m. i 97»4 Cornell University Library arV18532 The art of soap-making „ 3 1924 031 277 266 olin.anx Cornell University Library The original of tliis book is in tine Cornell University Library. There are no known copyright restrictions in the United States on the use of the text. http://www.archive.org/details/cu31924031277266 THE ART OF SOAP-MAKING THE AET OF SOAP-MAKING A PRACTICAL HANDBOOK ' 01? THE MANUFACTUEE OF HAED AND SOFT SOAPS, TOILET SOAPS, ETC. INCLUDING MANY NEW PEOOESSES, AND A CHAPTER ON THE RECOYBET OP GLYCEEINE FEOM WASTE LETS By ALEXANDER WATT AUTHOR 07 " ELECTBO-USTAIiLniiaT rBACTICALLT TBSATBD," ZTO. BTC. SSith S^umexoxts iUastrations LONDON CROSBY LOCKWOOD AND CO. 7, STATIONEES' HALL COTJET, LTJDGATB HILL 1S84 [All rights reserved] /^\ RNEi UN8VERSITY LIBRARY LONDON PKINTED BY J. B. VIUTUB ASD 00., LIMITBO CITY BOAD. PEEFACE. In compiling tiis took, the Author has endeavoured to fill a void in English technical literature. While almost every art is represented by treatises or handbooks of a more or less practical character, Soap-making, so far as the Author is aware, has not until the present time been furnished with a special book of reference f6r the con- venience of its numerous followers. In the United States, however, several elaborate treatises of foreign origin have appeared, and to these the author has been greatly in- debted for much valuable information, especially as regards the Continental methods of making ordinary soaps and toilet soaps, given by Dussauce, Oristiani, Ott, and Kiirten. An important feature in the present volume is the chapter on the Recovery of Grlycerine from "Waste Leys, in which many processes for recovering this valuable product are given. Although it would not have been possible nor even desirable to include every known process of soap-making, a great number of processes in an abridged form are given, which cannot fail to be useful to the manufacturer. To write an original work upon an art which has been VI PREFACE. built up, so to speak, by the ingenuity of the great host of inventors and patentees, would be an impossibility: the present work, therefore, must be accepted as an epitome of their collective processes and improvements rather than as an original treatise, and the Author trusts that in. his endeavour to produce a work which would be useful both as a practical handbook and a work of general reference, he may not have been wholly unsuccessful. CONTENTS. PAGE Inthodl'otion 1 OHAPTEE I. SAFONIFIGATION EXFLAINED. Chevreul's Theory — Liebig's Kesearches on Saponification . . 7 CHAPTER II. TEB SOAP FACTORY— ITS AFPASATUS AND AFFLIANGES. The Soap-pans — Morfit's Steam Series — The Ley Tanks — The Frames — "Wooden Frames — Iron Frames — Crutches — Steam Crutch — Various other Implements — Barring Apparatus . . . 16 CHAPTER III. MATERIALS USED IN SOAF-MAKING. The Fats and Oils — Olive-oil — Tallow — Lard — Palm-oil — Cocoa-nut Oil — Castor-oil ^-Bone-grease — Horse-grease — Kitchen-stuff — Oleine, or Tallow-oil — Fish-oils — Eesin, or Colophony — Ee- covered Grease or Torkshire Fat — The Alkalies — Caustic Soda — Potash — Silicate of Soda, or Soluble Glass — China Clay, or Kaolin — Sulphate of Soda, or Glauber's Salt .... 25 CHAPTER ly. CAUSTIC LEYS. The Ley Tanks — Method of Preparing the Leys . . . .32 vm CONTENTS. CHAPTEE V. MANUFACTURE OF HARD SOAFS. PACE Castile, or Olive-oil Soap — Pure Olive-oil Soap, or White Castile Soap — Marseilles Soap — French Marbled Soap — Notes on Mot- tling — French Formula) for Soaps — The Composition of Pure Olive-oil Soap — London Mottled Soap— White Curd Soap . . 36 CHAPTEE VI. MANUFACTURE OF SARD SOAPS— Cmtimed. Yellow, or Eesin Soaps — Continental Method — Dunn's Process — Meinicke's Process . . SS CHAPTEE VII. MANUFACTURE OF HARD SOAFS— Continued. Treatment of " Mgers " — Anderson's Process — Cocoa-nut Oil Soaps — Sturtevant's Process — French Cocoa-nut Oil Soaps . . .71 CHAPTEE VIII. MAKING SOAP BY TRE COLD PROCESS. Hawes's System — Making small Quantities of Soap — To prepare White Soap — Lard Soap by the Cold Process . . . .79 CHAPTEE IX. OLEIC ACID— SOAP FROM RECOVERED GREASE. Oleic Acid — Soap from Recovered Grease — Morfit's System of Soap- making — Oleic Acid Soaps — Kottula's Soaps — Instantaneous Soap ... 84 CHAPTEE X. CHEAPENED SOAPS. Dr. Normandy's Process— Silioated Soaps : Sheridan's Process — Gossage's Processes — Preparation of Silicate of Soda — Prepara- tion of Silicate of Potassa — Mixing Silicate of Soda with Soaps . 96 CONTENTS. ix CHAPTER XI. CEEAPENED SOAPS— Continued, PAGE Dunn's Process — Guppy's Process — Thomas's Process — Potato- flour in Soap — China Clay (KaoUn) in Soap — Douglas's Improve- ments— Fuller's Earth Soap— Davis's Process . . . .105 CHAPTEE XII. DISINFECTING SOAF. Chloridised Sanitary Soap — Bleaching Soap in the Pan — Pearlash added to Combined Soap — ^Lime Soap, by Lunge's Method . 112 CHAPTER Xin. SAPONIFICATION UNDER PMESSURE. Bennett and Gibbs's Process — Mr. G. W. Rogers's Process — New Process of Saponification — Gluten in Soap 117 CHAPTER XIV. VARIOUS PROCESSES. Kiirten's Process — Dumbarton's Process — Mr. Symons's Disinfecting Soap — Soaps made from Animal Kef use — Bemadet's Process — Villart's Process — CreveVs Process — Villaorose's Process — ^^Cut- ting Soap 123 CHAPTER XV. . MANUFACTURE OF SOFT SOAPS. Preparation of the Potash Ley — ^The Fatty Materials employed — Scotch Soft Soap — London " Crown Soap " — Eesin in Soft Soaps — Continental Methods 128 CHAPTER XVI, MANUFACTURE OF SOFT SOAPS— Continued. Belgian Soap — Russian Soft Soap — Gentele's Process — Jaoobson's Process — Soap for Silks and Printed Goods — Fulling Soap — ^M. Loch's Soft Soap ......... 136 CONTENTS. CHAPTEE XVII. MANUFACTTTRE OF TOILFT OR FANCY SOAPS. PAGE Apparatus for Be-meltiiig the Soap — Machine for Slicing the Soap — Ee-melting the Soap— Mixing Colouring Matters and Perfumes- Cutting the Soap — Stamping the Soap HO CHAPTER XVIII. MANUFACTURE OF TOIZET SOAPS— Continued. Eose Soap, or Savon a la Eose — Orange-flower Soap — Cinnamon Soap — Musk Soap — Bitter Almond Soap, or Savon d'Amandes Amferes — ^Windsor Soap — Brown Windsor Soap — Violet Windsor Soap — Savon au Bouquet — Savon a la Cannelle (Cinnamon Soap) — ^Almond-oil Soap — Marshmallow Soap — ^Vanilla Soap — Benzoin Soap 149 CHAPTER XIX. MANUFACTURE OF TOILET SOAPS— Continued. French System df making Toilet Soaps — Formulas for French Toilet Soaps — Savon de Guimauve (Marshmallow Soap) — Savon aux Fleurs d'ltalie — Savon de Crim^e — Savon de Palme — Violet ap (Yellow) — ^Vanilla Soap — Eose-leaf Soap — Savon h, la Marechale — Lettuce Soap — ^Amhergris Soap — Elder-flower Soap — Lemon Soap — Orange Soap — Glycerine Soap — Savonuettes or Washballs — Violet , Washhalls — Honey Savonnettes — Savon- nettes of Sweet Herbs — Savonnettes of Camphor — Savonnettes of Neroli — Savonnettes a la Vanille — ^Marbled Savonnettes — Savon- nettes au Miel (Honey Savonnettes) — Floating Savonnettes — Sand-Balls 154 CHAPTER XX. SOFT TOILET SOAPS. Kaples Soap, or Almond Cream— French Method— White Soft Toilet Soap— Powdered Soaps — Shaving Paste — Essence of Soap Essence de Savon Vienne — Essence de Savon Corinthe — Trans- parent Soap 165 CONTENTS. XI CHAPTEE XXI. MEDICATED SOAFS. PAGE Sir >H. Marsh's Sulphur Soap — Mercurial Soap — Medicinal Soft Soap — Antimonial Soap — Carbolic Acid Soap — Medicated Tar Soap — Tooth Soap — Liquid Grlycerine Soap — Bordtardt's Herb Soap — ^Arsenical Soap — A Soap for Washing Dogs — Turpentine Soap — Tar Soap — Black Soap — Various Substances introduced into Manufactured Soaps . . . • 172 CHAPTEE XXII. MISCELLANEOUS FROCESSES. Jennings's Processes — Levat's Process — Violet's Palm-oil Soap — Hampel's Shaving Soap — Mrs. Marriott's Process — Sawdust in Soap-^Lewis's Process — Borax Soap — Camphor and Ammonia Soaps — Mackay and Seller's Process — Petroleum Soap : Bastet's Process — Besson and Eemy's Process — Tardani's Process — Half- resin Soap — Mr. G. Payne's Process — Mr. Bankinann's Process — Mr. W. Jeyes's Process — M. Varicas's Process — Lorbui'y's Process — Cleaver's Terebene Soap — Scharr's Liquid Soap — Mr. Bichford's Process — Marking Soaps 176 CHAPTEE XXin. ALKALIMETET— METHODS OF DETERMINING TSE PER- CENTAGE OF REAL ALKALI IN COMMERCIAL SODA ASS, FOTASH, AND CA USTIO ALKALI. Mohr's Alkalimeter — Preparation of Test- Acid, or Standard Solution — Sampling Alkalies — The Assay — Normandy's Method — Test- ing Commercial Pearlashes — To determine the Percentage of real or anhydrous Alkali 188 CHAPTEE XXIV. METEODS OF ANALYZING OR ASSAYING SOAPS. Soap Assay — Eampel's Method of Assaying Soaps — ^D'Arcet's Method ^Kichardson and Watt's System 201 CHAPTEE XXV. PURIFYING AND BLEAOSING OILS AND FATS. Bleaching Palm-oil: Wktt's' Chrome Process — Eecovery of the Chrome — Bleaching Palm-oil with Chromate of Lime — Purifying xu CONTENTS. PAGE Oils— Dunn's Method — Justice's Method of Purifying and Bleaching Oils and Fats 208 CHAPTEE XXVI. SSCOVERY OF TSE GLYCERINE FROM WASTE OS SFENT LEYS. Young's Process — Payne's Process — Versmann's Process — O'Farrell's Process — Thomas and Fuller's Process — AUan's Process — Lawson and Sulman's Process— M. Victor Clolus's Jlethod— Benno, Jappe, and Co.'s Method 215 CHAPTER XXVn. MI8CELLANE0VS SOAPS. vSoap to be used in Cloth Manufactories — White Cocoa-nut Oil Soap — Dresden Palm Soap — ^Altenhurge's EeainSoap — Ox-gall Soap — Soouring-Balls — Borax Soft Soap — Borax Soap Powder — ^London Soap Powder 223 CHAPTEE XVIII. USEFUL NOTES AND TABLES. Pickling Soap — The Oleometer — Aluminate of Soda — To determine the Quantity of Resin ia Soap — Detection of llesiu in Soap — Cheap Almond Soap — ^Analyses of Soft Soaps— Potato-flour in Soft Soap — Saponification of Neutral Fatty Bodies by Soaps — Jellifying — Twaddell's Hydrometer — Causticising Soda — Soda Soft Soap — Half-palm Soap — Adulteration of Commercial Silicate of Soda — Soaps for Calico-printers — Fulling Soaps — Table showing Percentage of Soda in Caustic Ley at 60° Fahr. — Table showing the Percentage of Anhydrous Caustic Potash in a Ley at 60° Fahr. — Comparative French and English Thermometer Scales — Table showing the Specific Grravity corresponding with the Degrees of Baumg' s Hydrometer for Liquids denser thanWater — Table showing the Specific Gravity corresponding with the De- grees of Baume's Hydrometer for Liquids lighter than Water — Table of Essential Oils— Fusing and Congealing Points of Fats and Oils — Kiirten's Table, showing the Composition and Product of Soap by the Cold Process from Concentrated Ley and Mixture of Cocoa-nut Oil with Palm-oil, Lard, and Tallow — Boiling- points of some Volatile Oils— Boiling-points of Caustic Alkaline Leys— Table showing the Quantity of Ca,ustio Soda in Leys of different-Densities— Table of the Mechanical Power of Steam ; 228 THE ART OP SOAP-MAKING. INTRODUCTION. AccoKDiNG to the great Roman Hstorian, Pliny, the G-auls- were the original inventors of the art of soap-making— their best product being a combination of goats' fat and the ashes of the beech-tree. The Romans subsequently acquired a knowledge of the art, and eventually intro- duced it into Italy after their successful invasions of Gaul. In proof of the antiquity of soap as an article of com- merce, a soap-maker's shop has been discpvered in the ruins of Pompeii, and is still exhibited to travellers. Prior to the invention of soap, the ancients employed the. juices of certain plants as detergents, and also fullers'- earth, which was first spread upon the surface of their clothes, and then stamped in by the feet. By this means greasy matter was removed on subsequent scouring, the fullers'-earth having the property of absorbing grease to a considerable extent. Sometimes this earth was em- ployed as a cleansing medium in baths, and even up to the beginning of the eighteenth century this system was adopted in Rome by persons of the highest distinction. In the eighth century there were many soap manufac- tories in Italy and Spain, but it is a remarkable and interesting fact that nearly five hundred years elapsed ere soap manufacture was introduced into France and practised as an art by the Phoceans, an intelligent and industrious race, of Grecian and Egyptian origin. The first soap manufactories in France were established at Marseilles, a city surrounded with natural advantages of soil and climate for the production of all the crude mate- B 2 THE ART OF SOAP-MAKING. rials necessary for soap-making. The olive-tree, tlie fruit of -which yields a fixed oil in great abundance, flourished in the south of France, while the shores of the Mediterra- nean yielded an ample supply of maritime plants, from which crude soda was obtained by calcination, Marseilles, however, with all these advantages, was unable to produce sufficient material to meet the demands of her manufac- turers ; therefore, as time progressed, Italy furnished supplies of olive-oil, while Spain contributed crude soda, or barilla. The manufacture of soap in France was entirely con- fined to the combination of olive-oil and soda until the beginning of the present century, when palm-oil and cocoa-nut oil were also employed in the artj and subse- quently toilet, or fancy soaps, were introduced, and ulti- mately formed an extensive and important addition to the soap trade. The exact period at which soap was first manufactured in England appears somewhat uncertain,, but it was pro- bably in the fourteenth century, when it was chiefly made upon the French system, that is to say, with barilla (crude carbonate of soda) ; and some other manufacturers adopted a method practised in Germany, in which potash, followed up by salt, superseded the use of soda obtained by "the calcination of maritime plants. We find that the first patent for improvements in the manufacture of soap was obtained in 1622, by Messrs. Jones and Palmer, an abridgment of which is given below : "The misterie, arte, way, and means of makinge of hard soape, comonly called by the name of Venice or castile soape, without the vse of anie fire in the boyling or makinge thereof, and with a materiall comonly called, or known by the name of berillia, and The art, misterie, way and means of makinge of softe soape without the vse of fire in the boylinge and. makinge thereof." From the_ above period up to the present time, many patents for important improvements in soap-making have been taken out in England. INTRODUCTION. 3 Having passed through a long period of rude and un- scientific manipulation, the art of soap-making at last — namely, at the beginning of the present century — com- manded the attention of scientific men, and the world was startled first by Leblanc's splendid process for the manu- facture of soda from common salt, which process was practically developed in this country by the lato. Mr. James Muspratt, of St. Helen's, near Liverpool. The advantages of this invention are far beyond estima- tion, and although it has since been superseded to a certain extent by the ammonia process, it can never be forgotten that its introduction did more for. the soap and glass manufacturer than any other invention under the sun. The next great discovery, though not second in im- portance, was due to another French chemist — Chevreul — who raised soap-making from empiricism and rule-of- thumb guesswork to its present exalted position as a truly scientific art. With the rapid advance of chemical knowledge which followed the discoveries of Davy, Dalton, Chevreul, and other English and foreign chemists, the art of soap-making gradually improved, and many saponifiable substances were introduced from time to time, until, at the present day, the lengthy list includes oils and other fatty matters which were never dreamed of by our forefathers. It would not be incorrect, however, to say that up to forty years ago soap manufacture was generally conducted without any reference to scientific principles or chemical theories. Except in very rare instances, the aid of science was never consulted, and the operations were frequently carried on by persons abso- lutely void of even the rudiments of chemical know- ledge. Indeed, the manufacturers were so completely in the power of their soap-boilers that any attempt to recog- nise an improvement, by giving it a fair trial, was invariably opposed and frustrated by the so-called " prac- tical man." At the time we refer to, the prejudice against chemical interference, if we may so call it, was so great, that even scientific men of the highest ability 4 THE ART OF SOAP-MAKING. were spurned, and their attempts to improve tlie crude art were foiled in every possible way. There were, how- ever, a few exceptions to the general rule (of thumb), and several large firms — notably the firm of Benjamin, William, and Thomas Hawes, of Lambeth — who dared to admit the teachings of science within their portals. Not only did these manufacturers encourage improvements based upon chemical principles, but they also employed chemists in their works, who, furnished with a laboratory and appliances, soon converted the operation of soap- making into an art, in the proper sense of the term. The estimation of the actual amount of alkali in a given sample of soda-ash was determined by their own chemist, in many instances indicating a wide difference when com- pared with the analysis of the alkali-broker's chemist. All " goods " were subjected to examination by the soap- maker's analyst before purchase, and thus the intelligent manufacturer was protected from fraud and imposition, which gave him an incalculable advantage over his un- aided competitors. Although the great French chemist, Chevreul, had clearly explained the nature of the reactions which take place when fatty substances are treated with boiling solutions of caustic alkali, few soap-makers would venture to modify their antiquated system of manufacture by calling to their aid the man of science. The soap- maker's argument seemed to be : " My soap has a large sale, it yields a good profit ; what more can I require ? " If the chemist told him that he was liberating a large portion -of glycerine, which flowed away with liis waste leys into the river or sewer, instead of being recovered, and he was thereby losing a large sum annually, the soap-maker cared not, for he still had a good profit on his soaps. In 1836, the author's father, the late Mr. Charles Watt, patented his now well-known process for bleaching palm-oil by means of chromic acid ; but it was not until several years after that soap-makers "took up" the process and adopted it. So great was the prejudice against INTRODUCTION. 5 any and all improvement, that even a trial of tlie process was for a time rejected ; and when at last the trade were induced, after some of the more intelligent firms had become licencees under the patent, to give the process a trial, not unfrequently would the workmen put raw (that is, unbleached) palm-oil into the batch which had been operated upon, during the patentee's absence, so that their employers might denounce the demonstration as a failure. In at least one instance a trick of this kind was practised upon the author, who for many years conducted the opera- tion of bleaching palm-oil, on his father's behalf, ia London and the provinces. Referring to the importance of chemical knowledge in soap manufacture, Mr. William Hawes, in a paper which he read before the Society of Arts on the 28th of March, 1856, stated that 6,000 tons of tallow were converted into glycerine annually, causing a loss of about £180,000, and there is no doubt whatever that the whole of this waste could be avoided by manufacturing soap by the cold pro- cess, or at all events this valuable product should be recovered as hereafter described. At the present day, in most of the larger soap-works, the teachings of science are not only recognised, but an experienced chemist is engaged, under whose skilful guardianship the various operations are conducted. In some instances the sons of members of the firm have been properly instructed in chemical knowledge, and to them are instrusted the scientific details of this strictly chemical art. In some establishments, the principals, or at least one of them, have acquired suflieient knowledge of chemistry to enable them to conduct their operations miih a knowledge of what they are doing ; so that we may now say that at last science and soap-making go hand in hand, except in a few instances where the British workman is still looked upon as an idol. Another important feature in the manufacture of soap was the application of steam, and superheated steam, in place of the ordinary fire. Again, improvements were made in the machinery and appliances of the soap-works, '6 THE ART OF . SOAP-MAKING. amongst which may be noticed the substitution of cast- iron frames for the old-fashioned wooden ones, from which many a ton of soap leaked out before solidification took place ; the steam-pump superseded the ordinary ladle for fitted soaps ; the steam-crutch, in some works, supplanted the wooden or iron hand-worked implement, and (in America more especially) many mechanical contrivances have been introduced for diminishing labour and hasten- ing the operations of manufacture. To these may be added the long series of patented processes having for their object the cheapening of the manufacture by the in- troduction of certain substances which, without injuring the soap, enable it to be sold at a lower price to the con- sumer. The various processes will be fully described when treating of the manufacture of hard soaps. CHAPTER I. SAPONIFICATIOjy JEXPLAINED. C!h8vreura Theory. — Liebig's Researclies on Saponification. The combination of fatty matters with an alkali — as soda" and potash, for example — by the aid of water and heat, is the result of chemical action. It is not a mere com- bining of the substances in the ordinary sense, for we find, after their perfect imion has been effected, that the constituents of tallow, for instance [stearitie, palmitine, and oleine*), have undergone a remarkable change — each of these substances has acquired the properties of an acid. This important discovery was made by Chevreul, and when properly understood the practice of soap-making becomes not only more certain in its results, but infinitely more economical. Chevrenl's Theory. — Chevreul discovered that when soap was decomposed by an acid, the fatty matter which thus became separated or set free, possessed properties entirely different from the original substance. When melted, it reddened litmus paper ; it was freely soluble in warm alcohol, and was capable of forming salts, like ordinary acids. When a solution of carbonate of soda was added to the separated and saponified matter, soap was agaia formed, while a third substance, possessing a very sweet taste, remained in the " mother liquor," which was found to be glycerine. The gifted chemist thus proved that soap made from tallow was in reality a cqpipound of stearate and palmitate of soda, and thatglycerine was set free during the process of saponification, which substance, being soluble, remained in the waste or spent leys, and eventu- * The liquid constituent of tallow was generally termed oleine until more recent research proved it to be a compound of palmitine and oleine. 8 THE ART OF SOAP-MAKING. ally found its way into the sewer, or river, as the case might be. The acids liberated during the process of converting fats and oils into soap are called "fatty acids," those obtained from tallow being chiefly stearic and palmitic acids. Olive-oil and other soft fats yield on sapobification oleic acid. Palm-oil yields a mixture of palmitic and oleic acids; and cocoa-nut oil furnishes palmitic, oleic, and lauro-stearic acids. Soap, then, is a compound of fatty acids combined with alkali and water. Other substances, however, besides oils and fats are employed in soap-making ; for example, resin, a - compound of several vegetable acids, is used, with tallow, to form yellow soap. Metallic soaps, as they are called, are produced by boiling oxides of metals with oils or other fatty matters. Diachylon-plaster, which is formed by boUing litharge (oxide of lead) with olive-oil and water, is an insoluble soap composed of oleate and margarate of lead. The glycerine formed during the process remains with the water. Soaps are divided into iwo principal classes, namely Hard and Soft Soaps. The former are produced by combining soda and water with fatty matters, and the latter are made with potash combined with horse-oU, fish, and other inferior oils, and hence these are sometimes dis- tinguished as soda soaps and potash soaps. Hard soaps are of various kinds, the most important being Castile Soap, White Curd, Mottled, Yellow, and Transparent Soap. These soaps are combinations of tallow, palm-oil, cocoa-nut oil, olive oil or other fatty substances with caustic soda — that is, soda deprived of its carbonic acid by boiling with fresh lime and water. When tallow is boiled for a considerable time in a solution of caustic soda (or ley, as the solution is called) the fatty matters, stearine and palmitine, assume a granular or curd-like appearance, entirely losing their greasy and oily character ; and if a small portion be pressed between the folds of a piece of paper it. will not produce a greasy SAPONIFICATION EXPLAINED. 9 stain. This is proof that the conversion of the fatty sub- stances into stearate and palmitate of soda is complete — that the mass is saponified, in fact. If the boiling has been suflB.cient, and an excess of caustic alkali remains in the ley, this will subside,- and the soap, after being allowed to repose for a short time, will appear on the surface. It now a small portion be treated with warm alcohol, it will readily and entirely dissolve, forming a transparent solu- tion of soap. After expelling the alcohol by evaporation, the transparent soap will remain, which on cooling wiLL assume considerable hardness. In saponifying the various fatty matters employed at the present time in soap manufacture, and which differ greatly in their composition, much care is exercised as to the strength of alkalme ley used in the first and subsequent operations of boiling. If the ley be too strong, its superior density will retard its free diffusion through the mass of fatty matter. It is commonly the practice, there- fore, with tallow soaps, to apply caustic ley of a moderate strength at first, and when this has become exhausted or " spent," as it is termed, it is pumped out of the copper or pan, and a fresh charge of ley of superior strength given, and the boiling continued until the grease or fat is " killed " or neutralised by the alkali. During the boiling glycerine is liberated, and this substance, being soluble in water, subsides with the ley. Until recently, the exhausted leys were allowed to flow away as a waste product ; at the present time, however, the glycerine is usually recovered by one or other of the various processes fully described in Chapter XXVI. It is well known that caustic ley acts differently upon the various fatty bodies with which it comes in contact. For example, a weak ley will act upon tallow until its alkali becomes exhausted, or nearly so ; whereas a ley of equal strength wiU scarcely, if at all, saponify cocoa-nut oil. When, however, cocoa-nut oil is blended with other fatty substances, it will readily become acted upon by weak leys. Again, resin, although it is readily converted 10 THE ART OF SOAP-MAKING. iato soap by treatment with alkali, will not form a hard soap unless combined with a certain proportion of tallow, which, during the process of saponification, exerts a powerful influence upon its constituents, probably by chemical action not yet fully understood. Iiiebig's Besearcbes on Saponification. — Justus Liebig — to whose original mind we are indebted for so many valuable discoveries in organic chemistry — ^made some important researches on the saponification of fatty bodies, and his views should be well .understood by the soap- maker who recognises the value of scientific knowledge in the pursuit of his interesting art. "Potassa and soda soaps," says Liebig, "are readily soluble in hot water and alcohol. The addition of a quantity of water to the aqueous solution produces precipi- tation, the neutral salts of stearic and margaric acid decomposing into free alkali, which remains in solution, and stearate and margarate of the alkali (potash or soda), which precipitatfes in the form of pearly crystalline scales. Potassa soaps are more soluble in water than those con- taining soda. Stearate of soda may be considered as the type of hard soaps, and when in contact with ten times as much water it undergoes no striking change. Stearate of potassa forms a thick paste with the same quantity of water. Oleate of soda is soluble in ten parts of water, while oleate of potassa dissolves in four parts of water, forming a gelatinous mass with two parts, and possesses such a strong affinity for water that 100 parts absorb 162 parts in a moist atmosphere. Margaric acid acts like stearic acid. From this it follows that soaps are soft in proportion to the oleates, "and hard in proportion to the stearates and margarates, they contain. Soda soap exhibits a peculiar behaviour with common salt ; it loses the power of being penetrated by ley or dissolving in a solution of salt of a certain strength, and this remarkable action is an important condition in its manufacture, on which depends the separation of all free alkali and oxide of glyceryl (glycerine), its percentage of water, and its marketable condition. SAPONIFICATION EXPLAINED. ii " If a piece of common hard soap be cut into pieces and then put into a saturated solution of salt, at the ordinary- temperature, it floats on the surface without becoming moistened, and if heated to boiling, it separates into gelatinous flocculse, which collect on the surface, and upon cooling unite into a solid mass, from which the solution flows off like water from grease. If the flocculss be taken out of the fluid, they congeal on cooling into an opaque mass, which may be pressed between the fingers into fine laminse without adhering to them. If the solution of salt be not quite saturated, the soap takes up a certain quantity of the water, and the flocculfe separate through the fluid in boiling. But even when the water contains -3-5^^^ of common salt, boiling produces no solution. " If the soap be boiled in a dilute and alkaline solution of salt, and allowed to cool, it again collects on the fluid in a more or less solid state, depending on the greater or less concentration of the solution — that is, on the quantity of water taken up by the soap.. Bv boiling the dilute solu- tion with soap for a considerable time, the watery flocculse swell up, and the mixture assumes a foaming appearance ; but they still are undissolved, for the solution separates from them. The flocculse, however, have become soft and pasty, even when cold, and their clamminess is due more or less to the quantity of water they have taken up. By continued boiling this character again changes, and in proportion as the evaporation of water renders the solution more concentrated, the latter again extracts water from the flocculse, the liquid continues to foam, but the bubbles are larger. At length a point is reached when the solution becomes saturated ; but before this, large iridescent bubbles are observed to form, and in a short time all the froth disappears, the liquid continues to boil without foam, all the soap collects in a translucent mass on the surface, and the solution and soap cease to attract water from eacb other. If the plastic soap be now removed and cooled while the solution is pressed out, it will have become so solid as scarcely to receive an impression from the finger. In this condition it is called grain soap. 12 THE ART OF SOAP-MAKING. "The addition of salt, or a solution thereof, to a con- centrated alkaline solution of soap in water, precipitates the soap in gelatinous flocculae, and the mixture behaves precisely like solid soap boiled with a dilute solution of salt. Carbonated and caustic potassa act exactly like salt, bj' separating soap from the alkaline fluid (ley) in which it is absolutely insoluble." These observations, so carefully made and clearly ex- plained, cannot fail to be of the greatest value to the manufacturer of a commercial article so important as soap, and which, at the present day, is made from such a great variety of fatty materials, each requiring a different treat- ment for its skilful and economical conversion into soap. Continuing his observations, Liebig says, " The application of the above to the manufacture of soap is evident. The fat is kept boiling in an alkaline ley until all pasty matters disappear, but the ley should have only a certain strength, so that the soap may be perfectly dissolved in it. Thus tallow may be boiled for days in a caustic potassa ley of the specific gravity of 1"25° without saponifying. If the ley be stronger, a partial saponification takes place, but, being soluble in the fluid, it floats upon the surface as a solid mass. By the gradual addition of water and con- tinued boilings, at a certain point the mass becomes thick and clammy, and with more water a kind of emulsion is formed, which continued heating renders ;^erfectly clear and transparent if a sufficient quantity of alkali be present. In this state it may be drawn into long threadg, which on cooling either remain transparent, or are more milky and gelatinous. As long as the hot mass, when it drops from a spatula, exhibits cloudiness or opalescence, the boiling is continued or fresh alkali added. When excess of alkali is present the cloudiness arises from imperfect saponification or insufficiency of water: the former is seen by dissolving a little in pure water, which becomes perfectly clear when the whole is saponified. If the ley contains lime the mixture is also clouded, but the addition of carbonated alkali instantly clarifies it'. " In order to separate the soap from water, free alkali. SAPONIFICATION EXPLAINED. . 15 and oxide of glyceryl, a large quantity of salt is gradually added to the boiling mass, on each addition waiting until it is dissolved. The first addition increases the consistency of the mass, while each successive portion renders it more fluid, till it loses its threading character, and drops from the spatula in short, thick lumps. As soon as the conge- lation is complete — that is, when the gelatinous flocculss separate froma clear watery liquid — the fire is extinguished, the soap allowed to collect on the surface, and cooled either on the liquid or ladled out and allowed to solidify. In the former case it is impure from water, free alkalies, or other impurities of the ley, and is therefore unfit for the market, although sufficiently good for domestic use. As in other chemical operations a precipitate is purified by boiling it in a fluid in which it is not soluble, so is soap purified by a solution of salt rendered alkaline. " When the saponified fluid is made with potassa, the salt (chloride of sodium) operates in a two-fold manner : it dissolves in the pasty liquid and decomposes, forming on the one hand chloride of potassium, and on the other soda soap. When potash ley is employed in soap-making, the first salting requires more than twice the quantity of salt. In the preparation of potash soaps, a concentrated potassa ley is employed for separating the soap. The saponification of fats is not completed by the first treat- ment with leys, and the subsequent addition of fresh leys, besides purifying, also renders saponification more perfect." It must be obvious, on perusing the above remarks of the great German chemist, that the first duty of the soap- maker is to make himself thoroughly conversant with the principles of saponification, and not to rely solely upon his own observation. The soap-boiler, be he ever so skil- ful and observant — and there are many such — should avaU himself of such important information as is conveyed in the above lucid and practical observations. It will be seen that the combination of alkali with fatty matter is not by any means a rapid process, but is the result of slow and gradual chemical action, during which 14 THE ART OF SOAP-MAKING. considerable heat is generated over and above the actual temperature of the materials when placed in contact. Although saponification is hastened by the process of boiling, it is not advisable to applj' vigorous boiling in the earlier stages of the operation. On the contrary, it is found better in practice to allow the boiling to be gentle at first, and to increase its rapidity toward the close of the operation, or when the materials have absorbed their full percentage of alkali. Although it is practically impossible to make soap with- out liberating a portion of the fatty matters as glycerine, this soluble substance may be recovered, as a valuable by- product, by either of the processes hereafter described. The proper strength of leys, their gradual combination with the various fatty bodies with which they come in contact, and the slow and gentle augmentation of the boiling operation while saponification is progressing, are im- portant considerations, upon which too much care cannot be bestowed. Indeed, it is gratifying to know that of late years some of our leading soap-makers have devoted much attention to alkalimetry, and the treatment of various fats and oils with alkaline leys of appropriate strength, according to the nature of the fatty matter to be used. The examination, by analysis, of samples from various boils of soap enables the manufacturer not only to regulate his mode of working, but also to determine the intrinsic value, so to speak, of his productions. In making what are called " fitted soaps," the ingre- dients are boiled into a thin liquid mass, or emulsion, during the first operation, after which a second dose of ley, as also a considerable quantity of common salt, are introduced into the pan for the purpose of " cutting the pan," as it is termed, by which the soap separates, from the ley and salt, and rises to the surface, while most of the impurities and foreign matters subside with the ley. If the materials are not sufficiently saponified and purified, the ley is pumped out and fresh ley introduced, with further boiling, and the mass is again "cut," or separated, by the addition of weaker ley and salt, the operation SAPONIFICATION EXPLAINED. 15 being repeated, if necessary. The application of common salt not only promotes the separation of the saponified or semi- saponified matters from existing impurities and the exhausted alkaline ley, but it also, by its density, facili- tates their subsidence. Moreover, the presence of salt in the ley doubtless enables it to acquire a higher tempera- ture during the subsequent boilings, and thus hastens the evaporation of water from the saponified materials. CHAPTER II. TSE SOAP FACTORY— ITS APPARATUS AND APPLIANCES. The Soap-Pans. — Morfit's Steam Series. — Ley Tanks. — Frames. — Wooden !Frames. — Iron Frames. — Crutches. — Steam Crutch. — Various othet Implements. — Barring Apparatus. "When we consider the magnitude of the operations con- nected with the art of soap-making, and the large quanti- ties of soap annually produced by our numerous manufac- turers, we cannot help reflecting upon the comparative simplicity of the apparatus and utensils employed at an ordinary soap-works. A series of iron pans or coppers, set in brickwork, with firegrate below, or steam-pipes passing into the interior of each pan ; a series of wooden or cast-iron frames to receive the finished soap ; sundry pails or buckets, shovels and trowels; iron pumps and "shoots" for removing waste or spent leys; a few hydrometers and thermometers ; tanks for preparing caustic alkali; wheelbarrows and trollies for conveying materials ; " swimmers " and ladles of various kinds ; " crutches " and stirrers ; a wooden machine for cutting soap into bars, with ihe usual firing tools, form the chief requirements of an ordinary soapery. In some of the more extensive works, however, many mechanical improvements have been introduced, which will be referred to in the following pages. For the present we will endeavour to demonstrate the requirements of a soap factory of moderate dimensions, in which advaniage has been taken of some useful labour-saving appliances, as also of the application of steam, in place of fire, in the operations of soap-boiling. APPARATUS AND APPLIANCES. 