is carried round the annular space, and makes it--, exit by a second pair of squeezing rollei's at G. The chamber is constructed of boiler-plate, so that the goods can be submitted to high-pressure steam. Another foi-m of continuous steaming - machine is that in which loose rods, supporting the cloth in a similar manner, are passed continuou.sly by means of endless chains through a large rectangular brick chamber tilled with very low-pressure steam. If in the mordanting process the cotton was merely diied after the preparing with sulphated-oil, there are pro- duced upon the fibre the aluminium compounds both of the ether and of the oxy- or trioxy-oleic acid ; but if it was also steamed, there is then fixed on the fibre essentially the normal aluminium compound of oxy- or tiioxy-oleic acid (Liechti »fc Suida). A brighter colour is obtained by adding a small pro- portion of stannous chloride to the aluminium solution, or stannate of soda to the oil solution- After mordantincr and washinjx, a sliofhtlv basic aluminium salt remains on the fibre, its basic character being generally caused by the calcareous condition of the water. Traces of lime are also present. If, pi-evious to washing, a warm chalk bath is used, a much more Cliap. XX.J ALIZARIIT. 449 basic and more calcareous aluminium compound is formed. During the dyeing process there is probably formed the Alizarin compound of the basic oxy- or trioxy-oleate of aluminium and calcium just referred to. If there is a deficiency of oil on the fibre, the brightest shades are always obtained by dyeing at the low temperature indicated (70° C), but otherwise the temperature may be raised to the boiling point, although there is then a tendency of a portion of the oily mordant being softened and boiled out, especially if it is in slight excess. With the use of pure Alizarin — i.e., the '■ blue shade of Alizarin," as it is generally called— a fiery brilliant red is not obtained ; Jience such as contains Isopurpurin (An- thrapurpurin) — i.e., the "yellow shade of Alizarin " — is generally preferred. The second preparing and steaming operations have for their object the neutralising of the basic compound present on the fibre at this stage. This operation of steaming after dyeing has a most remarkable effect in giving brilliancy and fastness to the colour, especially if the dyeing has been conducted at a low temperature. If 100° C. was employed, then the brightening effect has taken place to a considerable extent, if not entirely, already in the dye-bath, as above mentioned. Sometimes the second preparing is omitted, and a small quantity of neutralised sulphated-oil is added to the dye-bath instead. The method of " clearing " described (see p. 434), in which the cotton remains stationary while the liquor cir- culates through it, gives very much better results than if tlie cotton were worked vigorously in the solution, since in this latter case much of the red-lake would be mechanically removed by friction, and the colour would look poor and weak. 403. The Action of Lime-salts in the Dye-bath. ' — One of the most interesting facts connected with the 4^0 DYEING OF TEXTILE FABRICS. [Chap. XX. aijplication of Alizarin, is the necessity of the presence of a lime salt in the dye-bath, in order to obtain a really good serviceable colour. The general result of researches made by Schlumberger, Rosenstiehl, and others, with a view to elucidate this point, seems to favour* the idea that the Alizarin-red-lake, as fixed upon textile fibres, is not simply an aluminium compound of Alizarin, but one which also contains calcium as an essential constituent. The following results of Liechti and Suida's re- searches bearing on this point will explain this. Pure aluminium hydrate, whether in its precipitated form or fixed on the fibre, cannot be properly dyed with Alizarin except in the presence of lime compounds. Normal aluminium phosphate behaves similarly. Normal alu- minium alizarate [Al2(Ci4Hg04)3] is a purplish-red com- pound soluble in water, alcohol, and ammonia. Basic aluminium alizarates — e.g. [Al2(Cj^HgOJ(OH)J and [Al^(Cj^Hg04)(0H)jQ] — are, on the contrary, bright red compounds, insoluble in water and alcohol, and little soluble in ammonia. Aluminium-calcium-alizarates of very varied composition, prepared by dyeing aluminium hydrate with Alizarin in the presence of calcium acetate, are mostly reddish-brown insoluble compounds. The amount of lime-salt present in the dye-bath determines the quantity of Alizarin which will be taken up by the alumina, and the amount of lime taken up by the lake is determined by the quantity of Alizarin employed. The relative proportions of Alizarin, alumina, lime, and fatty acid present in tlie lake abstracted from Turkey- red and Alizarin-red- dyed cotton, vary considerably, ac- cording to the method of dyeing employed ; as a rule, a large excess of alumina, in proportion to the lime and Alizarin, is present. The above-mentioned authors find that alumina-mordanted cotton, when dyed with Alizarin in the presence of calcium acetate, takes up |^ molecule of lime for each molecule of Alizarin, and they consider that the composition of the lake in unsoaped Alizarin- Chap. XX.1 ALIZARIK. 451 red -dyed cotton is best expressed by the formula [Al,Ca(C,,HA):3(0H),]. 404. Another Method of Dyeing Alizarin Red on cotton, in use among calico- printei*s, but which does not give quite such %st colours as those described above, is given in the foliowmsr resume: — 1. ]\Iordant with commercial aluminium acetate, 5o_3o r^^ (Sp^ Qy 1-025 — 1-04), dry, and age for 1 — 2 days, by hanging in a chamber heated to 50° C, and having a somewhat moist atmosphere. During this " igf^i^ig " process much of the acetic acid escapes, and alumina or a basic aluminium acetate is fixed on the fibre. 2. In order to fix the alumina more completely, work the cotton for a few minutes at 60^ C. in a bath of phosphate, alienate, or silicate of soda, 5 — 10 grams per litre ; then wash well in water. 3. Dye with Alizarin, and dry. A small addition of acetate of lime is used if necessary. Since the cotton at this stage contains no oil, it is essential to the obtain- ing of a bright colour, that the dyeing should take place at a temperature not exceeding 70° — 75° C. 4. Prepare with a neutralised solution of sulphated- oil, 50 — 100 grams (50 per cent.) per litre, and dry. 5. Steam for h — f hour, at 21b. pressure. 6. Clear as before. 405. Alizarin Pinks, Purples, &c., on Cotton. — Alizarin i^inks are obtained by precisely the same me- thods as are adopted for reds. The aluminium mordant employed must, however, be considerably weaker — use, say, aluminium acetate at 10° Tw. (Sp. Gr. 1 05). Basic mordants are avoided, since they give uneven colours, and even normal aluminium sulphate may be used with advantage; the amount of AJizarin (20 per cent.) may be reduced to about 1 per cent, of the weight of cotton, and the proportion of oil-preparation re- quired is correspondingly diminished. The most plv^s- mg pinks are those produced by using a " blue shade of 452 DYEING OP TEXTILE FABRICS, [Chap. XX. Alizarin," i.e., one free from Isopurpurin, Flavopui-purin, or Purpurin. Very good fast shades of j)urple and lilac are obtained from Alizarin, either with or without the use of oil- preparation ; indeed, the use of oil does not seem to add anv particular brilliancy to the colour, but serves mainly to fix the mordant, and to make the colour a little faster to boiling soap solutions. When the cotton is prepared with oil, according to either the Emulsion or Steiner's process for Turkey -red, it is mordanted, worked and steeped for a short time in a solution of fen'ous sulphate at 3° — 4° Tw. (Sp. Gr. 1-015 — 1*02); it is then allowed to lie over- night, and is finally well washed. The amount of iron precipitated on the fibre, and of AKzai-in subsequently taken up in the dye-bath, is de- termined by the amount of oil previously fixed, and not merely by the concentration of the ferrous sulphate solution. For the darker shades of purple, tlierefore, the cotton should be well prejDared with oil, while for pale shades the preparation is slight. The best and bluest shades are only obtained when the mordant is thoroughly saturated with Alizarin, any excess of uncombined mordant gives the colour an unpleasant dull-reddish appearance. The use of pyrolignite of iron gives somewhat darker, brighter, and bluer shades than the sulphate. Very deep purplish blacks are obtained, and with less oil-preparation, by steeping the cotton, previous to mordanting, in an infusion of gall nuts, or other tannin matter. After mordanting, the cotton is well washed and dyed with 5 — 15 per cent, of Alizarin (10 per cent.). If the water is not sufficiently calcareous, it is very essential to add the necessary quantity of chalk or acetate of lime to the dye-bath (1 — 2 per cent.). After dyeing, the cotton should be washed and soaped at a temperature of 60' C. When not prepared with oil, the cotton Ls prepared with tannin, by working it in a cold infusion of tannin matter (equal to 1 — 2 grams of tannic acid per litre); it is C:np. XX.") ALIZARIN. 453 then mordanted i« a solution of pyrolignite of iron 1°— 3° Tw. (Sp. Gr. 1-005— 1-015), and finally \yashed. One may also mordant the cotton by impregnating it with pyrolignite of iron, 1° — 3° Tw., wringing out the excess, and then working it for ten minutes at 50° C, in a solution containing 20 cubic centimetres of silicate of soda 16° Tw. (Sp. Gr. 1-08) per litre, and finally washing it. Anthrapurpurin gives greyish violets, Flavopurpurin and Purpurin reddish violets, which are little esteemed. Various shades of chocolate, claret-red, &c., are ob- tained v/ith Alizarin, by mordanting the oil-prepared cotton with a mixture of aluminium and iron mordants, either in the state of sulphates or acetates. Whether the cotton is prepared with oil according to the Emulsion or Steiner's process, or by the Sulphated-oil method, it is advisable to work it in a weak tannin bath before mordanting, especially for the darker and bluer shades, since a better proportion of iron is fixed by tliis means. The difierent shades are produced by varying the relative proportions of aluminium and iron mordant, remembering always to vary the concentration of the tannin bath in accordance with the latter. After mordanting, the cotton is washed, dyed with Alizarin, prepared with weak sulphated-oil, steamed, and soaped, as already described. Certain shades of claret-red may also be obtained by mordanting with a solution of chromium acetate, instead of with the mixture of iron and aluminium salts. Although Alizarin and Anthrapurpurin have been mainly alluded to in the above, the other members of the anthracene group — namely, Flavopurpurin and Purpurin — may be applied in exactly the same way, and give rise to similar shades. 406. Applicatio7i to Wool. — Alizarin is capable of yield iug a number of pleasing shades on wool, according to the mordant used, and ought to be largely employed whenever fastness to milling and to light is required. In conjunction with other colouring matters which are 454 DYEING OF TEXTILE FABRICS. [Chap. XX. similarly applied, it may yield an endless variety of shades. Its application presents little or no difficulty. To obtain Alizarin-red on wool, mordant the wool with 6 — 10 per cent, of ahunvniiim sulphate (cake alum) and 5 — 8 per cent, of cream of tartar. Introduce the wool into the cold solution, raise the temperature gradually to the boiling point in one hour, and continue boiling ^ — |- hour. Wash well, and. dye in a separate bath, with 10 per cent, of Alizarin (20 per cent.) and 4- -6 per cent, of acetate of lime (solid). In order to ensure an even colour it is well to work the wool for half an hour in the cold dye liquor, then to raise the temperature gradually in the course of an hour to the boiling point, and boil a quai-ter of an hour, or till the bath is exhausted. After dyeing, wash well, and dry at a low temperature or in the open air. The addition of cream of tartar to the mordanting bath is absolutely essential to the production of a full rich colour. Excess of tartar tends to give intensity, but diminishes the brilliancy of the colour. Care must be taken that the aluminium sulphate used is free from iron. With a deficiency of mordant the colour lacks brilliancy and inte.nsity, and if the deficiency is excessive only a poor dull brick-red is obtained. With excess of mordi\nt the colour tends to become yellower and less intense. Brighter and more orange shades are obtained by using, along with the aluminium sulphate, 1 — 4 per cent, of stannous chloride, in which case a further addi- tion of 1 — 4 per cent, of cream of tartar is necessary. The addition to the dye-bath of acetate of lime (or an equivalent amount of ground chalk) is also absolutely necessary if the water employed is not sufficiently calcareous. Without lime, the colour is poor and worthless, and the dye-bath is nob exhausted ; with excess, the red is darker and duller. On comparing the colours given by the various members of the Alizarin family of colouring matters, it is found that Alizarin itself yields a very blue shade of Chap. XX.] ALIZARIN. 