17 The Soap-Fans were generally made of cast-iron, with a flange round the upper surface. These pans are concave at the bottom, and are fitted with steam-pipes which terminate in a perforated coil which rests on the bottom of each pan. The pans are set in brickwork, and an iron pump for removing the finished soap and leys is fixed between each pair of pans. This pump is worked by steam, and is connected to two movable arms of broad iron tubing, one of which rests in each pan. These tubes are raised or lowered by means of a chain and pulley, so that they may be allowed to dip into the soap to any required depth, or into the ley beneath it. The pump can empty the contents of one or both pans at the same time. The pans project about three feet above the floor, which enables the soap-boiler and his assistants to manipulate them with perfect ease. Each pan is fitted with an iron lid, or with a wooden lid covered with sheet-iron. The lids are lowered or raised by a chain and pulley. The soap-pan or copper (or as the French and Ameri- cans term it, kettle), is sometimes made of cast-iron, in several divisions, imited together by iron cement, the lower portion, or pan proper, being of a concave form, the whole being sfet in brickwork, which is so constructed that the fire plays only upon the lower part of the pan, and not upon its sides. Soap-pans of large dimensions are generally made of wrought-iron plates riveted together. The soap-pan is sometimes extended by placing what is termed a curb above its upper rim, which is made of stout sheet- iron, or of wood bound with iron. The object of the curb is to prevent the overflow of the soap during the more vigorous operation of boiling. Sometimes (when steam heat is employed) stout blocks of wood are placed round the flange of the pan instead of employing the curb. Morfit's Steam Series. — The accompanying engraving (Fig. 1) represents" a'steam series designed by Mr. Morfit. Although not so simple as the arrangement previously de- scribed, it is an ingenious system, and might be adopted with t8 THE ART OF SOAP-MAKING. advantage. The three pans represented may be employed, if preferred, for boiling three different kinds of soap — namely, one for white or curd soaps, another for yellow or resin soaps, and a third for superior soaps, w is the boiler, to which the main pipe or feeder g is connected. The boiling-pans, which are of iron, are each fitted with a wooden curb A A, hooped round by iron bands. The Fig. 1. lower part of each pan b is of cast-iron. Connected to the bottom of the pans is a pipe and stop-cock i, for drawing off the spent leys, h h is a downward pipe for conveying the steam to the coU, which terminates in a vertical length of piping X for the escape of waste steam. The taps h h are used for turning the steam on or off. A " blowpipe " L is connected to the maia pipe g. This blowpipe terminates ia a single coil perforated with a number of holes. The object of the blowpipe is to give additional heat, when necessary, and to assist in stirring up the con- tents of the pan. The tap p is used for regulating the pressure of steam from the boiler w. Steam-jacket pans, especially for small operations, are very useftil in a soap factorj-, and are admirably suited for APPARATUS AND APPLIANCES. 19 remelting, in the preparation of fancy soaps. Such pans are much used in dissolving silicate of soda, sulphate of soda, and other materials employed in cheapening soaps. The Ley Tanks, containing caustic alkali of Tarious ascertained strengths, are sometimes placed at one end of the series of soap-pans, and at a suitable height above them, so that the lej'^s may be conveniently run oflf by iron shoots into each pan, by turning the tap connected to either tank. These tanks are commonly made of wrought iron plates riveted together. The Frames for casting the finished soap are now generally made of cast-iron plates, united by movable bolts and screws — the ends and' sides of which fit into an iron base. These frames generally hold about 11 cwt. of Wooden Frames, which formerly were used for all varieties of soap, are now chiefly used for mottled soaps, which are required to cool slowly in order to acquire the agreeable marbled appearance for which they are famed. These wooden frames are furnished with pegs and holes, so that they may be piled one above another, and form, as it were, one deep frame or well, ca- pable of holding a considerable quan- tity of soap. In- deed, sometimes these frames are built up, through several floors, to a great height, form- ing a receptacle for an entire boil of m.any tons of soap. Sometimes the frames are bound together by long iron screwed rods which pass down through them. Iron Frames.— The engraving (Fig. 2) represents an a FiS. 2. THE ART OF SOAP-MAKING. iron frame partly screwed up ; Fig. 3 is a single wooden frame, and m Fig. 3. m Fig. \^4 several woode% frames are slio%n con- nected £sY their Degs t^pch other. "^"^ nterior m widtf frai s> ^ c \^ ^ \ \^ ^ : \^ ^ . > ^ r A corre- Vj the 1 a bar and the f a frame to the Kg. 4. sponi lengt of length is equa_ - - thickness jof about twenty loars of so^. i "When it is desirable to adM to true soap oth^r substances, abr the purpose of cheapening oT modifying it for various special purposes, the d^ditional matter is frequently introduced by being " crutched' in," as it is termed. For this purpose cer- tain tools called " crutches " are employed. These are made * of wood or iron, or of iron with a wooden handle. Two forms of these are given in Figs. 5 and 6. Steam Crutch A far more effective way of mixing other ^substances (as silicate of soda for example) with soap is by means of the steam crutch and crutchmg-pot, by aid of which a perfect incorporation of Fis. 6. APPARATUS AND APPLIANCES. the materials is effected, 'witHout manual labour, in a few minutes, and the soap thus treated is much more uniform than it is possible to become if hand-crutched in the frame. The arrangement for steam crutching may be thus briefly described : — A wooden platform is erected about ten feet above the floor of the boiling room near the soap-pans ; in this a small pan is set for containing the liquid materials to be added to the soap, and which receives the required charge of liquid for a frame of soap. By the side of this platform, and connected to a shaft above, is a vertical revolving spindle, furnished with several flat steel blades (Fig. 7) fixed alternately and in an angular direction. This revolving spindle or "steam crutch" is raised or lowered by means of a rope and pulley. When required for use, the crutching pot is- wheeled up to and immediately beneath the crutching spindle, the wheels of the " pot " being placed in grooves or hollows in the floor. The pot having received a supply of soap, the quan- tity of which has been duly gauged by a notched stick, the steam crutch is lowered, and sinks into the soap, re- volving with considerable rapidity. The contents of the little pan are now allowed to flow into the pot, and soon after the required qtiantity has been crutched in, the revolving shaft is stopped, and the crutch raised out of the pot, which is then wheeled away to make room for a second pot, and is then drawn up close to a frame, and its contents allowed to pour out by raising an iron gate situated near its base. Fig. 8 represents the crutching pot with its gate A raised by the lever B ; and at Fig. 7 is a drawing of the steam crutch, in which its several blades are shown. The. bevel wheels above indicate its connection with the usual shafting. In small works, where steam is not extensively Fig. 7. 22 THE ART OF SOAP-MAKING. employed, waste leys are pumped from the soap-pans by iron hand-pumps, which are lowered into the pans by means of a chain or rope. Fig. 8. Various other Implements are employed in the soap- boiling department ; these are the trowel (Fig. 10), the ladles (Figs. 11 and 12), the " swimmer " (Fig. 13), and various broad shovels and iron " shoots " (Fig. 9), the /L ^ "I^Z. Fig. 9. latter being used for conveying leys and soap to and from the pans. Besides these, however, wheelbarrows and Fig. 10. Fig. 11. troUies are used for conveying materials, such as casks of fatty matters, resin, and other goods. APPARATUS AND APPLIANCES. 23 One of the most important, and at the same time most disagreeable, operations connected with a soap-works is that of making the caustic leys. This is generally conducted in a building at a convenient distance from the boiling room, and in such a situation that the lime- waste resulting from Fig. 12. Pig. 13.. the operation can be readily removed to a part of the adjacent ground where it will be out of the way. The soda and slaked lime employed in the production of caustic soda are, with the necessary addition of water, boiled toge- ther by means of steam, and the resulting ley, after subsi- dence of the carbonate of lime, is pumped out or drawn off into tanks ready for use. Barring Apparatus. — The ordinary apparatus employed for cutting soap into bars con- sists of a wooden machine run- ning upon wheels (Fig. 14)- A back of stout timber pro- jects several feet .above the grooved table a, upon which the slabs of soap are piled, and are kept in position by the upright back, b. Two men, provided with a length of brass or steel wire looped at each end, take their stand at the machine, and first mark the width of the bars by means of the toothed gauging stick (Fig. 15), which, being drawn Pig. 14. 24 THE ART OF SOAP-MAKING. evenly downwards, marks each slab as a guide for the cutting wire. Each man now takes one end of the wire, VWW\AAAAAAAAAAAA/W\AA/v\/WWWW\/ Kg. 15. and passes a wooden handle through the loop. The wire is then placed in the notches made by the gauge, and is then steadily drawn downward until it sinks into the groove beneath. One of the men now removes his handle from the loop, and the other draws the wire through the groove and returns the end of the Tifire to his mate, the same operation being repeated until the entire number of slabs are cut. The bars of soap are then removed, and a fresh batch of slabs placed upon the machine. Bars of soap are usually about 14^ inches long by 2\ inches thick, and 2§- inches in width. In some factories cutting machines are used which will cut into bars a considerable number of slabs at one time. This machine consists of strong wooden framework with wrought-iron fittings, and a series of steel wires fixed at equal distances. Although this machine is capable of cutting a great number of bars by a single movement, the wires are very liable to break, and this frequently causes delay while the broken wires are being replaced. The machine, however, is a very time-saving one when in good order. CHAPTER III. MATERIALB USJED IN SOAP-MAKING. The Fats and Oils.— Olive-oil. — Tallow.— Lard.— Palm-oil— Cocoa-nut Oil. — Castor-oil. — Bone-grease. — Horse-grease. — Kitchen-stuff. — Oleine or Tallow Oil. — Fish-oils. — Eesin. — Recovered Grease. — Tlie Alkalies. — Caustic Soda. — Potash. — Silicate of Soda. — China Clay. — Sulphate of Soda. The Fats and Oils. — ^From the period when the prin- ciples of saponification began, to be understood by soap- makers, the employment of other than the ordinary soap materials commanded attention ; and, aided by the in- vestigations of chemists, the manufacturers gradually ' added to their list of fatty, or saponifiable, matters, until, at the present time, any material that will form soap is worked up in some way or other. Olive-oil, as we have shown, formed the basis of con- tinental soaps prior to the art being introduced into England. This oil is expressed from the fruit of the olive- tree, and Gomes into the market in three different con- ditions : the finest, or virgin salad-oil; an inferior kind obtained by greater pressure of the berries with the aid of boiling water, and a third quality obtained by boiling the residuum with water. It is the latter variety which is more commonly employed in soap-making. When olive-oil is lowered to the temperature of 38° Fahr. it begins to congeal, and at 20° it separates into two distinct substances, elaine, or oleine, which is fluid, and margarine, a solid pearly substance. Margarine is not a true chemical compound, however, but is a mixture of stearine and palmitine. The proportions are (about) 72 per cent, elaine, and 28 per cent, mar- garine. Olive-oil is frequently adulterated with poppy and other oils. These are distinguished by not congealing at the same temperature as olive-oil, and also by retaining 26 THE ART OF SOAP-MAKING. air, when shaken up, more readily than pure olive-oil. I£ 5 per cent, of any other oil be present, the consolidation is slower and less firm, but if 12 per cent, of foreign oil be mixed with it, this floats on the surface for several days. Oils of poppy, sesame, rapeseed, or cocoa-nut may be thus recognised when mixed with olive-oil. Tallow is chiefly obtained from the fat of sheep and oxen, the taUow being first rendered, as it is technically called — that is, separated from the membranous matter with which it is associated in the form of suet. The rendering of tallow is accomplished in various ways : by first re- ducing the suet to small pieces, and then passing a current of steam through it by means of perforated piping, or by the method patented by the late Mr. Charles Watt, in 1836, which consists in adding to the fat, while in the steaming tub, dilute sulphuric acid, to which a little nitric acid is added, and a small quantity of bichromate of pot- ash. When the lumps of fat are nearly dissolved, about one pound of nitric acid, diluted with one quart of water, is poured into the tub, followed, shortly after, by about two ounces of alcohol, the whole being briskly stirred in. When this process was first introduced, for the operations of the taUow-melter, it was found that candles made from the tallow, thus treated, required no storing, as it was termed. In those days candles were frequently stored for several months before being considered fit for lighting purposes. The object of the process was to destroy the tissues sur- rounding the fat, which steam alone did not accomplish. London, or " town," tallow is generally considered the. best material of its kind, but E.ussian, South American, and, in later years, Australian taUows enter the market in large quantities. Fats or greases of various kinds, other than tallow, are also largely employed in soap-making. Lard, or the fat of hogs, is extensively used, especially by the French, in the manufacture of soaps. According to TJre it is composed of 62 parts of oleine and 38 parts of stearine in 100 parts, and its fasing point is 81° Fahr. Palm-oil, which is stated to be used more extensively MATERIALS USED IN SOAP-MAKING. 27 by English soap-makers than any other fatty material, is obtained from the fruit of Elais guineaensis, and E. melano- cocca, species of palm- trees growing on the west coast of Africa. The oU. as it comes into this country is of a deep orange- red colour, due to the mode of its extraction from the fruit — from which no doubt the colouring matter is derived, since the oil itself is nearly colourless. This valuable veget- able fatty matter, which it would be more correct to term butter than an oil, is composed of about 30 parts of a solid substance called palmitine, and 70 parts of a fluid, elaiim or oleine. It is solid at ordinary temperatures, but fuses, or melts, at 117-5 Fahr. By exposure to the aii- it turns rancid and loses its characteristic red colour. The process of bleaching palm-oil by chromic acid will be fully described in a future chapter. Cocoa-nut Oil is derived from the fruit of Cocos nudfera. Like palm-oil, it is solid at ordinary tempera- tures, and is a pure white, and of a buttery consistence. It is extensively used in soap-making — especially for the inferior kinds of soap, and will bear a large admixture of water, in combiaation with silicate of soda and other sub- stances, and yet form:- a hard soap. All soaps made with even a small percentage of cocoa-nut ofl. impart an offensive smeU. to the skin after washing with it. This oil is very extensively used in the manufacture of artificial mottled soaps, but more especially in the north of England, where enormous quantities of it are consumed annually. Castor-oil, from the seeds of Ricinus communis and R. EuropcBa, is also used as a soap material. It is obtained largely from the East and West Indies, and also from North America. Castor-oil is supposed to contain three fatty acids, namely, ricin-oleic, margaritic, and elaiodic acids. When treated with hyponitrous acid, a solid fatty mass is produced, which is caAeA. palmine. Although not soluble alone in alcohol it will, according to Dr. Pereira, dissolve in this spirit when mixed with other fixed oils. Castor- oil is capable of forming soap with caustic alkalies, but is always used in combination with other fatty matters for this purpose. 28 THE ART OF SOAP-MAKING. Among the other vegetable fixed oils used in soap- making may be mentioned the oils of heinpseed, rapeseed, cotton-seed, poppy, linseed, sesamum, colza, beech- nut, etc. Besides the ordinary fats and oils, certain fatty matters called greases are much used by soap-makers. Bone-grease is supplied by bone-boilers, and forms a useful soap material for mottled soaps. Horse-grease, although not an abundant article, is available as a soap material. Kitchen-stuff, as prepared by the " stuff-melterSj" is a very useful material for mottled soaps, and is largely used by the London soap-makers for this purpose. Being the produce of kitchen waste it contains many di£Ferent kinds of fatty matter, but after its separation from the more solid particles, as gristle, rind, bones, fibrin, etc., by pres- sure, it forms an uniform fatty mass of good consistency, and contains a considerable proportion of stearine, which renders it well suited to the manufacture of a curd soap such as the London mottled soap. Oleine, or Tallow-oil, which has been separated from stearine by pressure, in order that the latter may be used alone for candle-making, is a useful material, in combina- tion with stronger fats. Fish-oils are chiefly used in the manufacture of soft, or potash soaps, in combination with tallow. Besin, or Colopliony, was first employed as a soap material in England. It is extensively used in the manu- facture of yellow soaps, the pale, or yellow resin being pre- ferred for this purpose. Yellow resin generally contains a little water, which does not exist in the darker varieties. Recovered grease, or Yorkshire fat, is obtained from the suds and washing waters of the fulling mills. It is of a brown colour, of disagreeable odour, and of a sticky consistence. When melted, and a strong solution of carbonate of soda added to it, efiervescence takes place, from the disengagement of carbonic acid, the grease con- sisting of several fatty acids, which act powerfully upon the carbonated alkali.* "When neutralised, and mixed * This grease often contains oils which cannot he saponified. MATERIALS USED IN SOAP-MAKING. 29 witli other soaps, the recovered grease is useful in the manufacture of the cheaper kinds of Windsor and other scented soaps. The Alkalies used in the saponification of the various fatty substances employed in soap manufacture are soda and potash, the former being used, in a caustic state, in the preparation of hard soaps, and the latter, also being caiisticised, is used for |making soft soaps. The soda supplied to soap-makers is an impure carbonate of that alkali. As we have said, soap was formerly made from barilla, a crude carbonate of soda obtained by the calcination of certain plants which were fovmd on the coasts of France, Spain, and other countries ; it was also made from kelp, obtained by burning a great variety of seaweeds on the shores of Scotland, Ireland, Brittany and Iformandy in France. When Leblanc, however, introduced his invalu- able process for converting sea-salt, first into sulphate of soda by treating it with sulphuric acid, and afterwards into carbonate of soda by calcining with fine coal and chalk, the employment of barillas and kelps gradually, and eventually entirely, ceased. And now, after enjoying a long period of unbounded success, other improved pro- cesses are fast taking the place of Leblanc's process. . For a lengthened period, and indeed up to the present time, soap-makers were accustomed to purchase their alkali under the name of soda ask, which usually contains a/bout 50 to 52 per cent, of soda, the exact percentage being determined by processes to be explained hereafter. Soda ash, besides other impurities, usually contains from 2 to 3 per cent, of common salt. Caustic Soda is now supplied to soap-makers at a reasonable price, consequently they prefer purchasing this important article to making their own caustic soda, which involves not only considerable trouble and delay in its preparation, but also an accumulation of lime-waste, which is not always easy to get rid of in large cities and towns. The author, in conjunction with Mr. J. Berger Spence, obtained a patent, in April, 1882, for making caustic soda 30 THE ART OF SOAr-MAKlNG. by the decomposition of common salt by electricity, and by this process it is expected that the cost of making this important article of commerce will be greatly reduced, even beyond the present extremely low prices. Potash, previously rendered caustic by boiling with quicklune and water, is used in the manufacture of soft soaps. American potash is, however, chiefly used for this purpose. Silicate of Soda, or Soluble Glass, as supplied to the trade, is in the form of a thick, viscid, translucent mass, which flows very slowly from the casks in which it is stored after the heads or bungs have been removed. It is pre- pared by boiling ground flints (silica) in a strong solution of caustic soda. When dissolved in hot water it forms a solution which unites with certain kinds of soap very readily, forming a cheapened compound readily market- able ; and since the silicate of soda possesses considerable detergent properties, its admixture with genuine or pure soap gives an advantage to the consumer which few soap adulterants can boast. The introduction and method of preparation of this interesting article into soap is due to Mr. Sheridan, who obtained a patent for his invention as far back as 1838. Since that period, however, many other patents have been obtained for the manufacture and employment of silicate of soda, all more or less based upon Sheridan's invention. Silicate of soda (or soluble glass) is now commonly made by calcining together, in a rever- beratory furnace, 9 parts of soda ash of 50 per cent, with 11 parts of clean sand or powdered quartz, for hard soaps ; or equal parts of pearlash (previously dried) and sand for soft soaps, the latter mixture forming silicate of potash. After perfect combination of the alkali with the silicious matter, it is cast into moulds, and afterwards quenched with water. It is next ground in a mill, and then boiled in water containing alkali — potash or soda, as the case may be. The solution thus obtained is evaporated until it in- dicates 59 by Baum^'s areometer, or hydrometer. In this condition it is ready for mixing with so'aps, but the soluble glass is generally supplied to soap-makers in the form of a MATERIALS USED IN SOAP-MAKING. 31 ttick, viscid mass, which they reduce with hot water to any required strength. China clay, or Kaolin, is sometimes used as an adulterant in the manufacture of some of the cheaper soaps. Sulphate of Soda, or Glauber's Salt, is also extensiyely used in combination with soaps of the cheaper krad, the mixture producing a soap of considerable hardness, while reducing its percentage of fatty material. CHAPTER IV. CAUSTIC LETS. The Ley Tanks. — Method of Preparing the Leys. The Ley Tanks are large vessels made of wrought-iron plates riveted together ; in some factories they are con- structed of brickwork lined with cement. Dussauce recom- mends large tuns lined with sheet lead, with a perforated false bottom, which he believes would be the most durable apparatus for this purpose. A cock should be fitted near the bottom of each tun, and through it the clear ley, collecting in the lower part of the vessel between the diaphragm and the bottom, can be drawn off into vessels placed beneath. Near the vat should be a pump with its spout arranged for a supply of water. The arrangement of ley tanks in a Marseilles soapworks is as follows : — No. 1 is called the fresh vat, into which the fresh alkali and lime are introduced ; No. 2 is termed the avanqaire, it being one step in advance ; No. 3 is the small avanqaire, being two steps in advance, and therefore containing weaker liquor, and No. 4 is called the water vat, because it receives the water directly. Into No. 3 the moderately exhausted or spent leys are thrown. From No 3. the ley is pumped into No. 2 to be strengthened, and in like manner from No. 2 to No. 1. Upon the lime paste in No. 4, which has been taken from No. 3, water is poured ; the ley thus obtained is poured upon the lime paste of No. 3, which has been removed from No. 2. No. 3 is twice lixiviated, and No. 2 once. The receiver under No. 1 has four compartments ; into No. 1 the third ley, and into No. 4 the fourth ley, which is so weak as to be CAUSTIC LEYS. 33 used for lixiviation instead of water. The lime vat No. 4, when exhausted, is emptied out of the window near which it stands, in which case the water is poured upon the contents of No. 3, and the weakest ley upon No. 2. No. 1 is now avangaire to No. 4, because this has become in its turn the fresh vat, into which the fresh soda and quicklime are put. The ley discharged from No. 3 comes in this case upon No. 2, and after being run through it, is thrown upon No. 1. In some large factories the ley tanks are placed in a building apart from the soapery, and from thence the ley is pumped into tanks situated near the soap-pans, a very cleanly and convenient arrangement. Method of Preparing the leys — This operation is thus directed by Messrs. Charles Tennant and Co., the exten- sive alkali manufacturers of St. RoUox, Glasgow : " A layer of fresh burnt lime, say five measures of 112 lbs. each, is to be laid equally over the bottom of the vat, and a few gallons of water to be thrown upon the lime, until it begins to slake or fall. This layer is then to be covered immediately with 6 cwt. of soda ash, the next layer with four measures of lime slaked as before, the fourth layer with the same quantity of soda ash, the fifth layer with lime as before, and the last layer with the same quantity of alkali. " After standing two hours, the vat is to be stanched by filling it with water or weak ley of a former vat ; this is to be done gradually. After standing about fifteen or six- teen hours, the plug is to be gently loosened, so as to allow the ley to run ofi" or trickle clear, and caustic after infiltra- tion through the beds of lime. This is called the first runnings. As soon as the ley ceases to run, the plug is to be tightened, and the vat again filled with water, and after standing a sufficient time, to be run down as before. This is the second runnings, and worked together with the first runnings in the soap-pan is an excellent ley, and works freer and better than if used separately. After the vat is run dry, it is to be turned over into another vat, covered with water, and again run down. This ley is very weak, D 34 -THE ART OF SOAP-MAKING. and is seldom worked in the soap-pan, being used instead of water, to stanch or fill up the strong or first set vats. As soda ash is not all equally soluble, it is sometimes necessary to turn the contents of the vat over a second time in order to obtain all the free alkali ; but experience and care are the only sure guides. The receivers for the ley are generally much smaller vats, but it is preferable to have them of the same size, it being at all times desirable to have a sufficient supply of strong caustic ley. " Should the ley in the course of the process of boiling the soap ' close,' as it is termed, with the materials, and not separate, a small quantity of common salt thrown with care into the boiling soap will effect a separation ; but this is always to be avoided if possible. The ley may be taken out of the vat with a pump or syphon. A third running may be taken from the first vat to stanch with." In order to ascertain whether the soda has been properly and ' fully causticised, a few drops of hydrochloric acid (muriatic acid) are added to a small quantity of the ley, and if efi'ervescence takes place it is a sure indication that uncausticised carbonate of soda is present. In this case the ley must be returned to the lime again and again, if necessary, until it is perfectly caustic. Boiling the lime and soda ash is a method frequently, if not generally, adopted, and indeed there is no doubt that it is a surer method of rendering alkalies caustic than by a cold process. . A simple method of ascertaining if there be any carbonate of soda remaining in the ley is to pour a little of the ley into clear lime-water, when if the mixture assumes a milky appearance (from the formation of carbonate of Hme) it is proof that uncausticised carbonate of soda is present. In making caustic -soda by steam boiling, fifty pounds of fresh slaked lime are required for each one hundred pounds of soda, and about ten to twelve parts of water to each part of soda. It is usual to slake the lime with hot water, and when the soda and lime with the water have been put into the tank or vat, the steam is turned on and CAUSTIC LEYS. 35 the mixture allowed to boil for several hours. The agitation produced by the boiling greatly aids the rapidity of the causticising process- by keeping the soda and lime in close contact with each other. "When the boiling has been sufficient, which is ascertained from time to time by the tests before referred to, the steam is turned off, and the contents of the vat allowed to repose, so that the carbonate of lime which is formed may subside. The ley is then drawn off and the lime washed several times with fresh water, the last runnings being used instead of water in future operations. Caustic potash, for employment in the manufacture of soft soaps, is prepared in the same way as caustic soda, except that eighty parts of lime to each hundred of potash must be used. CHAPTER Y. MANUFACTURE OF SARD SOAPS. Castile or Olive-oil Soap. — Pare Olive-oil Soap. — Marseilles Soap. — French marbled Soap. — Notes on Mottling. — French Formulae for Soaps. — Composition of Pure Olive-oil Soap. — London mottled Soap. — White Curd Soap. Castile or Olive-oil Soap is considered the type of all hard soaps, and when made from pure materials is white, emollient (from emollier, to soften), and is almost entirely free from odour. It is unquestionably the best known soap. The commercial article, which is also called Marseilles soap, from its manufacture in France having been first practised in that city, has a pleasing mottled or marbled appearance with red and grey veins permeating its substance throughout, and which are due to certain im- purities in the alkali, or produced artificially by the intro- duction of a little sulphate of iron (green copperas) in the process of manufacture, which becomes decomposed and converted into red oxide (peroxide) of iron. As formerly made, this soap was exceedingly hard and brittle, but the introduction of other ingredients, as the oils of hempseed, linseed, and poppy, for example, render the soap less disagreeably hard, while at the same time reducing the cost of manufacture. Pnre Olive-oil Soap, or White Castile Soap, is used in pharmacy in the preparation of liniments, plasters and cerates, and also in pills. It is made from pure olive oil and caustic soda free from coloured impurities. Marseilles Soap. — La the manufacture of Marseilles soap for commercial purposes, great care is exercised as to the strength of the leys, and also the proportions to be applied to a given quantity of olive oil. After a series of MANUFACTURE OF HARD SOAPS. 37 careful experiments, made at Marseilles, it was found that the following were the proper proportions of caustic soda and oil for making this kind of soap. Each 100 lbs. of olive oil require fifty-four pounds of caustic soda ley of 36° Baum^ for perfect saponification, and this amount of ley represents about 15-50 of solid caustic soda — the utmost amount that must be applied to each 100 lbs. of the oil used. Since this oil, however, varies in the proportion of solid matter (margarine) which it con- tains, the strength of the ley employed in the first opera- tion of boiling must be regulated accordingly. For a thin oil (or one containing a low percentage of solid matter) the ley is reduced by water until a Baume's hydrometer float- ing in it marks 10° to 11° (degrees). For an oil containing a much larger percentage of solid matter (as lard oil, lard, or other solid fat) the strength of ley should be about 8° or 9° B. First operation. — The requisite quantity of ley (in the proportions above given) is to be first run into the pan, filling it to the extent of about one-third of its capacity. Heat is then applied by fire or steam, as the case may be, and when the liquor comes to a boil, 1,600 lbs. of oil are added at one time with constant stirring. In a very short time a thick mass of a pasty consistence is formed by the reaction of the hot caustic alkali upon the oil. If from miscalculation, or other circumstance, an excess of oil has been added, this excess will show itself upon the surface, when an additional quantity of ley must be at once applied. On the other hand, if, instead of forming into a thickish paste the mixture is very thin, this indicates an excess of ley, and more oil must be added by degrees. This addition will, of course, somewhat cool the mixture, but the tempera- ture soon rises again, and the mass again boils with con- siderable frothing. The boiling must be kept up for eighteen or twenty hours. During the boiling, considerable evaporation takes place, whereby the ley becomes stronger ; it is therefore necessary, when the pasty condition becomes thick, to add weak ley from time to time, since the paste is not soluble in strong 38 THE ART OF SOAP-MAKING. ley. PreTious to the addition of weak leys, however, the " spent," or exhausted, leys are pumped or drawn off. The addition of fresh leys is kept up until the whole of the fatty, matter is lulled, as it is termed (that is, neutralised), or whenever it is found that the ley has lost its causticity, which is ascertained by dipping the tip of the finger in the ley and applying it to the tongue. Every addition of fresh ley is accompanied by constant stirring. After four or five changes of ley, with continued boiling and stirring, the mass becomes of an uniform soapy consistence, and a small portion pressed between the fingers becomes immediately hard and flaky. Frequently the alkali from which the leys are made contains common salt, sulphate of soda, and other impurities, which have the effect of retarding the process of saponi- fication by keeping the alkali and fatty matters in a more or less separated state, whereas they require to be inti- mately associated to effect a perfect chemical union. When it is found, therefore, that the process is progressing slowly from this cause, it is customary to throw into the pan a quantity of soap scraps to aid the operation. When the soap-pans are heated by fire, it is necessary to use every precaution to prevent the burning of the soap at the sides of the pan. Should this occur, however, the fire must be slackened, and a small quantity of strong ley added, with brisk stirring, which will partially separate the pasty mass from the ley, bringing the latter ia contact with the metal of the pan, and thus prevent the burning of the saponifying matter. Second operation. — The oil being now completely neutralised with alkali, the combination in its present' state also contains a large quantity of water in the shape of exhausted or spent ley. To remove this, many sub- stances may be employed, but common salt, which answers the purpose admirably, is from its cheapness generally employed. The process ^f separation, which is generally termed "cutting the pail," is effected by throw- ing into the pan a concentrated solution of common salt, or a few shovelfuls of the same, each portion being MANUFACTURE OF HARD SOAPS. 39 Fig.. 16. allowed to dissolve before the next is added. For con- veying the salt, the truck shown in Fig. 16 is a very con- venient vehicle. "When sufficient salt has been thrown in, the soap separates from the leys (which also hold glyce- rine in solution) and coagu- lates in flakes or granular clots. The soap-boiler, by freely using his shoyel — by repeatedly dipping it into the boiling mass and observing its condition — can tell in a moment when enough salt has been added. At this period the ley runs clear off the shovel or trowel, leaving the soap in separated lumps upon its surface. By continuied boiling the clots assume a granular or grain-like appearance, in which condition the soap is said to be " boiled to a curd." If the boiling be continued too long after this stage, it will, by making the salted leys too con- centrated, render the curd so stiff that the vapours arising from the boiling of the liquor beneath will with difficulty make their escape through the mass. "When the soap has assumed the form of grains or curds, it is known that all the superabundant water — that is, its uncombined mater — is separated from it, and at this stage the fire is drawn or the steam turned off, as the case may be, and the pan is allowed to repose for a few hours to enable the leys to deposit. When sufficient time has been allowed for this, the leys are drawn off by means of the cock situated at the lower part of the pan. Third operation. — This is termed finishing the soap, by which process it becomes cleansed from saline or other impurities, which are still loosely attached, or m.echanically mixed, with it and, at the same time, any portions of the fatty ingredients which may not have been thoroughly saponified, undergo perfect conversion into soap. This important operation is effected by means of a ley of such strength that it cannot dissolve the made 40 THE ART OF SOAP-MAKING. soap. It may be here mentioned that although soap is soluble in very weak leys, it is absolutely insoluble in strong solutions of caustic alkali. All the spent leys having been drawn off the soap, it is now gently boiled with a ley of the strength marking 18° or 20° B., to which 8 or 10 per cent, of salt is added. The quantity of this saline ley must be just sufficient to coagulate or close the soap, and to prevent it from adhering to the sides of the pan. "While the boiling gently proceeds the soap is constantly stirred. The ley is now allowed to subside, when it is drawn off as before and fresh ley added, until, after again boiling, the leys retain their causticity — when saponification is known to be complete. At this period the boiling becomes more violent and frothy, and the soap-boiler keeps the pan from boUing over by constantly using his shovel, with which he scoops up the soap and throws it over the boiling mass. As soon as the soap yields an odour resembling violets, and is scaly when pressed between the fingers without ad- hering to them, the finishing process is complete. The time occupied in this operation is from eight to ten hours in winter, and from ten to fifteen hours in summer : the length of time, however, depends greatly upon the quantity of material operated upon. When the operation is complete the fire is withdrawn, and the soap is allowed to rest for a few hours, after which the ley is again drawn off. The finished soap is white and firm, and con- tains from 16 to 25 per cent, of water. When the leys are impure, containing salts of iron and sulphur, it assumes a dark shade owing to particles of metallic soap permeating the mass. When this is the case, it must be again treated with weak ley, and very gently heated, when the dark-coloured soap, which is called niger or nigre, being more dense than the fine soap, and not soluble in weak ley, subsides. To facilitate this the cover of the pan is lowered, and the soap again suffered to repose, when the white soap, which forms the upper stratum, may be ladled into the frames. The fourth operation, which is termed mottling, or MANUFACTURE OF HARD SOAPS. 41 marbling, is the result of certain reactions wliicli occur between the impurities of the ley (chiefly iron, sulphur, and alumina) and the saponaceous matter. "When these impurities exist in considerable quantity, they give a slate- coloured tint to the soap. By examination it has been found that the fatty acids of the soap exchange bases with the saline impurities, an insoluble dark-coloured (ilumino-ferruginous soap being formed, which is diffused throughout the mass, with, also, black sulphuret of iron. These being held in suspension by the thick soapy mass form bluish veins in the white ground, thus giving the soap a marbled appearance. By exposure to the air, how- erer, the iron salts become oxidised, and acquire a reddish hue from the formation of peroxide of iron. When the alkali, from which the leys have been made, contains a large quantity of iron and sulphur impurities, the soap becomes mottled without any artificial means. This being seldom the case with the alkali mq,nufactured at the pre- sent day (excepting the black ash) the desired effect is produced by adding to the soap, after it is finished or clarified, and without separating it from the niger or nigre, four ounces of green copperas (sulphate of iron) for each 100 lbs. of oil in the soap. The iron salt is first dis- solved in weak ley, which is added to render the paste thinnish, and the mixture must be cooled gradually, so that the coloured soap may become thoroughly difi'used through the mass. Too much ley must on no account be added, otherwise the darker and heavier soap will sink to the bottom. Again, the cooling of the soap must not be too rapid or the coloured veins will close too much, and thus spoil the " strike " of the soap. The soap is allowed to remain in the pan to cool a little, after which it is ladled into the frames. In France ladles with perforated bottoms are employed, so that any ley that may remain mechanically mixed w'ith the soap may run off. After each frame is filled the soap is well crutched to make it homogeneous, and, if it be desired to add water, the requisite quantity is well crutched in while the soap is still hot. The frames are sometimes 42 THE ART OF SOAP-MAKING. covered witli sacks in cold weather, so that the soap may cool slowlyj upon which much of the beauty of the " strike " or mottle depends. It has been ascertained that bhree pounds of olive-oil will yield five pounds of marbled Marseilles soap, whereas the same amount of oil will only produce four pounds four ounces of white soap, which proves that the former retains more water in its composition than the latter. Frencli Marbled Soap. — Dussauce, in his admirable "Treatise on the Manufacture of Soap," gives an elaborate description of the manufacture of marbled soaps, as con- ducted .in France, from which we give the following extracts : — ' "Besides olive-oil, the earth-nut, sesame, linseed, cole- seed, and black garden poppy-oils, greases, tallows, etc., are also used in the fabrication of marbled soaps ; but the soap resulting from these difierent combinatioiis of oily and fatty matters, while being of good quality, cannot be compared to those obtained by the direct saponification of olive-oil. The latter are always denser, firmer, and finer. " However, we may remark that the mixture of olive- oils with other oils containing less stearine, gives, if not the best, at least the finest kinds of marbled soap. They are also more unctuous, and their cut is softer and smoother, as they contain less stearate of soda than those prepared from olive-oil, — they are more detersive and more advantageous for use. " The sodas employed for these soaps are of two kinds ; one, called soft soda, is the most alkaline ; the other, called salted soda, is composed of soft soda and common salt. Well-prepared soft soda ought to be free from com- mon salt ; it is employed to produce the pasting in the first operation. The salted sodas are a mixture of soft soda and salt. The proportions of salt are from 30 to 40 per cent, of the weight of soda. Th.eir alkalimetric degree is from 18 to 22 per cent, of pure alkali. " In certain circumstances salted soda can be substituted by common salt ; nevertheless, it ought to be remarked MANUFACTURE OF HARD SOAPS. 43 that an excess of salt is injurious to the marbling of the soap, and salted soda must be used whenever it is possible to obtain it. " Soda ash is . not so suitable for the fabrication of marbled soaps as crude soda. Being entirely deprived of colouring matter and of sulphurets, when it enters in too large a proportion into the preparation of the lyes, it lessens the beauty and intensity of the marbling. " The fabrication of marbled soaps requires several dis- tinct operations, which may be thus summed up : — • 1. Preparation of the lyes. 2. Pasting, or saponification of' the oils and fatty substances. 3. Separation of the saponified paste from the weak lyes it contains. 4. Coction (boiling). 5. Mottling or marbling." In preparing the ley for the first operation the follow- ing proportions of soda and lime are given : — Crude soft soda (black ash) at 34° to 38' 2,250 lbs. Recently calcined lime 4S0 „ .The soda (if in hard lumps) is first broken or crushed, and the lime slaked by immersion in warm water. "With warm water," says Dussauce, " the penetration of the liquid is more complete. After one or two minutes of im- mersion the lime is quickly taken out and spread on a hard, smooth, and dry floor ; if the lime is of good quality it soon grows warm and falls into powder, this poyder is then thoroughly mixed with the soda by means of large iron shovels. The mixture is conveyed to filters made of masonry or sheet iron, holding from 125 to 150 gallons, each filter being provided with a false bottom pierced with holgs and supported by four little pieces of wood, which keep it about two inches from the bottom. A layer of straw is placed over the false bottom to prevent the mixture from passing through the perforations and to aid the filtration. A plug or cork is placed between the tVo bottoms of the vessel for the convenience of drawing off the ley. The mixture of soda and lime is now covered with water, when, after a while, it swells and' becomes warm. After about twenty-four hours the ley is drawn 44 THE ART OF SOAP-MAKING. ofiF, when its strength is usually from 22° to 25° B. Fresh water is then added, and, after many hours, is drawn off as before, the washing being continued so long as caustic alkali be present." The preparation of salted ley is in all respects similar to the preceding, except as regards its formula, which is as follows : — Crude soft-soda ash at 33' to 38° 3,376 lbs. „ salted Boda at 18° to 20° 1,025 „ Frestlime 900 „ The pasting operation is thus given : — Take Olive-oil 1,125 lbs. Earth-nut oil 900 „ Black garden poppy-oil 225 „ 2,265 „ The saponification is effected in a sheet-iron kettle hold- ing about 1,000 gallons, into which from 125 to 150 gallons of "soft ley," at 10° or 12° B., are poured. Heat is applied, and, when boning commences, the oils are added by degrees, with constant stirring. Soon after the oils have been added, and the boiling again started, a violent agitation takes place with considerable foaming. At this time the mixture swells up greatly, when the heat must be lowered, or the mass would inevitably boil over. After awhile the foaming ceases, and a perfectly homo- geneous mass of a dull white colour is formed. The boiling is continued for four or five hours. By the ebulli- tion the mixture of the materials becomes more and more intimate ; it also acquires more consistency and strength by the evaporation of the water from the ley ; then add 25 to 30 gallons of ley at 15° or 18° B., with stirring for about ten minutes. Boil .a few hours, and, when the mix-~ ture has acquired a thicker consistency, add to it one pound of green vitriol (sulphate of iron), previously dis- solved in a few quarts of boiling water. By this addition the paste, which was of a reddish white, assumes instan- taneously a greenish colour, the intensity of which MANUFACTURE OF HARD SOAPS. 45 depends upon the degree of sulphuration of the ley. To combine the sulphate of iron with the paste the mixture is well stirred for a few minutes ; under the action of the soda, the iron is decomposed, farming an oxide of iron. The chemical union of this oxide with the sulphuret of sodium, which always exists in the leys of crude soda, produces the colouring principle of the marbling of the soaps. In order to ensure an intimate combination of the fatty matters with the ley, and also to give a good consistency to the paste, from 25 to 30 gallons of soft ley at 25° B. are added gradually, with constant stirring, and the boil- ing continued for several hours. The pasting operation, as it. is termed, generally occupies about fifteen hours, when a perfectly neutral soap is obtained. The separation of the soap is thus conducted. In soap factories, to produce separation, they throw on the soapy mass, by small quantities at a time, limpid re- generated leys at 25° to 30° B. When these leys cannot be had, new salted leys, at 20° to 25°, can be used, or a solution of salt at 20° B. To obtain 25 gallons of salt solution at 20°, 14| lbs. of salt are employed. When the saponification is complete, and the paste has the required consistence, it is watered with a sufficient quantity of old and salted ley at 25° to 30°. To render the action of the leys more thorough upon all the molecules of soap, a large board is placed over the kettle, on which a man, provided with a beater or crutch, stands to stir the mass continually, from bottom to top, in such a manner that the ley brought to the surface penetrates every portion of the soap. The' paste now separates into clots or curds, and, if the ley runs off freely from the shovel or trowel, it is known that the separation is complete. The soap is then allowed to rest, when the ley slowly subsides. After a few hours the ley is drawn off, which consists of from 175 to 188 gallons of ley at 17° or 18° B. This ley, after being passed over an old residuum of soda exhausted by wash- ing with water, is used in the operation of mottling. The next operation is called coetion (boiling), by which 46 THE ART OF SOAP-MAKING. the complete combination of the oils or fatty matters with the alkali is ensured. It is this operation, also, which gives hardness and consistency to the soap, increases its density, and deprives it of all disagreeable odours, besides rendering it more detergent. The 'leys used in this operation are termed salted leys, being a mixture of soft (not caustic) soda and artificial, salted sodas, causticised by lime, as before described ; but before the application of this ley the soap is treated with 88 gallons of cold soft ley at 20° to 25° B., which is thoroughly well crutched in. This has the effect of separating the soap into flakes which float on the ley. After stirring for half an hour the cover is lowered to keep in the heat, and, in about four hours after, the ley is drawn off. Dussauce says : " Some manufacturers for the first service use salted lyes, but, in our judgment, soft leys are to be preferred. Indeed, there is already in the paste an excess of salt, due to the lyes employed for the separation, and, as too large a quantity of salt interferes with the useful action of new lyes on the molecules of soap, it is proper and rational to eliminate it from the paste as much as possible. The soft lyes contribute to this result. This advantage is not the only one, the lyes of coction, used in considerable quan- tities in the separation, have set free some fatty matters imperfectly combined ; then the soft leys, while purify- ing the paste from the excess of salt it contains, deter- mine the incorporation of the oily or fatty substances which had not been combined before, and could not be if salted lyes had been used." The above observations are of considerable value, in- asmuch as they guard the soap-maker against falling into a very common error — ^that of applying salt before saponification is known to be complete. The first application of the salted ley is given after the ley of the last operation has been drawn off. From loo to 115 gallons of salted ley, at 25° B., are put into the pan and heat applied, with stirring so soon as boil- ing commences. The boiling is to be continued until MANUFACTURE OF HARD SOAPS. 47 the ley ceases, to taste caustic, which is generally after seven or eight hours. A black foam or "fob" appears on the surface^ which only ceases when the materials are completely saturated with alkali. The heat is now checked, the mass allowed to rest for three or four hours, after which the ley is drawn off. A second dose of 115 to 125 gallons of salted ley is now given, of a strength equal to from 25° to 30° B., and the boiling resumed and kept up for twelve to fifteen hours, with occasional stirring. About every hour, during the first eight or ten hours, about 5 gallons of ley, at 28° to 30°, are added to supply the 'place of the evaporated water and complete the satura- tion of the soap. It is usually towards the close of this boil that the operation is complete, the foam having dis- appeared, and the soap is now stiff, clean, and dry, and furrowed by deep channels. The ley, though coloured, is clear, and should be slightly caustic to the taste. If these conditions are not fulfilled the ley must be drawn off, after repose for two hours, and 75 galloils of salted ley at 28° or 30° B. added, with further boiling for seven or eight hours. Mottling. — The next and last operation is termed mottling. The soap having rested for an hour or two, the last ley is drawn off, an4 a pure ley, at 12° to 15° B., is sprinkled over the surface of the soap with continual stirring, which thus becomes of a somewhat softer consistence. A weaker, pure ley, at 8° to 10° E., is then added and well stirred in, , when the soap, which up to this time was in hard, granu- lar, and curd-like lumps, becomes softer, the grains of soap being more plastic and viscid. The operation is now finished by boiling with leys at 5° or 6° B., which are gradually introduced, otherwise the weaker ley would spoil the adhesiveness of the soap. When the soap floats on the ley in large flakes of a greenish colour it is known that it is ready for the frames. If the condition of the soap, with the above treatment, is defective, it arises from one of two causes. 1. The additioa of the cold leys has cooled the soap too much ; or, 2, the soap contains an excess of saline matters. In 48 . THE ART OF SOAP-MAKING. the first case the soap must be heated gently, and when the ley is sufficiently warm, stir well until the proper con- sistence is obtained. In the second case, run off the leys, and add fresh pure ley at 10° to 12° B., with gentle boiling and stirring. Before putting the marbled soap into frames, it is usual to first place a little warm ley at the bottom of each frame, to prevent the soap from adhering to it ; sometimes, also, a piece of canvas is laid over the bottom of the frame with the same object. When properly boiled, the soap is in the form of hard and separate grains, the entire mass having a bluish-black colour, the intensity of which depends upon the quantity of metallic soaps present in the mass, and which are due to the salts of alumina and iron contained in the ley. These metallic soaps, during the cooling of the mass, separate from the white soap (which forms the ground or base) in irregular veins of varied colour, and thus a marbled appearance is obtained, the beauty of which depends greatly upon the skilful manipulation of the " mottler," or workman who superin- tends this part of the operation. It is an important point to run the soap into the frames when the proper condition for good mottling has been attained. Notes on mottling. — The strongest ley is first intro- duced, then the medium, and lastly the weakest. The principal points to be observed in mottling are : 1. The introduction of weak leys into the paste ; 2. The application of gentle heat to keep the mass in a fluid state ; and, 3. Continual stirring. The precautions to be observed are : 1. Not to add more leys than are necessary, so that the heavier metallic soaps (which are the colouring principles of the mottling) may be thoroughly disseminated through the mass of white soap, and ultimately produce the marbled veins which are characteristic of the soap. 2. The temperature of the soap must not be too high. 3. If too much weak ley has been applied, this, by thinning the mixture, wiU cause the heavier metallic soaps to sink into the leys, and the soap will be white instead of being marbled. 4. If the MANUFACTURE OF HARD SOAPS. 49 leys be too strong, the metallic soaps will not separate properly, and the entire mass will contain less than its full proportion of water, thereby entailing a loss to the manufacturer. All circumstances being favourable, the following cha- racteristics win present themselves : the flakes of soap are separated from each other, and float on the ley ; they are soft and bulky, of a fine green colour, and of a viscid consistence. When ready for the frames, the graias are " pliant and elastic, and have a tremulous and gelatinous appearance." The soap must not be put into the frames until it has cooled down a little, the proper temperature being between 158° and 166°. Frencli Formnlse for Soaps. — The following formulae represent some of the fatty combinations used in difierent localities in France in the manufacture of soap : — I. Olive-oil 675 lbs. Earth-nut oil 675 „ Lard 900 „ 2,250 ,, This produces a white, odourless soap. II. Bleached palm-oil 1,675 lbs. Oil of sesame 450 ,, White tallow 225 „ 2,250 „ Produces a very hard soap, of good quality, but not so white as the above. It turns slightly yellow by keeping. III. Olive-oil 450 lbs. WhitetaUow 1,350 „ Earth-nut oil 450 „ 2,250 „ This is considered to form a very good soap, and superior E so THE ART OF SOAP-MAKING. to that of MarseilleSj but " unfortunately it has a faint smell of tallow, whicli restricts its use in domestic economy." (!) IV. Olive-oil 675 lbs. Couoa-nut oil 22S „ Lard : 675 „ Tallow ....; 675 ,, 2,260 „ This formula makes a good white soap, but the presence of cocoa-nut oil gives the soap a disagreeable odour, although it improves its lathering properties. The Composition of Pure Olive-oil Soap, according to Tire's analysis, is : — Fordgn, Soda 9-0 Fatty acids (oleic and margaric) 76 -S "Water and colouring matter 14'6 100-0 English imitation. Soda 10-5 Fatty matters 75-2 Water, mth a little colouring matter 14-3 100-0 The ordinary commercial Marseilles soap contains from 62 to 65 per cent, of fatty acids. Loudon Mottled Soap is generally made from melted kitchen stuff, bone grease, cheap tallow, and any inferior fatty matter that will prove serviceable. The leys are made from crude soda ash, termed black ash, the impurities in which give the mottled or marbled " strike," for which this variety of soap is famed. The " goods," as the fatty materials are called, are first put into the pan, when the first dose of ley, at sp. gr. 1-050, is run in, after which the fire is made up beneath the pan, and the materials brought to a steady boil. To assist the combination of the fatty substances with the ley, a workman constantly MANUFACTURE OF HARD SOAPS. s' stirs tlie ingredients with a long iron rake. After a while the fatty matters, which at first float on the surface of the ley, combine with it, forming a thin creamy emulsion of a perfectly uniform appearance, and from which no liquid separates on cooling. Should the mass not present these characteristics, the soap-boiler adds either water or some weaker leys than were at first employed, and the boiling is continued, with occasional stirring, until a perfect emul- sion is obtained. At this stage of the operation the compound ceases to taste alkaline — the tongue being the usual test employed by the soap-boiler — and it is thus known that the combina- tion of the fatty matters with the caustic ley is complete. Stronger leys are now added repeatedly, the boiling being continued until the leys taste of free caustic alkali. When this is the case, more oily or fatty matters are added, as also, from time" to time, stronger leys. Great care is taken, in this operation, that there is no excess of alkali in the mixture when the soap-pan has be- come sufficiently filled with the alkaline and fatty ingredients. The mixture is next treated with common salt, which is thrown into the pan by shovelfuls at a time, each portion being allowed to dissolve in the ley before adding the next. When sufficient salt has been added, the sapo- nified matters separate into grains of soap combined with a definite quantity of water, but as yet not containing its full percentage of alkali. The leys, which are called " spent leys," consist of salt and glycerine in solution, and should be quite free from alkali. The fire being withdrawn (or steam turned off), the imperfect soap is allowed to rest for a few hours, so that the ley may subside, and this is then drawn or pumped off. The second operation consists in adding weak ley, with which .the soap is again boiled, until the soap (at first granular) becomes homogeneous, or " closed," as the soap- maker terms it. If the full quantity of fatty matters had not been introduced in the first operation, the soap-boiler now completes the addition of them, with also the addition 52 THE ART OF SOAP-MAKING. of more strong ley, until, after long boiling, the compound has acquired a strong alkaline taste. Common salt is now again added to separate the soap as before from the ley, and the boiUng continued for some hours in contact with the caustic ley, so as to ensure the perfect saponiii- cation of every atom of fatty material. Soda which contains sulphurets (as the so-called black- ash) is preferred for making mottled soaps, for reasons which have been already explained. Mottling is com- monly practised in some London soap-works byintroducing into the nearly finished soap a certain quantity of strong crude soda ley through the rose spout of a watering-can. The dense sulphuretted, liquor, in passing through the pasty mass and ley, gives it a marbled appearance. Some- times a small quantity of a solution of Prussian blue is used for this purpose. When crude sodas, however, are used in the manufac- ture of mottled soap, the mottling is efiected, towards the close of the operation, by a mere mechanical mixture of the dark-coloured ley with the soap. It is effected in this way : the workman breaks the paste in all directions with his rake, after which he holds it perpendicularly till it reaches the ley, when he raises it vertically with a jerk, making it act. like the piston of a pump, by doing which he lifts some of the ley and spreads it over the surface of the paste. In its subsequent descent through the numerous fissures and channels of the soap, on its way to the bottom of the pan, the dark-coloured ley impregnates the soapy particles in various forms and degrees, thereby producing veins or markings which, when the soap is afterwards cooled, give it the desired marble-like appear- ance. This operation has also the advantage of cooling the soap in some degree, which is necessary before it is put into the frames, or the " strike," or mottling, would not be perfect, owing to the superior density of the dark particles which form the coloured veins of the soap. When mottled soap is ready for framing, it is in the form of a thick, gelatinous mass, interspersed with leys, and in this condition it is ladled out into large pails and MANUFACTURE OF HARD SOAPS. 53 put into frames, which are preferably made of wood, since this material retains the heat longer than iron frames, and by the more gradual cooling a finer marbled appearance is obtained. When mottled soap is moulded in cast-iron frames, the ends of the bars are liable (from rapidity of cooling at the sides of the frames) to have a plain whitish appearance, instead of being marbled. White Curd Soap — The finest quality of this soap is made from pure tallow, rendered, as before stated, from the suet of oxen and sheep. English, or " town tallow," as the London tallow melters call it, in contradistinction to the products imported from Russia and other foreign countries, was generally preferred until the introduction of American and Australian tallows, which, being of good quality, are equally serviceable in the manufacture of this soap. Besides tallow, however, other materials, as lard, bleached palm-oil, olive-oil, or mixtures of these in varying propor- tions, are used in making curd soap. To produce one ton of curd soap, from 10 to 14 cwt. of tallow or olive-oil are required. The process of saponifi- cation is the same as for mottled soap, excepting that the removal of all colouring matter and impurities of. the ley must be effected by boiling the soap repeatedly with fresh leys after the removal of each previous dose of ley, or by thinning the soap with a small quantity of ley with gentle boiling, and then covering the pan and allowing the soap to repose for several hours, to allow the leys to subside. By thus washing (as we may say) the soap with ley, all the dark-coloured impurities are removed, and subside with the leys, leaving the soap clean, and, when cold, white. "When finished, the curd is ladled out of the pan and put into the frames, which should be covered with canvas, or clean empty sacks, so that the soap may retain its heat, and thereby enable it to close properly. The following is the French system of making tallow curd or grained soap : to transform 1,000 lbs. of tallow into grain or curd soap, 400 lbs. of potash have to be taken. The tallow is placed in the kettle (pan), about 400 lbs. of ley of 10° B. added, and the fire kindled. In a short time Si THE ART OF SOAP-MAKING. from tlie commencement of tlie boiling, the fire is kept ■well up, but afterwards it should be moderated. After the usual frothing, it should be ascertained whether the fat has combined with the ley. This is known by the yellow- brown mass, which, under gradual upheaving, continues quietly to boil. What adheres to the spatula, when dipped into the mass and withdrawn, has a gelatinous, greyish- white appearance, without separation of ley. When the ley and fat are not combined, the mixture moves in the kettle to and fro without rising upward, except now and then, in isolated spots, with a booming noise. When the combination is complete, there are added, at short intervals, and in four or five portions, about 1,000 lbs. of ley at 16° to 17° B. The boiling now becomes dense and languid, and the mass appears of a yellowish-brown, and runs off the spatula in cohesive, long, translucent strings, and the soap boils to a paste. If some of the soap be dropped on glass, and the sample, while still hot, does not appear per- fectly clear, ley is still wanting. A small quantity of ley should now be added, until the soap, while hot, appears perfectly clear. When this period is reached, the "cutting of the pan" begins. The salt has here a double purpose to fulfil. It must transform the potash into a soda soap, and also separate its glycerine, sulphurous liquor, ley, and impurities. The full quantity of salt required for this purpose is not applied at once, but a repeated "salting out" should be given. After each " salting out," the under ley is sepa- rated from the soap, and the latter brought in contact with water and salt. By boiling tallow and potash, when the materials are not very pure, the "salting out" is usually performed in three operations. The ley is now removed from the soap in the usual way. The salt is either thrown into the soap in the dry state, or in solution of about 20° B. When the mass turns white, and ebulli- tion occurs all over the pan in patches, the soap rising with considerable vigour, it is known that sufficient salt has been added. The frothing now disappears. The boiling is continued for an hour longer, and then stopped MANUFACTURE OF HARD SOAPS. 55 by extinguishing the fire, so as to allow any impurities still in the mass to settle. When the ley has been removed from the pan, 700 lbs. or 800 lbs. of water, with 70 lbs. or 80 lbs. of salt dissolved in it, are now added, and the mass again brought to a boil. After boiling up, it should be examined to see that the "cutting of the pan" has been properly effected. The boiling is then continued for some time, after which the mass is allowed to repose as before, and the saline ley again drawn off. Although the second liquor and boiling have greatly hardened the soap, yet this is not sufficient ; therefore a third boiling, with 50 lbs. to 60 lbs. of salt dissolved in 700 lbs. to 800 lbs. of water, is made, by which the hardness of the soap is perfected. As soon as it boils and froths up, the soap must be again examined to ascertain if the proportions of salt and ley have been sufficient. If enough salt has not been added, froth appears on the surface of the boiling soap, and the latter burns readily. In this case more salt must be added, until it boils up in regular lumps of soap. If too much salt be present, the soap appears upon the spatula [trowel] in a separated form, the ley running off, and little gutters formed. This fault is remedied by adding a few buckets of water. If a little portion of the soap be pressed by the thumb in the palm of the hand, it hardens imme- diately ; and if, on rubbing it, the sample retains a cohesive character, it possesses the required firmness, and is solid ; if, on the other hand, it crumbles, more water must be added, and if the sample spreads or smears, a fresh ley of salt of 15° B. must be added until the proper condition is reached. The operation of clear boiling and fitting is next pur- sued, to perform which one-half of the kettle is covered with wooden planks, and a man, furnished with a stirrer or beater, beats down the mass, so that it does not run over. By this operation the soap particles are drawn more closely together into globular grains. These grains sink, and on the surface of the kettle appears a white flaky froth. To prevent the falling of the mass, great S6 THE ART OF SOAP-MAKING. heat is now needed. The fire is briskly kept up, and the entire kettle covered with planks and cloths. The soap now boils up with considerable frothing, and to prevent it from running over, one of the planks is removed, and the foam is beaten with a long iron rod until it subsides. The kettle is again closely covered, and the boiling re- sumed, the prevention of overflow being again regulated as before. The violence of the ebullition gradually diminishes, but in its stead a whistling noise is perceived in the kettle. One of the planks is removed from time to time, and the soap examined ; when, if large and perfectly translucent bubbles rise up, the soap is finished, and the fire is there- fore extinguished. The wooden planks are next removed to allow, the soap to cool, and a few buckets of soap ley are poured into the kettle. The soap is now ready to be put into the frames, and care is taken that as little ley as possible enters the frames. Boiling with soda ley presents this advantage, that the soap may be finished in one water. The first ley is applied at the strength of 10° to 12° B. The whole of the fat is placed in the kettle, with one-fourth of the ley requisite for saponification, and the boiling carried on as usual. After boiling up, the mixture is examined to ascertain if the proper combination has taken place, in which case further addition of ley, at 16° to 18° B., is added. The addition of this ley is continued until a sample placed on a piece of glass appears perfectly clear. The cutting of the pan follows, which removes the glycerine formed, and the surplus water. In this case much less salt is required than when boiling with potash ley. For each 100 lbs. of fat 10 lbs. to 12 lbs. of salt are required. The salt may be applied in the dry state or in solution, as preferred. The remaining operations are conducted as before de- scribed. Soda soaps made by this process have some advantages, principally because it is impossible to remove all the potash ; besides which, they are generally very neutral and plastic. — Dussauce. MANUFACTURE OF HARD SOAPS. 57 It was formerly the practice in England to make tallow soap with potash leys, as above described, and the soft soap thus produced was converted into hard soap by additions of salt in sufficient quantity to furnish the proper proportions of soda by the reaction of the potash with the neutral salt. The high price of potash, and a great reduction in the cost of soda, however, caused this system to be abandoned in this country. CHAPTER VI. MANUFACTURE OF HARD SOAPS— { Yellow or Eesin Soaps. — Continental Method. — Dunn's Process. — Meinicke's Process. Yellow or Besin Soaps. — Althougli resin is freely soluble in alkaline leys, it is not capable of being converted into soap proper by itself. When mixed ■with fatty matters in various proportions, however, it forms a series of soaps possessing high detergent power, and exceedingly emol- lient and agreeable in use. A well-made resin soap is no doubt the most pleasant of all soaps for washing the skin. Possessing no "body " of itself, the smallest proportion of sound tallow which it requires to make a hard soap is an equal part. It is seldom, however, that so large a pro- portion of resin is used in soap. The peculiar odour of resin is greatly disguised by its combination with fatty matters, and it has been stated that rancid tallow disguises the odour of resin in soap more than any other description of fat or oil, except cocoa-nut oil, we might add, which gives an odour to soap that even the most powerful per- fumes overcome but for a time, and when they have evaporated, the rank and frowsy smell of the cocoa-nut oil remains. • Since resin will not make a soap of itself, when treated with caustic leys, it is usually introduced into the soap-pans when the other goods, or fatty matters, have undergone the process of saponification. Indeed, if the resin were put into the pan with the first charge of materials, the caustic ley would seize it at once and dissolve it, and thus prevent the ley from performing its proper function — that of MANUFACTURE OF HARD SOAPS. 59 saponifying the fatty materials. It is commonly the practice to first make the hard soap in the usual way, and when the last charge of leys has been given, and when, after the usual boiling, the ley ceases to be absorbed by the soap, the desired quantity of resin is added gradually, and it is an advantage to have it previously broken up into small pieces. The proportion of resin varies from one-third to one-fourth the weight of tallow, but of course weaker goods will take less. While the resin is being shovelled in, the boiling must be kept up, with also the addition of caustic ley. The soap is examined from time to time by the soap-boiler, who freely uses his shovel when he considers that the combination of the resin with the soap is near completion. When a sample of the paste, after being allowed to cool, is firm and solid, and exhibits a good grain or " feather " when cut, the soap is finished. The heat being checked by turning ofi" the steam, the soap is allowed to rest, after which the leys are drawn or pumped out, and the process of •purifying the paste is next resorted to, whereby all impurities of the resin and other materials are deposited below the surface of the soap. Por this purpose a quantity of ley at 8° B. is run into the pan, and the steam again turned on, the soap being well stirred for some time with the rake and the boiling kept up for awhile, after which the soap is again allowed to rest, and the ley again pumped out. A second service of leys at 4° B. is now given, and the boiling and stirring renewed, after which the leys are again allowed to settle, and are then drawn ofi". A final service of very weak leys at 2° B. is now introduced, the stirring and boiling being resumed as before, when the operation is finished. After a long rest the leys subside, and a skin forms over the surface of the soap, whicVi is skimmed off before running the soap into the frames, and put aside to be worked up with future batches. In small works the soap is ladled out of the pans into large iron pails by means of a ladle having a very long wooden handle (Fig. 11). This ladle is of considerable 6o THE ART OF SOAP-MAKING. size, and in order to diminish its weight, when full of soap, it is raised by means of a rope running in a pulley by a second man, while the first holds the handle of the ladle, dips it into the soap, and guides it to the pail which is rested upon the edge of the pan, and is carried when full to the soap frames. To hasten the operation of filling the frames, several men, each carrying his own pail, are usually occupied when a "cleanse," as it is termed, is going on. In larger factories, where the application of steam is extensive, the finished soap is pumped out of the coppers into wrought-iron "pots" (Fig. 8) running on wheels, and which are also used for crutching in " liquor " of various kinds ; these pots, being wheeled up to the frames, are emptied into them, or the soap is pumped into iron or wooden shoots, one end of which is slung on to the pump, while the other rests on the upper edge of the soap frame, and when the frame is full, the shoot is shifted to the next, and so on. Cleansing. — When cleansing yellow soaps, great care is necessary to avoid removing, with the finer soap, the dark-coloured compound called niger, which forms a stratum between the leys and the pale soap. This dark brown soap derives its colour from the resin and impurities in the ley, and although it possesses all the characteristics of a good soap, is unsalable by itself as a commercial article, and should therefore be worked up with other lighter goods in the making of cheaper soaps. Another formula for yellow soap is the following : — TaUow 2,000 lbs. Eesin, about 600 „ These being put into the pan, from 150 to 175 gallons of soda ley at 10° to 20° B. are run in, and the steam turned on. When the materials are melted, the pan is brought to a boil, constant stirring being applied to prevent the resin from adhering to the bottom and sides of the pan. When the mass swells up excessively, the heat must be checked. The boiling is continued for only about two or three hours, owing to the rapidity with which the combina- MANUFACTURE OF HARD SOAPS. 61 tion of the materials and the alkali is effected. The steam being now turned off, the mass is allowed to rest for about six hours, when the spent ley is drawn off and fresh ley is then added, and the boiling resumed and continued for about three hours. After repose for six hours, the ley is again drawn off, and fresh ley run into the pan. The various boilings with fresh leys are continued daily until the soap has acquired the proper consistence, which is ascer- tained by the soap-boiler pressing a sample previously cooled between his finger and thumb. If the soap divides into hard flakes, it is finished, or nearly so ; but £f greasy, sticky, and soft, it requires further boiling with fresh ley. If the soap sample is satisfactory, boil briskly for a short time, and then tiirn off the steam, and throw in a few pails of cold water. After about two hours, the ley is to be drawn off as before. This being done, six or eight pails of water are added and well stirred in, and the boiling briskly pursued. If from samples taken from the paste the ley runs off clear, more water is to be added, and the boiling continued. If it does not separate from the ley, an excess of water is present, and a small quantity — about half a pailful — of strong brine must be added. Finishing. — One of the most important and delicate parts of the operation is that cii finishing the soap. When the. soap has been properly 7?^fe^, as above, it will cKng to the shovel or trowel and have a gelatinous texture. This being the case, the soap is properly finished. Sometimes, in order to give the soap a bright yellow colour, a little raw (that is, unbleached) palm-oil is added. This oil, while imparting an agreeable odour to the soap, is believed to disguise in some degree the natural odour of the resin. A quicker process for making yellow soaps than the fornier is performed in the apparatus known as Papin's digester. The following gives the proportion of goods and ley employed in this process : — "White tallow 800 lbs. Palm-oil ...-. 200 „ Kesin (.powdered) 400 „ Caustic soda ley at 25° B 175 gallons. 62 THE ART OF SOAP-MAKING. These materials are put into the Papin digester, and boiled for an hour under pressure at the temperature of 252° Fahr. At the end of this time the soap is finished, and is, after being allowed to cool down a little, run into the frames. Contmental Metliod ^The French method of making yellow or resin soap in many respects differs from our own system, but since it presents many interesting features we give the process described by Dussauce in his Treatise. It will be observed that by this method the resin is con- verted into a resinous soap, so called, before it is added to the hard soap with which it is to be combined. First process. — ^Into a pan holding from 625 to 750 gallons introduce 1,000 lbs. of taUow, which is to be melted by the aid of heat. When melted, it is to be saponified with about 75 gallons of fresh caustic (soda) ley at 7" or 8° B. While running in the ley, the mixture is to be well stirred. All the ley being added, the heat is to be aug- mented, and the stirring continued for twenty-five or thirty minutes. A white emidsion is thus formed, the ley and tallow having perfectly combined, and a homogeneous paste is the result. An hour after the last ley has been added, the boiling becomes manifested by a tumultuous movement in the mass, and the formation of a very abun- dant white scum. The heat must now be moderated, and the paste stirred. If these precautions are not sufficient, a few pails of cold water or weak ley are thrown into the pan. When the effervescence has ceased, the foaming diminishes, and soon disappears entirely. The paste is now homogeneous and white, or of a yellowish tint. Continue to boil gently ; by boiling, the mixture becomes more intimate and perfect, and acquires more consistency by the evaporation of the ley. Continue the saponification with leys at 15° to 18° B., which are added in portions of 6 gallons at a time every fifteen minutes for one and a half hour. After the last addition of ley, continue to boil gently for a few hours without adding new doses of ley. By continuing the boiling, the paste is saturated slowly MANUFACTURE OF HARD SOAPS. 63 and gradually with alkali ; it becomes denser and firmer, and may then receive stronger leys without fear of the tallow separating from the already saponified mass. There would be no danger of separation if too strong leys were used when the paste is imperfectly saturated with alkali. To prevent this inconvenience, the mass is boiled for a few hours after the addition of the ley. The object of this boiling is to render the union of the molecules more intimate and complete. The saponification is finished by the addition of 25 gallons of new ley at 20° to 25° B., which is added, 6 gallons at a time, every ten or fifteen minutes. When all the ley is added, the steam is turned ofi", and the mixture stirred for half an hour. By combining with the strong ley, the paste thickens and acquires a consistency proportionate to the quality of the tallow. The time of this operation varies from eight to ten hours. Separation is efiected with clear leys of coction * at 20° to 25° B. While the ley is being added gradually, the mass is kept constantly stirred. When the quantity of ley added has been sufficient to efiect the separation of the soap, a spontaneous change takes place in the condition of the paste, which forms into small grains interspersed with ley. When the separation is complete, which is known by the ley freely separating from the soap, the operation is finished. The stirring is, however, kept up for half an hour or longer, so that the separation may be perfect throughout the mass. If " leys of coction " cannot be had, dissolve from 50 to 60 lbs. of salt in about 75 gallons of new ley at 16° to 18° B. The effect will be the same, but the leys will con- tain an excess of salt. The employment of the former is to be preferred whenever it is possible to obtain them ; 75 gallons of such ley at 20° to 25° B., or the same quan- tity of new ley, after the addition of salt, are sufficient to * "leys of coction," or, as we should call them, "salted leys," are passed through the residuum ot soda and lime left in the ley vats, which separates any fatty matter they contain, and renders them clear. The leys are passed repeatedly through filters which are richer in soda, and thus acquire additional strength. 