455 red, or a claret-red ; Antlirai)urpnrin, a briglit red ; Flavopiirpurin, a somewhat duller and yellower red ■ Purpurin, a shade approaching that given by Alizarin,' but much yellower, namely, a dull brownish-red. To obtain Alizarin-orange on wool, mordant the wool with 5— 8 per cent, of stannous chloride {tin-crystah) and an equal weight of cream of tartar. Dye with 10 per cent. of Alizarin (20 per cent.) without the addition of acetate of hme. With the addition of 4—5 per cent, of acetate of hme a bright orange-red is obtained, but without, the colour is very much yellower. Excess of lime makes the orange still redder, but it is apt to be uneven. Alizarin- orange may also be dyed in a single bath. Alizarin gives a bright reddish orange ; Flavopurpurin a bright yellowish-orange. The colour yielded by Anthrapurpurin holds an intermediate place; it is a bright orange. Purpurin gives a moderately bright orange-red. Very rich claret-brown shades are obtained by mor- danting the wool with 3 per cent, of bichromate of potash and 1 per cent, of sulphuric acid 168° Tw. (Sp. Gr.1-84). The addition of the sulphuric acid is beneficial, since it tends to give a somewhat yellower and fuller colour; it is not, however, absolutely essential. Dye with 10 per cent, of Alizarin (20 per cent.). The addi- tion of 2—4 per cent, of acetate of lime to the dye- bath makes the colour somewhat less yellow, or bluer, though apparently slightly less intense. Strange to say' its addition is by no means essential, as in the case of the aluminium mordant for dyeing reds. Good colours are also obtained by the single-bath method ; use 1 per cent. K/Jr.O- and 1 per cent. HoSO^, 168"' Tw. Numerous fast shades of brown, olive, purple, (fee, are obtained by associating Alizarin with such colouring matters as Gallein, Coerulein, and many of the dyewoods. The shades yielded by the different members of the Alizarin group with chromium mordant are as follows : Alizarin gives a dull purple colour; Anthrapurpurin, a much reddershade, namely, a claret-brown ; Flavopurpurin, 456 DYEING OF TEXTILE FABRICS. [Chap. XX. a yellower shade of claret-brown ; Purpiirin gives the most intense colour of all, namely, a deep claret-brown. Very good sliades, ranging from bluish-Aiolet to slate, are obtained by mordanting wool with 4 — 8 per cent. ferrous sulphate and 4 — 8 per cent, cream of tartar, and dyeing in a separate bath with 10 per cent. Alizarin (20 per cent.) and 5 per cent, carbonate of lime. With the single-bath method darker colours are obtained, but thev are much browner and duller ; use G per cent, ferrous sulpliatc and 0*6 per cent, oxalate of potash. Iron-alum employed instead of ferrous sulphate gives good results. Copper sulphate as the mordant gives claret-browns, either by the mordanting and dyeing method or by the sinde-bath method. With the use of ammoniacal sulphate of nickel and uranium salts, as mordants. Alizarin yields nice shades of grey and slate. Application to Silk. — Alizarin is as yet little used in silk-dveing. Good colours may be obtained by mor- danting the silk according to the ordinary methods, and working it, after dveing, in hot soap solution. 407. Nitro-Alizarin. [Ci^H3-X02'(OH)..]— This col- ouring matter, also called Alizarin Orange, is produced by the action of nitrous acid on Alizarin. It is aj^plied to the various fibres in the same way as Alizarin ; although it yields fast colours, it finds as yet only a comparatively limited employment. Application to Wool. — With aluminium mordant it yields very good orange colours. Mordant the wool with G — 8 per cent, of aluminium sulphate and 7 — 9 per cent, of cream of tartar. Excess of mordant renders the shade dull. The addition of acetate of lime to the dye-bath makes the colour browner. With, stannous chloride mordant the colour obtained varies very considerably, according to the amount cf mordant employed. With a small amount (1 ])er cent, of stannous chloride and 1-5 per cent, of cream of tartar), a ver^ reddish-orange is obtained; with double the amount^ tmap. XX.] ALIZARIN BLUE. 457 tlie colour becomes a yellowish-orange ; witli 4 per cent, of stannous chloride, only a dull brown is obtained, the normal colour being evidently destroyed by the reducing action of an excess of mordant. The addition of acetate of lime to the dye-bath is not beneficial, since the yellowish-orange colour is thereby changed to brown. With stannic chloride (equivalent to 6 per cent, stan- nous chloride, SnCl2'2H20) an orange colour is also ob- tained. Excess of mordant does not destroy the colour as in the case of stannous chloride. With copper sulphate mordant a very good brownish- red is obtained. Use 4 — 6 per cent, of copper sulphate, without calcium acetate. With ferrous sulphate as the mordant a purplish- brown is obtained. Use 6 — 8 per cent, of ferrous sul- phate, without calcium acetate in the dye-bath. Bichromate of potash as the mordant yields dull brownish-reds. Use 3 per cent, of potassium dichromate and 2 per cent, of sulphuric acid, 168*^ Tw. (Sp. Gr. 1*84). When potassium dichromate alone is employed, the colour becomes darker with increase of mordant, even till 16 per cent, be employed. 408. Alizarin Blue [C17H9NOJ. — This colouring matter, also called Anthracene Blue, is derived from Nitro-alizai'in by heating it with glycerine and sulphuric acid. It may be considered as the quinolin of alizarin, and has in consequence both btisic and acid properties. It is met with in commerce in two forms, namely, as a paste containing about 10 per cent, of dry sub.stance, and as a ])Owder under the name of Alizarin Blue S. The former is insoluble in water, although certain com- mercial marks (WX, WR) possess some degree of solubility. The latter, which is, indeed, a sodium disul- pliite compound of Alizarin Blue (Cj--H,jiSrOj^-2NaHS03), is readily soluble in wat«r, with a brownish- red colour. Its solutions decompose, if heated to 70"^ C, with preci- l)itation of the insoluble form of l)lue. With lime it forms an insoluble compound ; hence the presence of 458 DYEING OF TEXTILE FABRICh. [Cbap. XX lime salts in the dye-bath must he avoided, otherwise there will be a loss of colouring matter. The insohible form of Alizarin Bhie may be apj)lied in dyeing, according to the indigo- vat method, by reducing it with zinc powder and carbonate of sodsi, or by the ordinary method of mordanting and dyeing in separat-e baths, ^\'hen the latter method is employed, a certain proportion of disulphite of soda may be added to the dye-bath to render it soluble, or the dyeing at 100^ C. must be long continued. Avoid the use of copper dye- vessels. AYith Alizarin Blue S the mordanting and dyeing method only is employed. Application to Cotton. — Mordant the cotton with chromium according to the alkaline method. Dye in a separate bath with Alizarin Blue ; raise the temperature gradually to the boiling point in the course of an hour and a half, and continue boiling for half an hour. Applkation to Wool. — The most suitable mordant to employ is hlchromate of potash, in the proportion of 3 — 6 per cent, of the weight of wool. The addition of sul]thuric acid, 168'^ Tw. (Sp. Gr. l'S4), is not beneficial if used in larger amount than 1 per cent. Dye in a separate bath with Alizarin Blue ; raise the temperature gradually to the boiling point, and continue boiling until a bright puie shade is obtained. With insufficient boiling the colouring matter is only superficially attached to the fibre. The colour obtained is a bright indioro-blue, with purplish bloom. It is exceedingly fast to scouring, mill- ing, light, ttc, and has the advantage of not rubbing off. When aluminium sulphate is the mordant employed a purplish-blue is obtained, which is very liable to be uneven unless great care is taken. Use 6 — 8 per cent, of aluminium sulphate and 5 — 7 per cent, of cream of tartar. With stannous chloride mordant a much redder purple is obtained. Use 4 per cent, of stannous chloride (crystals) and 2 i>er cent, of cream of tartar. This mordant Is not suitable for employing alone. Clifip. XXI.] CACHOU L»K LAVAL. 459 Ferrous sulphate, as a mordant for Alizarin Blue, is also little suitable. It gives a greenish-blue colour, pos- sessing little brilliancy, and apt to be uneven. Mordant with 4 per cent, ferrous sulphate and 8 per cent, cream of tartar. Application to Silk. — Mordant the silk with alumi- nium or iron in the usual manner ; wash and dye in a separate bath with Alizarin Blue. Brighten the colour afterwards by boiling the silk in a soap bath. CHAPTER XXI. ARTIFICIAL COLOURING MATTERS CONTAINING SULPHUR. 409. Cachou de Laval (Poirrier). — This dyestuff is produced by fusing sodium sulphide with waste vegetable or animal matter. Care should be taken to preserve it from becoming damp by exposure, otherwise it is deteriorated, becomes more or less insoluble, and dissolves with a brown colour. It is specially applicable to cotton, and yields various buff and grey colours, which are very fast to acids and alkalis, and fairly fast to light. Application to Cotton. — Dissolve the dyestuff in boiling water. The normal colour of the solution is a deep bottle-green ; if it is brown, add a little carbonate of soda, and boil for a short time. Avoid using calcareous \vater, either for solution or in the dye-bath, since this precipitates the colouring matter. If lime is present, acidify slightly with acetic acid. Add the colour solution to the dye-bath, also sodium sulphate in the proportion of 40 — 70 per cent, of the weight of Cachou de Laval. Dye the cotton for about half an hour, at a tempera- ture of 60° C, in a somewhat concentrated solution (100 grams per litre). Add the colour solution gi'adually. .•\i'ter dyeing, wash well, and work the cotton for 5 — 10 460 DYEIXG OF TEXTILE FABRICS. [Chap ^TYT . minutes, at 50^ C, in a dilute solution of one or other of the following : — dicbromate of potash, ferrous sulphate, copper sulphate, sulphuric acid, hydrochloric acid. Wash and dry. Cachou de Laval acts also as a mordant, so that various shades can be obtained by dyeing afterwards in solutions of basic coal-tar colouring matter's. Dyewood extracts may also be applied, since these are attracted by rtjason of the metallic oxide present in the finished Cachou colour. 410. Canarin (C3N3S3H). — This yellow colouring matter is simply perthiocyanogen. It is produced as an insoluble powder when potassium tbiocyanate (sulj)ho- cyanide of potassium) (CX'SK) is oxidised by potassium chlorate in the presence of sulphuric and hydrochloric acid. It is dissolved bv boilins: it with a solution of ]x)rax (100 grams per liti'e). It is specially adapted for dyeing cotton, on which it gives bright yellow or orange shades extremely fast to light, alkalis, acids, and hypochlorites. It acts as a mordant for Ijasic coal-tar colouiing matters ; hence pleasing compound shades may \je obtained by ap- plying these in a separate bath, AppJicat'fOJi to Cotton. — Add to the dye-bath the necessary amount of boi^ax Canarin solution and a small amount of soap. Introduce the cmton cold, and i-alse the temj^erature gi-adually to the boiling point. Rinse in cold water and dry. The use of calcareous water in dveing must be avoided. Wool may be dyed in a similar manner. 461 APPLICATION OF THE MINEEAL COLOUEING MATTERS. CHAPTER XXII. CUROME YELLOW — IRON BUFF MANGANESE BROWN — PRUSSIAN BLUE. TuE mineral colouring matters applied in dyeing are extremely limited, and they are almost entirely confined to the vegetable fibres, the most notable exception in this respect being Prussian Blue, and this, strictly speaking, is not a mineral colouring matter. 411. Chrome Yellow. — Pteference has already been made to the production of this colour, in describing the application of bichromate of potash and of lead salts to the cotton fibre {see pp. 207, 225). In addition to che methods there indicate 1, the following, specially intended for orange, may be used. Prepare a bath of plumbate of lime by adding a solu- tion of 15 — 25 kilos, of pyrolignite of lead to milk of lime containing 20 — 30 kilos, of lime, and 500 litres of water. The mixture is well agitated, and then allowed to settle for about two hours. The cotton is worked, and steeped in the more or less milky supernatant liquid for 1 — 2 hours, then squeezed and washed. Dye in a cold or tepid (40° — 50° C.) solu- tion containing 5 per cent, of bichromate of potash, and i— 1 per cent, of sulphuric acid, 168° Tw. (Sp. Gr. 1-84). Wash, and develop the orange colour by passing the cotton into clear, boiling, lime-water, then wash and dry. The cotton must be removed from the lime-water bath whenever the full orange colour is developed, other- wise the colour loses brilliancy. 412. Iron Buff. — This colour simply consists of 462 DYEING OF TEXTILE FABRICS. [Chap. XXII, ferric oxide. It is produced by first impregnating the cotton with a ferrous salt solution, then passing it through an alkaline solution, to precipitate ferrous hydrate ; the latter is then changed into ferric hydrate by simple expo- sure to the air, or, preferably, by passing the cotton into a cold dilute solution of bleach in g-powder. Instead of a ferrous salt, one may also employ a ferric salt, e.g. J ferric sulphate or nitrate. The cotton is simply impregnated with the ferric solution, then squeezed, and passed rapidly through a dilute solution of carbonate of soda, ammonia, or milk of lime. In this case, ferric hydrate is at once precipitated on the fibre, and no subse- quent oxidation is necessary. Iron Buffs are very fast to light and boiling alkaline solutions, but are sensitive to the action of acids. 413. Manganese Brown. — The production of this colour on cotton is briefly described on page 225 ; it is exactly analagous to the production of Iron Buff from ferrous salts. The process is simplified by adding a little sodium hypochlorite to a solution of caustic soda, passing the cotton impregnated with manganous chloride at once through this mixture. In this case, precipitation and oxidation take place simultaneously. It is very important always to use caustic soda free from carbonate, otherwise a little manganous carbonate is i^recipitated on the fibre, and since this compound does not oxidise readily, the colour is apt to be ir- regular. According to A. Endler, irregularity of colour may also arise from the unsuitable physical properties of the precipitate itself, when it is produced in the ordinary manner described. Endler obviates these defects by passing the cotton, after impregnation with manganous chloride, into a bath containing 25 litres of water, 7 litres of ammonia, and 500 grams of bichromate of potash. A somewhat unstable chromate of manganese is formed on the fibre, which, on decomposing, allows the chromic acid to react on the manganous hydrate and change it into Cliap. XXII.] PRUSSIAN BLUE. 4G3 some higher state of oxidation. A final passage in dilute bleaching-powder sohition completes the process. Manganese Brown is very fast to the action of light, alkalis, and acids. 