64 THE ART OF SOAP-MAKING. effect the separation. After repose for five or six hours, the ley is drawn off. Boiling. — The ley being drawn off, pour into the kettle 75 gallons of new caustic ley at 24° or 25° B. and apply heat. When the boiling begins, considerable foaming appears upon the surface of the soap, which disperses only when the soap is entirely boiled. If after five or six hours' continuous boiling the ley is still caustic, it must be kept up imtil all the foam disappears. If, on the other hand, the ley has lost all its causticity, 75 gallons of new ley at 30° B. are to be added, and the boil kept up for four or five hours longer. The operation being finished, the soap is in the form of very hard white grains, which, when pressed between the fingers, are reduced to scales. The steam is now to be turned off, and the mass allowed to rest for four or five hours, after which the ley is drawn off, the quantity of which will be about 50 or 60 gallons, and of a strength equal to 27° or 28° B. Fitting is effected by running into the pan 58 gallons of water, and heating, to the boiling-point, with constant stirring. When the grains of soap are well melted, and have the appearance of flat particles separated from the ley, the operation is finished. It is known that the soap is separated from the ley when by taking it up with the shovel the ley runs off in a colourless stream. The steam is now turned off, or the fire drawn, and the pan is well covered, after which the whole is allowed to rest for seven or eight hours. At the end of this period the pan is uncovered, and the ley drawn off. The soap is then ready to receive its admixture of resinous soap, which is prepared . as follows : — Preparation of Resin Soap. — Put into a pan, capable of holding about 375 gallons, 75 gallons of fresh soda ley at 30' B. Apply gentle heat, and when the ley begins to boil throw in, every five or six minutes (about 16 to 20 lbs. at a time), 1,200 lbs. of resin, previously reduced to a fine powder and pa ssed through a coarse sieve. The mixture must be well stirred during the whole time to MANUFACTURE OF HARD SOAPS. 65 prevent the resin from " clogging " and adhering to the sides of the pan. It is important to moderate the heat, as the resin soap has a great tendency to expand, and an excess of heat would cause it to boil over. The heat, however, must be kept up to near the boiling-point, other- wise the mass will become thick and of a very dark colour. When kept at near, the boiling-point it is always perfectly clear, and its colour of a reddish-yeUow. If during the boiling the resin soap rises and threatens to overflow, the heat must be. checked, and a few pails of cold water thrown into the pan, which at once has th& desired effect. It is absolutely necessary to stir the mass- continually, otherwise the resin wiU agglomerate in masses- and thus prevent the ley from acting freely upon it. The saponification of 1,200 lbs. of resin occupies about two- hours, and the resulting compound is perfecijy fluid, and free from solid particles. The soap being now ready, it is introduced into the tallow soap, and thoroughly incor- porated with it by constant stirring. Before doing so,, however, it is necessary to pass the resin soap through a coarse sieve, so as to free it from pieces of straw, wood,, and other like impurities with which it is frequently contaminated. It is considered a bad plan to keep powdered resin in barrels, especially in a warm situation, Since it is liable to- agglutinate and form a more or less compact mass. It is better to have the resin reduced to a powder only a short time before using it. After being well mixed and run into frames it is some- times the practice to "crutch" each frame until ^ pellicle (or skin) forms on the surface, after which the soap is left to cool. Soap thus made is said to be firm and slightly alkaline, producing a good lather even in sea-water. The produce, from the proportions of materials given, should be 2,250 lbs. of good soap. The colour, however, is of a very dark-brown yellow, and, by modifying the process, a lighter-coloured soap is obtained, but the produce is less. The second process is as follows : — Put into the pan 250 gallons of soda ley at 8° or 10° B. 66 THE ART OF SOAP-MAKING. Apply heat as usual, and, when the ley is 'warm, add 1,000 lbs. of white tallow. Boil gently for iive or six hours, with occasional stirring. When perfect combi- nation is effected, and a homogeneous paste formed, add 50 gallons of ley at 16° B., and boil to secure the thickening of the paste. Now finish the saponification with 30 or 40 gallons of ley at 20° B., and stir well for half an hour. Turn off the steam and separate the soap with leys of coction (old leys) at 20° to 25° B. in the same way as before. After a few hours' rest draw off the ley and continue the boiling with 175 to 200 gallons of soda ley at 25° B. If, after boiling for eight or ten hours," the ley is still caustic, and the soap forms thin hard scales when pressed between the fingers, from 600 to 800 lbs. of yellow resin must be added, which gives the soap a fine yellow colour, and the grain of the soap is more homogeneous. The boiling must be continued, and 75 to 100 gallons of ley at 25° to 28° added, which will complete the saponification of the resin. After four or five hours' boiling the ley should stiU be caustic, when it is known that the soap is finished. A small sample, dropped upon a cold surface, should set hard and firm in a few minutes. After the usual repose the ley is run off. Now run into the pan from 100 to 125 gallons of ley at 4°, and again boil, with constant stirring, until the mix- ture becomes liquefied. When all the grains are melted, forming a nearly homogeneous paste, from which the ley, however, separates, the operation is finished ; if the ley does not separate, an addition of clear old leys must be made to aid the separation. The steam is now to be turned off and the lid of the pan lowered upon it. After a repose of twenty-four hours the leys, together with aU impurities, will have subsided, leaving the pure, finished soap above, which may then be cleansed — that is, put into the frames— in the usual way. When all the soap is in the frames it is to be stirred until cool, and if it be desired to give the soap a slight perfume, an ounce of anise oil for. every 100 lbs. of soap may be crutched in. To impart to MANUFACTURE OF HARD SOAPS. 67 the soap an agreeable odour, sometimes 15 per cent, of bleached palm-oil is combined with the tallow, and the whole saponified together. This improves the soap by- making it lighter in colour. Dunn's Process. — This is recommended by the inventor to be performed by steam heat, thus conducted: — Into each of the ordinary soap-pans a circular coil of l;|^-inch piping, perforated with holes, is iixed in the well of the pan, just far enough from the bottom to allow the .free movement of the stirrer beneath it when it becomes neces- sary to stir the contents below. The circular coil of pipe is supplied with atmospheric air from a cylinder blast Or other suitable forcing apparatus, the circular coil being connected' with such forcing apparatus by means of a pipe attached thereto, and rising up to the top of the pan, where it is furnished with a stop-cock and union-joint for the purpose of connecting the parts of the pipe within and without the soap-pan. For a clean yellow soap, put into the pan 90 gallons of leys of the specific gravity 1"14 made from strong soda ash. The fire being kindled, the pan is charged, in the usual way, with, say, 2,050 lbs. of grease, and as soon as the ley is hot and on the boil, or nearly so, the blast is set in action, while a good brisk fire is kept up, so as to bring the materials as near boiling as possible. "When the leys are exhausted more ley is gradually added until the grease, oil, or fatty matter is " killed." Then add 550 lbs. of fresh resin, a pailful at a time, with more ley occasionally, until 300 gallons of the above strength have been used, keeping the blast in action the whole time if the fires draw well, but if not, it is advisable to stop the blast for a short time, before adding the resin, to allow the contents of the pan to approach ebullition. When the whole of the resin is melted and completely mixed with the soapy mass, and the strength of the leys taken up, stop the blast, and give a brisk boil- ing to the contents of the pan, and then let it rest, so that the spent leys may separate and settle. The leys being now drawn off, the soap is then brought to strength on fresh leys as in the ordinary process of soap-boiling. 68 THE ART OP SOAP-MAKING. During the operation of the blast the soap must be kept in what is technically termed an " open or grained statej" and for this purpose salt or brine is to be added when necessary. Experience proves that it is better not to make a change of ley during the operation of the blast where the ley of the strength before mentioned is used, but if a weaker ley is employed, one or more changes may be made, as is weU understood. It is found desirable that the soap should be kept at what is called " a weak state " during the movement of the streams of air through the materials, otherwise the soap is apt to swell up from the air hanging in the grain, and this is found troublesome to get rid of, requiring long boiling. If dark-coloured materials are used, it is well to keep the blast in operation three or four hours after the resin is melted, provided the soapy mass is kept weak and open-grained. When a charge is to be worked upon the nigxe, such nigre shoidd be grained, and the spent ley pumped or drawn off as usual, and the fresh charge added in the manner before mentioned, using less ley in proportion to the quantity and strength of the nigre, takmg care not to turn on the blast until there is 8u£B.cient grease present to make the nigre weak. Meinicke's Process requires that the soap-pan should be furnished with a still-head and cooling- worm, since the resin is added in the form of white turpentine, which, during the boiling, gives off its volatile oil as a distillate, which is condensed and saved as a by-product, and thus decreases the cost of the soap. 1,000 lbs. of white tur- pentine are melted in the pan by steam heat with 800 lbs. of tallow or inferior fat, and when the mixture reaches 108° Fahr. it must gradually receive, with constant stirring, 800 lbs. of caustic soda ley containing 30 per cent, of dry soda. The imion of the materials is very prompt at the above temperature, the acids of the resin and grease being completely neutralised and converted into liquid melted soap. The essential oil of turpentine is set free at the same time, and in order to promote its MANUFACTURE OF HARD SOAPS. 69 vaporisation salt brine is added.* The head being care- fully luted upon the pan and adjusted to the worm, and the mixture brought to a boil, the steam and vapour of the spirit become united and pass over into the worm, and are condensed. When all the essential oil is distilled over, the remaining soap is finished in the usual way. Practice shows that the greatest excellence in resin soap is not obtained by adding the resin directly to the oil or paste. The best plan is to make the grease and resin soaps separately and then to mix them in proper propor- tions. The resin soap is first prepared by stirring 80 lbs. of powdered resin, a little at a time, into 100 lbs. of soda ley at 25° B., and boiling into a perfect solution. The acid properties of resin render the combination easy and prompt, even when the ley is made from a carbonated alkali. The resino-alkaline solution is then to be well stirred into the finished paste, made from tallow, while it is stm in the pan ; but its temperature should not be above 135° to 140° Fahr., otherwise perfect homogeneity of the mixture cannot be obtained. In this way 16 per cent, of resin may be introduced without materially darkening the colour of the tallow soap. Moreover, the quality of the product is good. Sometimes several per cent, of starch or bran are used to assist the combination of the two soaps. When the soap materials are worked by fire instead of steam the boiling should be continued gently until the paste is uniform throughout, and then the salt is to be added. Yellow, or resin soap, may be prepared from curd soap by adding to it about 25 per cent, of resin, and then adding from 2 to 4 per cent, of carbonate of soda, and 1 or more per cent, of alum or sulphate of alumina, the whole being boiled with water until a perfect combination takes place. To prevent the resin from becoming preci- pitated, about 2 per cent, of dilute sulphuric acid (1 part acid to 9 parts water) are stirred into the mixture. * It is well known ttat the addition of salt to water enatles that liquid to attain a higher temperature than 212° F., the hoiling-point of water. 70 THE ART OF SOAP-MAKING. According to Eicliardson and Watt it is better to saponify the resin and tallow separately, and to mix the two soaps in the pan, and then to boil until a perfect union takes place. Salt is then added, and the soap finished in the ordinary way. The usual proportions of palm-oil and resin are 3^ parts of the former to 1 part of the latter. CHAPTER VII. MANUFACTURE OF SARD SOAPS— {continued;). Treatment of the "Nigers." — Anderson's Process. — Cocoa-nut Oil Soaps. Sturtevant's Process. — Frencli Cocoa-nut Oil Soaps. Treatment of ITigers. — In the manufacture of yellow or resin soaps, the materials, or "goods," are boiled over successive portions of caustic soda ley, of various degrees of strength, or density, as before explained, until the last leys still retain their causticity after continued boiling with the fatty matters. After a few hours' repose the leys are drawn off, and the process of " fitting " commenced. To accomplish this, the paste is brought into a thin con- dition, by adding either very weak leys or water, and the boiling resumed, until the mass assumes the form of an emulsion. The heat is then checked, and the soap allowed to rest for two or three days, when a dark- coloured substance subsides, which is called niger or nigre. The finished soap is then " cleansed " by pumping it off from the niger into the frames, great care being taken that none of the dark-coloured material is allowed to be drawn off with it. The niger is usually either worked up in subsequent boils of soap or converted into an inferior quality of yellow soap, according to the requirements of the soap- maker. The iitilisation of the niger, however, has frequently proved a source of trouble to the soap-maker, especially when employing large quantities of dark- coloured resin. Mr. Anderson, a well-known London soap-maker, turned his attention to this subject many years ago, and subsequently obtained a patent, fr6m which we extract the following : — 72 THE ART OF SOAP-MAKING. Anderson's Process. — " I find that when curd soap is boiled to strength and subjected to a fitting process, some- what similar to the fitting process used in making yellow soap, there separates from it a peculiar substance analo- gous to the niger of yellow soap, and that by removing this niger and boiling the remainder of the goods into, curd soap, I obtain a curd soap of better quality than the original charge of goods would yield without this opera- tion. I also find the niger, which I remove, eminently adapted for making mottled soap, to which purpose I apply it accordingly. " In carrying out my process, I proceed in all respects ia the manner practised commonly by soap-makers up to a certain point ; that is, I place in the copper the ordiaary materials for making curd soap, with the or- dinary leys, and boil them together until the goods are to ' strength,' and ' ribbon out ' well on the finger ; but at this stage, instead of boiling out the head and finishing as heretofore practised, I commence the performance of my process. I pump out the strong ley, on which the goods have been boiled, and treat the goods with successive portions of weak ley or water, and boil them together until they assume the appearance of a fitting yellow copper. This condition being arrived at, I stop the operation, and allow time for the niger to deposit, which inay require from twenty-four to thirty-six hours. I now proceed to separate the niger, which I either pump out from under the purified goods to an adjacent copper, or I remove the purified goods from above the niger to an adjacent copper, as I find most convenient ; but in either case, the ^oods being thus deprived of the niger, I add to them the proper finishing ley for curd soap, and boU to a suitable curd, or until the soap is found to be in a condi- tion for cleansing into the frames. "When I operate upon a charge of very impure materials, or when from any circumstance I consider it an advantage, I repeat the purifying or fitting process one or more times, in which case, after separating the niger, as before, I add to the residual partially purified MANUFACTURE OF HARD SOAPS. 73 goods a ley of moderate strengtli only (instead of tlie finishing ley for curd soap) and boil, taking care that no ' head ' is formed. I then pump out this ley, and again treat the goods with weak ley or water until sufficiently diluted, so as to perform the fitting process, after which I aUow time for subsidence, separate the niger, add the finishing ley, and boil to a curd as before." He next describes his method of treating the niger, and the way in which he converts it into mottled soap. After separating the purified soap from the niger, as before, he adds to the latter the ordinary ley used for finishing mottled soap, and boils until the soap is fit for cleansing, or framing. The quantity of niger obtained from one bpil, however, is not sufficient to make a boil by itself; therefore Mr. Anderson takes the niger resulting from four, six, or more boils of soap, and finishes them in one operation, as above. Sometimes he adds to the nigers a certain quantity of tallow, fat, bone grease, melted " stuff," or other suitable materials, and then proceeds to finish, as with an ordinary mottled soap. Cocoa-uiit Oil Soaps. — One of the most important addi- tions to the list of fatty matters suitable for soap-making was the vegetable substance called cocoa-nut oil or cocoa butter, which, from its extreme whiteness and capability of forming a hard soap, soon became an acceptable sub- stitute in some degree for the more costly tallow. Soap made from this oil, or vegetable butter, is capable of taking up a larger percentage of water — and still form a hard soap — than any other known fatty material. The soap made from it, moreover, is more soluble in saline or " hard " waters — even sea^ water — and for this reason it has long been made into a soap called Marine Soap, for use on board ship. Cocoa-nut oil, however, when saponified, has the great disadvantage of imparting an exceedingly disagreeable odour to the skin and even to articles cleansed by its agency; and even when but a small percentage of this substance is blended with other soap materials, its pecu- liarly offensive odour will rest upon the surface of the skin 74 THE ART OF SOAP-MAKING. for many hours after washing with it. Soap made from this oil, therefore, should never he introduced into toilet or fancy soaps, even in small quantity, except for the very low-priced qualities. Cocoa-nut oil does not readily saponify with caustic soda leys, when hy itself, but when added to tallow, or palm-oil, it does so without difficulty. When saponified by itself it forms a soap of almost unusable hardness, and for this reason, besides its objectionable odour, it is always asso- ciated with other fatty materials when employed iu the manufacture of soap. Stnrtevant's Frocess. — One of the earliest processes for making soap with cocoa-nut oil as an ingredient was patented by Sturtevant, in 1841. It consists in first steam- ing the oil in a wooden vat, and adding to it 6 lbs. of sulphuric and 12 lbs. of hydrochloric acid to each ton of oil, to remove as far as practicable its objectionable odour. After allowing the oil to rest for a while, it is drawn ofi", and is then ready for the soap-pan. To make a White Cocoa-oil Soap. — The materials are taken in the following proportions : 2,072 lbs. of cocoa-nut oil, either as it is imported or refined as above ; 168 lbs. of olive or other sweet oil, or tallow ; 325 gallons of soda ley at 24° B., and 60 gaUons of potash ley at 20° B. The cocoa-nut oil, tallow, or oil, as the case may be, are first put into the pan, and heat applied. About 10 gallons of the soda ley is then added, and when the whole materials are united, the same quantity of soda ley is added from time to time, with continued boiling, care being taken that each portion of ley is well combined with the fatty matters before the next is applied . As soon as the whole of the soda ley has been used, the boiling is kept up for about half an hour. The potash ley is then added, graduallv, as before, and when the whole quantity has been used, the boiling is kept up for about fifteen minutes, after which about 84 lbs. of common salt are sprinkled slowly over the mass, this operation occupying about a quarter of an hour. The boiling is then continued for about half an hour, after MANUFACTURE OF HARD SOAPS. 75 whicli the steam is turned off, or the fire drawiij as the case may be. When the manufacture of the soap is complete, it has the consistence and tenacity, or " closeness " of melted glue. It is now allowed to cool down, and is afterwards cleansed or framed in the usual way. The potash ley is em- ployed with the soda ley only for the finer qualities of soap. To make Yellow Soap with Cocoa-oil, by the above process, these proportions are given: 1,072 lbs. of cocoa- nut oil ; 112 lbs. of raw palm-oil ; 336 lbs. of bleached palm-oil: 448 lbs. of tallow; 224 lbs. of resin; 112 lbs. of common salt, and 450 gallons of soda ley at 23° B. All the fatty matters and the resin are first put into the copper, heat applied as usual, and the whole operation conducted in the same way as already described. There have been numerous modifications of Sturtevant's process for manufacturing soaps with cocoa-nut oil as an ingredient ; and, indeed, this useful vegetable product is very extensively used by most soap-makers both at home and abroad, but more especially in this country, where it is employed in enormous quantities. As we have said, however, cocoa-nut oil, unless blended with some other fatty material, does not make a good soap. Tallow or palm-oil, therefore, are employed, in variable proportions, in combination with it, in the manufacture of certain soaps, and it is also the practice to use potash as well as soda leys in making soaps containing cocoa-nut oil. Soap made from this oil being soluble in weak leys and saline solutions, requires a much larger proportion of salt in the process of separation. The proportions of tallow or palm-oil which may be successfully employed with cocoa-nut oil for a genuine — that is, not a reduced, or " liquored " soap — should be 60 parts cocoa-nut oil and 40 parts tallow ; or equal parts palm and cocoa-nut oils. For the latter combination, an equal volume of caustic soda ley at 27° B. and a third of a volume of caustic potash ley at 10° B. are used with the boiling until perfect combination takes place. A small 76 THE ART OF SOAP-MAKING. quantity of very weak ley is then added, the temperature of the mass not being allowed to exceed from 180° to 190° Fahr. The boiling should be continued for about two hours, at the end of which time the ley wiU have become exhausted. A little weak ley is then added, and salt thrown in, with stirring, mitil a sample, allowed to cool, appears clean, dry, and free from greasiness. If it does not possess these characteristics, and there is no evidence of causticity, a further dose of ley must be added, and if necessary more salt. If too much heat be applied, the soap will become too thin, causing a separation of the tallow or palm-oil from the cocoa soap, and the same objectionable result will be obtained if there be an excess of salt or ley. In the latter case, the steam is turned off, and a little fresh cocoa-nut oil must be added, with constant stirring, until the proper condition is obtained. The heat is to be kept up for five or six hours, with frequent stirring, so that a perfect and uniform combination may take place. When the opera- tion is finished, the soap is allowed to rest until the fol- lowing day, when the pan is to be again heated, whereby the union of the alkali and fatty matters becomes more perfect, and the soap turns out harder and better than if framed at once on the completion of the boiling. It is also considered advisable to allow the soap to cool in the pan until it indicates a temperature of 155° Fahr. before removing it to the frames, and to well crutch it, when' in the frames, until it begins to stiffen, whereby a more homogeneous condition of the soap is secured. The crutching, however, must not be applied when the soap has cooled down to 130° Fahr., or it will separate from the ley. If, after allowing the soap to repose in the pan during the night, it should be wanting in strength, a little more ley must be added, until it tastes slightly caustic. Should this not be effectual, warm strong brine must be gradually added, and well stirred in until the desired result is obtained. Soap containing a large percentage of cocoa-nut oil is MANUFACTURE OF HARD SOAPS. 7; capable of holding in its constitution a very considerable quantity of water, and yet form a hard soap ; indeed, in some soaps we have seen, water has been not only the chief ingredient, but almost the only one ! French Cocoa-nut Oil Soaps. — In France they make white and tinted soaps from cocoa-nut oil ; and since their method of manufacture somewhat differs from that adopted in this country, the following process, given by Dussauce, will be read with interest. " White and Rose Soaps. — For these soaps the oil must be very white and concrete ; that of Cochin is the best and the most highly esteemed. Suppose that a soap is to be prepared yielding 500 to 600 per cent., introduce 2001bs. of oil into a sheet- iron kettle (pan) of a capacity of from 375 to 400 gallons. Melt the oil by a gentle heat, and as soon as melted pour in it 50 gallons of new ley of soda ash at 15°, and boil the mixture, adding from time to time small portions of ley at 18° to 20°, until the paste has acquired a caustic taste. When in this state it 'is a sign that it is entirely saturated. The first operation lasts four hours. " To' harden the soap and make it produce the quantity named above, add to it salt water (brine) at 18° to 20° in the proportion of 5 gallons every fifteen minutes, and at the same time continuing the ebullition. It is in this second stage of the operation that the degree of coction (boiling) of the soap must be ascertained, and for this purpose a certain quantity is taken from time to time and allowed to cool on a dish. When the sample becomes solid by cooling, the operation is finished. Generally the quantity of salt-water used is about the same as that of the ley, and at about the same degree. For the above proportions the operation lasts about seven or eight hours, during which the mixture is constantly kispt in a state of ebullition. When the operation is finished the steam is turned off, and the soap, before being run into the frames, is suffered to cool and rest for twelve or fifteen hours. " If the soap is to be. rose, it is coloured as soon as run into the frames, and while yet fluid, with 4 lbs. or 6 lbs. of 78 THE ART OF SOAP-MAKING. vermilion, which, is well distrihuted in the mass by stirring. To have an uniform colour it is important that the paste should be very fluid, for if too cold, a part would remain white." We shall have again to refer to the subject of cocoa- nut oil soaps when treating of reduced or cheapened soaps, which form an important branch of the soap-making industry, especially in the northern parts of England. CHAPTER VIII. MAKING SOAP BY THE COLD PROCESS. Hawes's System. — ^Making small Quantities of Soap. — To prepare a White Soap. — Lard Soap ty tlie Cold Process. It had long been the desire of soap-makers to possess some process of saponification less tedious and costly than the ordinary systems of soap-boiling. It was well known that caustic alkalies would convert into saponaceous matter fats and oils, without the application of heat, and it was also well known that during the process of saponification by the ordinary system of boiling over caustic leys, a con- siderable amount of glycerine was set free, and which, being a substance soluble in water, passed away with the spent or waste leys, causing a direct and .positive loss in the manufacture. Hawes's System. — One of the most ingenious practical attempts to modify the ordinary system of soap-making was that devised by Mr. "William 'Hawes, a gentleman who had long been connected with the soap trade, and was indeed a member of one of the largest and most enter- prising firms in London. The process is well known as the COLD PEOCEsSj and is thus described by the inventor : — " I take any given quantity of tallow, say 2 J tons, and having melted it, keeping the temperature as low as . pos- sible, I mix it with the quantity of alkaline ley which is. required to completely saturate the tallow and convert it into soap ; and such mixing I perform by mechanical means, and the apparatus or machinery I employ is here- after described. I use the ordinary ley of soap-boilers,- preferring that made from the strongest and purest alkali. " The saponification of the tallow, or other fatty inatter. 8o THE ART OF SOAP-MAKING. may be ascertained by the absorption or combination of the tallow or fatty matter with the ley, care having been taken, in the first instance, to use a sufficient quantity thereof, or about 20 gallons of ley of 17" B. to every 100 lbs. of tallow. It is necessary to state that the pro- portion of alkali varies with the different fats and oils. The combination of the fatty matter and ley may be effected in an ordinary boiling caldron, with the addition of a machine to produce an intimate admixture, and the minute division of the tallow. The whole apparatus is HHHHH^HHHH Kg. 17. represented in the drawings ia Pig. 17. It consists of an upright shaft, from which arms, aaaa, radiate to the sides of the caldron b b. This shaft, either permanently or tem- porarily fixed ia the copper, may be of wood or iron. The mode of fixing the apparatus and the materials used first will depend upon the nature of the caldron an^ the con- venience of the manufacturer. An oscillating motion, or a rotary motion, may be given to the shaft and connected arms by any of the ordinary methods of communicating mechanical power ; or a cylinder may be employed with a shaft c, passing through it horizontally, and from MAKING SOAP BY THE COLD PROCESS. 8r which arms, c c c c, may radiate, when a rotary motion will thoroughly incorporate the fatty matter and the ley. " The size of the cylinder, for about 2^ tons of tallow, will be about 6 feet in diameter and 12 feet in length. It must be provided with convenient doors, d d, for charg- ■ ing and emptying. Motion being communicated to the machine, and the caldron having been previously charged with the tallow, the ley is to be gradually added thereto, and in a short time every particle of the fatty matter wiU. be brought into intimate contact with the alkaline ley, and by such means saponification will take place. The stirring is continued for about three hours, or until the taUow appears completely saponifi.ed, as is indicated by the mass thickening, after which it is allowed to stand from one to four days, according to the quantity of the paste. " Should a cyiiider be used, then immediately upon its being charged with tallow, at a temperature just high enough to keep it fluid, the ley is run in, and motion com- municated to thelshaft, and continued from 3 to 4 hours, or less time, if tne mass becomes thick sooner. As the benefit of this pricess arises mainly from the saponification of the ordinary |naterials in a comparatively cold state, it is desirable, as sbon as the mass thickens, and the ley is absorbed, that tVe cylinder should be emptied, and the contents turned into an ordinary caldron, preparatory to being finished and converted into yellow soap, by the addition of resin ; or into mottled soap or white soap, by the operation of finishing leys, as at present practised by soap-boilers generally. By this transfer from the cylinder to the ordinary caldron, time is allowed for the combina- tion of the tallow and alkali to become perfect." The adoption of th^ cold process in this country has not, we believe, extended much beyond the limits of very small operations, such as toilet-soap making, for example. Indeed, the difficulty of obtaining leys sufficiently con- centrated, without evaporation, would, to some extent, stand in the way of its extended application. At the present time, however, when soap-makers are supplied with caustic soda in a solid state, which renders it 82 THE ART OF SOAP-MAKING. unnecessary for them to make their leys in the ordinary wa)^, it may be advisable, perhaps, that they should once more take the cold process into consideration. Although soaps made by this process retain more alkali than those made by the ordinary methods of boiling, and would, therefore, be less suitable for toilet purposes, it is certain that good household, or laundry soaps, if carefully prepared, could be advantageously made by this system. For making small quantities of Soap by the cold pro- cess, the ley should have a density of about 36° B. This may be obtained either by evaporating strong new caustic ley prepared in the ordinary way, or by dissolving com- mercial caustic soda in water until the required strength is reached. To prepare a White Soap. — Put into a pan, capable of holding about 100 gallons, tallow, lard, or bleached palm- oil, 120 lbs. ; cocoa-nut oil, 40 lbs. ; apply gentle heat, with occasional stirring, until all the fatty matter is melted. When the liquid grease has attained the heat of about 120° Fahr., add, gradually, 80 lbs. of ley at 36° B., and stir well until a complete union of the fatty matters and alkali is effected. The temperature of the ingredients, at the time of adding the alkaH, must not be higher than 122° Fahr., otherwise there wUl be a separation of the ley from the fatty materials. If the stirring has been diligently pursued, the saponification will be complete in about two hours, and the soap is then ready for the frame. If it is desired to perfume the soap, this should be done while it is in the pan, and before it has had. time to cool. It is not a good plan, when making small quantities of soap, to add the perfume after the soap is in the frame, since it is then more difficult to effect a perfect incorporation of the respective materials. When soap made by the cold process has been in the frame for about five hours, a considerable augmentation of its temperature takes place, owing to the chemical reaction of its constituents, whereby a more perfect combination is effected. In order to favour this reaction, the frames, should be closely covered so soon as it has been filled with ' MAKING SOAP BY THE COLD PROCESS. 83 the soap. The quantities of materials given should yield about 236 lbs. of soap of a pure white, and, owing to the proportion of cocoa-nut oil, it lathers very freely. In making coloured soaps by the cold process, it is recommended to add the colouring matter to the fatty materials before the ley is poured in, by which it becomes more thoroughly mixed. Lard Soap by the Cold Process is made by taking, say, 112 lbs. of lard, and melting as before, at a gentle heat ; 28 lbs. of caustic soda ley, at 36° B., are then added gradually, with constant stirring, and when these are well incorporated, 28 lbs. more caustic ley of the same strength are added, and stirred in as before. The temperature of the paste must not be allowed to exceed 149° Fahr. When a sample of the soap is examined, it should feel somewhat unctuous when pressed between the fingers, but exhibit no greasiness. It is then ready for the frame, and after about two days will be sufficiently cold for cutting. The same process has been applied to making soap from beef marrow, oil of sweet almonds, &c., for toilet purposes. Oleic acid, or red oil, has also been employed in the follow- ing way : — 1,300 lbs. of caustic soda ley, at 18° B., are run into a pan, and boiled. Then 1,000 lbs. of oleic acid are added, gradually, with constant stirring. The oil, being a fatty acid, is quickly absorbed by the ley, with strong evidence of chemical action, and considerable foaming, which requires to be subdued by continually breaking the foam with a shovel, or other suitable implement. If the . paste has a strong caustic taste after two or three hours' rest, more oil must be added, little by little ; or, on the other hand, if it has no allcaline taste, additions of ley must be given, until the soap is slightly alkaline. After reposing for about twenty-four hours, the soap is put into frames in the usual way. CHAPTER IX. OLEIC ACID.— SOAP FROM REG OVJSREI) GREASE. Oleic Acid. — Soap from Eeoovered Grease.— Morfit's System of Soap- making. — Oleic Acid Soaps. — Kottula's Soaps. — Instantaneous Soap. Oleic Acid. — In the manufacture of stearine 'for candles, ordinary tallow is boiled in wooden vats by high-pressure steam, with slaked lime, for several hours, by which a lime soap is formed. This is transferred to another vessel and treated with dilute sulphuric acid, which, combining with the lime, forms sulphate of lime, which deposits, while the fatty acids {stearic and oleic) rise to the surface. The mix- ture of fatty acids, thus formed, is next placed in vessels to cool, and is afterwards subjected to pressure, whereby - the olieic acid separates and flows into vessels ready to receive it. At the extensive candle works of Price and Company the vegetable fats are decomposed into their constituents, fatty acids and glycerine, by the action of superheated steam alone, that is, without previous saponi- fication. By another process, palm and cocoa-nut oils are decomposed by strong sulphuric acid at a temperature of about 350° Fahr., produced by superheated steam, and the restdting mass is afterwards distilled by the aid of steam heated to about 550° Fahr. This is called sulphuric acid saponification. It will readily be seen, therefore, that as a by-product of the candle factory, oleic acid must be an abundant soap- making material, and so indeed it is : and, theoretically, it should be convertible into soap (oleate of soda) by means of a carbonated (not caustic) alkali. Taking advantage of this fact, Mr. Morfit, many years since,- pursued a long OLEIC ACID— SOAP FROM RECOVERED GREAS. \ 85 series of practical experiments with a view to developing a process by which commercial oleic acid, commonly known^ as oleine, brown oil, and red oil — resulting from the processes above referred to — could be converted into soap without the employment of caustic leys. The processes which he subse- quently introduced included the manufacture of soaps from the fatty acids generally, including " recovered grease," or "sudoil." Since the treatment of fatty acids with carbonated alka- lies, instead of employing them in the caustic state, as in ordinary soap-making, involves the escape of carbonic acid, and a consequent swelling up of the materials when brought in contact, even without boiling, ample room must be left in the pan to allow for the great increase in bulk which occurs after repeated additions of alkali. Soap from Recovered Grease. — Before giving a brief description of Mr. Morfit's process, it may be well to refer to a series of experiments conducted by the author some years ago, with the object of converting recovered grease into a marketable soap. The grease was first melted at a temperature sufficiently high to liquefy it, when small doses of a warm solution of soda crystals were added from time to time, with constant stirring, until efliervescence no longer occurred on the addition of the soda solution. The fatty acids being now neutralised, the saponaceous mass was next treated with a solution of chloride of soda, with the object of lightening its colour. The powerful bleaching proper- ties of this solution soon afiected the colour of the soap, rendering it many degrees paler, but some portion of the colouring matter remained unacted upon by the bleaching liquor, which became evident when the chloride ceased to produce anj'' further effect. The soap was afterwards boiled over a strong salted ley, and the resulting paste mixed, in varying proportions, with other spaps ; but although the chloride of soda had diminished the peculiar odour of the grease to some extent, it was found that only a small percentage of the fatty acid soap could be worked up with soaps of better quality, and even then a keen nose would recognise its presence. When 86 THE ART OF SOAP-MAKING. j)erfumed witli nitro-benzol or cassia its odour was effectu- ally disguised, and it could, therefore, be employed in mode- rate proportions in some kinds of fancy soaps. As a rule, soap-makers have a great dislike to recovered grease, or Wakefield fat, owing chiefly to its odour, but which, after all, is neither so disagreeable nor so lasting on the skin or linen washed with it as that imparted by cocoa-nut oil soaps., Morfit's System of Soap-mating. — This has foritsobject the conversion of the fatty acids of commerce into soap by means of carbonate of soda, instead of employing caustic leys, whereby the inventor produces soap containing defi- nite proportions of fatty materials, soda, and water, these proportions being determined before the manufacture com- mences. The time occupied in making a batch of soap is stated to be two-and-a-half hours, and in two days after the soap is ready for cutting. Thus four boils may be made in one day in each pan, thereby rendering it un- necessary to keep large stocks of soap on hand. Although soap made by this system can be "run," that is, cheapened by the addition of large quantities of water and ■other adulterations, " it does not, in its integrity, con- template any such degradation. On the contrary, it is designed to furnish soap of the greatest possible excellence at the lowest possible cost, so that the manufacturer may have a creditable means of securing both profit and success against the dishonest competition of very much inferior soaps as made by the older methods." The fat acids, being already deprived of their glycerine, do not suffer loss in the same way that neutral fats neces- sarily do in the process of saponification, consequently the whole of the material used, in combination with specific proportions of soda and water, are ultimately obtained in the form of soap. Amongst the advantages which are claimed for the oleic soaps is the following : they " cleanse better in cold and hard waters than the highest grade of soap that can be made from neutral fats. Indeed, for most purposes, it is not necessary to use hot, or even warm water to bring out their best effects." MORFIT'S SYSTEM. 