414. Prussian Blue. — AjyjjHcation to Cotton. — Prussian Blue was formerly very much dyed upon cotton. Since the introduction of Aniline blues it has beenmuch less employed. The cotton is first dyed an Iron Buff, and is then dyed in a cold solution of potassium ferrocyanide, 20 grams per litre, with the addition of 10 grams of sulphuric acid, 168° Tw. (Sp. Gr. 1-84). Wash and dry. The intensity of the blue depends upon the quantity of ferric oxide fixed upon the fibre in dyeing the buff. Fine purplish shades of blue are obtained by working the cotton at 30° C. in nitro-sulphate of iron at 5° Tw. (Sp. Gr. 1 -025) to which 2 — 3 per cent, of stannous chloride has been added, and then dyeing in a cold acidified solution of potassium ferrocyanide. Wash and dry; or if a still more purplish tone of colour is required, work for a short time in a tepid bath containing Methyl Yiolet or Logwood liquor. Alkaline or boiling soap solutions readily decompose Prussian Blue, leaving brown ferric oxide on the fibre. Prolonged exposure to sunlight causes the blue to fade, but it is restored if kept for some time in the dark. Application to Wool. — Prussian Blues (sometimes also called Royal Blues) are obtained on wool by means of red and yellow prussiate of potash, i.e., potassium ferri- and ferrocyanide. The former gives the best results. The method depends upon the fact that when a mineral acid is added to solutions of either of these salts the corresponding hydro-ferri- or hydro-ferro-cyanic acids are liberated, and these, under the influence of heat, and by oxidation decompose and produce insoluble Prussian Blue. If, then, wool is boiled in an acidified solution of these salts, the liberated acids are taken up by the wool, decomposition takes place gradually, and Prussian Blue is precipitated, and becomes fixed on the wooL 464 DYEING OF TEXTILE FABRICS. (Chap. Xill. The wool is introduced into a cold bath containing a solution of 10 per cent, of red prussiate of potash, and 20 per cent, of sulphuric acid at 168° Tw. (Sp. Gr. 1*84) ; the temperature is gradually raised in the course of an hour to 100° C, and this temperature is maintained for J — J hour. The colour is rendered brighter and more purplish by adding 1 — 2 per cent, of stannous chloride during the last half to three-quarters of an hour of the boiling. Although sulphuric acid gives the best result, one may also use nitric or hydrochloric acid, in which case the shade of blue is modified slightly. Nitric acid, for example, makes the shade greener. It is very usual with dyers to employ a mixture of all three acids, especially when yellow prussiate of potash is emj^loyed. This mixture of acids, which is called " royal blue spirits," or merely " blue spirits," may vary slightly in composition with different dyers, A usual mixture is the following: 4 measures of sulphuric acid 168° Tw. (Sp. Gr. 1"84), 2 measures of hydrochloric acid 32° Tw. (Sp. Gr. 1'16), and 1 — 2 measures of nitric acid 6i°Tw. (Sp. Gr. 1-32). When yellow prussiate of potash is employed, the use of nitric acid gives the best result, probably by reason of its oxidising action. For 10 per cent, of yellow prus- siate of potash use 8 — 12 per cent, of nitric acid 64° Tw. Instead of stannous chloride in the crystalline state, the dyer generally uses it in solution, as "muriate of tin." It is often sold to the dyer as " iSLnishing blue spirits," though under this name it generally contains a alight ad- dition of sulphuric or oxalic acid, or both. These additions, however, are not essential. Another method of dyeing Prussian Blue, but one now seldom employed, is the following : — The wool is worked for two hours at 30° C., in a solution of ferric sulphate 2° Tw. (Sp. Gr. I'Ol), con- taining 2 — 3 per cent, of stannous chloride, and 2 — 8 per cent, of cream of tartar. The material is then well washed, and worked for two to three hours at 80° — 90° 0., in a ULap. XXIl.J PRUSSIAN BLUE. 465 bath containing 1 per cent, of yellow prussiate of potash, and 4 per cent, of oxalic acid, or sulphuric acid, 168° T\v. (Sp. Gr. 1-84). In the first batii there is fixed on the wool ferric oxide, which combines with the free hydro-ferrocyanic acid contained in the second bath. The depth of blue is regulated by the strength of the ferric sulphate solution, and the amount of yellow prussiate in the second bath should correspond to the amount of ferric oxide fixed upon the wool. Application to Silk. — Prussian Blue is now seldom dyed on silk, except as a groundwork for black. What was formerly known as Raymond's Blue was dyed as follows : — Work the silk in basic ferric sulphate (nitrate of iron), 5° Tw. (Sp. Gr. 1-025), for a quarter of an hour, wring out, and let lie over-night. Wash well, and work for a quarter of an hour in a boiling soap bath containing about 10 per cent, of soap ; wash, and dye at 40" — 45° C, for J — J hour in a fresh bath containing 9 per cent, of yellow prussiate of potash, and 12 per cent, of hydrochloric acid, 32° Tw. (Sp. Gr. M6), and finally v/ash well. So-called " Napoleon's Blue " is a brighter blue, pro- duced as follows : — Work for half an hour in a cold bath containing 50 per cent, of basic ferric sulphate, 50° Tw. (Sp. Gr. 1*25), 10 per cent, of stannous chloride, and 5 per cent, of sulphuric acid, 168° Tw. (Sp. Gr. 1'84); wring out, wash, and work for half an hour at 40" C.,in a second bath contain- ing 10 per cent, of yellow prussiate of potash, 2 — 5 per cent, of red prussiate of potash, and 12 — 15 per cent, sulphuric acid, 168° Tw. (Sp. Gr. 1*84). After wringing out from this second bath, the whole process is repeated. Previous to drying, the silk is softened and brightened by working it for half an hour in a cold bath containing an imperfectly made sulphated-oil. For one kilo, of silk, use a mixture of 150 grams of ob've oil and 15 grams, of sulphuric acid, 168" Tw. (Sp. Gr. 1-84). £ £ 466 THE DYEING OF MIXED FABRICS CHAPTER XXIII. FABRICS OF COTTON AND WOOL. 415. Mixed fabrics, or unions, may be of the most varied character. The wool and cotton may be inter- mingled throughout the whole fabric ; or, what is more usually the case, each fibre may be confined to separate threads, forming either weft or warp. One large class, comprising Cashmeres, Coburgs, Sicilians, Alpacas, Delaines, ^ Tw. (Sp. Gr. I'Olo). "Wash and dye the cotton yellow in a cold decoction of Quercitron Bark, then wash and dye in a cold decoction of Peach- wood, until the proper shade is obtained. 2. Dye the wool in the usual way with one of the Chap. XXnt] DVEIXG OF MIXED FABRICS. 469 Azo Scarlets, wash, and dye the cotton with a cold solution of Crocein Scarlet and alum. The cotton may also be dyed by preparing it ^^dth Sumach and tartar emetic,' and dyeing with a mixture of Safranine and Auramine. 3. A tliird method would be to dye the cotton and wool in one bath by means of Congo Red or Benzopurpurin. 418. Yellow. — Dye the wool with Flavin, stan- nous chloride, and tartar, or v.ith a coal-tar Acid- Yellow ; wash, and dye the cotton. Prepare it first with tannic acid, then with tartar emetic ; wash and dye in a cold solution of Flavaniline or Auramine. 419. Orange. — Orange is d}'ed in the same manner as yelloWj but a little Cochineal is added along with the Flavin, or one may use one of tlie acid Azo Oranges to dye the wool. For the cotton, a little Safranine must be used in addition to the Flavaniline or Auramine. 420. Green. — 1. Dye the wool first with Old Fustic, Turmeric, Indigo Extract, alum, and tartar. Dye the cotton by padding the pieces once or twice in nitrate of iron, 3^ Tw. (Sp. Gr. l-Olo). then wash, and pad in a cold solution of yellow prussiate of potash. When the cloth is uniformly impregnated with it, acidify the solution with sulphuric acid, and pad the clotli in the solution again. The cotton will thus be dyed Prussian Blue, and this is changed to green by padding in a cold decoction of Old Fustic, to which has been added acetate of alumina (red liquor). Wash slightly and dry. Another method is the following : 2. Dye the wool in a neutral bath with Malachite Green, or in an acid bath with an Acid Green, and wash. Mordant the cotton with tannic acid, then with stannic chloride or tartar emetic, and wash. Dye the cotton in a cold solution of Malachite Green. If yellow shades of green are required, add Auramine in the requisite quantity. 421. Blue.— 1. Lif//d Blue— Dye the wool a pale blue with Indigo Extract, alum, and taitar, and wash. Dye the cotton cold in two baths : (1) a weak solution of 4?0 DYEING OF TfeXTILfi FABRICS. [Ohap. XXtll. nitrate of iron ; (2) a dilute solution of yellow prussiate of potash, acidified with sulphuric acid. 2. Royal Blue.- —Mordant the cotton by padding the pieces in nitrate of iron 4^ Tw. (Sp. Gr. 1*02), then in carbonate of soda (4° — 6° Tw.), and washing in water. These operations may be repeated two or three times, according to the shade of blue required. Dye both the cotton and the wool in a solution con- taining yellow prussiate of potash and sulphuric acid 168° Tw. (Sp. Gr. 1-84) (10 per cent, of the weight of cloth of each). Enter the cloth cold, and raise the temperature gradually to the boiling point in the course of 1 — IJ hour. During the last half-hour add a small quantity of stannous chloride to brighten the colour. Should Ihe colour of the cotton suffer during the dyeing of the wool, and become too pale, it can be readily restored by worlcing again in weak nitrate of iron, and in an acidified solution of yellow prussiate of potash. Another method of dying Royal Blue is, to dye the wool first with an acidified solution of yellow prussiate of potash, in the manner already given, and wash. The cotton is then dyed a Logwood purple by working the goods for a short time in a cold, weak infusion of Sumach, then in a solution of muriate of tin 2° Tw. ^Sp. Gr. I'Ol) for half an hour. Wash and dye in a cold weak decoction of Logwood. Without washing, the cloth is then padded in weak nitrate of iron, and after being well washed, the cotton is dyed blue, by first working in a cold solution of yellow prussiate of potash without acid, then acidifying suitably with sul])huric acid, and working the cloth in it until the blue is properly developed. 3. Aniline Blue. — Dye the wool first with Alkali Blue, and wash. Dye the cotton Prussian Blue by padding first in a weak solution of nitrate of iron, washing, and dyeing in an acidified solution of yellow prussiate of potash. The cotton ma}" also be dyed with aniline blue by Chftp. XXIIJ.J DYEING OF MIXED FAP.lMCa. 471 working the cloth first in a sohition of tannic a.ud, and then m tartar emetic, and dye with Night Bhie, Methy- lene Blue, or Soluble Blue acidified by the addition of alum or sulphuric acid. 422. Purple.— Dye the wool first, according to the usual method, with Methyl Violet or Acid Violet, and wash well. Mordant the cotton with tannic acid and tartar emetic, wash, and dye cold with Methyl Violet. 423. Brown.— Mordant the cotton in a cold infusion ot feumach, then m dilute nitrate of iron, and lastly in dilute stannic chloride. After washing well, dye tlie cotton and the wool together with a decoction of Peach- wood, Logwood,|Turmeric,in suitable proportions, to which has been added a certain amount of alum and copper sulphate. Dye at a temperature of 80°— 100° C. Browns are also frequently dyed by employing mix- tures of suitable coal-tar colours. 424. Drabs, Greys, &c.— Tlie wool is dyed first according to the usual, methods, with decoctions of Peachwood, Old Fustic, and Indigo Extract, in suitable proportions, to which have been added alum and tartar As a rule, it is best to dye the cotton slightly darker than the wool, for if it is in the least under-dyed, the cloth has a mottled appearance. The cotton is dyed by first padding it in a cold decoc tion ot bumach, and afterwards in nitrate of iron. The strength of both these solutions varies accordincr to the depth of shade required. ° _ It is impossible to give the precise amounts of each ingredient to be employed, so much depends upon the exact tint to be obtained. 425. Black.— Mordant the cotton by working it for 2—3 hours in a cold infusion of tannin matter, then for about one hour in nitrate of iron 4° Tw. (Sp. Gr lO'?) and wash well. ' '''' Mordant the wool by boiling ^—1 hour with 2—3 per cent, of bichromate of potash, "and wash. Dye tha 472 DYEIXG OF TEXTILE FABRICS. [Chap. XXIIL oottou and the wool simultaneously by boiling with Logwood and Old Fustic. 426. The dyeing of mixed fabrics of cotton and silky and wool and silk^ is of comparatively little importance. It is met with rather as a speciality than as a prominent branch of dyeing. It does occur, however, e.g., in the dying of Barege, Grenadine (silk and wool), umbrella cloths (silk, wool, and cotton), k<:., and perhaps most of all in the re-dyeing of worn articles of clothing (job- dyeing). Fabrics of cotton and silk would be treated somewhat like those of cotton and wool, while those oonsistiiig of wool and silk would present less diffi- culty, since the behaviour of these two fibres towards ooloanng matters is more or less similar, and a modifica- tion of methods suitable either for wool or silk might be adopted. 