87 The raw materials employed in Morfit's system include thirty-one varieties of commercial fat acids, but he gives the preference to oleic acid prepared from cotton-seed oil. In carrying out his process he employs superheated steam, at a pressure of from 50 to 60 lbs. The soap-pan is made of wrought iron, with steam-jacket, and revolving stirrer fixed in strong iron framework. The stirrer con- sists of a vertical wrought-iron spindle fitted with two wings, or sets of blades, moving in opposite directions, by which a more rapid and complete incorporation of the materials is effected. A simpler arrangement, however, is to fix a series of toothed blades to the sides of the pan, for breaking the paste as it is carried round the mass by a single wing. This is the least costly arrangement, and would be nearly, if not quite, as efiectual. When charging the pan, the proportions of raw materials are either weighed or measured accurately ; but, before putting them into the pan, this is first thoroughly heated by letting steam, under high-pressure, enter its jacket. " The charge of red oil or fat acid, say 1,000 pounds, is then to be run into the pan through a sieve, and the heat of the steam raised by superheating. The usual custom, in the absence of a superheater, is to raise the steam in the boiler to a pressure of five to five and a half atmospheres ; but this latter should be the extreme. When the introduction of the superheater is employed, its tubes must be kept at a violet or bright violet redness. Care should be observed also to stir well for three to five minutes after drawing up the thermometer, and just previous to adding the alkali liquor, in all those cases where solid fat or resin mixture forms part of the fat stock; otherwise the resulting soap paste will not be homogeneous or handsome." The alkali is not introduced into the pan until the materials have acquired the tem- perature .of 320° Fahr., the highest point it must be allowed* to reach. The alkali liquor for the above quantity of fat acid is prepared by dissolving in boiling water 190 lbs. of soda ash of 52°. The quantity of water must be in the pro- 88 THE ART OF SOAP-MAKING. portion to form soda crystals, namely — 62-80 per cent., or, say, 1 gallon of water for every 5 lbs. of ash. This quan- tity of alkali forms a neutral soap ; for stronger soaps, from 210 to 226 lbs. of ash are used. The solution of soda must mark 212° F. before being added to the hot material ia the pan, and only from six to twelve minutes' time allowed to run in the whole of the liquor. The stirrer is then set in motion a minute or less after the alkali begins to flow, and is kept up, with the heating, until the process is complete. The brisk chemical action which is set up causes a great swelling of the mass, to allow for which a curb is fixed above the pan. Soon after the last portion of alkali has been run in, the mass begins to sub- side, and " changes from its spongy state into that of a clear, soft, homogeneous paste, which soon assumes a bril- liant appearance. Later it becomes more consistent ; and in an hour and fifteen to thirty minutes from the moment that the alkali commenced to fall into the oil, the paste is so stifi" and dry that it ' cuts,' or peels from the walls of the pan and the blades of the stirrer." The paste is now sprinkled over with eight or ten gallons of boiling water, the stirring and heating being contiaued, until the paste, at first quite soft, regains its stiffness. Soap thus made consists of in 100 parts : oleic acid, 65"00 ; soda, 6'7 to 7-50 ; water, 27-50. Instead of employing a solution of soda ash, Mr. Morfit sometimes uses soda crystals, fused in their own water of crystallisation ; and since this salt of soda has attaiaed a remarkably low price, it would, doubtless, in this country at least, prove the most facile, as also the most economical, form of soda to apply to this system of saponification. Oleic acid is extensively used by soap-makers in the ordinary processes of soap-making ; but it is generally associated with a considerable portion of tallow or other fat containing stearine, by which a firmer and harder soap is obtained than with oleic acid alone. From 30 to 40 per cent, of tallow is a fair proportion. To make soap from oleic acid and tallow, the pro- portions may be — oleic acid, 1,350 lbs. ; tallow, 900 lbs. OLEIC ACID SOAPS. 89 The oleic acid is first run into tlie pan and heated, after which, about 100 gallons of old ley, at 22° to 25° B., are introduced. In a short time the oil assumes a spongy condition. If necessary, the operation may be hastened by adding a few gallons of fresh ley at about 28° B. The heat is to bo kept up moderately for five or six hours, with occasional stirring, until the grains of soap formed become dissolved. As soon as this is effected, the whole is to be brought to a gentle boil until a thick foam appears on the surface ; tuis foam must be kept under by con- tinual agitation, and if there is a disposition of the mass to rise above the edge of the pan, from 12 to 15 gallons of ley at 20° or 25° B. may be dashed in. It is better, how- ever, to check the heat at times, and to add the leys cautiously, rather than to be compelled to resort to the application of fresh leys to subdue the rising of the mass. During the boiling, a perfect separation must take place, and the soap appear in the form of small grains. When this condition is arrived at the boiling is to be continued for about a couple of hours, the steam then turned ofi", and the soap allowed to stand for about eight or ten hours. At the end of this period the leys are drawn ofi", and the operation of saponifying the tallow commenced. This tallow is first put into the pan, when 75 gallons of fresh ley at 20° to 28° B. are run in, and the whole well stirred, to ensure perfect combination of the leys with the tallow. The mixture is then sufiered to rest until the following day, when the steam is to be again turned on. After a while- the grains formed during the saponification of the oil gradually disappear, and the tallow begins to assume the usual pasty condition. As soon as this is complete, which is determined by frequent examination of small samples taken from the mass during the boiling, the steam is turned aS, and the process oiseparation commenced. To separate the saponified materials, small quantities of old leys at 22° to 25° are added (about 3 or 4 gallons at a time), when considerable effervescence occurs. Similar doses of ley must be added from time to time, with con- tinual stirring ; but each portion of ley must be allowed 90 THE ART OF SOAP-MAKING. to have its full effect before introducing the next, other- wise the uprising of the mass will be so great as to render it liable to overflow. The additions of ley must be made until separation is effected, which may be ascertained by dipping the shovel into the mass in the usual way, when, if the soap appears in small grains, from which the ley runs freely, the operation is nearly finished; but to ensure its perfect completion, 40 or 50 gallons of the same ley are introduced, with brisk stirring for about half an hour. The soap, which is now in the form'of very small grains, is allowed to repose for eight or ten hours, when the ley is drawn off as usual, and the saponification of the soap completed by boiling with two fresh services of leys. In the first service about 90 gallons of fresh caustic ley at 24° or 25° are run into the pan, followed by gentle boiling for eight or ten hours. At the end of this time the leys will be free from causticity. During the boiling, how- ever, to make up for the evaporation which takes place, 2 or 3 gallons of ley should be added about every hour or so. After the leys of the last operation have been removed, a second service of strong caustic ley is given. This ley should be of 27° or 28° B. From 60 to 75 gallons of this ley are now run into the pan, steam turned on, and gentle boUing applied for four or five hours, during which the soap acquires more consistency, and by the evaporation of water from the ley the mass decreases in bulk. As in the former operation, repeated small doses of strong leyjnust be added from time to time, and the thick skin which forms on the surface of the soap should be driven into the mass by a stirrer. At the completion of the operation the leys should still be caustic to the taste after a boil of eight or ten hours. The granular soap, if properly finished, should, when pressed between the fingers, form hard and dry scales or flakes, and readily powder when rubbed in the palm of the hand. The steam is now turned off, the cover of the pan lowered upon it, and the soap allowed to repose until the following day, when the ley is drawn off. OLEIC ACID SOAPS. 91 Fitting the Soap. — This is accomplished by running into the pan from 100 to 125 gallons of the ley used in the separa- tion, marking 6° or 7° B. The pan is again heated, and when the soap begins to boil, the grains expand, and become more viscid and elastic. The boiling is allowed to proceed gently, and occasionally a few pails of water are spread over the surface of the mass. . After four or five hours' boiling the soap assumes a more homogeneous condition, having lost its granular form, and is in clots or lumps, interspersed with ley. The strength of the ley is now tested, which is done by drawing ofi' a little of the ley, and placing it aside to eool. If the ley marks from 16° to 18° B., the operation is complete. If below the former mark, the boiling must be continued until the ley indicates the above density, otherwise the soap will be too soft. On the other hand, if the ley has a density of more than 18° or 12° B., the soap will be too hard. In the latter case, water must be added to reduce the strength of the ley. The soap being now finished, the pan is covered up, so as to retain the heat as long as possible, by which the leys, together with all impurities, gradually and efiectually sub- side, leaving the purified soap above. The soap is allowed to rest in the pan for at least twelve hours, when the lid is raised, and the scum carefully removed from the surface. It is then ready for cleansing, in the usual way. To insure an uniform condition of the soap, it is crutched in the frames until it has become cool and stiff. ' Sometimes, in making soaps with oleic acid as an in- gredient, the tallow, or other fatty matters are saponified separately, and afterwards mixed with the oleic soap by crutching in the frames, and if it is desired to give a slight perfume to the soap to disguise the characteristic odour of the oleic acid, a small quantity of nitro-benzol may be crutched in with the soap, which communicates to it the odour of oil of bitter almonds. A very convenient steam-jacket pan for making soap by the above process, or, indeed, for other systems of saponifica- tion, is that designed by Mr. Morfit (Fig. 18). A is the 92 THE ART OF SOAP-MAKING. interior of a cast-iron pan set in brickwork ; b a cast-iron jacket into whicli the pan fits closely, and is rendered steam-tight by proper luting, d d is the steam supply- Fig. IS. pipe, c is an exit-pipe for condensed steam. At E is a discharge-pipe for emptying the pan. "Red oil" is a very useful fatty material for soap-making. Formerly, stearine was obtained only from tallow, but the vegetable butters, or oils — ^palm and cocoa-nut — are now extensively employed in its manufacture. When stearine is made by sulphuric add saponification and subsequent distillation, the oleic acid is of a brown colour, and is known, commercially, as " brown oil." It has a strong empyreumatic odour, which may be partially removed by passing a current of superheated steam through it, and its colour may be considerably improved by treating it with a small quantity of solution of bichromate of potash and muriatic acid, as in bleaching palm-oil. These fatty matters do not require caustic alkali for their conversion into soap, since they have already been converted into fat acids, by the various processes employed in the m.anufacture of stearine for candle-making. It is usual, therefore, to treat these oils with carbonated alkali, as before shown. There are, however, several methods of neutraKsing these fat acids with carbonate of soda, from which the manufacturer may select that which has his preference. It is necessary that the soap-pan should be capacious, or that only a moderate charge of oil should be OLEIC ACID SOAPS. 93 operated upon at a time, since a profuse effervescence takes place immediately after the alkali and fat acids come in contact, whereby the volume of the materials is greatly increased. Again, the alkali must be introduced (with brisk stirring) very gradually, until the fuU proportion has been given. Oleic Acid Soaps, — In making these soaps it is the practice to estimate the exact quantity of soda that will be required to render a given weight of oleic acid neutral, although a slight excess, and for some soaps a larger excess, should be given. Sometimes, as in Morfit's system, soda ash is dissolved in the proper equivalent of water to form soda crystals, or soda crystals are melted in their [own water of crystallisation in a jacket-pan, by steam heat. Barilla, kelp, bicarbonate of soda have also been used to neutralise oleic acid, but there can be no doubt that the ordinary soda crystals of commerce, in their fused or melted state, are, from their comparative purity and convenience, to be preferred to all other varieties of carbonate of soda. The desired quantity of oleic acid being run into the pan (which should be a jacketed pan heated by steam), a m.oderate heat is applied, and the fused crystals allowed to flow in gradually, with brisk stirring — ^which is more effectually performed by the steam twirl of Morfit. The heat and stirring must be kept up until the effervescence ceases, and the mass assumes the condition of a homogeneous paste. If a soap of greater firmness is required, dried or effloresced soda may be used , in place of a portion of the fused crystals. The dried sal-soda is produced by passing currents of hot air through the crystals until they fall into a powder. Or finely-powdered and sifted soda ash may be used for inferior oleic soaps, instead of the dried soda crystals. In using the dry carbonate of soda, however, it must be added after the fatty acid has been brought to a paste with the portion of fused crystals employed. If resin is to be introduced, the requisite proportion is to be thrown into the previously heated fat acid, and the stirring continued until the whole of the resin has melted, after which the fused sal-soda is to be run in as described. 91 THE ART OF SOAP-MAKING. When the soap has acquired its proper consistence, it is to be shoTelled into the frames in the usual way, or may be blended with various proportions of other soaps. Kottula's Soaps. — A departure from the ordinary sys- tem of soap-making was introduced by Dr. Kottula about twenty-five years ago, and at the time attracted much attention. In conducting his process, Kottula adds to ordinary curd, mottled, yellow, or other soaps, made in the ordinary way, fatty matters, lime liquor, concentrated soda leys and alum, with the object of producing a cheaper neutral soap than he believes was hitherto produced. The fatty matters he employs are such as are commonly used by soap-makers. He first boils soda leys until they have acquired the strength of about 30° B., and then adds to them alum, in the proportion of about 3 J lbs. to each cwt. of ley. He then prepares a "lime liquor" by adding to any requisite quantity of water as much lime as it will absorb or take up, and to this lime solution he adds sal ammoniac in the proportion of about half a pound to each cwt. of the solution. Sometimes he omits the sal ammoniac. The fatty matters, concentrated soda leys, and lime liquor are now added to the melted soap in such propor- tions that the fatty matters will become duly saponified, and that the soap produced may be of the required descrip- tion. The whole are then boiled in the usual way. The proportions of fatty matter, concentrated leys, and lime liquor may be varied according to the character of soap required. The following proportions are, however, recom- mended : — Ordinary fitted soap, or curd soap, 10 tons ; fatty matters, 4 tons ; soda leys, prepared as above, 4 J tons; lime liquor, 6J tons. To produce a mottled soap he adds a certain quantity of ultramarine, oxide of manganese, or other suitable pigment, previously mixed with water, and the whole are then boiled together for half an hour, when the soap is ready for cleansing in the usual way. Instantaneous . Soap. — By a modification of the above process Kottula produces what may be termed an instan- taneous soap, by combining fatty matters with concentrated KOTTULA'S SOAPS. 95 soda leys and lime liquor as follows : — He first con- centrates the leys, by evaporation as before, until tbey mark 28° B., when he purifies them by adding to each cwt. of ley from 4 to 4J lbs. of alum, the whole being boiled for half an hour. The mixture is then removed to another vessel, and a further portion of alum (about 2 to 2 J lbs. to every cwt. of) added, with stirring until it is dissolved, after which the mixture is allowed to settle until it becomes clear. The lime liquor is prepared as before, with the addition of 1 5 to If lb. of sal ammoniac, the whole being boiled for half an hour. After resting until quite clear, ten tons of fatty matter, with or without resin, and nine tons of the leys as above prepared (or smaller quantities in the same proportions), are said to produce a " superior compact neutral soap," which may be coloured, mottled, or per- fumed in the ordinary manner. The rationale of this process is not apparent. If sal ammoniac is boiled with lime-water, it is quickly decomposed. The addition of alum to soda leys efiects merely the formation of sulphate of soda and of aluminate of soda, which, if needed, can be procured more cheaply (see page 229). CHAPTER X. CSEAPENEB SOAPS. Normandy's Process. — Silicated Soaps : Sheridan's Process. — Gossage's Processes. — Preparation of Silicate of Soda. — Preparation of Silicate of Potassa. — Mixing Silicate of Soda ■with Soaps. Previous to the abolition of the excise duty on soap, the addition of any foreign substance to soap, with a view to cheapen it, was resisted by the Excise Board and its myrmidons with wondrous pertinacity; and since the excise officer was ever on the premises, like a man in possession, and regularly locked up each copper when the hour for closing the factory arrived, evasion of the law was not easily managed. At this period, any process, patented or otherwise, which involved the introduction into soap of any substance other than fats, oils, leys, and salt (on which latter substance there was also a high duty) was a criminal offence. During this period, the high, prices of materials and the increasing demand for soaps rendered cheapening processes necessary for the public convenience ; but, until the duty was subsequently abolished, improvements in this direction could not be taken advantage of by the more enterprising firms, who were both willing and desirous to adopt improvements of a satisfactory nature. Dr. Normandy's Process, for cheapening soap by the addition of sulphate of soda, met with strong opposition from the excise authorities, and, instead of reaping the advantage of his ingenuity, he was subjected to constant irritation and official interference. Normandy's process, which has since been subjected to modifications, according CHEAPENED SOAPS. 97 to the requirements of tie manufacturer, is briefly as follows : — The soap being made in the ordinary way, and transferred to the cleansing copper, sulphate of soda, in the proportion of 20 lbs. for every 80 lbs. of soap, and 4 lbs. of carbonate of soda or of potash, or 2 lbs. of each, are thrown into the hot soap, and the whole well stirred until the mass is perfectly homogeneous, when the soap is ready for framing in the usual way. The sulphate of soda, and carbonate of soda or potash, may be introduced in the liquid state (that is, fused in their water of crystallisation). Supposing the quantity of soap to be treated is 3 tons, the sulphate and carbonate of soda are to be put into the " pot,'' or lower part of the cleansing-copper, in the proportion of 28 lbs. of the former and 4 lbs. of the latter for every 80 lbs. of soap, and then allowed to fuse into a liquid state. The soap is then to be run into the cleansing-copper with constant stirring, while the soap is being transferred, until the mixture is complete. Sometimes it is desirable to dissolve the sulphate and carbonate of soda in water, in which case, 3 cwt. of water, 2 cwt. of sulphate of soda, and 1 cwt. of carbonate of potash (or ^ cwt. of each of the two latter) are put into the cleansing-copper and dissolved by heat, as before; after which the soap is transferred from the boiling- copper, when 21 cwt. more of sulphate of soda and 3 cwt. of carbonate of soda or potash are to be added (or half this quantity), and the stirring continued as before until a perfectly homogeneous mass results. It is now commonly the practice to melt the crystals of sulphate of soda (Glauber's Salt), or carbonate of soda in a steam-jacketed pan, and to ladle the liquid as required into the melted soap, after it has been put into the frames, when the union of the materials is completed by crutching in the ordinary way ; or the liquid salts are introduced by means of the steam-crutch. One of the most important advantages of the above process — which, as we have said, is subject to many modi- fications — is t^iat the sulphate of soda, when mixed with H gS THE ART OF SOAP-MAKING. soap deficient in hardness, through poorness of the mate- rials of which it is composed, crystallises throughout the mass, and thereby gives it an artificial hardness, which prevents it from washing away too freely in the hands of the laundress. Indeed, soap may be rendered so hard by employing large quantities of -this salt, as to resist the strongest pressure of the thumb. When it is employed in excess, however, it is very liable to effloresce on the surface of the soap, rendering it not only unsightly but, to some extent, unsalable. Silicated Soaps: Sheridan's Process. — Of all the numerous cheapening substances which have been intro- duced into pure soaps, the silicate of soda, or soluble glass may be deemed the most important, since it not only favours the introduction of a large percentage of water in certain kinds of soap, but it also possesses in itself a high detergent property. The merit of applying silicate of soda to soap is due to Mr. Sheridan, who obtained a patent for his process as far back as the year 1835, at which period, however, owing to the then existing excise laws, it could not receive that extensive adoption which has fallen to the lot of subsequent processes based upon his original and most ingenious invention. Although the silicate of soda, or soluble glass, is now an extensively-manufactured article of commerce, and forms a necessary item in the long list of soap materials, it may be interesting if we give a brief outline of Sheri- dan's origiual process. He first formed a "detergent mixture," by boiling calcined quartz or flint (previously ground to an almost impalpable powder) or sand, with strong caustic soda, or caUgtic potash leys ; the pro- portions being one part by measure of ground calcined flint or quartz to two parts of either caustic alkali, mark- ing 28° B. These were boiled together for about eight hours, with continual stirring, until they became a "homogeneous mass, having the appearance of saponi- fied matter " [a viscous condition]. When in this state it was ready to be mixed with soap, which was done by introducing the " detergent mixture," as Sheridan called CHEAPENED SOAPS. 99 it, a pailful at a time, with constant stirring, until the desired quantity had been incorporated with the finished soap. The silicate solution must be as nearly as possible at the same temperature as the soap, and the mixture effected by the ordinary method of crutching. Respecting the proportions of silicate of soda which may be added to soap, Sheridan says, " I find that in curd soap equal quantities, by weight, of each will answer best ; in yellow soap about one-tenth more of the detergent. mixture may be used." He, however, recommends small sample batches, in varying proportions of soap and silicate, to be made to guide the soap-boiler as to the relative quantities of each which may be blended judiciously to form the quality of soap he may wish to produce. . He recommended mixing the soap and silicate of soda in a small pan capable of holding about half a ton, and from this it was transferred to an ordinary frame. The same invention related to the manufacture of soft soaps, for which the silicate of potash, before referred to, was applied, and which will be considered under the head of Soft, or Potash Soaps. Gossage's Processes. — Nearly twenty years after the publication of Sheridan's process, Mr. Gossage, of Widnes, obtained a patent, namely, in 1854, which bears a close resemblance to Sheridan's, except in the method of pre- paring the silicates of soda and potash. In the patent referred to Gfossage says, " The object of my invention is to provide a soluble compound for ..mixing with true soap, which compound shall possess in itself chemically deter- gent properties, and be obtained at a low cost, thereby enabling me to produce a compound soap the cost of which is greatly reduced, but possessing valuable detergent pro- perties, independently of the true soap contained in such compound. When silica is combined with soda or potash in such proportions thatjthe alkaline matter present is about double the quantity usually contained in glass, a compound is obtained which is known to chemists as ' soluble glass,' and when a solution of this compound is prepared, by boiling it with water, and this solution loo THE ART OF SOAP-MAKING. concentrated (by evaporation of water therefrom), a thick ■viscous compound is obtained, which is easily redissolved by the addition of water. This thick viscous compound contains alkali in a state of weak combination with silica, and is therefore analogous to true soap,* which contains alkali in a weak combination with fatty acids, and it is to this condition of alkali being weakly combined in both compounds, and therefore ready to enter into other com- binations, that the detergent properties of true soap and the soluble compound of silica and alkali are attributable. When the thick viscous compound of silica and alkali (above mentioned) is added to true soaps, and intimately mixed therewith, a compound soap is obtained, at a low cost, possessing valuable detergent properties." Preparation of Silicate of Soda. — Gossage prepares silicate of soda or silicate of potash by fusion, much in the same way as that adopted in the production of ordinary glass. He mixes together about equal parts of dry car- bonate of soda and clean sand, to which is added one part by weight of ground coke or charcoal for each nine parts by weight of carbonate of soda. This mixture is melted in the same way as mixtures of sand and alkalies are in glass-making. The melted mass is afterwards poured into cold water, which renders it more friable. The product is then ground to a fine powder, and afterwards dissolved by boiling in three or four times its weight of water. During the boiling liquid caustic soda is sometimes added. After reposing for a few hours the clear liquor is drawn off and concentrated by evaporation until it assumes a viscid con- dition suitable for mixing with pure soap. Preparation of Silicate of Potash.— In making silicate of potash, twelve parts of dry carbonate of potash, two parts of sand, and one part of coke or charcoal are mixed together, and the whole melted and treated as above. In place t)f sand, ground felspar may be used, in which case three parts of this mineral are substituted for two parts of sand, and only one-half the quantity of alkali is used. Sulphate of soda or sulphate of potash may be used instead * Or, as Sheridan said, " Having the appearance^of saponified matter." CHEAPENED SOAPS. ? loi of the carbonates of soda or potash in making the " soluble glass," in which case three parts of either sulphate are substituted for two parts of either carbonate, and four times the quantity of coke or charcoal above given. Gossage subsequently found that silicated soaps could be advantageously produced from pure soaps containing a much larger proportion of resin than was usually employed in the manufacture of hard soaps, whereby a very econo- mical and low-priced soap could be produced. In pre- paring a genuine soap he used not less than one part of resin for each two parts of tallow or oH, or a mixture of both ; and when th& soap had been fitted, and was ready for cleansing, he introduced the viscous solution of soluble glass in certain proportions, the specific gravity of which should be about 1"500 (water being 1000). "When manufacturing genuine soap, to be afterwards converted into silicated soap, in which a larger proportion of resin than six parts for each ten parts of tallow or oil, or a mixture of each, is used, he prefers to finish the soap as a " stiff curd," in which state the viscous solution of soluble glass is introduced. In mixing the soluble glass with soap, it is recommended that the first portion of the solution should be of the specific gravity of about 1"300, and the remaining portions at increasing specific gravities, until the whole quantity of the silicate solution averages the specific gravity of 1 '500. Mixing Silicate of Soda witli Soaps. — For effectually mixing genuine soaps with silicate of soda, Mr. Gossage employs certain apparatus, the simpler form of which is represented in the driawing (Fig. 19). A circular tub, a, having the form of an inverted cone, is fitted with a series of blades projecting, b b b, inside th^ vessel. A vertical shaft, b, also furnished with a series of blades, ccc, is supported by a- footstep, d, fixed at the bottom of the vessel, and by a journal, adapted to a metallic bridge-piece, e, which is fixed over the tub and secured by screw-bolts to its sides. A bevelled cog-wheel is adapted to the upright shaft, and a horizontal shaft, also provided with a bevelled cog-wheel, and supported by suitable bearings, is attached 102 THE ART OF SOAP-MAKING. to the tub, the two wheels being so placed that they will work in gear with each other. A driving pulley is attached to the horizontal shaft, which is set in motion in the usual way when the apparatus is required to be used. The • Fig. 19. diameters of the pulleys and wheels are so regulated.^that the upright shaft may make from sixty to eighty revolu- tions per minute. A spout, j'^ is attached to the lower part of the tub, with a stopper, g, through which the contents of the vessel are run off. " "When I am about to use my improved apparatus," CHEAPENED SOAPS. 103 says the patentee, " for the production of compound soap, by mixing genuine soap with viscous solution of soluble glass, I ascertain previously the highest temperature at which the mixture of such genuine soap, with the propor- tion of the viscous solution employed, will become too thick to admit of its flowing from such mixing apparatus. I then prefer to make a preparatory mixing, by means of paddles or crutches, of the genuine soap with the viscous solution employed, in such a tub or vessel as will contain about half a ton of soap, adding the soap and viscous solution at such a temperature as will yield a mixture having a mean temperature about ten degrees higher than the previously ascertained temperature before referred to." The mixture is now introduced into the mixing apparatus, the shaft of which is then set in motion, and when the incorporation of the silicate and soap is complete, the sliding stopper is withdrawn, and the contents of the vessel allowed to flow out, and be conveyed to the frames. During the rotary crutching, or mixing of one batch, ■further quantities of the soap and silicate are allowed to undergo the preparatory process of mixing as before. Another modification of the former processes consists in mixing the soluble glass, in a viscous state, with soap made by combining fatty matters with leys, containing such a proportion of alkali in solution as will be sufficient to perfect the conversion of the fatty or resinous matters into soap in one operation (as in Kottula's process), without necessitating the removal of exhausted leys, and adding a further quantity of ley to complete the saponification. The following is another process, formerly patented by Mr. Grossage : — 60 cwt. of palm-oil, or tallow, and 20 cwt. of resin are melted together, or either of the .fol- lowing formulae may be used if preferred, namely, 30 cwt. palm-oil or tallow, and 30 cwt. of oleic or stearic acid ; or 30 cwt. of palm-oil or tallow and 30 cwt. of cocoa-nut oil. 30 cwt. of anj' of the above mixtures of fatty or resinous matters, in a melted state, and at a temperature of about 150° Fahr., is added to a mixture consisting of 80 cwt. of solution of silicate of soda at a specific gravity 104 THE ART OF:.SOAPrMAS:iNG. of l-300°, and 20 cwt. of caustic soda ley of the specific gravity of 1'180°, the mixtiire being also at a tempera- ture of 150° Fahr. The whole are mixed together by agitation. Into an ordinary soap-copper is then put 30 cwt. of the same mixture of fatty, oily, or resinous matters, and 40 cwt. of caustic soda (sp. gr. 1*180) mixed with 20 cwt. of water, the whole being boiled together until saponification is complete. The former mixture of fatty matters, silicate of soda, and soda leys is then added to the above, and the whole again boiled together, when 3 cwt. of common salt are to be added. The boiling is to be continued ui^til the mass is reduced to about ten tons, when it is to be cleansed as usual. CHAPTER XI. CHEAP ENEB SOAPS— {continued). Dunn's Process. — Guppy's Process. — Thomas's Process. — Potato-flour in Soap. — China Clay. — Douglas's Improvements. — Fuller's Earth Soap. — Davis's Process. In making silicated soaps, the strength or density of the solution of soluble glass is regulated by soap-makers according to the quality of soap they desire to produce, and the nature of the " goods " employed in the manufac- ture — some materials forming a perfectly hard soap with a very large admixture of the silicate. It must be borne in mind, however, that whenever soluble glass is employed, and in however small a proportion, the insoluble base, silica, becomes separated in washing, leaving a deposit, more or less, upon the surface of the skin or linen cleansed by it. Moreover, although silicated soaps possess good detergent properties, they are not agreeable for toilet purposes, since they are very apt to impart an unpleasant roughness to the skin soon after using them. Dunn's Process. — The object bf this process is to com- bine silicates of soda or potash with soap, under pressure, . whereby a more perfect union is stated to be effected, and the same method is said to be applicable to ordinary soaps. For yellow soap Mr. Dunn takes the materials in the usual proportions, — say, tallow 7, palm-oil 3, resin 3 parts, and caustic soda leys at 21° B. from 140 to 150 gallons. These are placed in a steam boiler (Fig. 20), which is fur- nished with a man-hole, safety-valve, and all other append- ages of such an apparatus, with a thermometer dipping into a chamber of mercury. At A is a feed-pipe, and at B a io6 THE ART OF SOAP-MAKING. discharge-pipe, from which the finished soap passes to the receiving-pan at c. The fire being kindled, the boiler is heated until the pressure at the safety-valve is sufficient to enable the temperature in the boiler to rise gradually up to 310° Fahr., at which point it is allowed to remain for about an hour, when the contents of the boiler are dis- charged into the paii c, and the process is complete. Dunn prepares his silicate of soda or potash also under pressure, by placing in the boiler crushed flint or quartz and caustic soda or potash, in the proportion of 1 cwt. of silica to 100 gallons of ley at 21° B., and the whole is Fig. 20. then heated as before, under a pressure, until the tempera- ture of the boiler indicates 310° Fahr. The steam pressure should be equal to from 50 to 70 lbs. to the square inch, and after about three or four hours the silicate is to be discharged by the exit-pipe, and is then ready for mixing with soap in any required proportions. Guppy's Process. — An improvement was made in the above process by Mr. Guppy, who employed stronger leys, which were injected from a reservoir into the boiler CHEAPENED SOAPS. 107 gradually by means of a force-pump. Guppy's proportions of materials are — for every 24 lbs. of tallow, 10 pints of caustic soda ley at 17° B. are put into the boiler and beated to 300° F. Afterwards about 30 pints of ley at 25° B. to every 24 lbs. of tallow are tben introduced by means of a force-pump, and tbe heat continued for two hours at from 300° to 310° Fahr., when the saponification is complete. Samples are taken from time to time by means of a small cock fixed for the purpose. This modification of the former process is said to be more economical and quicker in its results. Thomas's Process. — In some of the processes we have described sulphate of soda, carbonate of soda, or both in combination, and silicate of soda or potash have been employed as cheapening materials for soap. By this process, however, silicate of soda or potash is used con- jointly with sulphate or carbonate of soda or potash in combination with soap, by which a supposed advantage is gained over their separate use. The silicate and carbo- nate of either alkali may be either mixed before adding them to the soap, or they may be introduced separately, but the patentee usually introduces the sulphate or car- bonate of soda in crystals, and then adds the silicate in solution at a specific gravity of about 1-600. The sul- phates or carbonates may, however, be uged in solution. It is preferable to use the soap as taken out of the pan at a temperature of from 170° to 200° Fahr., the proportions of soap andthesalts being regulated according to thequality of soap to be produced. The following proportions are said to yield good results : — I. Soap, 15 cwt. ; sulphate of soda crystals, 4 cwt. ; silicate of soda (specific gravity 1-600), 1 cwt. II. Soap, 12 cwt. ; sulphate of soda crystals, 6 cwt. ; silicate of soda (specific gravity I'SOO), 2 cwt. To combine the soap with the salts, a closed vessel is employed, surrounded by a jacket, and the vessel is fitted with a steam-tight cover, with man-hole and lid for charging, and a vertical shaft working in a steam-tight stuffing box with arms attached, extending to within half an inch of the sides, and with vertical blades attached to lo8 THE .ART OF SOAP-MAKING. the arms. The soap is first introduced through the man- hole and the shaft set in motion when the salts are added, and the rotary motion continued until perfect combination is effected. If the mass becomes too stiff the temperature is raised by turning on the steam to the jacket, or into the vessel itself, and the soap when finished is drawn off or blown out, through a passage or cock, at the lower •part of the vessel, and is conveyed to the frames in which it is crutched for a time, as is usual with soaps of this kind. Potato-flour in Soap. — The ingenious inventor of sili- cated soaps (Mr. Sheridan) conceived the idea of blending with pure soap certain proportions of potato-flour, which he carried into effect in the following way : — Equal parts by weight of potato-flour and cold water are mixed thoroughly, so that" no lumps may remain. To every 12§ lbs. of the flour used 37 lbs. of a solution of alum, free from sedi- ment, are added, and the whole well incorporated by stirring. To this mixture is added, in the same propor- tion as before, namely, for every ISj lbs. of potato-flour used, 40 lbs. of soda or potash leys at 22° B., and the whole mixed together into a homogeneous mass. For •making hard soaps the soda leys are to be used. The above mixture, which is called the "detergent mixture," is now to be heated at a temperature of from 170° to 190? Fahr., but not higher, for from three to five hours, which is best done by steam in a jacket-pan. During the heating the mixture is to be constantly stirred, to prevent it from adhering to the sides of the pan. The mixture, being now ready, is to be added to melted soap, when it is in the proper condition for cleansing. This is best done by placing the soap in a half- ton pan, when the detergent mixture, while still hot, is to be added, a pail- ful at a time, and well crutched in, in the same way that curd soap is crutched. It is necessary that the detergent mixture and soap should be as nearly the same tempera- ture as possible. The quantity of the detergent mixture which is to be added to the soap may vary from one-fifth to one-third by weight ; but the soap-maker should de- termine this by making small samples with different CHEAPENED SOAPS. . 