473 EXPERIMENTAL DYEING. CHAPTER XXIY. METHOD OF DEVISING EXrERIMENTS IN DYEING. 427. Experiments with Catechu. — In the present chapter it is intended to give some idea of the manner in which the intelligent textile colourist proceeds, in order to discover the best methods of applying colour- ing matters to textile fibres. As an interesting example, the fixing of Catechu on cotton may be taken : — First of all, the solubility of the colouring matter in ordinary solvents should be determined, e.g., in water, acetic acid, alkalis, &c. The behaviour of the solutions towards ordinary practically useful reagents should then be ascertained. An aqueous solution of Catechu thus tested would, for example, show the following properties : — Gelatin gives a voluminous I'eddish-coloured pre- cipitate. A Ikalis "ive the solution a brownish coloration. Lime-vmter gives a yellowish coloration, and a pre- cipitate. Aluminium salts cause the solution to become lighter-coloured and yellowish. Ferrous salts impart an olive-green coloration. Ferric salts impart a dark-green coloration. Copper sulphate gives an olive coloration. Copper acetate gives a copious dark-brown precipitate Lead salts give a yellowish-grey precipitate. 474 DYEING OF TEXTILE FABRICS. [Claap. XXIV. Potassium dichroinate gives a copious brown pre- cipitate ; etc. ko. If a piece of calico is impregnated with an aqueous solution of Catechu, then dried, and at once washed, most of the colouring matter will be removed ; if, however, previous to washing, it is allowed to hang for a lengthened period, or, bett-er still, if it is steamed, it will be observed that a portion of the colouring matter will become oxidised and thus fixed on the fibre. This takes place still more largely if a weak alkaline solution of Catechu be employed, or if some oxidising agents — e.g.y certain copper salts — be added to the aqueous solution. The best results, however, are obtjiined by passing the steamed calico through a solution of potassium dichro- mate, a fact which was already indicated by the result obtained in the last-mentioned of the examinations in the test-tube. Greenish tones of colour are obtained by passing the cloth afterwards into iron solutions, or by padding the white calico in an acetic acid solution of Catechu containing ferrous sulphate, dryiug, and steaming. If in this last case the steamed calico be fui-ther passed into potassium dichromate solution, the colour is greatly developed in intensity, and becomes browner. From the foregoing preliminary experiments, the method of applying Catechu to calico might be formulated as follows : Pad the cotton iu an aqueous, alkaline, or acetic acid solution of Catechu, dry, age, steam, pass through a solution of potassium dichromate, and wash, i.e., if browai tones of colour ai-e required. Por obtain- ing greenish tones, the method to be adopted would be to pass the calico, after steaming, through iron solutions, or to add ferrous sulphate to the padding solution. But, however interesting the observations just re- corded may be, only a very small portion of the problem has thus been solved ; tlie question still remains, what relative and absolute proportions of the various in- gredients should be employed, in order to obtain the Chap. XXIV.] EXPERIMENTAL DYEING. 475 most satisfactory result 1 Further, what are the best con- ditions under which the several substances must be applied, as regards temperature of solutions, duration of steeping, steaming, exposure to air, &c. To answer these questions, another series of experi- ments is necessary. Several solutions are made, containing 25, 50, 100 grams of Catechu per litre of hot water, in each of which a " swatch," " fent," or " sample" of calico of suitable size is padded, then dried, and steamed. In a similar manner several solutions of potassium dichromate are made, containing, e.g., 6, 10, 20 grams of KoCroOy per litre, and portions of each padded sample are passed into each dichromate solution, for, say, two minutes at the ordinary tempera- ture. Similar portions are passed through identical solutions at a medium temperature, say, 50^ C, and others again at the boiling point. The experiments can be further extended by sub- stituting alkaline chromate solutions for the potassium dichromate, or by adding varying quantities of some iron salt — e.g., ferrous sulphate — to the Catechu solution before padding, and then passing the cloth, as before, through acid or alkaline chromate solutions. Experi- ments may also be instituted to determine the best mode of applying other colouring matters in conjunction with Catechu, in order to obtain various shades of colour, (fee. 428. Experiments with Tannic Acid. — On adding a solution of tartar emetic to a solution of tannic acid (especially if ammonium chloride be added), a volumi- nous white precipitate is obtained, which, on experi- ment, is found to possess the powder of attracting most of the coal-tar colouring matters of a basic character from their solutions, and combining with them to form colour- lakes, insoluble even in soap solutions. With these pre- mises, let it be supposed that it is the object of the dyer to determine by a series of experiments Avliat are the most favourable conditions for producing these; colour- lakes upon the cotton fibre. 476 DYEING OF TEXTILE FABUICS. [Chap. XXIV The method of procedure would be, first of all, to pre- [»are several t-aiinin solutions of different degi'ees of con- centration, containing, for example, '2d, 5, 10, 15, 20, 25 grams of technically pure tannic acid per litre. In each of these solutions a piece of calico should be steeped for a definite i>eriod, say six hours, and after removing excess of liquid by squeezing, .XXIV.l EXPERIMENTAI, DYEING. 481 madf i'n'tl "l^^^'r^'^^.'^P^""^"*^ should then bo s^y wi h a '^r' ri'^'' °^ ^°°= ^^« mordanted, lu„ .^ .J""' ??"*• of aluminium sulphate alone, and o Uar T? •'^'""" °' "''"■^^^'"S amounts of cream M taitar. It is convenient to consiler the amount of a ummium sulphate employed as representing 1 mo ecule of the sal and to add the cream of tartar to the several method'of^' '^rT*'"" 1*'' '' 2' 3, 4. 6 molecule The asSvTrTT '^'' ''^'"^8 is conducted exactly the dvef.. 'f [■/•"'• °" '^°'^Pa"'>g the colours of ..nltTl!' f " *^\?'^ °^ "^""^ ^°<* '^l^' ^^^ ■"ordaut may be Ste, f^' ^^*''' °J ^^■'^"'taneously with the colouring matter, other series of experiments must be carried out m order to determine which of these methods is the bes , In comparing the dyed swatches, not only is the intensity purity, brilliancy, regularity ic, of t/e Colour .aken mo account, but also the effect produced upon the soa""!?!'"'''^^"^;"'"^ *'^« colour towards washi^^ soaping, scouring, milling, rubbing, light, &o. In all cases of experimental dyeing, indeed it i^i s'Sr *° -"d,;-* the.-Periments'undrr conditions a similar as possible to those which are met with on the arge scale, and m judging of the results, great care mu ? be taken to avoid the possibility of referring any effect produced to more than one cause at a time To sum up the whole system of experimenting on the said that, in order to determine the effect of each par- ticular ingredient used, the dyer must perform simu ta- wetht^ oIT ™°" t""f experiment^, in which equal weights of the same textile material are submitted to all the necessary operations under precisely the same condi ions, except as regards the amount employed of the mgredient whose action is to be studied 482 DYEING OF TEXTILE FABRICS. [Cliap. XXtV. Whatever, indeed, be the factor the influence of which is to be determined, whether it be the duration or temperature of mordanting or of dyeing, the character or amount of the several ingredients employed, and so on, that factor alone is varied, while the others remain unchanged. In this way a systematic series of dyeing experiments is carried out ; one by one the nature and value of each individual influence is carefully ascertained, until at lengthy by a cumulative process, the totality of conditiojis necessary to produce the best results is accurately determined. The actual number of experi- ments wliich it may be requisite to perform with any given colouring matter, before an-iving at a full know- ledge of its dyeing properties, is quite indefinite, and is more or less influenced by the character of the colouring matter, and by the general and special chemical know- ledge of the experimenter. Far too frequently, it is to be feared, the ' dyer neglects or declines to institute dyeing experiments on the above lines., but regards them either as of little use, or as too costly, or as taking up too much time, ignoring or forgetting that the knowledge thus obtained invariably leads to almost absolute certainty in carrying out dyeing operations on the large scale, and repays a thousandfold the time and trouble expended. As to the apparatus required, it is compai^atively simple. A water- or steam-bath, or an oil- or glycerine- bath, heated with gas or steam, provided with a per- forated cover for the reception of the dye-vessels, serves for the simultaneous and equable heating of the latter. The dye-vessels themselves should be of toughened glass or well-glazed porcelain, and capable of holding about half a litre or even one litre. Metallic vessels of whatever kind, although very useful for special work, are not to be recom- mended for general use, especially for experimental icool- dyeing, since the acids and acid salts so frequently used in mordanting and dyeing invariably dissolve traces of the metal, whicli, in many cases, aflect the ultimate result. Chap. XXIV.] EXPERIMENTAL DYEING. 483 For the same reason, stirring-rods or other apparatus moving the textile /— v-_^^-^^ •'a material during the mordanting or dyeing process, must also be of glass or porcelain. A good balance, a few glass beakers, porcelain basins. for measm-e glasses, burettes, pipettes, and hydrometers, complete the equipment. Figs. 96 and 97 show plan, ele- vation, and section of a very con- venient arrange- ment for experi- mental dyeing (made by Messrs. Broadbent and Sons, Hudders- field). It consists of a couple of strong cast-iron pipes B, into which iron cups c, for holding glycerine, are screwed. The porcelain dye- vessels A rest in the glycerine cups, and are clamped down by means of a flange. 484 DYEING 0? TEXTILE FABRICS. [Chap. XX IV. protected with india-rubber or asbestos rings. Tlie pipes B are so supported that they can be readily turned on their axes, by means of the handles f, for the purpose of emptying the dye-vessels. The axes ai'e hollow, and serve respectively for tlie introduction of steam at D, and the escape of condensed water at E. One of the difficulties hitheito en- countered in expeiimental dyeing arrancjements is that of beins; able to heat the water in a series of porcelain dye-vessels to the boiling point simultaneously, and in a sufficiently convenient and cleanly appai^tus. The one hei'e shown, in which steam at 50 — 60 pounds' pressure is used, will be found to answer every require- ment. 432. Exposure of Dyed Pat- terns to External Influences. — Although in the above, reference has been made to the method of determining the conditions of dyeing, tfcc, necessary to obtain the brightest, most intense, and best coloui"s, it must not be for- gotten that a dyer knows but half his business if he is simply acquainted with these conditions. He must not only learn how best to apply any given colour : he must also know the capabilities of each dyed colour : how it withstands the action of lio^bt, milliner, scourincj. (tc, — in short, all those influences, whether natural or artificial, to which the dyed fabric is likely to be sub- mitted. Hence, all dyers should habitually and syste- matically expose portions of dyed patterns to the sevei-al ^ Uhap. XXIV.] FASTNESS OF DYED COLOURS. 485 influences just mentioned, and, as already stated, all care must Le taken to avoid the possibility of referring any effect produced to more than one cause at a time. "Such exposed patterns must be afterwards carefully compared with the original patterns as dyed. 433. Fastness of Colours.— The term " fast colour " generally implies that the colour in question resists the fading action of light, but it may also imply that it is affected by washing with soap and water, or by the action of acids and. alkalis, scouring, milling, rubbing, bleaching, &c. In its wide sense, it means that the colour is not aflfected by any of those influences to which it is destined to be submitted, but its technical meaning is often re- stricted. To the cotton-dyer, for example, it may refer chiefly to washing with soap and water, and to"^ light. To the woollen-dyer it may refer to milling, scouring, and light ; and so on. Many colours may be fairly fast to washing with soap and water, and yet be very fugitive towards light; or they may be fast to light, and yet very sensitive to the action of acids or alkalis. The term " loose colour " generally implies that the colour is much impoverished, or even entirely removed, by washing with water or a solution of soap ; it mayi however, also mean that it is not fast to light. The word " permanent," as applied to colour, generally denotes that it is fast to light and other natural influences. A '' fugitive colour " is generally understood to be one which is not fast to light, or which volatilises more or less under the influence of heat. In the absence, then, of any definite meaning beinf^ attached to the above terms, it becomes imperative, in speaking of the fastness of a colour, to refer specially to the particular influences which it does or does not resist. 434. Influence of Light on Dyed Colours.— The chemical activity of the sun's rays is well known, and it has already been noticed that certain unstable mordant solutions seem to be decomposed and precipitated more 486 DYEING OF TEXTILE FABRICS. [Chap. XXFV. readily under the influence of light. It is not surprising, therefore, to find that light should also have a very marked eflect upon dyed colours. Under the prolonged influence of light and air almost all colours fade, and according to their relative behaviour in this respect, they are broadly divided into two classes, namely, those which are " fast to light," and those which are " not fast to light." There is, however, no definite line of demarcation between the two, and dyed colours are met with possessing all possible degrees of resistance. Each of the coloured rays of the spectrum possesses a diff'erent fading power. White light is the most active, then follow the yellow, blue, green, orange, violet, and red rays. Direct sunlight is more energetic than diffused daylight. The light of the electric arc acts in the same sense as sunlight, but is less powerful (about one fourth). According to Chevreul, the presence of oxygen and moisture assists very materially in the fading action of light, so that even some fugitive colours, dyed, for ex- ample, with Safflow^er, Annatto, Orchil, do not fade if exposed to light in dry oxygen or m vacuo. Chevreul has shown, too, that the nature of the fibre has consider- able influence in the matter, and that some colours are less fugitive on cotton than if fixed on wool or silk. Whethei- the essential action of light is one of oxidation or of reduction, or whether the action varies with each colouring matter, has not yet been determined. In the case of Prussian Blue, it is said to be one of reduction, but from the fact that air and moisture play generally an iuiportant part in the fading process, it is quite con- ceivable that in many cases it is one of oxidation. It IS known that during the evaporation of water, ozone or hydrogen peroxide is found in small quantities, and both are powerful oxidising, as well as bleaching, agents. Heat is found to act in some cases in the same sense as light, but in a very inferior degree. The following notes referring to the fastness of colours Chap. XXIV.] FASTNESS OF DYED COLOURS. 487 are taken from experiments made with dyed wool, samples of which were exposed to the light during periods of one, two, four, eight, and twelve months. The division of the colouring matters into "fast," " medium," and " fugitive," is more or less approximate, and is merely intended to convey in a simple manner the general character of each. Red Colours. Fast. Alizarin (Al), Isopurpurin, Purpurin, Flavo- purpurin, Nitro-alizarin (Cu), Madder. Medium. Cochineal (Sn, Al), Biebrich Scarlet and allied colours. Fugitive. Many of the Azo Reds and Scarlets, Ma- genta, Safranine, Aurin, Eosin, and allied colours; Peach wood (Al, Sn), and allied red woods ; Barwood (Al, Sn), Sanderswood (Al, Sn), Ammoniacal Cochineal (Sn). Orange and Yellow Colours. Fast. Iron Buff, Chromate of lead yellow, Canarin, Chrysamin on cotton (F. Baeyer), Orange G (m. l. k B.), Nitro-alizarin (Sn, Al), Alizarii? (Sn), Isopujpurin (Sn), Flavopurpurin (Sn). Medium. Crocein Orange, Diphenylamin Orange, /3 ^N'aphthol Orange, Azoflavin, Brilliant Yel- low, Fast Yellow, other coal-tar yellows, Weld (Sn), Old Fustic (Sn), Quercitron Bark (Sn), Flavin (Sn), Persian Berries (Sn). Fugitive, o. Naphthol Orange, Chrysoidine, Phos- phine. Fluorescein, Turmeric, Ajinatto, Young Fustic ('Sn). Green and Olive Colours. Fast. Ccerulein, XaphtholGreen, Persian Berries (Cu). Medium. Weld (Cu, Fe), Old Fustic (Cu, Fe), Quercitron Bark (Cu, Fe), Flavin (Cu, Fe). Blue Colours. Fast. Yat Indigo, Alizarin Blue, Prussian Blu& 488 DYEING OF TEXTILE FABRICS. [Chap. XXIV. Medium. Logwood (Cu, Fe, Cr). Indulines. Fugitive. Alkali Blues, Soluble Blues, Spirit Blues, Indigo Carmine,, Methylene Blue (this is very much faster on cottou), Logwood (Al). Purple Colours. Fast. Alizarin (Fe, Cr), Isopurpurixi (Fe), Gallein (Cr, Cu). Medium. Gallein (Al, Fe), Cochineal (Cr, Fe), GaUocyanin. Fugitive. Logwood (Sn),Ammoniacal Cochineal (Al), Orchil, Limawood (Cr, Fe), Methyl Violet, Hof- mann's Violet, Perkin's Violet, Eosaniline Violet. Brown Colours. Fast. Nitro-alizarin (Cr), Isopurpurin (Cr, Ou), Flavopurpurin (Cr, Fe. Cu), Purpurin (Cr, Fe, Cu), Madder (Cr, Fe, Cu), Cochineal (Cu), Catechu. Medium. Camwood (Cu, sadden). Fugitive. Camwood (Cr, Cu, Al, mordant and dye), Bar wood (Cr, Cu), Sanderswood (Cr, Cu), Bis- marck Brown, other Azo Browns. Some colouring matters — e.g., AHzarin — give fast colours with all mordants ; others — e.g., Limawood and Young Fustic — seem only capable of yielding fugitive colours; others again — e.^.. Logwood — give fast or fugi- tive colours, according to the mordant employed. The fugitive character of the colours obtained from Logwood by the use of tin and aluminium mordants, compared with the medium fastness of those obtained when copper, chromium, or iron mordants are employed, is rather striking. Some colours present somewhat abnormal properties. Wool mordanted with aluminium and tin mordants, and dyed with Camwood, yields reddish-brown colours, which during exposure become at first considerably darker, and begin to fade only after two or four months. The olive- Chap. XXIV.) DYEING OF COMPOUND SHADES. 489 gi'een colour yielded by Persian Berries and copper sul- phate is quite remarkable in this respect, since it actually becomes darker and greener, even after an exposure of twelve months. The pure greenish-yellow obtained Avith Picric acid exhibits a similar character ; on exposure it rapidly becomes orange, and this begins to fade only after a lapse of about twelve months. The mode of application also influences the fastness of the colour. Camwood and Catechu, for example, yield faster colours with copper sulphate by the saddening method than by the mordanting and dyeing method. In studying the beha^dour of the coal-tar colours towards light, one cannot fail to be struck with the manifest influence of their chemical constitution in the matter. All those colouring mattei-s, for example, in which the atomic arrangement is like that of IMagenta, are similarly fugitive to light, e.g., Methyl Violet, Benzalde- hyde Green, (fcc; such similarity extends even to Aurin and Safranine. Colouring matters allied to Alizarin, on the other hand, all possess the quality of fastness to light. There are, however, cases in which an apparently slight difference in constitution gives rise to remarkable differ- ences in fastness to light — com])are, for example, Fluor escein and Gallein, Indis^o Carmine and Yat Indisfo Blue. The popular fallacy that coal-tar colours are fugitive, and that the colours yielded by dyewoods are fast, has already been shown to be false, and is only referred to because it still lingers in the minds of some dyers. The origin of a colouring matter has of course nothing whatever to do with its properties : these are mainly, if not entirely, governed by its chemical composition and constitution. 435. The Dyeing of Compound Shades.— Compara- tively few of the colours met with on dyed fabrics result from the employment of a single colouring matter ; it becomes imperative, therefore, for the dyer to know how to apply two or more together. This knowledge can readily be gained by making a series of dyeing experiments 490 DYEING OF TEXTILE FABRICS. [Chap. XXIV. The result obtained by mixing, as it were, the dyed colours must be observed and studied much in the same way as the artist does with the pigments upon his palette. None of the colours here dealt with are pure, like those of the physicist ; hence the product of the mixture of dyed colours is for the most part totally different to what would be produced by combining together the various colours of the spectrum. A mixture of red and yellow produces orange^ yellow and blue produce green^ blue and red produce violet, green and violet produce blue. Orange and Green tend to produce yellow ; violet and orange tend to produce red. The compound colours, orange, green, and violet, vary in shade according to the amount and purity of tone of each constituent single colour. If, for example, in com- bining yellow and blue_, the yellow inclines to orange, or the blue inclines to purple, the green produced inclines to olive. With the physicist, white is produced either by a mixture of all the colours of the spectrum, or by mixing together what are known as "complementary colours," for example the following : — Purple and green. Red and bluish-green. Orange and turquoise blue. Yellow and ultramarine blue. Yellowish-green and violet. With the dyer, however, the opposite effect tends to 1)6 produced. A judicious mixture of red, yellow, and blue tends to produce sombre colours or even black. In the same way red and green produce chocolate or brown, blue and orange produce drab, «tc. It is beyond the scope of this manual to discuss the law of the mixture of colours. For information on this point the reader is referred to Bezold's " Theory of Colour," Rood's "Modern Chromatics," and other similar works. It is, however, always imperative, in the end, to gain positive and reliable information by actually making Chap. XXIV.] INFLUENCE OF MILLING ON COLOURS. 491 Bpecial dyeing experiments, and even then, long experience is required before one feels tliorouglily at home in pro- ducing any given compound shade. A very necessary, or at least desirable, point to re- member is, that all the colouring matters employed simultaneously should be really applicable to the best advantage, by the same process. A colouring matter which requires to be applied in an acid-bath ought not to be applied simultaneously with one which dyes best in a neutral bath. Basic colouring matters, although not re- quiring mordants, can, however, be frequently employed along with such as do, whenever the "mordanting and dyeing method " is used, since the latter are almost in- variably applied in a neutral dye-bath. If the compound shade is intended to be fast towards any influence — e.g., light, milling, &c. — then each consti- tuent colour yielded by the several dyestuffs, when separately employed, should be as similar in fastness to that influence as possible. Although dyers frequently apply fast and fugitive colours together in producing compound shades, or for the sake of improving the brilliancy of any given colour, it is always more or less iiTational, and ought to be avoided whenever possible. 436. Influence of Milling.— The process of '• milling," so much used in the heavy woollen trade for Tweeds, (fee, consists in saturating the woollen cloth with a strong solu- tion of soap (frequently carbonate of soda as well), and then submitting it to a violent kneading, beating, or pressinf^, in the wash-stocks (see Fig. 52) or "milling machine." It is an exceptionally severe treatment, and demands of the colour : that it shall withstand rubbing, that it shall not be decomposed by or be soluble in weak alkalis, and that whatever colour does rub off", this shall not permanently Btain contiguous fibres (bleeding). As a general rule the best colouring matters in respect of the last point are those which retpiire the aid of mordants, e.g., Alizarin, Logwood, (tc. Coal-tar colours, which are applied dii-ectly,' 492 DYEIXG OF TEXTILE FABRICS. e.g., Magenta, Azo Scarlets, (kc, are very prone to dissolve off and dye the neighbouring tibres. Some acid-colours are unsuitable because they are more or less decolorised by the action of the alkali, e.g.^ Acid Magenta, Acid Green, Alkali Blue, A^lkali Green, Gives no fluorescent solution on boiling with Al2( 804)3 ( distinction from Madder and Purpiirin). Bleaching powder and chromic acid bleach it. Boiled with Ba(0H)2 solution, fibre becomes violet, HNO3 gives a yellow spot. An alkaline solution of K3 FeCyg has no action, nor. has KMn04. HNO2 vapour converts it into yellow * Nitro-alizarin. On heating, Alizarin red loses brilliancy and becomes brownish, but regains most of the brilhancy on ex- posure to air. The ammoniacal, aqueous, or alcoholic solutions give characteristic absorption spectra. 502 DYKING OF TEXTILE FABRICS. RED COLOUBS Colotiring Matter. HCL H2SO4. NaOH. Crocein scarlet Fibre at first Concentrated Colour of fibre 7B. I violet, liquid^ acid, fibre and blue. (F. Laeyer &. colourless. Co.) On standing, fibre becomes! blue, liquid greenish-blue. ■ solution blue. NH4OH. Biebrich Scar- Fibre violet, 'Fibre and solu- let. (Kalle k liquid colour- Co.) less. On standing, liquid becomes sreenish-blue. Patent FastFibre dark tion green. Fibre dark blu- ish-red, liquid colourless. Red. (basf) ened, liquid slightly ting- ed red. Fibre violet, li- Fibre made quid colourless,' paler, and but on stand- ing bluish- vio- let. red colour ex- tracted. Fast Ponceau'Fibre violet,iFibre and solu- Fibre dark blu- B. (basf) Scarlet 2B. (m. L. & B.) liquid colour- less. On standing, liquidbecomes STeenish-blue. tion green. ish red, no colour ex tracted. Fibre not'DiluteH2S04,no Nearly de changed byl action. colorised. cold HCl, but'Concentrated on boiling: H2SO4 extracts nearly deco-j the colour, lorised andl much colour extracted. Scarlet SR.Fibre not i^M. L. k B.) changed even on boiling. Bluish-red li qmdexti"acted. No action. JS'early de colorised. No action. No action. No actioa Fibre palex. Little effect. TABLES OF COLOUR TESTS. 