109 proportions of the detergent, mixture land allowing them to cool. After well crutching, the soap and. detergent mixture, the compound, soap is put. into the ordinary- frames. - ...' , , China Clay (Kaolin) in Soap.^rThe introduction into 6oaps of solid ingredients which possess no detergent properties, in themselves, cannot be ^commended,, neither should this system of adulteration he encouraged by. soap- makers, whose success in the manufacture of soap depends upon their reputation. 'for lonesty. If the public rezY^, however (as they certainly do in the present age of adul- teration), encourage cheap, and worthless goods in prefer- ence to genuine articlea,i even the. most scrupnlo,us must yield to the demand. ,:,;.. . . , .1 . \ Douglas's " impro-ffenients " in the ;nanufacture of soap consists in combining i.any. Variety of clay with, soap ; the most approved substance, however, is kaolin, or China clay (a silicate of alumina,)^ which abounds extensively in, some districts in Cornwall.. The -clay is placed in ,a yessel, heated by steam or otherwise,i. and worked up into a paste with water; the clay being in the proportion of about 25 per cent, of the mass. .Heat being applied, the mixture ,of clay and water is effected by constant stirring. To this is then added a saturated solution of salt in the proportion of about one-twentieth part of the whole. The proportion of the above mixture.to .be. added to melted spap is regu- lated by the requirements of the manufacturer-^the-iutmost extent being 50 per cent, of the clay. Persons of peculiar fancy use these argillace9us soaps for toilet purposes. , Puller's Earth Soap..-^Of all the solid matters, which have been mechanically combined with soap, thet mineral substance known as fuller's", earth is undoubtedly the best. Moreover, being in itself a detergent, its combina- tion with soap partakes less of. the character of a mere adulterant than other argillaceous (or,clayey) isubstances. Indeed, long before soap was known, this substance was employed as a cleansing mediuna. , . It is nearly twenty years since the author . introduced into the market a combination of soap and fuller's earth. no THE ART OF SOAP-MAKING. under the title of Fuller's Earth Soap ; but although it met with considerable approbation as an agreeable toilet" soap, it failed to command an extensive sale. The method of preparing it is given below, but it should be stated that the object was to introduce into the soap the utmost amount of the detersive earth that could be mechanically mixed with it, in order that the latter, and not the former, should be considered the active ingredient. The fuller's earth should be of the best commercial quality, which occurs in large lumps, and first dried in an oven, at a moderate heat, the object being merely to expel the moisture with which it is associated, so that it will freely slaken when again moistened with water. It is a peculiarity in this, and other clays, that they are more friable, after being dried, and then moistened. When the fuller's earth is thoroughly baked, the lumps are placed on a flat slab, with a ledge round it, and are then sprinkled with water until they cease to absorb that liquid, which is ascertained when an excess of water ceases to be absorbed, or taken up by the dried earth. When the lumps have thus become saturated, the clay becomes very soft and pasty to the touch. It is now to be dried at a very gentle heat, until all the water is expelled, when it will assume the form of a fine, but not impalpable powder. In this condition it is easily reduced to a powder, but in case there may be any lumps present, it should be sifted through a fine gauze-wire sieve. To mix the fuller's earth with soap (resin soap by preference), the latter should be put into a steam jacket- pan, and the earthy powder spread over the surface, a little at a time, with constant crutching, until the full quantity has been introduced. Bearing in mind, however, that the dried clay dried is highly absorbent, after a certain quantity has been worked in, the mass will become con- siderably stiffened, and thereby render the crutching both laborious and difficult, therefore, to make up for the water expelled from the soap by evaporation, a small quantity of hot water may be added, if necessary, and finally, any desired perfume added, if for a toilet soap. In this way CHEAPENED SOAPS. iii it is possible to introduce at least one-third of fuller's earth, or one part to two parts of soap, whereby a very useful compound is formed which, as a skin soap, is most agreeable, and is, when not perfumed, specially service- able as a nursery soap. Davis's Process. — Another method of blending fuller's earth and other substances with soap, is that proposed by Mr. Davis, in which pipe-clay, pearlash, or calcined soda, are introduced. When pearlash, or soda, is employed it is first calcined and then ground up with the fuller's earth and clay until intimately mixed, and in this con- dition they are to be incorporated with the soap. The proportions are — To every 126 lbs. of soap, in a melted state, take 50 lbs. of fuller's earth, slaked 'or dried, 56 lbs. of dried pipe-clay, and 112 lbs. of calcined soda or pearl- ash, all in powder, and sifted as finely as possible. Incor- porate the whole by stirring or crutching, as quickly as possible before the pasty mass cools. If it is desirable to omit the fuller's earth in the above formula, the pro- portions are to be : — soap, 120 lbs. ; dried pipe-clay, 112 lbs. ; and calcined alkali, 96 lbs. This soap is said to be useful for general washing purposes at sea, and for washing white linen in salt water. Tor soap to be used for washing white linen in fresh water, 112 lbs. of "soap, 28 lbs. of dried pipe-clay, and 36 lbs. of calcined soda are used in the above process. CHAPTER XII. DISINFECTING SOAP. Chloridised Sanitary Soap. — Bleaching Soap in the Pan. — Pearlash added to Combined Soap. — Lime Soap, hy Lunge's Method. Chloridised Sanitary Soap. — The object of the process, for which the author obtained a patent in 1865, was to impart to ordinary household and toilet soaps, disinfect- ing, deodorising, and bleaching properties, and at the same time to increase the detersive action of the soap. The material employed was chloride of soda, wbich was prepared by mixing chloride of lime * (bleaching powder) worked up into a thin paste with cold water, with, a solution of carbonate of soda — either soda crystals or soda asb being used, according to convenience. The double decomposition which takes place when the two substances (chloride of lime and soda) are brought in contact, resiJts in the formation of chloride of soda in solution, and car- bonate of lime as an insoluble precipitate. To make the Disinfecting Mixtv/re. — Take of chloride of lime 28 lbs. and mix into a thin paste or " cream " with about 10 gallons of cold water, then dissolve 32 lbs. of soda crystals in 18 gallons of bot water. The solution of soda is to be placed in a clean tub or cask (a steamed oil cask will do), and a crutch placed in it for stirring. Two strips of wood are then laid across the upper rim of the vessel, upon which a fine wire-gauze sieve is to be rested. The chloride mixture is now to be ladled into the sieve, and as each ladleful is introduced the contents of the vessel are to be briskly stirred. The object of passing the chloride * Otherwise chlorinated lime. DISINFECTING SOAP. 113 througli a sieve is to keep back unmixed lumps, fragments of wood, and otlier impurities. When nearly all the chloride has been added, with constant stirring, the mass thickens and in a few moments after it becomes more fluid, when the decomposition is complete, and the mixture is ready for use. The proportion of soap for one frame being put into the frame, the mixture is to be added a pailful at a time, and well crutched by one, or by preference two men, care being taken to clear the .soap from the sides and ends of the frame, otherwise dark patches of the original soap wiU appear when the mass is cold. The best kind of soap for converting into the " sanitary soap " is a stiff curd, from which the leys have been allowed to draia as much as possible, by several hours' repose in the soap-pan. It is also important that the soap should not be of a higher temperature than 130° to 150° F., otherwise separation may occur. This is, however, readily avoided by adopting the precaution suggested. After crutching, the soap is allowed to cool as usual, and is then cut into bars in the ordinary way. "When this soap is prepared from ordinary London grey mottled soap, the bleaching property ofthe chloride of soda will manifest itself by the superior colour of the soap, which, while preserving, to some extent, the mottle or " strike," will be considerably improved ; and if the original soap has been made from rank and coarse goods, the chloride will have diminished their disagreeable odour in a great degree. Indeed, the chlorinated soap has an exceedingly agreeable odour as compared with ordinary mottled soaps. It will be observed that, in adding the above mixture to soap, the carbonate of lime resulting from, the decomposition also enters the soap, and this might naturally appear objectionable. It is but fight to mention therefore that when the mixture is properly prepared, and its incorporation with the true soap satisfactorily accom- plished, the impalpable particles of carbonate of lime are not perceptible, neither do they present any inconvenience when the soap is used for laundry or other purposes, while. 114 THE ART OF SOAP-MAKING. on the other hand, its very superior cleansing and bleaching powers render it infinitely more economical to the user. It has been found in large laundries that women whose hands had suffered much from using mottled soap containing caustic ley in its interstices, were agree- ably surprised to find their excoriated hands assume the normal condition after using the chloridised soap for a short time. Indeed it is a fact that this compound soap imparts a most agreeable smoothness to the skin, which, after using it, becomes remarkably soft and glossy. Instead of employing carbonate of soda in preparing the chloride of soda, as before described, a solution of silicate of soda (glass liquor) may be used, for which suggestion the author was indebted to his friend Mr. John Cowan, of the Barnes Soap Works. In this case, thp following pro- portions may be taken. Chloride of lime worked up into a thin paste or cream, as before 20 lbs. ; silicate of soda, 20 lbs., dissolved in warm water until it marks about 18° Twaddell. These materials are to be mixed and used in the same manner as before, and the proportions of the chlorinated mixture may be regulated according to the nature of the soap, from four to six 60 lb. pailfuls being a fair proportion for a half-ton frame. When the chloridised soap has been well prepared, linen and floor-boards washed with it become remarkably white with comparatively little labour, which facts have been demonstrated by repeated and extensive trials. It should be mentioned that the chloride has the effect of considerably bardening soaps free from resin, and is specially available for soaps containing a large percentage of cocoa-nut oil ; and even after being heavily " run " or liquored with silicate solution, several 60 lb. pails of the chloride mixture may be added with advantage. Soap of this kind however should be crutched, as usual, until begin- ning to " set." An important application of the chloride of soda is in bleaching soap made from the darkest nigers, which may be effected by introducing certain proportions of the DISINFECTING SOAP. 1^5 chloride, until the colour of the soap is evidently and suffi- ciently improved. Bleaching Soap in the Pan.^ — When soap is made from dark-coloured goods, or from materials in which a certain quantity of dark- coloured fatty matter forms a part, a con- siderable improvement in the colour of the batch may be made by adding a moderate quantity of solution of chloride of soda after the first operation of saponification is com- plete. The chloride solution is prepared in the same way as described in the first formula, but twice, or even three times the quantity of water should be applied, in order to facilitate the deposit of the carbonate of lime. After the materials have been mixed with, say, 28 gallons of water for each 28 lbs. of chloride of lime and 32 lbs. of soda crystals used, about 56 gallons more cold water are added and the mixture well stirred, after which it is allowed to repose for a few hours, when the clear liquor (which has a slightly greenish tint) may be drawn ofi' as required, and as much of it spread over the boiling contents of the pan by means of a ladle or swimmer as may be found necessary to bleach or decolour the saponified mass. When all the liquor has been ' drawn off the residual carbonate of lime, a quantity of fresh water should be added with brisk stirring, in order to wash out, as far as practicable, the remaining chloride, and the weaker liquor thus obtained may be used in place of water, in future batches, as in making ordinary leys. Although the process has been extensively adopted in various parts of the United Kingdom, with one or two honourable exceptions it has ^ been used without licence. Fearlash added to Combined Soap. — With a view to neutralise the spent leys (salts) contained in combined soaps — that is, curd and hydrated soaps combined, as in Blake and MaxwelPs process, or other such combinations — Kottula introduces a certain quantity of pearlash, the proportion varying according to the excess of spent leys contained in such combined s6a,p. About 1 cwt. of pearl- ash to 3 tons of soap is said to be sufficient, though a much larger proportion may be used for some soaps. m6 the art of soap-makjng. Lime Soap, by Lunge's Method. — A flat-bottomed pan is preferred for making this soap', into whicli is introduced any given quantity of fatty matter. To this is added double the quantity of water, and slaked lime equal to 12 per cent, of the weight of fatty matter. The whole is to be boiled and stirred (with an " agitator " by preference), when an insoluble hard lime soap and a solution of glycerine are produced, when the latter may be drawn off from the bottom of the pan. A certain quantity of water and commercial carbonate of soda (the latter .being slightly in excess of the quantity of lime used) are next added, and the boiling and stirring continued, when the hard insoluble lime soap will be decomposed, and a " granulated " car- bonate of lime will deposit, leaving a soluble soda soap floating in flakes on the surface of the liquid. If the soda employed does not contain suflBcient salt, a sufficient quantity of sea salt is to be added to promote the separation. " In this way," the inventor says, " it is possible to make a good soap from fatty matters with membranes, or impure oils, without previously extracting the pure fat or oil. When cocoa-nut or palm-oil is saponified by this process, the quantity of lime should be equal to about one- fifth of the weight of the fatty matter. The soap thus prepared is stated to be very soluble, even in salt water, and therefore a tolerably pure carbonated alkali should be used. CHAPTER XIII. SAPONIFICATION UNDER PRESSURE. Bennett and Gibts's Process. — Mr. Rogers's Process. — New Process of Saponification. — Gluten ia Soap. Bennett and Cribbs's Process. — There have been several attempts to produce saponification by other than the ordinary means, including the " cold process " of Mr. Hawes, before described, in which agitation of the materials performs the preliminary stage of the operation. Messrs. Bennett and Gibbs of New York obtained a patent in 1865 for a mechanical process which is said to possess the following advantages : 1. Rapidity of manufacture ; 2. Improvement in quality ; 3. Increased quantity ; 4. Economy in labour ; 5. Saving in fuel ; 6. The use of cheaper materials ; 7. Saponification of all the grease ; 8. Saving of the glycerine, which enters into the soap. The following description of the process is given in Dussauce's Treatise. "Their, process consists in agitating the saponifiable materials with caustic or carbonated alkalies in solution in water in a closed vessel, while under heat and pressure, in such a manner as to cause a thorough mixing of the fats with the alkaline solution, and producing an instan- taneous combination of the fatty acids with the base of the alkaline solution. We suppose a quantity of fatty matter enclosed in a vessel with a solution of carbonate of soda in water, and heat applied to produce a pressure of 220 to 280 lbs. per square inch, and a temperature of 350° to "400° F., a combination between the fatty acids and the soda of the solution will take place only at the upper sur- face of the solution when in contact with the under surface ii8 THE ART OF SOAP-MAKING. of the grease, the heavy ley occupying the lower -part of the vessel, and soap will only be produced where the fat and alkali unite. " If we now agitate in such a manner as to stir together and thoroughly mix the contents of the vessel, the whole wUl be instantly converted into a homogeneous and even quality of soap. It is advisable to use no more water than is wanted in the soap. " The inventors use a boiler or cylinder similar to a plain cylinder steam-boiler resting horizontally, and heated in any convenient manner. One or both heads of the cylinder is made so as to be conveniently removable, and is about the full size of the inner diameter of the Fig. 21. cylinder, so as to admit of the insertion of a revolving shaft, a a a (Fig. 21), which should be as long as the cylinder itself. The bearings of this shaft should be in the centre of the cylinder, and either or both ends worked through a stuffing-box c for the convenience of applying' to the pulley h power to revolve the shaft. On the shaft are fastened arms g g'with floats or stirrers//, extending nearly to the sides of the cylinder ; the arms, floats, or agitators on one side of the shaft when revolved carrying the fat down into the alkali, while the agitators on the other side carry the alkali up into the fat, thus, while under heat and pressure, thoroughly mixing the whole, and causing the conversion of the whole contents of the vessel instantly into a uniform, even, and good quality of soap. SAPONIFICATION UNDER PRESSURE. 119 "At the fire end of the cylinder are placed twq safety valves, one e on the top of the cylinder, thie other d on an outlet pipe inserted in the head of the cylinder. They also use a mercury bath k of about foui inches in length of gas-pipe, and which is screwed intd the boiler or cylinder in any convenient place for the insertion of the thermometer bulb. At the opposite end of the cylinder is an opening i for the insertion of a supply pipe ; at the fire end is also an opening I for the insertion of a second outlet pipe, and which is intended to be used only when it is desired to draw off the whole contents of the vessel. When the machinery is first put in operation, it is necessary to allow some carbonic acid to escape by one of the safety valves, if carbonate of soda is used, in order to prevent undue pressure by the liberation of the carbonic acid when combination of the fatty acids with the alkali takes place. If any of the liquids be allowed to escape before the temperature reaches 325° to 376°, they should be returned to the cylinder. "The safety valve on the outlet pipe d may be so loaded as to allow an escape of soap at a pressure of -250 to 270 lbs., and a quantity of ley and oil may be pumped in at the opposite end, the agitation being kept up, and thus a continual stream of soap is kept up as long as the feeding is continued. The product may then be prepared for market by cooling, moulding (framing) and cutting processes in ordinary use. By this process the soap is made in less than one hour from the time the ingredients are introduced into the boiler, but a uniform and thorough saponification is obtained at the instant that -the heat and pressure arrive at the required degree, be the time long or short ; if this degree is reached in five minutes, the soap is made." The proportions employed by the inventors are thus given : carbonate of soda (English) at 48° ; water, 100 lbs.; lard, tallow, or oil, 100 lbs.; 27 lbs. of carbonate of soda will, it is saidi make a neutral soap for soft water. The product obtained by the above 120 THE ART OF SOAP- MAKING. process is 200 lbs. of soap for every 100 lbs. of grease employed. The process is stated to be applicable to making any kind of soap, including soft soap, which is prepared with the same rapidity as any other, without requiring the use of so much potash as in the ordinary procesess. Mr. G. W. Rogers's Process. — By another process, namely, that of Mr. G. W. Rogers of Lancaster, N. Y., soap is made under pressure at a larc temperature, instead of the high temperature adopted in the above and similar systems, by which the inventor states there is a saving of time, inasmuch as the soap can be made in from fifteen to twenty-five minutes, with complete saponification: By this plan, moreover, the materials become bleached, thus enabling inferior goods to be employed in the manufacture. The materials are mixed in a tank heated by steam, and the mass thus prepared is run into an iron cylinder capable of holding one or more tons, and subjected to a pressure of about 400 lbs. to the square inch by :means of a force- pump driven by steam. The mass is kept in this cylinder until saponification is complete, when it is run into frames. By this system any of the usual combinations of fatty matters may be employed, and the product is said to be both firm and translucent. It shoiild be observed that in both processes given carbonate of soda is used instead of caustic soda, which also renders the employment of common salt unnecessary. New Process of Sapomficatiou. — ^M\ Berghart has patented a process by which animal or vegetable fats or oils are distilled into caustic or carbonated leys of soda or potash. The fatty matter is placed in a jacketed retort, heated by high-pressure steam, or in a retort otherwise heated to a temperature which will volatilise the oil or fat without charring it. When the oil or fat begins to volatilise, air or carbonic acid gas is blown into the retort, which carries over the fatty acids, which are con- densed in proper receivers. Atmospheric air alone, or in combination with superheated steam, is preferred in carry- ing out this part of the process. ,,,^ERGHART'S PROCESS. 121 The current of, air, or steam and air, is sometimes blown into tlie space above the liquid fatty matter in the retort, and when advisable it is blown direct into the melted fat. The current of air has the eflfect ,of carrying over the fatty acids in a more or less finely divided state, when they pass into a chamber, or series of chambers, which are fitted with partitions in such a way that the current, in passing through them, deposits the solid fatty acids in the ordinary way. When the fatty matters, as a printer's grease, for instance, contain alizarine or other colouring matters^ the fatty acids pass over from the retort, while the alizarine or other colouring matter remains in the retort, and is afterwards treated td separate any re- maining fat from the colouring matter, which is thus recovered. It is therefore important, when alizarine or other colour is present, to avoid too high a temperature in the distillation. In making soap by this process, the vapour of the fatty acids is passed direct into caustic or carbonate leys of soda or potash, the strength of which depends upon the nature of the fatty matter employed. If a slight excess of alkali is used, the ordinary process of " salting " is not required. The fatty acids are blown into the leys until the alkali is nearly or about neutralised. The ley is by preference contained in a closed tank, which communicates directly with the outlet pipe of the retort. If necessary, the fatty acids may be mashed before being treated with ley, in which case the vapours are allowed to pass into a cham.ber containing water. The inventor prefers to employ hot air and superheated steam in combination to carry over the fatty acids into the ley, by which the soap becomes boiled during its formation, and thus time is saved in the operation. The air has an important effect in aiding the chemical reaction, apart from its use as a vehicle to carry over the fatty acids. The steam is used principally to prevent the charring of the matters, and in the making of the soap to assist in the boiling of the same. By the employment of the high temperature, the fatty 122 THE ART OF SOAP-MAKING. acids are separated from the glyceryl compounds without the aid of sulphuric acid or of saponification. Glnteu in Soap. — This process, patented by Lorberg, consists in making a solution of gluten in caustic alkali, which is afterwards to be mixed with soap to the extent of about ten per cent. It is said to impart increased emoUiency to the soap. The solution of gluten is thus made-: — In a solution of caustic alkali (soda or potassa) at about 28° B. as much bran, ■ or gluten derived from any other source, is added as the alkali will take up after digesting for some hours, when a clear homogeneous mass is obtained. This is now strained through a fine sieve or coarse cloth, when it is ready to be added to the soap in the proportion given. It must be borne in mind that nitrogenous matters, such as gluten, are apt to undergo decomposition on treatment with caustic alkali. CHAPTER XIV. VAEIOUS PROCESSUS. Kiirten's Process. — Lutntarton's 'Process. — Mr. .Symons's Disinfecting Soap. — Soaps made from Animal Eefuse. — Bernadet's Proceaa. — Villart'a Process. — Crevel's Process. — Villacrose's Process. — Cutting Knrteu's Process. — In ttis process caustic potash is added to caustic soda in the manufacture of soaps. For making mottled soap, tallow, bone fat, or bleached palm- oil is boiled with ley and converted into a hard soap. The soap is then allowed to remain in the pan from three to six hours, so that the ley may settle. In the meantime a second pan is charged with cocoa-nut oil, and a ley composed of 3 parts caustic soda and 1 part potash added, and when the mass is turning into soap the former soap is added to it, and the two soaps boiled together until sufficiently hard, when the soap thus formed is to be put into frames as usual. It is said that soap thus made has a " beautifully mottled appearance," lathers freely, and has a smooth surface. In making yellow soap by this process, 2 parts of tallow or palm-oil and 1 part of resin are melted together, and, when nearly cool, for every 100 lbs. of the mixture 90 lbs. of solution of soda and 40 lbs. of solu- tion of caustic potash are added. The mass is then well stirred for five or ten minutes, when it becomes so thick that the ley cannot separate from it ; it is then ladled into the frames, and in the course of a day will become solid. The Soap is allowed to remain in the frames from three to six days. Now water, or a solution of potash, in the pro- portion of 10 lbs. to 20 lbs. for every 100 lbs. of soap, is put into the soap-pan, and, when boiling, the soap (pre- viously cut into small pieces) is added to it and allowed to 124 THE ART OF SOAP-MAKING. dissolve, but without boiling. If it is not sufficiently hard when dissolved, brine is to be added until it becomes quite thick. The novelty of this process consists " in the use of caustic potash, and dissolving and warming up the soap a second time without boiling it." Lnmliartoii's Process consists in saponifying fatt)' matters by boiling them with an alkaline mixture com- posed of carbonate of soda, quicklime, common salt, and alum, the ingredients being mixed in the following pro- portions: — Sub- carbonate of soda, 10 parts; quicklime, 10 parts; alum, 1 part; common salt, 1 part. These, being mixed with water, are added to the fatty matters, and the whole well boiled, when, it is said, they will be- come perfectly saponified. The soap produced by this process contains all the glycerine, and the product will be "a hard soap of very fine character ; has no disagreeable smell, and can consequently be used for toilet or ordinary washing purposes." Mr. Symons's Disinfecting Soap consists in adding to ordinary soaps the disinfecting and deodorising substance known as thymol or thymic acid, which is soluble in water, in solutions of alkalies, &c., forming compounds which are soluble in water. Its advantages over carbolic acid, creosote, &c., are that it has no unpleasant taste or odour, being very aromatic. Its solutions are " strongly antisep- tic, and possess disinfecting properties in a higher degree than carbolic acid, and its weaker solutions do not act cauterisingly but coolingly." Soaps made from Animal Befnse. — Although it is well known that caustic alkalies will saponify animal tissues, membraneous matters, and indeed all parts of animals except the bone, this source of soap-making material has not been much explored in this country. On the Continent, however, some attention has been devoted to this subject, and many processes devised for utilizing slaughterers' oflFal and butchers' waste as soap material. Some of these processes are given in Dussauce's Treatise, from which we make a few extracts : — " Bernadet's Frocess. — The intestines are deposited in VARIOUS PROCESSES. 125 caustic ley to prevent decomposition until they are to be used. The ley is then heated until entire saponification takes place, which operation is easy, and a very slightly- coloured grey soap is obtained. If required to be whitened, a solution of chloride of soda (see page 112) is poured into the pan, after which common salt is added to produce separation. " Villart's Process has for its object the conversion of animal matters in general into soap, but more especially the residuum of meat, scrapings of tallows (query, suets), intestines, &c. From these two kinds of soap are obtained, the first of a greenish- white colour, not very firm, and having a disagreeable odour ; the second is similar to the above, but with the addition of resin and tallow, properly saponified and mixed with the 'animal soap.' The pro- cess is divided into four operations : — " 1. Maceration. The substances are placed in wooden tubs capable of holding about 300 or 400 lbs., when a ley composed as follows is poured over them : — Lime, 10 parts ; soda ash, 12 parts ; water, 100 parts. The lime is first slaked and the soda ash dissolved in water, and this is then poured on the lime, with stirring, and the mixture then poured over the animal substances, the whole being allowed to remain in this condition for some time, but with occasional stirring. "2. Washing. When the saponification (by macera- tion) has been effected, the animal substances are washed in tubs, to remove the lime attached to them, after which they are exposed to the action of the air. " 3. Solution. After sufficient exposure to the air, the animal substances are placed in a pan, with a sufficient quantity of water, and for every pound of them add 12 gallons of ley at 4° prepared as follows : — Soda ash, 1 lb. ; lime, 1 lb. ; water, 6 lbs. This ley marks 15°, and has always succeeded ; however, weaker or stronger leys may be used, that is from 20° to 30°, and gives a good result. " The animal matters being completely dissolved, the solution is to be poured off from the lime, and the solu- 126 THE ART -OF SOAP-MAKING. tlon again boiled, adding, during the boiling, 25 gallons of the second ley for every 2 lbs. of substance, and con- tinue to boil until, on cooling, it has the appearance of a firm paste. "4. Coction. The object of this operation is to give the soap a consistency which will render it salable as a commercial article, for which purpose tallow and resin are added in proportions varying from 2 to 100 per cent, in the second ley above ' given. Thus, for treating 500 lbs. of the soap first obtained, take : resin, 100 lbs. ; tallow, 50 lbs. ; liquor, No. 2, 200 lbs. These are to be boiled until perfectly saponified, when the former soap is to be added, little by little, to avoid too much swelling, and the boiling continued until the paste, on cooling, becomes hard, when it is run into frames, and may be cut in about two days after." Crevel's Process. — Melt in boiling water the greases, meats, or other parts of animals, press, and keep the resi- duum ; triturate and grind the residuum, macerate it in alkaline liquor for several days ; put the macerated sub- stance into a pan, and boil until perfect liquefaction takes place, when it must be allowed to cool. The mass is then to be heated again, and alkali added gradually, care being taken not to employ too strong a ley. When the mixture has acquired the proper alkaline strength the heat is slackened and the mass allowed to cool. From 10 to 15 per cent, of resin should be added to the above, and when saponification is completed the soap is framed as usual. Villacrose's Process. — In this process animal sub- stances are saponified as follows : — Take animal substances, 200 lbs. ; caustic soda, 10 lbs. ; melted tallow, 40 lbs. The pan is first to be heated, and, when warm, the soda is to be thrown in, the small quantity of water it contains being sufficient to dissolve it.' Now, immediately intro- duce the animal substances and stir well. The heat must be gentle at first, and the temperature gradually raised to 167° F. During the melting the mass must be stirred until it thickens, then add the 40 lbs. of tallow (with a little water if necessary), which soon becomes saponified. VARIOUS PROCESSES. and the operation is complete, and the soap is framed as usual. Cutting Soap. — ^When the soap is cold enough to be cut, the bolts are detached from the iron frame (Fig. 2), and the sides and ends are removed and placed aside The sides and ends of the block of soap are. first scraped all over with the scraper, Fig. 22 ; it is then marked at each corner by means of the gauging stick (Fig. 15). A workman then takes the cutting wire (Fig. 23), and throws the loop over the block of Kg. 22. soap, when the wire is taken in hand by a second workman (see drawing, Fig. 24), who fits the wire into Fig. 23. Fig. 24. the two upper notches ; the first man then pulls the wire by its two wooden handles steadily until the first slab is cut. This top slab is cast aside to b^ used up with other waste in future batches. When all the soap is cut, the slabs are removed one by one and placed on the barring machine (Fig. 14), to be afterwards cut into bars in the manner before described. CHAPTER XV. MANUFACTimE OF SOFT SOAPS. Preparation of the Potash Ley. — ^The Fatty Materials employed. — Scotch Soft Soap. — lioudon "Crown Soap." — Eeain in Soft Soaps. — ;Con- tinental Methods. Although the production of soft soaps is far less extensive than of those commonly known as hard soaps, still it is an important branch of the manufacture, since these soaps are employed in many useful arts, as for example in the dressing of woollen textile fabrics. The alkali employed in the manufacture of soft soaps is potash, and it is a characteristic of all soaps made with this alkali that, instead of assuming a hard, solid con- sistence, as is the case with soaps made from soda, they are always soft, tenacious, and more or less transparent. Moreover, potash soaps always contain a large percentage of water, more in a state of mechanical mixture than in chemical combination ; and while 3 parts of fatty matter will generally yield about 6 parts of soda soap, the same proportion of fatty matter, treated with caustic potash ley, will yield from 6 to 7 parts of potash soap. Potash leys cannot be separated from the soap, as in the ordinary method of purifying soda soaps ; therefore the leys employed wholly enter into the composition of the soap. Much care is therefore necessary to avoid introduc- ing too great an excess of the alkali. Freparation of the Fotasli ley. — ^The pearlash of com- merce, or American potash (caustic potash), are ordinarily used for this purpose, and the former is converted into caustic potash, by means of fresh lime, in the same way as in preparing soda ley^. It is usually the practice to pre- MANUFACTURE OF SOFT SOAPS. 129 pare leys of two or three different degrees of strength, the weaker of which is employed in the first operation of pasting, or preliminary stage of saponification. On the Continent potash leys are prepared as follows : — If the potash is in the form of hard lumps, these are first crushed on a hard stone by means of an iron " punner," and if 300 or 400 gallons of ley are required, from 450 to 500 gallons of water are put into an iron-pan, and brought to a boil. The potash is then added, a little at a time, until the whole quantity is dissolved ; but care is taken that each portion is dissolved before adding the next, and so on, and the solution of the alkali is accelerated by con- tinual stirring. The boiling is kept up until the solution, while boiling, marks from 20° to 22° B. To causticise the above solution of carbonate of potash, from 60 to 70 per cent, of fresh lime must be taken, the weight of lime being determined by that of the potash used. The lime must first be slaked with water, as usual, and the hydrate of lime thus formed is to be gradually added to the hot solution of potash ; it is, however, con- sidered preferable to make the lime into milk of lime, by mixing it with a moderate quantity of water. While the lime is being introduced, the mixture is to be kept well stirred, and the boiling should be continued for several hours, when the, fire is withdrawn and the mixture- allowed to rest, so that the carbonate of lime may gradually subside. This ley, which is called ^e first, or strong ley, should stand at from 20° to 25° B. The clear ley is next run off into an iron tank or cistern, which must be kept closed to prevent the absorption of carbonic- acid from the air. When all the clear ley is drawn off, an equal quantity of water is poured on to the lime, and the pan well stirred for a short time, after which it is allowed to rest until the lime has again deposited, when the clear ley, called the second ley (marking from 12° to 16° B.) is to be drawn off into a separate tank. A third dose of water is then poured in, and the pan again stirred as before, and after about twelve hours' repose, a third ley is obtained at about 6° to 8° B. Further washings of the lime may then K I30 THE ART OF SOAP-MAKING. be given, until the lime is perfectly freed from the alkali, and these latter washings may be used in lieu of water in subsequent operations, or instead of using pure water in dissolving fresh quantities of potash when preparing other batches of ley. Some manufacturers employ variable proportions of soda with their potash leys, by which the soft soaps made with them acquire a firmer consistence than when caustic potash alone is used, besides which an advantage is gained by using a proportion of the cheaper alkali. When this is the case the soda may be dissolved with the potash in the first instance, the proportion of soda to that of potash being from 12 to 20 per cent. ; but when a larger pro- portion than 15 per cent, of soda is used, the resulting soap will not be so transparent as ordinary soft soaps. The Fatty XCaterials employed, — These are the animal and vegetable oils. Of the animal oils, those of the whale, seal, and cod are chiefly used ; the vege- table oils are olive, hempseed, linseed, rapeseed, coleseed, colza, poppy, &c. Sometimes oleic acid, palm-oil, and small quantities of tallow are also employed in the manu- facture, but the latter is only used to give the soap a granular or fig-like appearance. In making Soft Soap, the selected oils are first put into the pan, and moderate heat applied until the oils have be- come thoroughly liquefied, when the third ley, marking from 6° to 8° B., is run in gradually, with continual stir- ring, until a perfect combination of the alkali and fatty matters is efi'ected, which is determined by the mass assuming a perfectly homogeneous condition, there being no unoombined oil on the surface or ley at the bottom of the pan. The mixture is then gently brought to a boil, and this is kept up, with stirring, for several hours. As soon as the paste assumes a moderate degree of consistency, additions of the second ley, at about 12° to 15° B., are to be made gradually, that is a few gallons at a time every quarter of an hour or so, continuing to do this with con- stant boiling for a few hours, during which time the added alkali will become gradually absorbed. MAN.UFACTURE OF SOFT SOAPS. 