503 {continued). SuQa + HCl. Alcoh 3l. Other Tests. Fibre decolor- Little or no SNO3 gives at first a dark blue spot which changes jge(j_ action. *° bright yellow with a greenish-blue border Fibre decolor- ised. Little or no action. Fibre decolor ised. (Eesists tbis test better tban otber scarlets. ) Fibre decolor- ised. Fibro decolor- ised. Fibre decolor- ised. Little or no action. Little or no action. Little or no action. Little or no action. HNO3 gives at first a dark blue spot which change to brown with a dark blue border. HNO3 acts as with Crocem Scarlet 7 B. HNO3 gives a dark blue spot which changes to red brown with a dark blue or black border. HNO3 gives violet spot which afterwarda changes to bright yellow. HNO3, as with Scarlet 2R. 504 DYEING OF TEXTILE FABRICS. RED COLOURS Coloiu-ing Matter. HCL H0SO4. NaOH. 1 NH4OH. 1 Claret Red B. (m. l. &;b.) Fibre little changed, li- quid reddish violet. Fibre at first violet, finally blue. Liquid at .first colourless, af- terwar d s bright blue. Fibre orange- red, solution yellowish-red. No action. Madder. . . Fibre brown- ish-red. Fibre brownish- red, solution red. Fibre and so- Wool brown- lution purple, i ish-red, cotton not changed. 1 Cochineal. . Fibre orange - red, solution orange-pink. Fibre and solu- tion bright pink. Solution purple. lAswithNaOH. Peachwood. . Fibre dark red, solution pink. Fibre brown, so- lution yellow changing to brown. Much colour extracted, bluish-red. Cotton almost decolorised. As with NaOH. Barwood. No action. Fibre reddish- brown, solution dirty brown. Fibre purplish, solution col- ourless. AswithNaOH. Sanderswood. No action. Fibre and solu- tion reddish- brown. Fibre purplish, AswithXaOH. solution col- 1 ourless. Safflower. Cotton decolor- ised. Cotton decolor- ised. With dilute NaOH, cotton pale yeUow. Cotton, flesh- colour. Orchil. . . Solution red. Fibre and solu- tion purple, afterwards brown. Fibre bluish - purple. AswithNaOH. TABLES OF COLOUR TESTS. 505 [covfinued). SnCl2 + HCl. Alcohol. Other Tests. On heating, fibre becomes almost colour- less, or pale lilac. Little or no action. HNO3 gives a violet spot which afterwards hecomes brownish with a faiut blue bordei'. It is not affected so readily by HNO3 as the Crocein Scarlets are. Little colour extracted. No action. Nitric acid colours fibre bright yellow. Fibre and so- lution orange- red. No action. Nitric acid colours fibre yellow. Fibre and so- lution bluish- red on heat- ing. Pale yellow so- lution. Nitric acid colours fibre bro-\vnish-yellow. Boiling soap solution removes much colour, solution bluish- red. Fibre unchang- ed, solution red. Red solution. Nitric acid coloiirs wool dark olive. Fibre unchang- ed, solution red. Red solution. Nitric acid colours wool dark olive. Boiled with FeS04 colour becomes violet. Cotton straw yellow.- No action. At once de- colorised. Bluish-red so- lution. See Magenta. 506 DTKCfG OP TEXTILE FABRICS. YELLOW AND Colouring Matter. HCL H2SO4. NaOH. Picric Acid. Colour extract- ed on "boiling, liquid green- ish-yellow. NH4OH. Decolorised. Fibre becomes Fibre becomes orange, solu- paler, a yellow tion yellow. colourextract- ed on boiling. Victoria Decolorised, Yellow. ! washing re- stores the 00- lonr. Naphthol Yellow. Decolorised almost com- pletely. As with HCL Fibre orange, solution yel- low. Fibre paler, yellow colour extracted on boiling. Naphthol Fibre bleached, Decolorised. jFibre paler,Fibre little liquid yellow, changed, li- quid pale yel- Yellow S. solution CO- 1 lourless. low. Aurantia. . Fibre paleFibre yellow-Little or no] No action. I yellow. ish-drab effect. Cluy&oidine. (■p.. s. &: S-^i Fibre red. Yellow colour Fibre p a 1 e r Fibre yellower. extracted. and yellower. Fast Yellow. 'p.asf) Orange 3. F. Baever & Co.) Red Fibre brownish- red, liquid red. Solution brownish-yel- low. Little action. Fibre red, H-Fibre and liquid Fibre dull yel- Fibre not quid pink. bright bluish- red. lowish red. changed, li- quid slightly yellow. TABLES OF COLOUR TESTS. ORANGE COLOURS. 507 SnCl2+HCl. Alcohol. Other Tests. Fibre bleached, 'Yellow colour ^^ Picric Acid yellows taste bitter. fViP linm'd po Pvtrarfpfl Heated with KCN solution fibre becomes red tne nquia CO- exiractea. through the formation of isopurpuric acid, lourless. In compound colours the cloth should be extracted with alcohol, and the solution tested for Picric Acid with KCN. Fibre bleached, the liquid co louiiess. Warm water extracts the colour. Yellow coloiQ'iWater extracts the colour and the yellow solution is extracted. | decolorised by H2SO4. iBoihng KCN extracts a red colour. "Wrapped iu I white paper and heated to 120° C, leaves a stain on I paper. Bleached. No action. Fibre brown Colour readily on heating. extracted. BoiHng water extracts nothing. Heated to 120*^ C. in white paper, leaves no stain. Heated with SnCl2 gives dark brownish-red colour, afterwards decolorised. Almost decol- Yellow colour orised. ; extracted. Fibre bri ght A little colour HNO3 gives a bright red spot, red, after- extracted, wards decol- orised. Complete] yA little colour bleached. 1 extracted. 508 DYEING OF TEXTILE FABRICS. YELLOW AND ORANGE Colouring Matter. HCl. Orange 4. . Fibre reddish- A. Poirrier) violet, liqtiid violet. H2SO4. As with HCL NaOH. NH4OH. Kg action. Fibre not changed, li- quid yellow. Orange 2. . Fibre and li-As with HCl., Fibre deep red. No action. (A. Poirrier) quid bluish- j but bluer, red. ! Phosphine. . Fibre nearly Solution green- Fibre becomes Fibre becomes decolorised,} ish-yellow. J paler and yel- paler, a bright solution yel- low. lower. Nitro- alizarin. Fibre pale Fibre brownish- Fibre claret- I straw yellow, yellow, liquid red or brown- solution yel- yellow. I ish, liquid low. colourless. yellow. Madder. Little action. Fibre brownish- red, solution red. Fibre and so- lution purple. Cold, no action; hot, as with NaOH, but fi- bre not so dark. Fibre brown. Old Fustic. . Fibre and so- Fibre and solu- Fibre littleFibreunchang- lution orange.' tion brown. ; changed. ed, solution I yellow. Young Fustic Fibre unchang- Fibre and solu-lFibre reddish-l As with NaOH. ! ed, solution! tion reddish-} brown. I pale yellow. brown. Weld. . Fibre little af-Tibre brownish- Fibre little af fected, solu-j yellow, tion pale yel- low. fected, solu- tion pale yel- low. No action. TABLES OF COLOUR TESTS. 509 COLOURS {continued). SnC]2 + HCl. AlcohoL other Tests. At first fibre becomes deep violet on heat- ing-, gradually lighter and fi- nally bleached Yellow coloui' extracted. Completely bleached. No action. Fibre nearly decolorised. A little colour extracted. Fibre deep yel- low, liquid yeUow. No action. HNO3 gives a bright yellow spot. Boiling Ba(0H)2 colours the fibre claret-red. Fibre un- changed, solu- lution pale red. No action. Heated with FeaCls fibre becomes olive-brown. Fibre orange, solution col- oaiiess. No action. With HNO3 fihre pale yellow. Heated with EeoClG fibre becomes olive. Boiled with acetate of alumina gives yellow solution with bluish-green fluorescence. No action. No action. "With HNO3 fihre dark brown. Heated with Fe2Cl6 fibre becomes olive. Fibre Httle af- fected. No action. 1 i HNO3 no action. Heated with Fe2Cl6 fibre becomes oUve. Colour unchauged by boiling with lead acetate 510 DYEING OF TEXTILE FABRICS. YELLOW AND ORANGE Colouring Matter. HCl. H2SO4. NaOH. NH4OH. Quercitron Bark. Fibre little af- fected, solu- tion yellow. Fibre brownish- yellow, solu- tion yellow. Fibre little changed,solu- tion yellow. Fibre unchang- ed, solution yellow. Flavin. . . Fibre and so- lution yellow. Fibre and solu- tion yellow. Fibre and solu- tion yellow. Fibre little af- fected, solu- tion yellow. Persian Berries. Fibre unchang- ed, solution yellow. Fibre orange- brown, solution greenish- yel- low. Fibre unchang- ed, solution brownish-yel- low. Colour slightly extracted. Turmeric. Fibre reddish- brown, solu- tion colour- less. Fibre reddish- brown, solution brown. Fibre bright reddish - brown, solu- tion orange- brown. Fibre bright reddish - brown, solu- tion orange. A.nnatto. . . Little affected, or brownish- red. Fibre and solu- tion blue. Little affected. AswithNaOH Iron Buff. . Fibre straw- yellow or de- colorised. Little action. No action. No action. Chrome Yellow. Fibre decolor- ised, solution pale yellow. Fibre greenish - yellow or dull yellow. Fibre paler, liquid pale yellow. Little action. TABLES OP COLOUR TESTS. 511 COLOUES {continued). SnClo + HCl. Fibre Httle af- fected, solu- tion yellow. Fibre brown- ish-yellow, so- lution bright yellow. Fibre brown, solution yel- low. Fibre reddish- brown, solu- tion colour- less. Alcohol. No action. Other Tests. No action. With HNO3 fibre light brown. Heated with Fe2Cl^ fibre becomes oLLtc. Colour becomes orange by boiliog with lead acetate. With HNO3 fibre daxk brown. Heated with FeoCl^j fibre becomes olive. Boiling acetic acid gives yellow solution with green fluorescence. Colour becomes orange by boiling with lead acetate. With HNO3 fibre brown. Heated with FesCle fibre becomes olive. Colour becomes orange by boiling with lead acetate. Colour extract- With HNO3 fibre pale yeUow. ed solution ^°'^^^^'^,'^P^^^^'i^'^ ,^° ^^^ ^^^ alcoholic solution, orange or yel- lowwith gi-een fluorescence. gives bright red colour. Decolorised. Decolorised. Decoloi'ised. Solution bright Dyed blue with KsFeCye + HCl. yellow. No action. Fibre blackened with ammonium sulphide or HgS. No action. 512 DYKING OF TEXTILE FABRICS. GREEN Colouring ITatter. nci H2SO4. NaOH. NH4OH. Malachite Green. Fibre and li- quid bright orange : on washing wilh water the green coiout is restored. Fibre much bleached, hqmd bright orange. Decolorised. Decolorised. Methyl Green. (basp) Fibre and li- quid pale yel- low ; coioui- restored on washing. Fibre much bleached,liquid colourless. Decolorised. Decolorised. A.cid GreezL (Soe. Chem. Fibre pale green. Fibre brown, liquid yellow. Decolorised. Decolorised. Mkali Greea. Fibre dark olive - green, solution red- dish-brown. Fibre and solu- tion dark brown. Decolorised. Decolorised. HelvetiaGreen Liquid yellow ; green coloiu- restored on diluting with water. Decolorised. Fibre buff-yel- low. As with NaOH. Coerolein. (basp) 1 Fibre duller green, liquid claret-red. As with HCl, liquid dirty amber vellow. No action. No action. TABLES OF COLOUR TE^TS. / 513 COLOURS. SnCla + HCL Fibre almost decolorised, liquid yellow. Fibre almost Bluish - green decolorised, colour ex Alcohol. Green colour extracted. Other Tests. Heated to 100° C. colour does not change to bluish* violet. (Distinction from Methyl Green.) liquid yellow. Fibre almost decolorised, liquid yellow. tracted. Fibre not changed, blu- ish-green co- lour extracted. Almost com- pletely deco- lorised. Fibre brown ish-red, liquid brown; on washing with water colour gradually re stored. H H Green colour readily ex- tracted. Green colour extracted. Bluish - green colour ex tracted. No action. r Heated to 100" C. becomes bluish-violet. (Distinctio* from Malachite Green.) HNO3 gives a brown •i)Ot 514 DYEING OF TEXTILE FABRICS. GEEEN COLOURS Colouring Matter. HCl. Aldehyde FilDre bright Green. yellow Vat Indigo and Fibre paler, Old Fustic, liquid blue. H2SO4. Fibre orange. NaOH. NH4OH. Little action J At first little ao- fibre after-' ti on, aft erwardf wards paler, bleached. As with Ha. Fibre greenish- Fibre paler or blue, liquid blue, liquid yeUow. Vat Indigo and Yellow remov-IFibre dirty yel- 'Yellow remov- No action, yellow or greenish. Chromate of edatonce,blue Lead. afterwards ; liquid dull yellow. Indigo Car- Fibre at first mine and Pic- blue, after- ric Acid. wards very pale ; liquid blue. Chrome Green. No action. lowish-creen. As with HCl. No action. ed; liquid pale yellow Fibre almost As with NaOH. decolorised,! liquid pale yellow. No action. No action. BLUE Alizarin Blue. Fibre violet, Dilute H2SO4 ; Fibre bliuBh- No acti on (kasf) liquid yellow- ish-reid. fibre violet, li- quid slightly red. Concen- trated H0SO4 "gives violet liquid- green. TABLES OF COLOUR TESXa 515 {eontiriue(f). SnClo + HCl. Other Testa. Slowly d e- Green colour .HNO3 gi^es a brown spot, colorised. extracted. Fibre much See indigo. paler, liquidj greenish yellow. Fibre becomes^ See indigo, at first blue,! afterwards decolorised. Decolorised. No action. No action. Boiling glacial acetic acid gives green solution ; on diluting vrith. water blue is precipitated. Boiling Alo^SO^Is gives yellow solution with green fluorescence. _ Eemove yellow colour by boUing with, dilute NaaCOa, and test the blue remaining for indigo. Ash contains lead. Blackened by (XH4)3S. Bleaching-powder solution changes colour to yellow. Cold water extracts Picric Acid, test solution with KCN. BoUed with a solution of bleaching-powder gives yellow liquid containing chromate. Occurs only on calico prints. COLOrRS. Fibre at first violet,on'heat- ing brownish red, liquid is brown. No action. HNO3 gives a bright yellow spot which goes brown after a time. Soap and bleaching-powder have no action. Phosphoric acid gives orange-red solution, which on diluting with water and adding NH4OH becomes blue. A dilute ammoniacal alcoholic solution shows characteristic absorption stripes when examined with spectro6Coi)e. 516 DYEING OF TEJTILE PABRICa BLUE COLOUKS Colouring MaHter. HCl. H2SO4. NaOH. i KH4OH. Soluble Blue. Extracts blue Fibre and liquid Fibre reddish- Decolorised at (B, 5. & S.) colour. reddish-brown. brown. once. Spirit Blue. . Fibre dark Fibre and solu- Fibre brickred.|D ecol ori sed IX. PoLrrier) green, solu- tion reddish- slowly. tion brownish. brown. Alkali Blue Fibre greenish- Fibre and liquid Fibre at first Decolorised 3B. blue, solution reddish -brown reddish - rapidlv. (bast) almost colour- less. on standing. brown, after- wards decol- orised. Induline. . . Fibre violet, Solution dark Eeddish- violet As with NaOH. liquid deep blue. colour ab- blue. stracted, the solution de- colorised on addition of zinc powder. Violet colour restored by exposing fil- tered solution to the air. Methylene Fibre nearly Fibre and liquid Fibre bluish- No action. Blue. decolorised, green. violet. (BASy) solution bluish green. TABLES OF COLOUR TESTS. 517 {eontintied). SnCl2 + HCl. Fibre little changed, blue colour extrac- ted. Absolute alco- hol, even on boiling, eX' tracts no col our. Fibre not chan- ged, liquid colourless. Absolute alco- hol extracts the colour, even in the cold. Fibre not chan- ged, liquid colourless. Absolute alco hoi extracts the colour, even in the cold. Extracts a vio- let or green colour. Decolorised. Alcohol. Bluish. violet colour extract- ed. Greenish- blue colour extract- ed. Other Tests. HNO3 gives a dark spot, which changes to dark green with a black border. HNO3 gives a black spot, which changes to dark green. HNOjf gives a light green spot with black border. Induline NN is not changed by bJeaching-powder solution. HNO3 gives a dark bluish-green spot. Bleaching-powder solution changes some Indulinea to a reddish-grey, whilst others are decolorised. HNO3 gives a green spot which does not change further. Bleaching-powder solution turns it first green, and gradiially decolorises it. On cotton it is much faster than aniline blues, and withstands neutral soaps, light, and weak bleach- ing-powder. Very sensitive to chromic acid. A 3 per cent, solution of K2Cr207 changes it first to violet and finally decolorises it. If it has been fixed with tannin a brown colour is left. 518 DYEING OP TEXTILE FABRICS. BLUE COLOURS Colouring Matter. HCl. H2SO4. NaOH. NH4OH. Besorcin Blue. Dilute H2SO4, no action. Solution blue, with red fluo- rescence. AswithNaOa Indophenol Blue. Fibre greyish- brown. Fibre greyish- brown. No action. No action. Vat Indigo Blue. No action. Dilute H2SO4, no action. Concentrated H2SO4 gives a blue solution. No action. No action. Indigo ^ Carmine. Solution green- ish-blue. Solution blue. Fibre greenish. On boiling with dilute NaOH colour abstracted, so- lution little coloured, but becomes blue on acidifying. As with NaOH. Prussian Blue. No action. No action. Fibre brown on heating. No action. Logwood Blu£. Fibre red or brown, solu- tion red. As with HCl. Fibre and so- lution pm-ple. AswithNaOH. Ultramarine Blue. 1 Decolorised. Decolorised. No action. No action. TABLES OF COLOUR TESTS. 519 {continued). SnCl2 + HCl. Alcohol. Other Tests. Decolorised. Blue colour extracted. Boiled with oUve oil purplish colour is extracted. On heating fibre becomes paler, solution greenish- yel- low. Boiling abso- lute alcohol gives blue so- lution, which on standing becomes co- lourless with separation of indigotin. Chloroform extracts blue colour. Stroug HNO3 gives bright yellow spot. Indigo-dyed cotton if burnt gives off purple vapour, wliich can l#e condensed on a cold porcelain slab as a blue spot. Fibre decolor- ised on heat- ing. Little or no col- our extracted. Colour extracted by boiling with dilute NagCOs ; silk or wool may be dyed in the acidified solution. Nitric acid gives yellow spot. No action. No action. Ash contains iron. Concentrated nitric acid gives greeu spot. Boiled with NaOH, solution contains potassium ferrocyanide, on acidifying and adding FeaClg blue precipitate is obtained. Fibre and solu- tion at fii'st red, after- wards brown. No action. If used for topping vat indigo blue, it can be removed by boiling with dilute HCl, the indigo being uu- affected thereby. Decolorised. No action. Ou burning fibre blue-coloured ash remains. Only met with on calico or woollen prints. 520 DYEING OF TEXTILE FABRICS. VIOLET Colouring Matter. HCL H0SO4. NaOH. NH4OH. Gallein. . . Fibre brown- ish-red, liquid amber-yellow. As with HCl. Coloiir of fibre bluer. * No action. Alizarin. . . Fibre and li- quid dull yel- low. As with HCl. Colour of fibre bluer. No action. Methyl Violet. Fibre yellow- ish - brown, liquid amber- yellow ; the violet colour restored on diluting with water. As with HCl. Fibre at first pale reddish- violet, after- wards decol- orised. Fibre palelilac, nearly decol- orised. Benzyl Violet. Fibre yellow- ish - brown, liquid amber- yellow ; the violet colour restored on diluting with water. As with HCl. Fibre at first bluer, after- wards decol- orised. Almost deco- lorised, fibre pale bluish- lavender. Parkin's Violet. Fibre unchan- ged, solution bluish-pink. Little or no action. Fibre blue, colour re- stored on washing. No action. Naphthyl- amine Violet. Fibre grey. Little or no action. Phenyl Violet, or Spirit Violet. Fibre dark green, solu- tion brownish. Fibre and solu- tion reddish- brown. Decolorised. Decolorised. TABLES OF COLOUR TESTS. 521 COLOURS. SuCla + HCl. Alcohol. Other Testa. Fibre crimson, liquid red. No action. HXO3 ^ves a bright yellow spot. Bleachiag-powder solution has no action. As with HCl. No action. Destroy the colour by boiling with dilute HCl, wash and add NaOH ; the Alizarin remaining on the libre ia dissolved with purple colour. Fibre green, but nearly de- colorised on standing, li- quid yellow, ish-green. Colour ex- tracted. Fibre bright green, liquid pale yellow. Colour ex- tracted. Fibre dirty brown, but not decolo- rised. Colour ex- tracted. HNO3 has no effect. CI bleaches the colour slowly. Blue colour ex- tracted ; only decolorises, slowly. Colour ex- tracted. HNO3 gives a green spot. 522 DYEING OP TEXTILE FABRICS. BLACK Colouring Matter. HCl. H2SO4. NaOH. NH4OII. Aniline Black. No - action, or colour be- comes green- ish-black, re- stored by al- kalies. Acid so 1 ution brownish. As with HCl. No action. No action. Logwood Black. Fibre red or olive- brown, solution deep red. As with HCl. Solution pur- ple. As with NaOH. Woaded Black. Logwood col- our removed, indigo not affected, and fibre remains blue. As with HCl. Logwood col- our removed, indigo not affected. As with NaOH. Alizaxin Black, Fibre orange, colour restor- ed with NH3. As with HCl. No action. No action. Tannin Black. Bleached ±0 pale straw colour, steep- ing after- wardsin NH3, gives reddish- bro^vn colour. As with Ha. Fibre brown- ish-grey or black. No action. TABLES OF COLOUR TESTS. 523 COLOURS. SnClg + HCl. Alcohol. Other Tests. Fibre greenisli- Boiling alco- Bleachiiig-powder solution changes colour to brown- firrsv colour liol 6xtrQ.cts o. isn-rcu. „^„^' ^ 1 -. I •. '., , Several passages through a concentrated solution of restoredby brownish - red kMuOj and oxalic acid alternately, decolorise it. NHj. colour. "Weak oxidisiiig agents have no action. Fibre violet or greyish - red, solution red, afterwards brown. No action. Ash contains iron or chromium. Fibre becomes As with indiffo- First remove Logwood colours, etc., by boiling with dirty green-' blue, ish-blue. As with HCl. Decolorised. No action. Ash contains iron, Ooonrs only on printed calico. No action. dilute HCl, and test blue remaining for Indigo. Ash contains iron. 524 DYEING OF TEXTILE FABRICS. BBOWN Colonriiig' Matter. Alizarin. HCL Fibre brown- ish-orange, colour restor- ed by ISTHs. H2SO4. As with HCL Nitroalizarin. Fibre paler, li-Fibre darker, quid yellow, liquid orange. NaOH. NH4OH. Action slight, Fibre u n- fibre bluer, changed, liquid tinted blue. Fibre darker, solution col- ourless. No action. Catechu Brown. Little or noLittle or noLittle or noLittle or no Camwood Brown. Peachwood Brown. D ye wood Brown. Bismarck Brown, change, solu- change, tion pale orangre. change. change. Fibre red, li- quid yellow- ish-red. As withHOL Fibre and li-Fibre yellow- quid yellow-! ish-red, liquid ish-red. I yellow. Fibre and li-Fibre purple, quid purple. | liquid c^lour- 1 less. Fibre purple, Fibre purple, liquid cherry- liquid colour- red, less. jRed or purple] colour ex- ! ti-acted. As with HCl. Little change, Fibre unchang^ liquid tinged ed, liquid tin- red. I ged red- Fibre reddish- As with HCl, Fibre brownish Fibre unchang- I brown, solu- but darker. I yellow solu- ed, solution i tion red. 1 tion colourless.' brown. Phenyl Brown. Colour extract-! I ed, solution! I brownish-red | ' I Naph thyl- Fibre brown- amine Brown. ish-yeUow,so- I lution orange. Manganese Slowly decolor- Brown. ' ised. No action. Purplish -jEeddish-brown brown colour' colour ex- extracted. ! tracted. No action. Fibre yellow. No action. TABLES OP COLOUR TESTS. 525 COLOURS. SnCl2 + HCL Alcohol. Other Tests. As with HCl. No action. 4 As with HCl. No action. Fibre becomes paler, solu- tion colourless or orange. No action Ash contains chromium and sometimes copper. Colour more or less bleached by boiling solution of bleaching-powder. Fibre and li- quid cherry- red. Occurs only on wool. Fibre and li- quid cherry- red. Fibre redder, solution red- dish. No action. Ash contains aluminium and iron. Fibre almost decolorised. Red or pink colour ex- ti-acted. Boiling water extracts colour ; boihng glacial acetic acid still more, with yellowish-green fluorescence. Fibre reduced to pink, solu- tion|colourleBS. Dark brown- ish-red colour extracted. Fibre purple, solution pale pink. Solution blu- ish-pink. Rapidly de- colorised. No action. Ash contains manganese. 526 DYEING OF TEXTILE FABRICS. CJosTPAiugoN" OF Thermometer Scales. {Approximate.) Centigrade. Fahrenlieit Centigrade. Fahrenheit Centigrade- Fahrenheit i 100'' 212° 72* 162° 44<> 111° 98 208 70 158 42 108 96 205 68 154 40 104 94 201 66 151 38 100 92 198 64 147 36 97 90 194 62 144 34 93 88 190 60 140 32 90 86 187 58 136 30 86 84 183 56 133 28 82 82 ISO 54 129 26 79 80 176 52 126 24 75 78 172 50 122 22 72 76 169 48 118 ■ 20 68 74 165 46 115 1 Comparison of degrees Twaddell and Specific Gravity. In order to change degrees Twaddell into Specific Gravity, multiply by 5, add "l, 000, and divide by 1,000. Example. — Change 168^ Tw. iato Specific Gravity. 16Sx5 840 1,000 l,(K)0 )l,S40 1*84 Spec. Grav. To change Specific Gravity into degrees Twaddell, multiply by 1,000, subtract 1,000, and divide by 5. Example. — Change 1-84: Spec. Grav. into degi^eeg Twaddell 1-84 x1,000 1.840 1,000 5 ) 84 168° Tw. MEASURES OP LENGTH, WEIGHT, AND CAPACITY. 527 Measures of Length. The Metre, the unit of length, is the ten-millionth part of II line drawn from the Pole to the Equator. 1 millimetre 1 centimetre 1 decimetre 1 metre 1 decametre 1 hectometre 1 kilometre YT^th of a metre = th ,, „ = lOO l^th „ as atove 10 metres 100 „ 1,000,, Incli = 2"53995 centimetres. Yard= 0-91438 metres. 0-03937 inches. 0-39370 „ 3-93708 „ 3-2809 feet. 10-9363 yards. 109-3633 „ 0-62138 miles. Foot =z 3-0i794 decimetres. Mile = 1609-32 metres. Measures of Weight. The Gram, the unit of weight, is the weight of a cubic centimetre of distilled water at 4° Centis^rade. 1 milligram 1 centigram 1 decigram 1 gram 1 decagram 1 hectogram 1 kilogram xoV o^li of a gram r= as above = 10 grams = 100 „ = 1,000 „ = 0-0154 troy grains. 0-1543 „ 1-5432 „ 15-4323 „ 154-3235 „ [pois. 3-5291 oz. avoirdu- 2-20462 lbs. „ Pound (avoirdupois) = 453-59 grams. Ounce (avoirdupois) = 28-34 „ Measures of Capacity, dry and liquid. The Litre, the unit of the measures of capacity, Ji-y and liquid, is the volume of a cubic decimetre. 1 miUilitre = S ^W^li of a litre, or ) _ I 1 cubic centimetre \ 1 centilitre = TOTyth of a litre = 1 decilitre = J^th „ ,, = , vi fas above = 1000 1 Ihtre =1 cub. cent. \ = 1 decalitre =: 10 litres =. 1 hectolitre i= 100 „ = I kilolitre = 1,000 „ = 220-0967 „ "A gallon of water weighs 10 lbs. (avoirdupois). 15-432 grain measures, oi 0-06103 cubic inches. 0-61027 „ „ 6-10270 „ ,, 1-7608 pints. 2-2009 gallona. 22-0097 „ INDEX. A CETATE of lime, 245 •"- Acetic acid, 244 Acid potassium tax- trate, 243 Ageing process, 170 Albumen, 237 Alizaxin pink, 451 — purple, 452 — chocolate, 4s53 — blue shade, 426 — yellow shade, 426 — oil, 236 — Application to wool, 453 silk, 456 cotton, 426 Alizarin, 425 — orange, 455, 456 — blue, 427 Alpaca, 27 Alum, 163 Aliiminate of soda, 175 Aluminium acetates, 164 — chloride, 173 — mordants, 157 — nitrate, 174 — oxalate, 174 — sulphate-acetates, 167 — sulphates, 157 — tartrate, 174 — thiocyanate (sulpho- cyauide), 172 — thiosulphate (hypo- Bulphite, 175 Amaranth, 376, 422 Ammonia, 241 Ammonium carbonate, 241 Amyloid, 6 Aniline black, 390 — g-rey, 387 Annatto, 355 Anthracene colours, 425 — green, 407 — violet, 406 Aathrapurpurin, 426 Antimony potassium oxalate, 242 tartrate, 242 Argol, 213 Assistants, 243 Auramine, 385 Aurantia, 401 Aureosin, 40'1' I I Aurin, 403 Auro-phenylene, 402 Azariu, 418 Azo blue, 419 Azo colours, 412 Azoflavin, 416 Azuro-phenyleue, 402 T3AEBEEET, 367 -^ Barium chromate, 211 Barlow's bleaching kieis, 79 Barwood, 340 — red, 341 Bastose, 20 Bengaline, 387 Benzopurpurin, 416 Bichromate of potash, 206 soda, 211 Black, Aniline, 390 — Bonsor's, 329 — Copperas, on wool, 327 — Lquor, 178 — on cotton, 319 silk, 333 wool, 323 Bleaching of calico, 75 cotton yarn, 72 linen cloth, 88 yarn, 86 silk, 118 wool, 112 Blooming, 197, 274 Blue, Alizarin, 457 — Alkali, 379 — Blackley. 