131 During the boiling a considerable amount of fob or foam is formed, but this eventually subsides when the operation is getting near completion, and the mass be- comes limpid and transparent. The soap is now to be treated with the first or strong ley, at 22° to 25° B., added, as before, in small quantities at a time at short in- tervals. By continued boiling, and consequent evapora- tion of the water from the leys, the soap acquires a greater degree of stiffness, and samples should be taken occasion- ally and examined by pressing between the finger and thumb, in the usual way adopted by soap-boilers ; and when the proper consistence is nearly arrived at, small samples should be set aside to cool, in order that their actual condition may be ascertained. If the soap, when tried between the fingers, is stringy, the boiling must be continued, and if it does not possess a sufficiently alkaline taste, an addition of strong ley must be made, and the boiling kept up until the proper consistence is reached. Some manufacturers introduce a portion only of the oils into the pan in the first instance, and when this quantity has attained a temperature about equal to that of boiling water, the weak ley is added gradually, after which fresh oil is introduced, then more weak ley, and so on, until the entire charge of fatty matter is introduced into the pan, and the boiling is gently kept up until the mass has acquired the proper pasty consistence of the first operation. The additions of stronger leys are then made, as before de- scribed, the soap being, finished by_ adding the necessary quantity of the strongest ley. Boiling. — In boiling soft soaps, great care is taken that the ebullition is very gentle at first, owing to the powerful action exerted by the chemical union of the alkali and fatty matter, during which a considerable frothing occurs. If this caution were not observed, the mass would speedily boil over. When examining samples of the soap, if sa- ponification is complete a narrow opaque fringe appears round the outer edge of the sample, when the soap is said to be to strength ; when this appearance is not present it 132 THE ART OF SOAP-MAKING. is said to want strength ; or if. the opaque fringe first appears and then vanishes, it is said to haveya&e strength, and indicates that the saponification is incomplete. Scotcli Soft Soap. — A considerable quantity of soft soap is made in Scotland, and,- according to Ure,* the following process is that generally adopted : — " 273 gallons of whale or cod oil, and 4 cwt. of tallow, are put into the soap-pan, with 250 gallons of ley from American potash, of such alkaline strength that one gallon contains 6,600 grains of real potash. Heat being applied to the bottom pan, the mixture froths up very much as it approaches the boiling temperature, but is prevented' from boiling over by being beaten down on the surface, within the iron curb or crib which surmounts the caldron. Should it soon subside into a doughy-looking paste, we may infer that the ley has been too strong. Its proper consistence is that of a thin glue. . "We should now introduce about 42 gallons of a stronger ley, equivalent to 8,700 grains of potash per gallon, and after a short interval an additional 42 gallons ; and thus successively, till nearly 600 such gallons have been added in the whole. After suitable boiling, to saponify the fats, the proper quality of soap will be obtained, amounting in quantity to 100 firkins of 64 lbs. each from the above quantity of materials. It is generally supposed, and I believe it to be true, from my own numerous experiments upon the subject, that it is a more difficult and delicate operation to make a fine soft soap of glassy transparency, interspersed with the figged granu- lations of stearate of potash, than to make a hard soap of any kind." There can be no doubt whatever that considerable judgment and caution must be exercised in the boiling of soft soaps, and in determining the exact time when the fire should be drawn or the steam turned off, as the case may be ; and when this period has arrived, it is important that the further evaporation of water from the ley should be checked not only by turning off the steam, but, if con- venient, by introducing into the soap-copper a sufficient * " Dictionary of Arts, Manufactures, and Mines." MANUFACTURE OF SOFT SOAPS. 133 quantity of cold soap to reduce the temperature of the mass. London " Crown Soap " of the best quality is made from tallow, lard, and olive-oil, and the caustic potash leys are generally employed in two different degrees of strength, the weakest from 8°, and the strongest from 25° to 30° B. The proportions of materials employed for 18 barrels of soap are : tallow and lard 62 lbs. each, and olive-oil 70 gallons. About 400 gallons of ley being prepared, a third of this quantity is first put into the pan, when the tallow and lard are added and the steam turned on •; when the fats are melted the olive-oil is run in, and the boiling con- tinued gently, after which the mass is allowed to rest for about two hours, when the steam is again turned on, and about 20 gallons more ley added, and the mass again brought to a boil. Additional quantities of ley are added from time to time until the frothing, at first excessive, begins to moderate, and eventually subsides, and the boil- ing is continued until samples taken from the pan exhibit the proper consistence. If the sample tried by the trowel is stringy, more ley must be added; but if it appears whitish and clotted, this shows an excess of ley, when a moderate quantity of oil must be added. Towards the end of the operation brisk boiling should be given, and finally moderated ; and repeated samples should be taken until the soap is found to be perfected. A second quality of Crown Soap is made from taUow 286 lbs., sperm-oil 80 gallons, and caustic potash ley 135 gallons. 94 gallons of the ley and the tallow are first put into the pan, and the steam turned on; and when the tallow is melted the oil is to be introduced, after which the steam is to be turned off and the contents of the pan allowed to rest for about two hours. At the end of this time the steam is again turned on, and 19 gallons of ley added, and the whole brought to a boil, the heat being continued until the soap appears to be about half made. !9^ gallons of ley are then added, with renewed boiling, an^d finally the remaining 9 gallons of ley are introduced, and, the boiling continued until the soap is complete. 134 THE ART OF SOAP-MAKING. Kesiu in Soft Soaps. — In making soft soaps resin is sometimes introduced to the extent of 5 or 10 per cent, of the weight of the fatty materials used. The resin is generally introduced into the pan in the form of a fine powder, in the earliest part of the operation, whereby it saponifies with the other ingredients or fatty matters. Coutiuental Methods. — The method adopted for intro- ducing resin into this soap at Liege is, according to Dussauce, as follows : — " When the soap is nearly done, the quantity of resin required to be added is deposited in a large sbeet-iron caldron, pierced with holes like a skimmer. This caldron is then immersed to three- quarters of its height in the boiling soap. In contact with the excess of ley contained in the soap the resin' saponifies, and the resinous soap passes through the holes of the caldron and combines intimately with the mass of the soap in the kettle. This arrangement deserves to at- tract the attention of manufacturers. When the saponi- fication is finished, and when, bj"^ a well-managed evapora- tion, the soap is well boiled, its natural colour is a brownish-yellow. If this colour is required the heat is stopped ofi", and, after resting a few hours, the soap is drawn off into barrels open at one end. If, on the con- trary, the soap is to be green, this shade is given to it by adding a small quantity of indigo. To prepare this colour, macerate for a few hours indigo of good quality in boiling ley. After separating the ley, rub it in a mortar, and pass it through a fine sieve. To colour the soap, add a certain quantity of the paste to the soap, and incorporate by good stirring." In Belgium and Holland soft soaps are made from vegetable oils, with, sometimes, the addition of oleic acid, tallow, or other animal fats. The following formula is given for a soft soap of good quality: — Linseed-oil, 600 lbs.; coleseed-oil, 800 lbs.; oleic acid, 200 lbs. These materials are first put into the pan and heated gently, and, when in a liquid state, 75 gallons of caustic potash ley at 6° to 8° B. are added gradually, with con- tinual stirring. The pan is then brought to a boil, and MANUFACTURE OF SOFT SOAPS. 135 this is kept up for several hours. A stronger ley, mark- ing from 12° to 15° B., is then introduced a little at a time, care being taken to avoid the boiling over of the pan when the chemical action is at its most vigorous point. As soon as the usual frothing subsides, the soap will become clear and of a glutinous consistence, when doses of from 10 to 12 gallons of ley, marking 22° to 25° B., must be added at moderate intervals, the boiling being continued until the saponification is complete. The boil- ing is then to be kept up until, by the usual sample tests, the soap is known to be finished. Ordinary English and Scotch soft soaps, being made chiefly from fish oils, are of a brown colour, while the Continental soaps, which are mostly made from vegetable oils, are frequently of a green colour. Savon vert is the title given to these soaps, whether the green colour is derived from materials used in the manufacture, or from the artificial admixture of indigo, as before described. CHAPTER XVI. MANUFACTURE OF SOFT SOAPS— {continued). Belgian Soap. — Russian Soft Soap. — Gentele's Process. — Jacobson's Pro- cess. — Soap for Silks and Printed Goods. — Fulling Soap. — M. Loch's Soft Soap. Belgian Soap. — In Belgium, a half-hard soap is largely produced for the use of cloth manufacturers, and is employed in scouring -woollen textile fabrics. This soap contains an excess of alkali (potash), an essential feature in soaps employed for this purpose. The caustic ley is used at three different degrees of strength, namely, 18°, 20°, and 30° Baume, and these represent the first, second, and third leys used in the preparation of this soap. The fatty materials are divided into three groups, as follows : — No. I. No. II. itTo. Itl. Tallow.. ,, 380 lbs. Tallow.. .. 225 lbs. Tallow .. .. 150 lbs. Colza-oil ., 70 „ Tallow-oil .. 225 ,, Bleached palm- oil .. .. 300 „ Cocoa-nut oil ISO „ Cocoa-nut oil 150 „ Cocoa-nut oil,. 150 „ 600 „ 600 „ 600 „ The quantity of ley requisite for 600 lbs. of fatty materials, according to either formula, will be from 750 to 775 lbs. One third of this quantity must mark 18°, another third 24°, and the remainder 30° B. The two first- named fatty matters are put into the pan with the weakest ley, and these are boiled together, after which the second strength of ley is added gradually, followed by the strongest ley. The entire quantity of ley should be intro- duced within two hours, and the boiling is kept up until the paste separates from the ley when tried by the shovel MANUFACTURE OF SOFT SOAPS. 137 in the usual way. The soap is then allowed to repose, when the deposited ley is to be withdrawn, and the cocoa- nut oil in a melted state is then introduced, and a sufficient quantity of ley added to render the soap caustic. Boiling must be continued until the soap is sufficiently firm, and when this condition is reached the fire is withdrawn and the soap allowed to cool down, after which it is to be trans- ferred to shallow frames. By the separation of the ley which takes place in the above process, the saliae impurities contained in the potash are removed. About 12 cwt. of soap should result from the proportions giv6n. Russian Soft Soap. — In Russia a soft soap is made from a ley composed of three parts Russian or American potash, and one part pearlash (a carbonate of potash), the solution or ley being brought to 10° B. One half of the ley is added to the oils or fatty matters in the pan, and while these are undergoing the process of boiling the remainder of the ley is allowed to flow slowly into the pan from a cistern situated above that vessel. After the necessary boiling, and. when the soap has acquired the proper consistence, the fire is withdrawn and the soap left in the pan to cool. Geutele's Frocess. — A process was suggested by M. Gentele for making soft soap with one-fifth part of soda mixed with the potash ley. By preference, crystals of soda are used ; and it is important that the leys should be free from chloride of sodium or other saline impurities. The fatty materials recommended for this process are : red oil, 100 lbs. ; tallow,'40 lbs. ; hempseed-oil, 3,750 lbs. Jacobsou's Process. — The inventor prepares a very use- ful household soap by mixing oleic acid with soda or potash ley in the following proportions : — Distilled oleine 2 gallons. Ley 1 gallon. Hot water 5 gallons. While pouring the hot water into the pan (in which the oleine is first placed) constant stirring is kept up, and the ley then added gradually with continued agitation, until 138 THE ART OF SOAP-MAKING. the mass has assumed the appearance of a thick yellowish paste without granules. After twenty-four hours' rest, the soap is perfectly white and ready for use. The advan- tages claimed for this process are the rapidity and ease with which the soap is made and its extreme simplicity. The inventor says that adulteration is impossible, since other substances, if introduced, would interfere with the process of saponification. The economy of the process is also stated to be an important feature in this method of preparing a soft soap. Soap for Silks aud Printed Goods. — The late Professor Crace-Calvert, of Manchester, to whose indefatigable exertions in industrial chemistry manufacturers were indebted for much valuable information, suggested the following formula for soap to produce the highest brightening effect upon the various shades of colour : — For Madder JPurpUs. Patty matter 60-4 Soda 5-6 Water 34-0 lOO'O For Madder Finka. Patty matter 69-23 Soda 6-77 "Water 34-00 100-00 For bleaching raw silk, white olive-oil soap is used on the Continent. Oleic acid, saponified by potash ley, is a very suitable fatty material for making soft soap. The first potash ley should have a strength equal to about 20° B., and the soap may be finished with a stronger ley — from 25° to 28°, Fulling Soap. — The soap used by cloth manufacturers for fulling or cleansing woollen cloth requires to be rather more alkaline than ordinary household soaps, but at the same time it must not contain such an excess of alkali as to affect injuriously the more delicate colours of the dyed wool. Some manufacturers employ a mixture of oleic acid MANUFACTURE OF SOFT SOAPS. 139 (brown oil) soap, and mottled soap, in the proportion of nine parts of the former to six parts of the latter. M. Locli's Soft Soap — In addition to the usual fatty- matters the inventor introduces borax, binoxalate of potash (salt of sorrel), soap wort, pipeclay, sal ammoniac, and turpentine, whereby he professes to produce a cheap and economical soap, "particularly applicable for manufac- turers of woollen goods, cotton-mills, bleaching and scouring works, &c." To make 220 lbs. of the soap, 9 lbs. of soapwort {Saponaria officinalis) are boiled in 22 gallons of water, which is then passed through a sieve. In 13 gallons of this decoction, while hot, are dissolved 62 lbs. of slaked lime, and in the remaining 9 gallons, also while hot, are dissolved 9 lbs. of borax, 26 lbs. of potash, and 2*2 lbs. of binoxalate of potash. This solution is then poured slowly into the first-named decoction, and the mixture is boiled until the ley is found to be suffi- ciently caustic. The whole is again passed through a sieve, and then boiled gently with 66 lbs. of fixed oils until thick bubbles rise, and the soap assumes the required floc- culent condition ; 13 lbs. of resin and 13 lbs. of Iceland moss (previously boiled down and passed through a sieve). This mixture is then allowed to boil slowly until thick bubbles rise and all the ingredients have thoroughly com- bined. It is then allowed to cool, and finally, at the time of packing for transport, 6 "6 lbs. of sal. ammoniac and 2*2 lbs. of pure turpentine are mixed up with 220 lbs. of the soap. The packing for transport is by preference efiected in well-closed wooden cases, which are coated well inside and outside with silicate of soda, and a sheet of vegetable parchment should be placed over the soap before putting on the lid. The use of sal ammoniac and of binoxalate of potash in this process is not easily intelligible. Again, Panama bark [Quillaza saponaria) is far preferable to soapwort, but it is generally used, not in combination with soap, but as a separate agent. It is largely used in getting up the finest quality of white worsted goods. CHAPTER XVII. MANUFACTURE OF TOILET OR FANCY SOAPS. Amiaxatus for Ee-melting the Soap. — Machine for Slicing the Soap. — Ee-melting the Soap. — Mining Colouring Matters and Perfumes. — Cutting the Soap. — Stamping the Soap. Although the manufacture of toilet soaps occasionally forms part of the soap-makers' business, it is more gene- rally carried on as a separate trade, or is attached to the business of the perfumer. ^In either of the latter cases, the soap from which the toilet soaps are produced is generally furnished by the larger soap-makers, and is re-melted, perfumed, and tinted by the fancy soap-maker. Before explaining the system of manufacture, it wiU be necessary to direct attention to the apparatus employed and the methods of applying them, and in doing so, we may as well show how the manufacture can be conducted upon a moderate scale. Apparatus for Be-meltiiit; the Soap. — The pans for this purpose may be made from wrought copper, fitted into an iron steam-tight jacket, the size being regulated according to the probable requirements of the manufac- turer. These pans should be capable of containing from 2J cwt. to half a ton of melted soap. A simple form of apparatus, which the author has employed for this and other purposes, is shown in the woodcut (Fig. 25). It has the advantage of being cheap in construction and econo- mical in use. Several sound casks (rum puncheons answer admirably), having their heads removed, are to be well coopered, so as to be water-tight. Into each of these a • galvanized- MANUFACTURE OF TOILET OR FANCY SOAPS. 141 iron copper or pan, a, is placed, and is supported by its flanga upon the upper edge of the cask ; but, in order to prevent the escape of steam, by which these pans are to be heated, the flange is to be well luted with cement. This ma}' readily be done by first spreading' with a trowel a stiff paste of Portland cement inside the rim of the tub, and flush with its extreme edge. When this has set quite hard, a somewhat thinner paste of cement is spread upon the former layer, and the pan then carefully lowered into its place, when it will become imbedded in the Fig. 25. cement, which should then be trimmed neatly with the trowel. In a day or two the luting will be sufficiently hard to enable the vessels to be used. A wooden cover is provided for each pan. The horizontal iron pipe, b, conduces the steam to the vertical pipes c c c, each of which is furnished with a shut-off cock, D D D, and the ends of these pipes are bent so as to allow them to enter the casks through holes drilled about half-way down, and which are carefully secured in their position by calking with tow, or by any other convenient means. To allow the escape of con- 142 THE ART OF SOAP-MAKING. densed water, and as a vent for exhausted steam, a half- inch hole is drilled at the bottom of each cask, immediately- above the iron hoop; and these must always be kept perfectly free, otherwise the pans would be liable to become lifted by the pressure of the steam. When required for use, the taps are first opened full, in order to allow any water which may have remained in the pipes to flow into the tubs, and from thence to escape through the perforations at the bottom. The taps should then be half turned, and the steam moderately turned on at first, to allow the condensed water to escape freely. After a while the taps may be turned nearly full on, when the steam will issue from the water-holes at the lower part of the casks. The pans, a, will hold about 2 cwt. of soap each. A convenient • form of steam-jacket pan is given in Fig. 26. The dotted lines at a show the position of the Fig. 26. Kg. 27. pan in the jacket b. The supply-pipe, c, is furnished with a stop-cock, d is an exit-pipe for the escape of condensed water and waste steam. For small experi- mental operations the copper jacket-pan represented in Fig. 27 is a very convenient vessel. nXacliiue for Slicing the Soap. — Previous to re- melting the soap, which is in the form of bars about MANUFACTURE OF TOILET OR FANCY SOAPS. 143 14 inches long by 2J inches square, it is necessary to cut the soap into thin slices, by which the operation of melt- ing is considerably hastened. There are many forms of apparatus for this purpose, one of the simplest being represented in Fig. 28. This consists of a wooden bench supported by strong framework, and furnished with a blade of steel fixed angularly in a slit cut diagonally out of the flat surface of the bench. The blade is adjusted so as to project a little distance above the board, and the arrangement is like that of an inverted carpenter's plane. Beneath the cutter or planing-machine is a broad and deep drawer for receiving the shavings of soap. When Fig. 28. in use, a bar of soap is pushed lengthwise towards the blade and beyond it, when a thin slice is cut off and falls through the slit into the drawer beneath. By this simple contrivance, and by a quick workman, soap bars may be cut into thin shavings with sufficient rapidity to feed several such melting^pans as those described. For more extensive operations, the machine shown in Fig. 29 is much used. This consists of a cutter, a, attached to the centre of which is an iron shaft, at one end of which is a handle, c, to set the machine in motion. The machine is fixed on a wooden frame, dd. At e is an inclined plane of wood, upon which the soap,^] is placed to 144 THE ART OF SOAP-MAKING. be cut into shaTings. shavings as they fell Kg. 29. A wooden box, g, receives the from the machiae. The bar or slab of soap, being placed on the inclined plane, e, is allowed to touch the cutter ; the handle being now turned, the first blade removes a shaving, and is im- mediately followed by the second blade, and so on until the entire bar is cut, when it is replaced by another, and so quick is the operation, that in an hour two cVt. of soap may be reduced to shavings by this useful machine. Re-melting the Soap. — The soap to be re-melted for conversion into toilet soap should be pure " unliquored " soap, and of recent manufacture, otherwise those surfaces which may have become hardened by long keeping will be troublesome to liquefy. The bars of soap are first reduced to thin slices by the planiag-machine (Fig. 28), and a few of these are first placed round the interior of the pan and in contact with it, when the steam is to be turned on, and, after a short time, the. soap will begin to melt where it is in contact with the pan. To prevent^ the soap from becoming dry on the unmelted surfaces, it is a good plan to sprinkle it with water. After putting in the first few slices of soap, the wooden covers should be placed over the pans, and these should not be raised until sufficient time has been allowed for the pans to become well heated. If now, on raising the lid, the soap appears to have fairly commenced to melt, a few more slices of soap may be introduced, and the pan again covered. After a short time fresh quantities o£ soap may be put into the pan gradually, and care must be taken to avoid adding an excess of the cold soap, otherwise it will, by chilling the melted soap, form a conglomerate mass which will not readily liquefy. If these precautions are observed there will be no difficulty in the re-melting. As fast as the soap melts it will sink to the bottom of the pan ; and, in order MANUFACTURE OF TOILEl OR FANCY SOAPS. 145 to assist tte mingling of the melting soap with that which is already liquefied, gentle stirring may be applied, and fresh batches of sliced soap added gradually, until the pan is sufficiently full. The heat must be kept up, with occasional stirring with a small wooden crutch, until the mass is perfectly homogeneous and free from unmelted lumps. Since toilet soaps are required to be somewhat firmer and harder than ordinary household soaps, a certain amount of evaporation of their combined water must be allowed to take place during the re-melting ; but this must not be carried too far, otherwise the soap will be liable to crack during the subsequent pressing or stamping opera- tions. Again, it will be necessary to evaporate a portion of the combined water to allow for the addition of the essential oils or perfumes which are to be blended with it. When dry colouring matters, as vermilion, yellow- ochre, red-lead, and various metallic oxides have to be mixed with the melted soap, care must be taken not to allow the paste to become too stiff, otherwise, when these are incorporated with the mass, it may become unmanage- able. mixing Colouring Matters and Perfumes. — The pro- portions of colouring matter and essential oils to be added to the melted soap being weighed and measured, may be worked up together with a spatula, and the mixture ^--s^S^^^^^ then poured into the soap and thoroughly incorpo- rated by continual crutch- ing or stirring. Or the colouring matter may be added, ^ little at a time, to a ■ portion of the melted soap dipped out of the bulk by a small ladle (Fig. 30), and when tnis is well mixed it should be poured into the pan and stirred in, the remainder of the colour being introduced in Ijhe same way. By this method the colouring matters a^d essential oils may be very perfectly and uniformly blended with the soap paste. "When perfumes are used without colouring matters, they 146 THE ART OF SOAP-MAKING. sliould be slowly poured into the pan, with stirring, until the requisite proportion has been added. The soap being perfumed and coloured, small samples should be taken to determine if it be of the proper consistence to set hard and firm without being brittle. It is now ready for the frames, which, for scented soaps, are much smaller than those employed for household soaps. The condition of the soap when ready for the frames is that of a thick pasty mass, and must be transferred to the frames by means of the short-handled ladle (Fig. 30), or swimmer (Fig. 12) ; and when the frame is full the soap should be pressed or patted down, so as to prevent any hollows or cavities being formed through the irregular distribution of the soap in the frame. The soap should also be well covered with cloths, so that the cooling may be very gradual. Cutting the Soap. — When the soap is sufiBciently cold it is cut into slabs and bars proportionate to the size re- quired for the tablets, which generally run eight, six, four, or two to the pound. The bars are next divided into cakes or blocks, the width of which is regulated according to the size and weight of the tablets. Stamping the Soap. — As the tablets of toilet soaps are generally of an oblong form, with rounded corners, the cakes which have been cut from the bars require to be trimmed before they imdergo the process of stamping. This is generally done as follows : A workman, taking a cake in his hand, passes each sharp edge of the cake over the blade of a planing- machine, such as is shown in Fig. 28, the blade of the machine being so adjusted as to remove only a small portion from the edges. The corners are next trimmed with a knife, and each cake is weighed from time to time during the trimming, until it approaches the required weight for the tablet. The cakes thus prepared are next put aside to dry, or are placed in a drying-room, so that the surface may be free from stickiness before they are stamped. The cakes, after being trimmed and dried as described, are first moulded in a lever press (Fig. 31), which gives them the MANUFACTURE OF TOILET OR FANCY SOAPS. 14? desired form, a a is a strong woodea table, to which the press is firmly attached by bolts and screws ; b is a cast- iron pillar, to which the lever c „^ and the piston d (to which the upper half of the mould is con- nected) are attached ; e is the lower half of the mould. In applying this press the work- man places the cake of soap upon the lower half-mould, and then brings the lever down with considerable force, and then jerks it upwards, so as to separate the two- halves of the mould. If necessary, he gives ^" the cake several blows, after which he removes it and replaces it by another cake. The cakes thus stamped are again set aside until their surface is perfectly dry, after which they are slightly scraped all over, and a little alcohol is sometimes rubbed over them to impart brilliancy to their surface. Fig. 32. t3,The cakes are finally stamped in a second press, which maybe of the form given in Fig. 32, which is called a " fly " 148 THE ART OF SOAP-MAKING. or screw press. This -useful press is, like the former, sup- ported upon a strong wooden table, which latter must be secured to the floor by bolts or screws, a a represents the frame of the press ; h the screw, furnished at its lower end with a socket, into which the. upper half-mould is secured by a screw ; c is the lower half-mould, and which is connected to the movable rod d. The fly, e e, is sur- mounted by two heavy balls, _/y. The upright wrought- iron rods, gg, are adapted by screws to the horizontal bar below, h h. These rods pass beneath the cast-iron or brass matrix, i i, and raise the movable rod d after each stroke of the press, by which means the stamped tablet is set free, and, being removed, is replaced by another. In the upper half-mould is fixed, by means of a screw, the en- graved stamp which is to impress the soap. After stamping the tablets they are carefuUy trimmed at the edges, and are then ready for wrapping up. CHAPTER XVIII. MANUFACTURE OF TOILET SOAPS— {oontimed.) EoBe Soap. — Orange-flower Soap, — Cinnamon Soap. — Musk [Soap. — Bitter Almond Soap. — "Windsor | Soap. — Brown Windsor JSoap. — Violet Windsor Soap. — Savon au Bouquet. — Savon a la CanneUe. — Almond-oil Soap. — Marshmallow Soap. — Vanilla Soap. — Benzoin Soap. Bose Soap, or Savon k la Bose, may be made from either of the following formulae, the soap being previously well melted, as before described :— I. White curd soap, made from best tallow 60 lbs. Olive-oil soap 40 „ Vermilion in fine powder 3 ozB. The vermilion is to be first well mixed with the soap, great care being taken to ensure perfect incorporation. The steam is then to be turned off, and when the soap has cooled a little the following perfumes are to be added in about the proportions given : — Essential oil of rose 6 oza. „ oils of cinnamon and cloves, of each 2 „ ,, 'oil of bergamot 5 „ Soap prepared from the above formula has a delicate rose colour, is very fragrant and emollient, and is indeed one of the finest of toilet soaps. II. White curd soap 100 lbs. Vermilion 10 ozs. Oil of rose 15 >, „ bergamot 5 „ „ neroli , 2J ,, Oils of cloves and cinnamon, of each 5 „ ISO THE ART OF SOAP-MAKING. Orange-flower Soap. White curd Boap 60 Iba. Palm-oil soap 40 „ Colour with Yellow-green pigment 16 ozs. Minium (red-lead) 2| „ Perfume with Oil of Portugal 15 ozs. „ ambergris 15 „ Ciuuainou Soap. White curd soap 60 lbs. Pahu-oil soap 40 ,, Colour with 2 lbs. of yellow ochre and perfume with OU of cinnamon 14 ozs. „ sassafras 2^ „ ,, bergamot 2^„ Mnsk Soap. I White curd soap 60 lbs. Palm-oil soap 40 ,, Colour with Brown ochre, or Spanish brown 8 ozs. Perfume with Oils of musk and bergamot, of each 7 ozs. Powder of cloves, pale roses, and gilliflower, of each 9 ,, Bitter Almond Soap, or Savon d'Amandes Am&res. White curd soap 100 lbs. Oil of bitter abnonds ; . . . 20 ozs. Windsor Soap. — This famous toilet soap, as prepared in London, is generally made from tallow nine parts and olive-oil one part, and is perfumed (for every 1,000 lbs. of the paste) with Oil of caraway , , , 6 lbs. Oils of lavender and rosemary, of each l^lb. Or, for each 100 lbs. of soap, Oil of caraway 5 ozs. ,, bergamot 10 ,, » cloves 1\„ „ thyme ,,,, 5 „ MANUFACTURE OF TOILET OR FANCY SOAPS. 151 Or, for the same quantity of soap, Oil of caraway 10 ozs. „ bergamot S ,, Oils of lavender and rosemary, of each. 2j ,, Brown Windsor Soap is prepared as above, and coloured either with, burnt sugar (caramel) or umher. In making this soap some perfumers have adopted a system of making what is called an instantaneous soap. This consists in saponifying the fatty matter, which is generally a mixture of hog's lard and tallow, with strong ley. Twenty parts of the fatty matters are taken, to which is added ten parts by weight of caustic soda ley at 36° B., and these being put into a small jacket-pan, steam heat is applied until the mass assumes a fluid condition, when five parts more ley are introduced, with constant stirring for an hour or so. At the end of this time an additional five parts of ley are given, and the agitation continued, the heat of the mass not being allowed to exceed 150° F. "When the ley has deposited, and the paste become perfectly homogeneous and of the proper consistence, it is trans- ferred to another pan, and the perfumes are then added, after which the soap is ladled into the frame. In about Jiwenty-four hours or less the soap will be caol enough to (J-lt. It must not be allowed to remain until quite cold, or it ^511 become too hard for cutting. These instantaneous soaps are best made direct from the fatty acids, with car- bonate{t;^ soda, as recommended by Mr. Morfit. Win^ gjbr Soap is also made from lard in the same way as oli\ /-oil soap, and the perfumes — oils of caraway, lavendw-, and rosemary — are added so soon as the soap has acquired the proper degree of firmness. Violet Windsor Soap is made from lard, 50 parts ; palm-oil, 33 parts ; and spermaceti, 17 parts ; and the per- fume employed is essence of Portugal, to which a little oil of cloves is added. The well-known violet odour of the palm-oil, modified by the perfumes, gives an agreeable fragr.mce to the soap. Po wdered cassia is a useful substance for giving an agree:9.ble brown colour to toilet soap, but it must be added IS2 THE ART OF SOAP-MAKING. a little at a time, and well crutched or stirred into the melted soap. Savon au Bouquet. — This soap is prepared from the following : — ■White curd soap 60 lbs. Oliye-oil soap 40 ,, Perfume with Oil of bergamot 13 ozs. „ neroli i Ij oz. Oils of clove, sassafras, and thyme, of each 1 J ,, Colour with Brown ochre 22 lbs. Savon a la Cannelle. (Cinnamon Soap.) White curd soap 60 lbs. Palm-oil soap 4 ,, Colour the paste with Tellow ochre 2 lbs. And perfume with Oil of cinnamon 14 ozs. ,, sassafras and bergamot, of each 25 ,, Almond-oil Soap is, according to Dussauce, prepared in France as. foUows, and since it is sold at a high price, the materials must be of the best and purest qualitj-. "The oil of sweet almonds must be perfectly fresh, and the carbonate of soda chemically pure. The sod^ :i3 dis- solved in water, adding to it one-third of its -Jm o^it of slacked lime; stir from time to time, and aftMlJg^ral hours, filter; concentrate the ley by evaporationwe^til it marks 36° B. ; then take 12 parts for 25 partsfof oil, introduce the ley into a jar, and gradually incorpoitate the oil, being careful to stir the mixture until it has t'he ap- pearance of a soft grease. In two or three dsWs its consistency is such as that it can be run into china nfoulds, if placed in a room the temperature of which is from 71° to 107°. In about one month it can be taken froia the moulds. The temperature of the ley must be from kO° to 59° (104° to 140° Fahr.), but the soap may be pr€pared more rapidly by placing the mixture on warm ashes, and MANUFACTURE OF TOILET OR FANCY SOAPS. 153 adding a little warm water to the ley, so as to prevent its concentration. This soap is very white, with a sweet taste and odour. It becomes very hard." Uarshmallow Soap, White curd soap and palm-oil soap, of each 40 Its. Colour with Yellow oclire 4 ozs. Orange mineral 4 „ Gamboge 1 J oz. , Perfume with Oil of lavender 10 ozs. „ lemon 2 ,, ,, neroli 2 ,, ,, vertena 10 ,, ,, mint.... I 3 ,, Or, the following : — Oil of Portugal 6 ozs. „ thyme 4 „ „ lavender 1^ oz. ,, cinnamon 2 ozs. „ cloves 3 „ This soap may be coloured rose with vermilion, or be left as a white soap if desired. Vanilla Soap. "White curd soap 40 lbs. Tincture of vamlla 2 „ OU of rose 2 j drms. Colour with Burnt sienna 7 ozs. Benzoiu Soap. White curd soap 40 lbs. j Tincture of benzoin 64 ozs. The soap must be in the form of a very stiff paste, otherwise the tincture of benzoin will render it rather soft. Brown ochre may be used as the colouring agent. CHAPTEE XIX. MANUFACTURE OF TOILET SOAPS— {cmtinued). French System of making Toilet Soaps. — Formulae for French Toilet Soaps. — Savon de Guimauve. — Savon aux Flours d'ltalie. — Savon de Crimee. — Savon de Palme. — Violet Soap. — Vanilla Soap. — Eose-leaf Soap. — Savon a la MarSchale.^Lettuce Soap. — ^Ambergris Soap. — Elder-flower Soap. — Lemon Soap. — Orange Soap. — Glycerine Soap. — Savonnettea or Washballs. — Violet WashbaUs. — Honey Savonnettes. — Savonnettes of Sweet Herts. — Savonnettes of Camphor. — Savonnettes of Neroli. — Savonnettes h. la VaniUe. — Marbled Savonnettes. — Savon- nettea au Miel. — Floating Savonnettes.- — Sand Balls. French System of making Toilet Soaps. — Instead of pre- paring toilet soaps from re-melted soap, as before described, a system is adopted on the Continent by which these soaps are made by a series of mechanical operations which we will 'endeavour to describe as briefly as possible. The various operations are arranged under the following heads : — 1 . Cutting the soap into shavings. 2. Mixing the essential oils and colours with the soap. 3. Grinding the soap. 4. Pounding the soap in a mortar. 5. Balling the soap. 6. Pressing. 7. Stamping. Cutting the soap into shavings is performed by a machine such as is shown in Fig. 29, and the shavings are placed in a lead-lined wooden box. The proper propor- tion of essential oils and colouring matter (except when the soap is required to be white) are first mixed in a separate vessel, with a little alcohol, and the mixture is then added gradually to the shavings, with continual stirring. The perfumed shavings are next placed in a grinding-machine, through which they are allowed to pass several times, until a perfectly homogeneous paste is formed. MANUFACTURE OF TOILET OR FANCY SOAPS. 155 The soap is next pounded in a marble mortar, by means of a wooden pestle, the object of which is to convert the soap into auniform mass. Only a fewpoimds (about ten or twelve) of soap are pounded at a time, lest it should become too dry for the subsequent operation of hailing, which is per- formed somewhat as follows: — The soap is placed on one end of a table on which is a marble slab, and in order that an allowance may be made for the reduction of weight which the soap has to undergo in the process of drying, the balls or cakes of soap are made about 25 per cent, heavier than the finished tablets. The directions for making the soap into cakes of the proper size, weight, and form for the pressing and stamping machines are thus given by Dussauce : — " Weigh as many pieces of 4^ ounces as you want of cakes of 3J ounces ; knead with the hands each little mass of soap, so as to form a ball, which is made round on the marble slab. For this purpose, the ball being on the marble, give it a rotary movement with the right hand. The ball being obtained, leave it on the marble, and give it a cylindrical shape by rolling it with the flat of the hand. This. cylinder must not be larger than the model (mould?). Nevertheless, as the cylindrical shape is not that which the soap ought to have, strike the cylinder on all its sides on the marble to square it — that is, to form an oblong square — and round the angles by striking them gently on the marble. If any unforeseen circumstance requires a suspension of the work, cover the pounded soap with a damp cloth and keep it in a cool place. If the soap is too dry, it will be difficult to work well. Once begun, it must be worked quickly and without interruption. "The small cakes being shaped as indicated, dispose them on trays or frames of white wood, traversed in their length by small rods of wood, in such a way that each frame presents as many empty spaces as full ones. These frames have a length of twenty-seven inches, by eighteen wide ; they. are arranged on shelves, at a distance of five or six inches from each other." In arranging the soap cakes as above, a space of about iS6 THE ART OF SOAP-MAKING, half-an-inch is allowed between each, so that the air may- circulate round them, and thus facilitate their drying on the surface. It is important that the drying should be as rapid as possible. In about a week the surface of the cakes will have become hardened, and ready for pressing. This is done by means of a lever press. Fig. 31, which merely gives to these cakes the preliminary form of the mould. To apply the press, one of the cakes is placed on the lower half of the mould, and the lever is then forced downwards and then raised, when the cake is removed and another substituted for it, and so on, until all the cakes have been struck. The edges of the cakes are then trimmed, after, which they are again set aside to dry, and when sufficiently so they are removed from the drying- room, and the hardened skin which has formed upon the surface is carefully removed by means of a sharp knife, with which the cakes are dexterously scraped by the work- man. It is said that a good workman can scrape forty dozen of cakes in a day. When the cakes have been scraped they are moistened with alcohol, to improve the smoothness of their surface. To accomplish this, the fingers of the right hand are dipped in alcohol, and this is spread quickly over the cake, which is then rolled in both hands, by which it becomes moistened all over in a few moments. The cakes are again dried for about twenty-four hours, after which they are ready for the final stamping, which is effected in the fly or screw press, by which an active man can mould 1,500 cakes of soap per day. In the above process there is a loss of about 14 or 15 per cent, of water during the several drying operations, but this is allowed for in the operation of balling, in which the cakes are made heavier than the resulting finished soap is required to be. The scrapings of the cakes are afterwards worked up in future batchefs of the same kind of soap. Fonanlse for Frencli Toilet Soaps. — The following are some of the formulae for toilet soaps adopted by the French makers : — MANUFACTURE OF TOILET OR FANCY SOAPS. 