379 — China, 379 — Cotton, 379 — Coupler's, 387- — Diphenylamine, 377 — Elberfeld, 387 — Ethyl, 377 — Ethylene, 397 — Fast, 379 — Fluorescent, 402 — Gentiana, 377 — Guemsev, 379 — Humboldt, 377 I — Imperial, 377 — Lyons, 377 — Methyl, 377 Blue, Methylene, 393 — N aphthol, 410 — Napoleon's, 405 — Navy, 379 — Neutral, SS9 — New, 390 — Nicholson's, 379 — Night, 379, 386 — Opal, 877 — Parma, 377 — Peacock, 384 — Prussian, 463 — Quinoline, 398 — Kaymond's, 465 — Resorcin, 402 — Eosaniline, 377 — Eoubaix, 387 — Eoyal, 463 — Serge, 379 — Soluble, 378 — spirit, 357 — stone, 222 — verdigris, 223 — Victoria, 386 — vitriol, 222 — Water, 379 Boiled-off liquor, 116,247 Boiling-off silk, 116 Bordeaux, 422 Brazilian cotton, 2 Brazilwood, 338 Brown, Bismarck, 413 — Cuinamon, 413 — Fast, 421, 422 — holland, 89 — Manchester, 413 — Manganese, 462 — Phenyl, 399 — Phenylene, 413 — Orchil, 418 Buff, IroB, 461 Burl dyeing, 468 pACHOTJDE LAVAL. ^ 459 Calcium acetate, 245 — carbonato, 242 Camwood, 340 Canarin, 460 Canelle, 413 Carbjnate of potash, Manufacture of, from raw wool, 40 Carbonising, 32 530 DYEING OF TEXTILE FABRICS. Cardinal, 376 Carmines, 196 Casein, 239 Cashmere, 27 Castor-oil as a mordant, 235 soap, 236, 444 Catechu, 368 — Experiments with,473 Caustic soda, 240 Cellulose, 4 Cerise, 375 Chalk, 242 Chemical theory of dye- ing, 145 ChemicMng, 83 Chemistry of retting, 16 China grass, 21 Chocolate, Alizarin, 453 Cholesterine, 38 wool, 323 — yellow, 461 Chrome-alum, 211 — hlacks on cotton, 321 Chi-omium acetate, 215 — chloride, 218 — mordante, 206 Alkaline, 219 — nitrate, 218 — -nitrate- acetate, 218 — sulphate, 214 sulphate-acetate, 217 — thiocyanate (sulpho- cyanide), 218 Chrysame'in, 420 Chrysamin, 419 Chrys6olin, 418 Chrysolin, 403 Chrysoidine, 412 Chrysoin, 418 Claret red, 422 Coccin, 404 -- New, 422 Coccinin, 423 Cochineal, 348 — crimson, 348 — scarlet, 349 Coerulein, 407 CodOla, 17 Collodion, 7 Colorimetry, 492 Colour acid and colour bases, 153 Colouring principles, 147 Comparative dye-trials, 493 C omplementary colours, 490 Compound shades, Dye- ing of, 489 Copper acetate, 222 Copper chloride, 223 — chromate, 211 — mordants, 222 — nitrate, 223 — sulphate, 222 — sulphide, 223 Copperas, 176 — hlack on wool, 327 Corallin, Eed, 403 — TeUow, 403 Cotton, Action of acids on, 6 alkalis on, 8 chlorine on, 11 colouring mat- ters on, 12 frost on, 6 lime on, 10 metallic salts on, 11 mildew on, 5 — Chemical composition of, 4 Cotton-hleaching, 71 — cloth - drying machi- nery, 267 — cloth -dyeing machi- nery, 260 — cloth -washing ma- chinery, 262 — Dead, 3 — dyeing, Notes on, 248 Operations, &c., in, 249 — Microscopic appear- auce of, 3 — Mordanting of, 150 — plant, 1 — Physical structure of, 2 — Sea Island, 2 — TJnspun, drying ma- chinery, 250 — tin spun, dyeing ma- chinery, 250 — TJnspun, washing ma- chinerj', 250 — yam drying machi- nery, 259 dyeing machinery, 250 washing machi- nery, 254 Crabbing, 111 Cream linen, 89 — of tartar, 243 Crocei'n, Brilliant, 423 — 3 Bx, 422 — Scarlet, 423 Cross-dyeing, 466 Crystal carbonate, 241 Cutch, Prepared, 370 Cyanosine, 405 "r)AHLIA, 377, 382 ■^ Dead cotton, 3 Dead wool, 30 Defects in indigo vats, 312 Dextrin, 7 Dip, The, 87 Dolly, 108 Drying-arrangement, Open-air, 282 Drying-machine, Cylin- der, 286 Hank, 259 Hot-air, 268 Loose wool, Mc- Naughfs, 277 Tenter, 287 Wool, Continuous, 278 Dunging process, 170 Dyeing, Irregulnr, 287 Dyeing - machine. Bo- den's hank, 252 Mather and Piatt's spiral, 261 — — Pitt's woollen yam, 280 Union cloth, 283 Warp, 253 Wilson's hank, 251 Winch, 282 WooUen yam, 279 tfiCEU silk, 119 -^ Egyptian cotton, 2 Elasticity of silk, 57 Emulsive oil, 234 Eosin, 404 — Methyl, 404 — Ethyl, 4^4 Erythrin, 404 Erythrosiu, 404 Experimental dye ves- sels, 483 — dyeing, 473 Experiments in mor- danting cotton, 479 wool, 480 — 'with colouring mat- ters, 478 Extracting, 32 FASTNESS of colours, 485 Fast and fugitive co lours. List of, 487 Ferric acetate, 191 nitrate, 192 INDEX. 531 Ferric cMoiide, 192 — nitrate, 191 suli)liate, 190 — sulphate, 178 — ^- acetate, 192 Ferrous acetate, 178 — chloride, 181 — nitrate, 181 — sulphate, 176 — thiosulphate (hvpo- sulpbite), 181 Fibroin, 63 Firing of tin spirits, 202 Fixing agents for moi*- dants, 239 — liquor, Purple, 179 Flavaniline, 397 Flavin, 363 Flavopurpurin, 426 Flax, 12 — breaking, 16 — Chemical composi- tion of, 19 — hackling, 17 — scutchiug, 17 — retting, 14 — line, 17 — plaut, 12 — Physical structure of. 17 — tow, 17 Fleece-wool, 30 Fluorescein, 403 Flurt silk, 51 Fugitive colours, 485 Fustic, Old, 359 — Young, 364 (^lALLEJtN, 406 ^-^ Galloc3'anin, 411 Gas bleaching, 112 — singeing, 77 Gelatin mordant, 239 Glauber's salts, 245 Glossing, 55 Glucose, 7 Glue as a mordant, 239 Grassing, 89 Greasy wool, 35 Grey, Aniline, 387 — sour, 80 — washing, 78 Green, Acid, 374 — Aldehyde, 396 — Alkali, 375 — Anthracene, 407 — Benzaldehyde, 373 — Benzoyl, 373 — Brilliant, 373 — Ethyl, 373 — Guinea, 375 Green, Helvetia, 375 — Ligbt, 375 — Malachite, 373 — Methyl, 383 — Naphthol, 402 — New, 373 Victoria, 373 — Solid or Fast, 373 — Victoria, 373 — vitriol, 176 Grenadine, 375 Gun-cotton, 7 XTAIE and wool, Dif- -"-^ ference between, 24 Hank -dyeing machine, Boden's, 252 Wilson's, 251 Hank- washing machine, Scotch, 255 German, 257 Hawking machines, 315 Helianthin,415 Heliochrysin, 401 Huile toivmante, 234 Hydro-cellulose, 7 extractor, 281 Hydrogen dioxide, 112, 114, 120 Hyposulphite of soda, 226 TNDIGO Carmine, 317 -^ —dyeing operations, 313 on cotton, 297 silk, 317 wool, 304 Theory of, 295 — extract, 317 on silk, 318 wool, 317 — grinding mills, 296 — hydrosulphite vat, 304 — lime and copperas vat. 297 — potash vat, 307 — soda vat, 308 — substitute, 325 — urine vat, 308 — vats, Defects in, 312 — woad vat, 303 — zinc powder vat, 302 InduUne, 387 Injector bleaching kier. 81 Iron alum, 193 — liquor, 178 — mordants, 176 Alkaline, 193 Iron, Nitrate of, 181 191 — Pyrolignite of, 178 Isocholesterine, 38 Isopurpurin, 426 JIGGER dyeing mor " chine, 262 Jute, 20 — bleaching, 21 KEMPS, 26 Keratin, 30 T AC dye, 354 ■^ Lactarine, 239 Lant, 92 Lead acetate, 224 — chromate, 211 — mordants, 224 — nitrate, 224 — Sugar of, 224 Level dj-eing, 276 Light, Influence of, on dyed colours, 485 Limawood, 488 Lime-boil, 78 — -sour, 80 Linen bleaching. Che- mistry of, 90 — cloth bleaching, 88 — Cream, 89 — fibre, 12 — yam bleacbing, 86 Liquid bleaching, 11 (• Llama-wool, 27 Logwood, 319 — blacks on cotton, 319 silk, 333 wool, 323 — blues on cotton, 323 wool, 331 — greys on cotton, 322 — pui-ples on cotton, 323 wool, 332 Loose-wool scouring, 94 Lut^cienne, 404 ^/r ADDER, 344 ^^^ —bleach, 75 Madras cotton, 2 Magdala red, 389 Magenta, 375 — Acid, 376 Magrma process, 101 jVlMgnaneries, 44 Mandarin S., 420 Manganese mordants. 225 Manganous chloride,225 Market-bleach, 85 532 DYEING OF TEXTILE FABRICS. Matching-off, 291 McNfiTight'swool scoTir- xng macliiiie, 100 Mechamcal theory of dyeing, 145 Mercerised cotton, 9 Metapectic acid, 19, 90 Metastannic acid, 202 Methods of vrool-dye- ing, 269 Milling, Influence of, on dyed colonrs, 451 Mixed fahries. Dyeing of, 466 Mohair, 27 Mono-genetic colouring matters, 147 Mordanting and dyeing method of wool-dye- ing, 270 — General methods of, 149 Mordants, 156 — Albumen, 237 — AlitminiTim, 157 — Casein, 239 — Chrominm, 206 — Copper, 222 — Glne, 239 — Iron, 176 — Lead, 224 — Manganese, 225 — Oil, 232 — Silica, 226 — Sulphur, 226 — Tannic acid, 227 — Tin, 194 Mulberry silt, 4i Mnllings' scouring pro- cess, 102 Muriate of tin, 195 -TSn-IGEOSINE, 387 ■^ Nitrate of iron, 181 tin, 199 yjtro-alizarin, 456 NiTro-ceUnlose, 7 Nopalin, 404 Notes on cotton dyeing, 248 silk, 294 wool, 269 /~\IL as a mordant, 232 " — Castor, as a noor- dant, 235 — Emulsire, 234 — Ohve, as a mordant, 234 — Snlphated, 234 Old Fustic, 339 Oleic acid, 233 OHve oil as a mordant, Orans-e- Alizarin , 455, 456 — o-Naphthol, 419 — /5-Xaphthol, 420 — Dimethyl-aniline, 414 — Diphenylamine, 415 — ex\T3., 420 — Gold, 415 — I., 419 — n., 43.0 — in., 415 — IV., 415 — G, 420 — N, 415 — Palatine, 401 Orchil, 3o5 Organzine silk, 4S, 50 Orseillin, No. 3, 421 Orer-chroming, 209 Overgrown wool, 30 Oxycellulose, 11 pEACHWOOD, 338 -^ Pectic acid, 4, 16 Pectine, 16 Peetose, 16 Persian berries, 366 Peruvian cotton, 2 Phenol colours, 398 Phloxin, 4i;J5 Phosphine, 386 Physic, 2-iJl Picric acid, 398 Piece-dyed goods, 289 Pigments, 147 Pink, Alizarin, 451 — cutting liquor. 201 — Napthalene, 3S8 — salt, 200 Pitchy wool, 38 Plat^e-singeing machine, 76 Poly-genetic colouring niatters, 78 Ponceau, 375 Potassium dichromate, 2;i6 — ferrocyanide, 243 — permanganate, 22? Pot-ejes, 78 Preparing salt, 204 Primrose, 400, 40i Primula, 3S2 Pro-argol, 244 Purple, Alizarin, 453 — Ethyl, 386 — Begina, 381 Purpurin, 426 Pyrohgnite of iroB, 178 Pyrosin, 404 Pyroxylin, 7 QUI^CITEON l«rk, 362 T)AMIE, 21 -^^ Eauracienne, 421 Raw silt, 43 — wool, 35 Red, Anisol, 423 — Barwood, S4l — Claret, 422 — Conzo, 416 — CoraUin, 403 — Fast, 422, 421 — French, 420 — Imperial, 404 — liquor, 168 Common, 169 Tin, 169 — ]ilag-dala, 3S9 — Neutral. 389 — Peonv, 403 — Phenetol, 423 Eeehng, 87 Eesin boil, 83 Setting of flax, 14 Eheea, 21 Eocelline, 421 Eosaniline colours, 373 Rose Beng-al, 404 — JB, 404 Eoseine, 375 »::^lane, 387 1" c acid colours, 403 E-ouge frangais, 420 Eouille, 182 Rubbing, 89 Rubeosine, 404 Rubidin, 421 Rubine, 375 OADDENING, 224 ^ Safflower, 356 SafEron yellow, 400 Safranine, 3S9 — and induline group of colours, 337 Saf rosin, 4C4 Sanderswood, 34d Sapanwood, 338 Saxonv blue, 317 Scald," The, 87 Scarlet, Biebrich, 423 — Brilliant, 422 — Cochineal, 349 — Crocein, 423 — Crystal, 422 — Fast, 423 -G.^O INDEX. 533 Scarlet GG, 421 — GT, 420 — Impei-ial, 423 — E, 420 — 2E, 421 — 3R, 421 — 4R, 421 — 5R, 423 — 6R, 422 — S, 423 — SS, 423 — Xylidine, 420 Scliappe-silk, 51 Scouring agents, 92 — of loose wool, 94 union goods, lOS woollen-cloth, IDS yarn, 102 Scroop, 53 Scutching of flax, 17 Seek, 94 Sericin, 64 Silica as a mordant, 226 Silicate of soda, 241 Silk, Action of acids on, 66 alkalis on, 67 colouring mat- ters on, 69 metallic salts on, o8 water on, 65 — Blacks on, 333 — bleaching, 118 — Boiled-off, 115 — Chemical coi^' ~v tion of, 62 — cocoon, 47 — conditionine, 59 — Culture of, 43 — dyeing — indigo, 317 — — Notes on, i:94 — Ecru, 119 — glue, 64 — lustreing, 57 — Microscopic appear- ance of raw, 46 — Mordanting bath for, 186 — Origin of, 43 — Physical properties of, 53 — Eeeling of, 49 — scouring, 115 — scroop, 63 — Souple, 117 — Squeezing machine for, 187 — Stretching of, 117 — Stringing of, 55 — washing machine, 189 J J Bilk weighting, 371 — Wild, 61 Singeing of calico, 76 Single -bath -method of dyeing, 273 Skying, 300 Soda, Caustic, 240 — crystals, 241 Sodium arsenate, 2tO ■ carbonate, 241 ^ -^ diclu-omate, 211 — hydrate, 240 — phosphate, 240 — sulphate, 215 — tetrasiUcate, 241 — thiosulphate, 226 Soluble glass, 211 — oil, i£6 Souple silk, 117 [261 Spix-al dyeing machine. Spirit, Amaranth, 198 — Aniline, 203 — Bar wood, 201 — Blue, 464 — Bowl, 199 — Cotton, 201 — Crimson, 201 — Finishing, 198 — Plum, 198 — Purple, 201 — Eoyal blue, 464 — Scarlet, 199 — Scarlet finishing, 198 — Yf llow, 198 Sprits, 89 Squeezing machine. Birch's, 266 for woollen cloth, 284 — rollers, 265 Stanuate of sorla, 204 Stannic chloride, 199 Stannous chloride, 195 — nitrate, 198 Staple of wool, 23 Steiner's process of Turkey - red dyeing, 438 Stoving, 112, 431 Stretching of silk, 117 — woollen-yam, 102 Stringing, 55 Stutliug and saddening method of dyeing, i:71 Su-ar of lead, 224 Suli)hated oil, 234 Sulpho-muriate of tin, 198 Sulphur as a mordant, 226 Sulphuric acid, 245 Sulphur stove, 113 Sun gold, 401 Super-argol, 244 Surat cotton, 2 Sweeteuing, 83 rpANNIC ACID as a -*- mordant and fixing agent, 227 Experiments with, 475 Tartar, 243 emetic, 242 — substitute, 244 Tartaric acid, 243 1 enacity of silk, 57 Theories of dyeing, 144 Thiosulphate of soda, 226 Tin composition, 201 — crystals, 195 — mordauts, 194 — Muriate of, 195 — Nitrate of, 199 — Nitro-muriato of, 201 — Oxymui-iate of, 2101 — salt, 195 — spirits, 197, 200 — spots, 352 — Sulpho - muriate of, 198 Tram silk, 48, 50 Tramping, 429 Tropaeohn D, 415 — G, 415 — 0,418 — CO, 415 — 000, No. 1, 419 — 000, No. 2, 420 — 0000, 420 — E, 418 — Y, 418 Turkey-red bleach, 85 clearing, 4j4 — — dyeing, Emulsion process, 427 oil, 236 stove, 441 — , Steiner's pro- cess, 43S , Sulphated oil process, 442 , Cahco-printer's process, 451 liquor-padding ma- chine, 440 — — oil -padding ma- chine, 439 — — jarn steaming chamber, 445 Turmeric 3G7 534 D.YEISG OF TEXTILE FABRICS. Taru-hankiiig, 90 Tussnr silk, 51 bleaching of, 119 TTinOX goods, Scour- ^ VDg Of, lOS Dyeing of, 467 Unripe c-otton, 3 Uranin, 403 TTACUTM bleaching ^ Ider. 81 Vat, Hydrosnlphite, 308 — FerroTLS snlphate, 297 — Potash, 307 — SO'ia, 303 — Urine, 303 — Woad, SOS — Zinc powder, 302 Yeriiigris, 223 Vesuvliie, 413 Vienna wool, 27 Vin^ar, 244 Violaniline, 387 Violet, Acid, 383 — Alkali, 3S3 — Benz vl-rosaniline, 3S3 — Crystal, 35d — Hofmann's, 332 — Imperial, 331 — Methyl, 352 — Naphthylamine, 396 — Neutral, 3S9 — Xew Fast, 411 — Paris, 3?2 — Parma, 351 — Perkin's, 3S7 — Phenyl, 381 — Eosaiiiline, 381 — Spirit, 381 Viridin, 375 TrrABP-DTEIX G ma- » * chine, 253 Wash stocks, 254 Washing machine, CalicrT, 263 German hank, 257 Scotch hank, 255 Square beater, 265 — of loose wool, 277 woollen cloth, 285 woollen yam, 281 Waste silk, 50 Wat*;r, Alkaline carbo- nate as imparities in, 127 — Calcareous and mag- nesian impurities in, 122 — , Correction and puri- fication of, 123 — purification, Clark's process, 131 Gaillet-Huet pro- cess, 134 Porter-Clark pro- cess, 133 — Fermginons, 126 — Organic impuritiea in, 127 — Peaty acids in, 127 — Soft and hard. 121 Weiehtin? silk, 371 Weld, 356' Whitening, 2i2 Whit-e-sour, 84 Wild silk?, 51 Woaded blacks on wool, 330 Woad-vat, 303 Wool, Action of acids on, 32 nTk-a.b"R on, 33 colouring mat- ters on, 34 heat on, 31 metallic salts on, 3i — analysis, 36 — Blacks on, 323 — Chemical composi- tion of, 30 — Conditioning of, 28 dyed goods. 289 — di.'eing. Methods of, 269 Operations in, 274 fat, 37 — -fibre, 30 Physical structure of, 24 — Lustre of, 29 — perspiration, 38 — Baw, 35 — scouring, 91 — -sorter, 24 sorter's disease, 27 — steeping, 95 i Wool, Varieties of, 22 j — Wash-water prc«iucta I of raw, 40 Woollen cloth dyeing I machinery, 254 squ-ezing, 284 drying, 283 scouring, 10^ — yam dyein^'. 279 drying, £84 scouring, 105 stretching, 102 washing, ^1 Wools, Foreign, 27 PhysicaJ proper- ties of, 27 — — Loose, Soouring of, 94 Worsted and woollen goods, 23 XAisTHOPBOTEIC acid, 32 YARN-dred goods, 289 Yellow, Acid, 4L4 — Aniline, 412 — Brilliant, 415 — Campobello, 400 — Fast, 414 — Fluorescein, — French, 400 — Golden, 400 — Imperial, 401 — Indian, 416 — Manchester, 403 — Martin's, 400 — Metaril, 415 — Xaphthalibe, 400 — Xaphthol, 4O0 — X, 415 — New, 401 Manufacture of, from raw wool, 41 — Quinoline, 395 — Eesorcinol, 413 — Saifron, 40J — S. Xaphthol, 400 — Victoria. 4(X) Tolk ash, 39 furnace, 98 — (of wool), 35 — solutions, 97 Young Fustic, 351 FETSTED BY CASSELX A5X» COMPAST, tTMITEB, LA BiXLE SAUYAGK, K.C. 10.996