157 • Savon de Gnimanve. (Marslimallow Soap.) White tallov soap 10 Its. Falm-oil soap 10 ,, Colour with Tellow oclire 1 oz. Orange mineral i „ Gamboge 5 dxms. Perfume with OU of lavender IJ oz. „ mint I „ „ caraway | „ „ lemon S drms. Oils of rosemary and thyme, of each 2 J „ Savon aux Fleurs d'ltalie. White tallo-w soap 20 Iha. Perfume with on of citronella 1^ oz. ,, geranium | „ „ verbena 1 >> ,, mint 2^ dims. Colour with Brown ochre 2\ ozs. Savon de Crim^e. White curd soap 16 lbs. Pahn soap i „ Colour with Yermilion 2^ drms. Brown ochre 1 oz. Ivory black | „ Perfume with Oils of thyme, mint, and rosemary, of each .... 1 oz. OU of lavender 2^ drms. „ cloves l| drm. Tincture of benzoin I5 oz. . Savon de Palme. Palm soap 10 lbs. HaU-palm soap .; 10 ,, Perfume with Oil of bergamot 2 ozs. ,, cloves J oz. Oils of cinnamon and lavender, of each 1 „ 158 THE ART OF SOAP-MAKING. Violet Soap. (Yellow.) Yellow cocoa-nut oil 20 Ib^ Palm-oU 20 „ TaUow 10 „ Soda ley at 36° B 26 „ Powdered orris-root 4 „ To ^hich are added the following perfumes : — OU of lemon 4 ozs. „ rhodium 2 „ „ thyme 2 „ Tincture of musk 4 ,, Colour with cadmium yellow. Vanilla Soap. Lard, with vanilla 30 Ihs. Cocoa-hutter 10 „ Palm-oil 10 „ Caustic ley, 36° B 26 „ Wax 2 „ Starch 2 „ Perfume with Tincture of vanilla , 4 ozs. „ musk 2 „ „ amhergris 2 „ Oil of rose ^ oz. Lard with vanilla is prepared by adding the vanilla to the lard (1 oz. to the lb.), keeping it at a moderate heat for some days, then straining, &c. Bose-Leaf Soap. Bose pomade 20 lbs. Lard 20 „ Cocoa-nut oil 10 „ White wax 2 „ Soda ley, 36° B 20 „ Potash ley, 30° B 12 „ Gum tragacanth 8 „ Perfume with Oil of roses 2 ozs. „ geranium 2 „ „ rhodium 1 oz. „ bergamot 2 ozs. „ cinnamon (Oeyloii) ^ oz. Colour with aniline (fast red) a light pink. MANUFACTURE OF TOILET OR FANCY SOAPS. 159 Savon \ la Mar^chale. Lard, ■with musk 10 Its. „ amberette 10 „ Pomade (aux fleurs) cassia, jasmine, and rose, ofeach 10 „ Olive-oil 1 lb. "White wax 2 lbs. Gum tragaoanth 2 „ Caustic ley, 36° B 28 „ Saponify carefully and colour with a little caramel (burnt sugar). liettnce Soap. Lard, with lettuce 20 lbs. Cassia pomade 10 „ Spermaceti 5 „ Castor-oil , 5 „ Palm-oU (bleached) 10 „ Caustic ley, 36° B 26 „ Gum tragacanth 3 ozs. Perfume with Oil of bergamot 6 ozs. thyme 2 „ „ valerian 1 oz^ „ cloves 1 „ Colour light green. The lard with lettuce is made by melting the lard with its own weight of lettuce-leaves, keeping it at the melting- point — about 90° F. — ^for some hours, or until the leaves have parted with their colour and their juice. Then steam off for use. Ambergris Soap. Grease perfumed with ambergris and musk 25 lbs. Jasmine pomade : 10 „ Bose 10 „ Gum tragacanth 3 ozs. Caustic soda ley, 33° B 25 lbs. Colour light brown with caramel. This soap is made of select materials by the cold pro- cess, and after being made is allowed a few days to dry before melting. The musk and ambergris have to be added to the grease some weeks before, frequently melting and stirring. i6o THE ART OF SOAP- MAKING. Elder-flower Soap. Half-palm soap 100 Its. Dextnne 3 „ Perfume with Oil of bergamot 8 oza. „ lavender 2 „ „ thyme 2 „ „ cloves 1 02- „ cassia ^ i> „ almonds i d Colour light green. Lemon. Soap. ■White soap 50 lbs. Starch 2 „ Perfume with. Oil of lemon 4 ozs. „ bergamot 2 „ „ lemon-grass 2 „ „ cloves 1 oz. Colour light yellow with cadmium yelloW. Orange Soap. Wbite soap , 50 lbs. Starch 2 „ Perfume with Oil of orange-peel 8 ozs. „ cinnamon \ oz. „ thyme 2 ozs. Colour dark yellow with naphthaline yellow. Glycerine Soap. Tallow (mutton) 44 lbs. Cocoa-nut oil 44 „ Castor-oil 22 „ Glycerine (pure) 22 | „ Caustic ley, 40° B 27 „ Alcohol, 96° 48-4 „ Water 9-9 „ Melt the grease at 104° F., and add the alkali by slow degrees, keeping the heat low to prevent evaporation, and stir constantly. When the ley has become absorbed, after three or four hours' stirring add the alcohol, which should be warmed ; stir till it becomes clear, then add the glyce- rine, and when mixed, the water and perfume ; turn into MANUFACTURE OF TOILET OR FANCY SOAPS. i6i the frame,. pouring slowly. This soap, if carefuUy made, is a very superior one. — Cristiani. The same author gives the following formulae for pre- paring white Castile soap, with or without olive-oil : — 1. Olive-oil 40 parts. Grotmd suet 30 „ Tallow , 30 „ 2. Olive-oil 30 „ Lard 30 Palm-nut oil 40 ,', 3. OUve-oil 30 „ Cotton-seed oil .... , 30 ,, TaUow-oil '. 40 „ 4. Palm-oil (bleached) 50 „ Sesame-oil 20 „ Tallow 30 ,', Savounettes, or Washballs. — These may be made from any of the milder toilet soaps, or from the subjoined formulae. The spherical form is given by pressing the soap in moulds, or by first forming them into balls with the hand, and when quite dry and hard turning them in a lathe. According to Mr. Beasley, " they are formed into spherical balls by taking a mass of the prepared soap in the left hand, and a conical drinking-glass with rather thin edges * in the right. By turning the glass and ball of soap in every direction the rounded form is soon given ; when dry, the surface is scraped, to render it more smooth and even." Washballs are sometimes made with the addition of powdered starch or farina, and sometimes sand. Having but a comparatively limited sale, they are usually pre- pared in small quantities. Violet Washballs. Palm-oil soap , 4 Its. Farina (starch) 2 „ Fine powdered orris 1 lb. Cut the soap into fine shavings and m.elt over a hot water-bath, adding a small quantity of water. Then add the farina and incorporate it well by stirring. Lastly, add the orris powder, and mix well. * A brass tool is commonly used for this purpose. M l62 THE ART OF SOAP-MAKING. Honey Savounettes. Knest yello-w soap 7 Its. Palm-oil Boap .- J lb. Melt and then add Oil of Terbena, rose, geranium, or ginger-grass ... 1 oz. Oil of rosemary \ „ Savounettes of Sweet Herbs. — Melt 12 lbs. of white curd soap, and then add the following mixture of essential oUs: — Oils of lemon and bergamot, of each 4 ozs. „ thyme, lavender, wUd thyme, myrtle, and marjoram, of each 1 oz. ,, mint, sage, and wormwood, of each \ „ „ fennel 2 ozs. Savounettes of Camphor. White ctrrd soap 3 lbs. Melt, with the addition of a little water, and then add Spermaceti 4 ozs. Camphor (cut small) 2 „ These are first to be melted together, and then added to the liquid soap. Savonnettes of ITeroli. Melted curd soap 12 lbs. Orris powder 1 lb. Orange powder 3 ozs. Oil of .neroli 12 drms. Essences of musk and ambergris, of each 4 ozs. Savonnettes a la Vanille. "White curd soap 12 Its. Melt, with a little water, and then add the following mixture : — Tincture of ranilla 4 q^s. Balsam of Tola , \ 4 ,. I'eru ..'.'.'.'.'.'.'. 2 " Tincture of cinnamon I02. Oil of cloves !!!]!'.;!!!!!! 2 d^s. Tinctures of musk and amber, of each 1 oz. MANUFACTURE OF TOILET OR FANCY SOAPS. 163 Marbled Savonnettes. — These may be formed as fol- lows: — For red, cut white curd soap into small squares, and roll these in powdered bole or rouge, then press them strongly with the hands into halls, taking care to mix the colour as little as possible. For blue, roll the pieces of soap in powder blue, and then treat them as above. For green, roll the cakes of soap in a mixture of yellow ochre and powder blue. By varying the colour of the powder savonnettes of any shade or colour may be produced. A very pleasing and real marbled appearance may be given to soaps in this way : Melt in one vessel any required quantity of white curd soap, adding a little water. When thoroughly melted put a small quantity of the soap in a separate vessel, previously warmed, and add to it a sufficient quantity of ultramarine, vermilion, or any other colour (previously mixed with a little water), to stain the soap. Now add the coloured to the white soap, and stir round and round in one direction only until the coloured soap has formed a series of circular veins in the mass. Care must be taken to do this slowly, so that the coloured soap may merely streak the white soap. Allow 1!he soap to cool, when it may be scooped out in small lumps with a half-round and bright trowel, and these marbled lumps may then be fashioned into balls or tablets according to requirement. If preferred, the marbled soap may be carefully put into a frame while hot, but this must be done cautiously, so as not to mix the colour with the white ground. The required perfumes should be added to the white soap before the coloured soap is introduced. Savonnettes an Miel (Honey Savonnettes). "White curd soap (melted) 1 lb. Honey 1 „ Essential oil of any kind rec[nired 2 ozs. Rose-water •. 2 „ Add the honey to the melted soap, then add the rose- water, and lastly the perfume. Floating Savonnettes may be made by adding a little water to any of the perfumed soaps in a melted state, and l64 THE ART OF SOAP-MAKING. briskly stirring the mass, so as to mix or beat air into the soap. This agitation should be kept up until the mass is at least doubled in volume. Sand-Balls are made by incorporating with melted and perfumed soap certaia proportions of fine river sand. About one-third sand to two-thirds soap is a fair propor- tion. The sand, however, should be passed through a fine sieve before using. Sometimes finely-powdered pumice is substituted for the sand. CHAPTER XX. SOFT TOILET SOAPS. Naples Soap, or Almond Cream. — French Method. — White Soft ToHet Soap. — Powdered Soaps. — Shaving Paste. — Essence of Soap. — Essence de Savon Vienne. — Essence de Savon Corinthe. — Transparent Soap. The alkaline base of these soaps is potash, and the fatty matter generally used is good hog's lard, though some- times cocoa-nut oil is introduced to promote the lathering properties of the soap. This latter oil, however, should he used sparingly, since it invariably leaves a disagreable odour on the skin after washing — a serious objection in toilet soaps. ITaples Soap, or Almond Cream. — This elegant pre- paration, which has been much used as a shaving soap, is prepared as follows : — A potash ley, marking 36° B., is first prepared. Now take 20 lbs. of clarified hog's lard, and place this in a small copper jacket-pan or other con- venient vessel, and apply gentle heat, stirring continually with a wooden stirrer. When the lard is about half melted, but free from lumps, add 5 lbs., by weight, of the potash ley, and continue the agitation and also the same degree of temperature, when, after an hour or so, soap granules ^^JLhave deposited at the bottom of the pan, while a layer of unsaponified fat will float on the surface. Another 5 lbs. of the same ley must now be added and the mixture stirred, when the graniiles and oil will disappear, and the mass assume the form of a paste. The heat and occasional stirring must be kept up for about four hours, by which time the mass will becc ne a stiff paste, when it requires to be beaten lightly, ll^lie heat should then be withdrawn. OAP-MAKING. .ed over, so that tte cooling may lOW. ., the soap is to be put into a marble pounded with a wooden pestle, by which parated particles become united, and a per- ugeneous paste formed, which has a beautiful iUstre; hence it is sometimes called fearl soap. preparation is usually perfumed with oil of bitter -imonds ; hence it is also called almond cream. French Method. — Fifty pounds of hog's lard and 10 lbs. of cocoa-nut oil are placed in ■ a steam-jacket pan, and melted ; 50 lbs. of potash ley 'marking 20° or 21° B. are then added gradually, with constant stirring, and the heat of the mass is to be kept at from 140° to 158°. After a while the mass thickens, by the evaporation of the water from the ley ; if a tendency to separation of the fatty matter is exhibited, the heat must be lowered, and if necessary, a little stronger ley added until saponifi- cation is complete, which generally occupies about four hours. To finish the operation, 30 lbs. of potash ley at 36° B. must now be added, with continual stirring, and care must be taken to keep the heat below the boiling-point of water. When the paste has become quite stifi', the steam is to be turned off, and the paste allowed to cool down, after which it is put into stone jars for future use. To convert this into pearl soap it is pounded in a marble mortar, a few pounds at a time, from \\ to 2 drachms of oil of bitter almonds being added for each pound of soap. When the soap is required to be of a delicate rose colour, from 15 to 30 grains of vermilion to each pound of soap must be added, and well incorporated by the pestle and mortar. Although the oil of bitter almonds is principally used as a perfume for these soap creams, as they are called, other fragrant substances are occasionally employed. For example, Creme Ambroisie is perfumed with liquid storax and benzoin, and Creme de Cacao Mousseuse with oil of cacao. White Soft Toilet Soap,— Cristii ni gives the following SOFT T0ILE2' SOAPS. 167 directions for making a white soft toilet soap: — Melt in a sheet-iron kettle, of a capacity of about . 50, gallons, 50 lbs. of white fat and 13 lbs. of ooeoa-oil. When the fatty matters are entirely melted, add ^0 lbs. of potash ley at 20° or 21° B. Stir all the timej so- as to aid the saponification, the temperature being kept at from 140° to 150° F. Under the influence of heat and stirring the aqueous part of the ley evaporates and the mixture acquires a thicker consistency. Sometimes it happens that a part of the fatty matter separates. This is produced especially where the temperature of the mixture is raised near the boiling-point, because at that temperature con- centrated leys have little affinity for fatty substances. This effect may also^ be produced by the insufficiency of alkali in the mixture.^ In the first case the homogeneity is re-established by moderating the action of the heat, and in the other by pouring into the kettle a portion of strong ley necessary to complete the saponification. The first stage of the operation lasts about four hours. To obtain a perfect soap, add 10 lbs. of potash ley at 16° B., and be careful to keep the mixture very uniform by continual stirring. Keep the temperature below the boiling-point, and as much as possible between 140° and 150° F. The saponification is finished when the paste has acquired a very thick consistency. At this point turn off the steam. Many perfumers prepare this soap in iron kettles with a double bottom, heated by steam ; some juse silver kettles, which are preferable, because in them the soap will retain its whiteness. The engraving Fig. 26 represents a jacket or kettle with a double bottom, heated by steam. This kettle is of tinned copper, and may be also used to purify tallow and greases. The operation lasts in all from seven to eight hours. "When the soap is Entirely cooled down, pour it into large stone jars, in which it is kept for use. Soft soap, as obtained by the saponification of fatty matters by potash, has not that bright nacreous (pearly) appearance required for the toilet. To obtain it in this state it is ground in a marble mortar and aromatised with oil of bitter almonds. 1 68 THE ART OF SOAP-MAKING. Powdered Soaps. — ^All hard soaps may be reduced to a fine powder, when perfectly dry, by trituration with a pestle and mortar, but the operation is generally confined to cosmetic soaps for shaving or other toilet purposes. The soap, being previously perfumed in the usual way, is cut into thin shavings, and these are laid upon sheets of paper and placed in the drying-room, or dried in any convenient way. As soon as the shavings become brittle they are in a condition for powdering. Small quantities at a time should be carefully reduced to a powder in a mortar, and the powder afterwards passed through a fine sieve, the fine powder being placed in a jar and kept well covered. All coarser particles retained, by the sieve should then be pulverised and sifted as before, until the entire quantity is reduced to a powder fine enough to pass through the sieve. Although it is better to colour the soap in the ordinary way before powdering it, the colouring matter may, if preferred, be introduced into the mortar when the soap is about half reduced to powder, and then worked up with the soap until thoroughly incorporated. For rose-colour, about one drachm of vermilion to each pound of soap should be used. For yellow, from one to two drachms of finely-powdered gamboge. Other shades of colour, how- ever, may be given if desired. Powdered soaps, named after their respective perfumes, are much esteemed as shaving soaps by the fastidious ; and perhaps the so-called rose soap, perfumed with oil of rose and tinted by vermilio.n, may be considered one of the most delicate preparations, provided that it has been piade from a good white tallow soap free from cocoa-nut oil. Shaving Paste. — This popular cosmetic may be pre- pared in various ways, but the following formulae may be taken as representing tbe mode of manufacture : 1. Take jSTaples soap, 1 lb. ; Castile or Marseilles soap, \ lb.; honey, i lb. ; essence of ambergris, oils of cassia and nutmeg, of each 20 to 30 drops. Mix these ingredients well together in a mortar, adding a little rose-water, until a perfectly homogeneous paste is formed. 2. Take of white or virgin SOFT TOILET SOAPS. 169 wax, spermaceti, and almond oil, of each 2 ozs.; melt o\a?r a water-bath, and then add 3 ozs. of Windsor soap pre- viously worked up into a paste with a little rose-water. Mix all well together and place in a jar, which should be kept well covered. 3. White soft soap, 12 ounces ; sper- maceti and olive-oil, of each 1| oz. Melt these ingredients all together, and stir until the mass is nearly cold ; per- fume with any essential oil, or a mixture of perfumes, according to taste. Essence of Soap. — Under this title various prepara- tions are made ; but they are all solutions of soap in warm alcohol, with, generally, the addition of a small quantity of potash. Soaps made from vegetable oils are preferred, because they remain clear and liquid when > cold, whereas those prepared from animal fats become solid in cooling. Dussauce gives the following formula for preparing this soap : — White Marseilles soap 6j ozs. Aloohol at 85° 1 quart. Potasli 6 drms. Cut the soap into fine shavings, and put them into a bottle holding about half-a- gallon (a "Winchester" bottle would suit admirably) ; add the alcohol and potash, and heat gently, without boUing, over a water-bath ; stir with a glass rod. When the solution is complete, take it out of the water-bath, and add the essences. A very sweet perfume may be given to this preparation by adding to it— Oil of geranium Ij drm. „ verbena , 2j drms. To colour yellow, add 2 J drachms of safiron. This essence continues limpid at the ordinary tempera- ture. To use it, pour a little into half a tumbler of water, and stir quickly. Essence de Savon Vienne. White soap 3 ozs. Carbonate of potash 1 drm. Alcohol at 95° 18 ozs. Lavender-water 6 , , Digest and filter. 1 170 THE ART OF SOAP-MAKING. Essence de Savon Coriuthe. '' Dry white soap 10 ozs. Alcohol at 80° 1 quart. Potash 2 ozs. Essential oil a few drops. Digest as before. Any perfumed toilet soap may be conTerted into an "essence," but doubtless the white Castile soap would form the most elegant preparationj besides being the most emollient. Transparent Soap. — Soap, when perfectly dry, is readily soluble in warm alcohol, and advantage is taken of this chemical fact in the manufacture of Transparent Soap — perhaps the most elegant form which this substance is capable of assuming. To prepare transparent soap, either tallow, almond, or soft soaps may be used, but in either case the soap must be rendered perfectly free from water. The soap is first cut into thin slices or shavings, and these are then dried over a water-bath, or by hot air. Equal parts by weight of the dried soap and rectified spirit are put into a still, heated by a water-bath. Only moderate heat is applied, otherwise the spirit would pass over without dissolving the soap. It is Sometimes the practice to powder the soap in a mortar after drying before treating it with the spirit, by which it becomes more readily dissolved. If it is desired to colour the soapj any colouring matter soluble in alcohol may be employed, and it is best to colour the spirit before adding it to the soap. When the soap is completely dissolved, it is allowed to rest for an hour or more, according to the quantity, after which the clear and transparent liquid is put into the frames, in which it will solidify on cooling. When cold the soap is cut into pieces of any required size, and these are moulded in the same way as other toilet soaps. The soap does not, however, acquire its characteristic trans- parency until after it has been exposed to dry air for a ■ ' considerable time. To colour the soap red, a strong tincture of archil may be used, and for yellow turmeric may be SOFT TOILET SOAPS. 171 employed. Any of the aniline colours, however, may be used for tinting the transparent soap, and are, indeed, well suited to this purpose. Resin soaps are considered very suitable for making these soaps, and the presence of a fair proportion of resin undoubtedly favours the transparency and beauty of the substance. Although transparent soaps are exceedingly pleasing to the eye, they do not- possess the active detergent powers of ordinary soaps. CHAPTER XXI. MEDICATED SOAPS. Sir H. Marat's Sulphur Soap. — Mercurial Soap. — Medicinal Soft Soap.— - Antimonial Soap. — Carbolic Acid Soap. — Medicated Tar Soap. — Tootli Soap. — Liquid Glycerine Soap. — Bordhardt's Herb Soap. — Arsenical Soap. — Soap for Washing Dogs. — Turpentine Soap. — Tar Soap. — Black Soap. — Various Substances introduced into Manufactured Soaps. Many different substances have been introduced into soap for the relief or cure of cutaneous affections and for other purposes, amongst which may be mentioned the following : — Sir H. Marsh's Snlplmr Soap. — White soap 2 ozs. and sublimed sulphur ^ oz. are triturated in a mortar, with 1 or 2 fluid drachms of rectified spirit, until a smooth paste is formed. The spirit should be first coloured strongly with alkanet root. A few drops of otto of roses are added to give the soap an agreeable fragrance. Mercurial Soap is made from powdered Castile soap 4 ozs., corrosive sublimate 1 drachm, dissolved in rectified spirit 1 fluid oz. These ingredients are to be thoroughly mixed in a Wedgwood mortar. Medicinal Soft Soap is made from pure olive-oil saponi- fied with a caustic ley made from pure potash. The ley is added gradually and cautiously to the oil during the boiling, and the greatest care taken to avoid an excess of alkali. When the mass' assumes a transparent and gela- tinous appearance, the addition of ley is stopped. The boiling is continued until the soap has acquired the proper consistence. MEDICATED SOAPS. 173 Antimouial Soap. — Pure Castile soap (white) in powder 1 J oz., golden sulphur et of antimony 2 drachms, solu- tion of caustic potassa 6 drachms. Dissolve the sulphuret in the potash and add to the soap ; then triturate in a mortar until a stiff paste is formed. It should have a greyish-white colour. Carbolic Acid Soap. — As a powerful antiseptic, carbolic acid had long been known, but it was not until the late Dr. Crace-Calvert had developed its manufacture upon an extensive scale that its usefulness could be fully taken advantage of. Since then, however, its employment as a disinfectant and deodoriser has become universal, and its incorporation with soap, which has taken the name of Carbolic Soap, has been very extensive. Indeed, this article has now become a necessary and useful article of commerce. About 2 per cent, of carbolic acid is added to soap in a melted state, and thoroughly incorporated by crutching. It is then put into a frame, and when cold is cut into squares and moulded in the same way as ordinary fancy soaps, or, for more extensive use, it may be formed into bars of the ordinary size. Carbolic soap may be prepared from the following : — Half-palm soap 20 Its. Starch 1 lb. Carbolic acid, in crystals 1 oz. OE of lavender 2 ozs. „ cloves. 1 oz. Medicated Tar Soap. Cocoa-nut oil 20 lbs. TaUow 10 „ Juniper tar 5 „ Soda ley, 40° B 15 „ Tooth. Soap. TaUow soap 20 lbs. Pumice powder (finely sifted) 5 lb. Prepared chalk 2 lbs. Starch 4 It . Lig.iiid Glycerine Soap is thus made : — Oleic acid 187 lbs. Cocoa-nut oil (best) 33 „ Potash ley 35° B H* .. Glycerine • • • 1" » 174 THE ART OF SOAP-MAKING. Tlie ingredients are saponified at a gentle heat, and sufficient alcohol at 95° added to make the soap clear. Bordhardt's Herb Soap. Olive-oil Boap 30 Its. Palm-oU soap 20 „ Dextrine 2 „ Perfume with Oil of rosemary 2 ozs. „ lavender Ij oz. „ thyme \\ „ „ sage 1 „ „ magnolia 1 ,, „ peppermint 1 „ Colour blue. Arsenical Soap is used by bird and animal stufPers to preserve the skins from the attacks of insects. It is prepared by the following formula : — White soap, arsenious acid, and lime slacked by air, of each 4 ozs. ; carbonate of soda, 12 ozs. ; powdered camphor, | oz. The whole of these ingredients are worked up into a paste, with pestle and mortar, a small quantity of water being added during the mixing. A Soap for Washing Dog's and other animals is some- times made by mixing Btockholm tar (wood tar) with melted soap. The tar should first be dissolved ia pyroxylic spirit (wood naphtha). Turpentine Soap, or Starkey's Soap, is prepared as follows : — Take of "Venice turpentine, oil of turpentine, and carbonate of potash, of each equal parts ; place these in a mortar (previously warmed), and triturate them together, adding a little water, until a homogeneous mass is formed ; put it into a paper mould, and after a few days cut the soap iato slices, and keep them ia a well-stoppered bottle. Tar Soap is made from soap cut into shavings, 2 parts ; tar, 1 part; and liquor of potassa, 2 parts; the whole being intimately mixed in a mortar. Black Soap, or Farrier's Soap, is a coarse kind of soft soap, made from fish oils and caustic potash ; sometimes tar is added. Besides the substances above named, iodine. MEDICATED SOAPS. 175 bromine, creosote, and many other chemical substances have been employed for making what are sometimes termed skin soaps, but they are all prepared much in the same way as above indicated. Various Substances introduced into Manufactured Soaps. — The following percentages of foreign substances which are added to manufactured soaps are thus given by Cristiani*: — Tannin soap, 3 per cent, of tannic acid. Salicylic soap, 2 per cent, of salicylic acid. Disinfectant soap, carl)olio acid, about 2 per cent. Thymol soap, 3 to 5 per cent, of thymol. Groton-oil soap, 2 per cent, of croton-oil. Benzoic soap, 2 per cent, of benzoic acid. Castor-oil soap, 20 per cent, of castor-oil with Other fats. Petroleum soap, 20 per cent, of petroleum-oil added to the other fata before saponification. Paraffin soap. The wax is added to the amount of 10 per cent, to the fats before saponification. Creosote soap, 2 per cent, of creosote. Iodine soap, 2 per cent, of iodine. Turpenti)ie soap, 5 per cent, of oil of turpentine. Borax toilet soap, 10 per cent, fiiiely powdered borax. Mercurial soap, 6 per cent, of mercurial ointment. Irish moss soap, 5 per cent, of Irish moss dissolved in a suitable quantity of water and strained. Bran soap, 10 per cent, of bran. Cornmeal soap, 10 to 20 per cent, of maize-flour. Oatmeal soap, 10 to 20 per cent, of oatmeal. Camphor ice soap, 5 per cent, of camphor added to cold cream soap would be very suitable. IFax soap, 10 per cent, of wax added to soap. It has some good and useful properties. * " Technical Treatise on Soap and Caudles." CHAPTER XXII. MISCELLANEOUS PROCESSES. Jennings's Processes. — Levat's Process. — Violet's Palm-oil Soap. — Hampel's Shaving Soap. — Marriott's Process. — Sawdust in Soap. — Lewis's Process. — Borax Soap.— Camphor and Ammonia Soaps. — Mackay and Seller's Process. Petroleum Soap : Bastet's Pro- cess. — BesBon and Eemy's Process. — Tardani's Process. — Half-resin Soap. — Payne's Process. — Bankmann's Process. — Jeyes's Process. — Varicas's Process. — Lortury's Process. — Cleaver's Terebene Soap. — Schaxr's Liquid Soap. — Bichford's Process. — Maxking Soaps. Apakt from the ordinary, or, if we may say so, recognised soaps, innumerable patents have been taken out from time to time for various "improvements," modifications, or additions, the merits of which may easily be determined by a small trial when the new process does not, which is too frequently the case, bear the brand of absurdity " on the very face of it.'^ The following abstracts from a few of the patent specifications will enable the reader to form his own judgment as to whether any of the processes described in brief will be worth a further acquaintance, in which case he will naturally obtain a copy of the specification, and if necessary, put himself in communica- tion with the patentee, provided, of course, that such patent is in full force. Jeuuings's Processes. — 1. Combine 1,000 lbs. of stearic or margaric acids, as free from olein as possible, or palmi- tine or any vegetable or animal stearine or margarine, at the temperature of 212° F., with a solution of bi- carbonate of potassa or soda of a specific gravity of about 1,500°; stir constantly until an intimate combination is obtained, and no separation visible when tried with the shovel or trowel. "When the mass has cooled down to MISCELLANEOUS PROCESSES. 177 about 60° F., add 1 lb. per cent, of liquid ammonia of about '880°, and 1 lb. per cent, of tbe strongest solution of caustic potassa; these are to be added gradually, and well mixed by stirring until perfectly combined. Dissolve 15 to 18 per cent, of resin by boiling it with a solution of carbonate of potassa and soda in equal parts, or as m.uch as will give the solution a specific gravity of or about 1,800° when boiling hot. Mix these perfectly with the stearic or margaric acids and carbonated alkali; then add a strong solution of caustic potassa or soda, until perfect saponification is produced. The dose of caustic alkali will much depend upon the purity of the stearine or margarine employed. The separation is now effected by using common salt or sulphate of soda as usual. If the soap is to be colourless, no resin must be employed, and a larger dose of liquid ammonia and caustic alkali must be used according to the dryness of the stearine to be operated upon. 2. White curd soap is dissolved in about one- third of its weight of water, to which is added colophony (black resin), carbonate of soda, and alum. For this purpose the resin (at the rate of 25 per cent, of the quantity of soap) is dissolvpd with about 6 per cent, of carbonate of soda of commerce to the resin employed, using about a like weight of water as there is of the resin. These matters being boiled together till the resin and alkali are dissolved, the compound is to be added to the dissolved soap, and the whole of the mattet's are to be boiled till the workman on taking a sample finds that the soap is hard and smooth, as is well understood by soap-boilers. To this compound is to be added a quantity of sulphate of alumina (common alum) with a view to improve the colour, say from about 2 to 4 per cent, of the tallow or oil and resin in the mixture, using more or less of the alum according as the resin is less or more pure. The whole compound is to be boiled up, and then allowed to stand from two to four hours. In order to prevent the resin precipitating, a quantity of dilute sulphuric acid is introduced and stirred into the above mixture. The strength of each solution of acid N 178 THE ART OF SOAP-MAKING. ■which is used is 1 part by weight of sulphuric acid to 9 parts by weight of water, of which about 2 per cent, in respect to the weight of tallow or oil and resin in the mixture is to be employed. The compound is then to be fitted, cleansed, and framed as usual. levat's Process. — The object of this process is to utilise the waste or residual oily products resulting from the distillation of essential oils, and to add to the emoUiency of the soap by the employment of lichen. The fatty matters are first heated to expel the alcohol left in them after the process of distillation, and they are then heated with a weak soda ley, after which stronger leys are used to complete the saponification. When the soap separates and the grain has the proper consistence, an infusion of lichen is added, when a perfectly smooth paste is formed. The soap consists of: — Fatty matters 58 parts. Soda 6 „ Water 34 „ Lichen 2 „ Violet's Palm-oil Soap. — 100 lbs. of palm-oil are melted, and at the temperature of 203°, \2\ ozs. of nitric acid are added, with Tigorous stirring for about a quarter of an hour ; 12 gallons of hot water are then added, and the stirring continued, after which the oil is allowed to rest. The oil is then well washed seyeral times to free it from the acid, and after being 'separated from the water is saponified with a weak ley at 8° B., followed by stronger leys of 10° and 15°. The boiling is kept up until the soap is of the proper granular consistence, and the grained soap, after being separated from the ley, is dissolved with lemon juice. This soap is called " Orangine." Hampel's Shaving Soap is made by his patented process as follows: — Cleaned olein 6'6 per cent, is first mixed thoroughly with 13 per cent, of hot water ; then 5*4 per cent, of soda ley at 25° is added, and the mass, which assumes the appearance of soft butter, is agitated untH it becomes cold and is easily liquefied, when 12*5 per cent, of best white soap and 50 per cent, of boiling MISCELLANEOUS PROCESSES. 179 water are added. All these ingredients are to be well mixed together, and finally 12"5 per cent, of spirit at 90° is to be added and well incorporated with the mass. The compound is then to be covered, and allowed to rest for a while, after which it is to be filtered, and is then ready for use. ]VErs. Marriott's Process. — For making " a washing or cleansing compound," the inventor mixes with common yellow or any fancy or toilet soap about an equal pro- portion of very finelj'^-powdered pumice, which is added to the soap in its melted state. The powdered pumice is to- be thoroughly incorporated with the soap, so as to be equally distributed throughout. This compound combines the detergent qualities of the eoap with the frictional action, of the pumice ; at the same time, when used for- washing or cleansing purposes, the soap lubricates the particles of the powdered pumice and modifies its abrasive action, thus preventing injury to the finest fabrics. Sawdust in Soap. — Mr. Waller forms a washing or cleansing compound by adding to melted soap certain, quantities of sawdust, and well mixing the whole together- by stirring or crutching. The sawdust may, if preferred, be introduced during the process of manufacture in the- same way that other ingredients are added to soap. Lewis's Process. — Mr. Lewis mixes potato flour, dex- trine, or other suitable farinaceous substances with a viscous solution of soluble glass or solution of silicate of soda or silicate of potash, in the proportion of about one part flour to ten or twelve parts of the silicate. The soap is manufactured from oleic acid in the usual way, with the addition of a small quantity of resin, say about one part of resin to about ten parts of soap. When the process is finished, and while the soap remains hot and in a fit condition for running into the cooling frames, the above compound of the silicate and farinaceous substance is added in the proportion of about one part by weight to three parts of the soap, more or less. These materials are thoroughlj'- incorporated or- mixed by crutching and stir- ring, and then the whole is transferred to the frames as usual. i8o THE ART OF SOAP-MAKING. Por household or laundry purposes he uses by pre- ference a soap made of oleic acid mixed with common tallow or animal grease and resin ; if necessary, he adds a certain proportion of French chalk to give firmness to the soap. The solution of silicate of soda should have a specific gravity of about 170° by Twaddell's hydro- meter. Borax Soap. — Mr. Rowbottom produces "borax dry soap, or soap powder " by adding borax to the usual carbonated or silicated ash or alkali, or other substance used in the manufacture of dry or powder soaps*. For borax soft soaps he adds a solution of borax to the ingredients usually employed for making ordinary soft soaps before or during the manufacture, or he dissolves by heat any ordinary soft soap in the borax solution, and incorporates the same, after which the mass is allowed to cool in the usual manner. Camphor and Ammonia Soaps. — Messrs. Cooper and Smith introduce these substances into ordinary hard or soft soap, the former being previously melted. The camphor is first dissolved in camphine or rectified oil of turpentine, or in alcohol. The solution of camphor is added to the hard or soft soap in any desired quantity according to the use to which it is to be applied. The carbonate of ammonia is first reduced to a fine powder, and this is well incor- porated with the soap by stirring. The carbonate of ammonia is added in the proportion of from one to five parts by weight to every 100 parts of soap. The addition of camphor to the soap is said to give it valuable disin- fecting properties, whle carbonate of ammonia increases the detergent power of the soap. The camphor may be used without the carbonate of ammonia, and the latter without the former, or they may both be added to the same soap. In addition to the camphor solution and carbonate of ammonia, the patentees prefer to add of borax about 10 per cent, to the soap, and also glycerine to the extent of 5 per cent. In adding borax it is dissolved in as small a quantity of water as is practicable, and the solution is MISCELLANEOUS PROCESSES. i8l added to melted hard soap. In treating soft soap the camphor and ammonia may be added either singly or conjointly, and with or without borax and glycerine. The borax may either be added in solution or in fine powder. In making soft soap for ships' use 2 per cent, of tar is added to soft soap in addition to the other ingredients, the tar being first dissolved in pyroxylic spirit. Mackay and Seller's Process. — The patentees' process consists in mixing with soap, during its manufacture, chlorate of potash " or any other substance which, in pro- cess of solution in water, will give off oxygen." The chlorate of potash is sifted into or mixed with the soap " on the point of its setting, or just before it is allowed to cool, in such manner that the oxidizing agent is not then dissolved in such soap base, but preserved therein more or less in contact with the soaps treated. The object of introducing the chlorate, or other oxidizing agent, is to facilitate the removal of dirt during the process of washing. Proportions : about 7 lbs. of chlorate to 113 lbs. of soap. Petroleum Soap: Bastet's Process. — Caustic ley at 36° B. is placed in a suitable vessel, and then equal parts of animal fatty matter and mineral oil are placed in separate vessels. The combined weight of the fatty matter and the mineral oil being taken as a standard, boracic acid sufficient to dissolve the alkali is used ; the mineral oil is heated to a temperature of about 90° F., and the animal fatty matter is melted by steam heat, and while in this condition a quantity of boracic acid is dissolved therein, which, with that acid used as before, will make up one-half per cent, of the combined weight of the fatty matter and mineral oil employed. The partially acidified animal fatty matter and the mineral oil being heated in separate vessels, are now united by gradually pouring the former into the latter, with constant stirring or agitation, in order to effect a perfect combination ; the acidified alkali is then gradually added, and the mass kept well stirred. i82 THE ART OF SOAP-MAKING. The process of converting the mineral oil into a solid is completed by gradually adding the ordinary or un- acidified alkali in sufficient quantities to effect this result, keeping up the agitation as before. When the entire mass is found to be granulated, the conversion into a saponaceous compound is complete. While animal fatty matter only has been mentioned, the same results can be reached by the use of vegetable fatty matter, or a mixture of animal and vegetable fatty matters. The soap is finished by the free use of steam. Liquefaction is accom- plished by a jet of steam to thoroughly deoxidise the saponified matter and disintegrate the compound. After the use of steam for this purpose, the soap is boiled by superheated steam. Besson and Bemy's Process. — This consists in forming a soap paste of any ordinary ingredients, and perfuming as desired. The soap is afterwards pulverised, as in mak- ing shaving powder, and the powder thus obtained is agglomerated by pressure in small moulds of special form, that is to say, of a form corresponding to that requiredin the pieces. This form is in section plano-concave, so that the middle portion is comparatively thin, and can be crushed by the finger with a very slight pressure applied to the flat side. The crushed piece, as it consists of agglomerated powder, at once becomes disintegrated, and forms a good lather in water, an effect which cannot be obtained from an equal-sized piece of ordinary toilet soap without much friction. Tardani's Frocess. — ^Any convenient quantity of oil or suet or other fatty matter is taken, and placed in a flat- bottomed boiler of iron, constructed in the form of a trun- cated cone, together with double the quantity of water and a proportion of quicklime previously slaked by a quantity of water equal to 12 per cent, of the weight of the oil or fat. The whole must be boiled and mixed by means of an agitator — a mechanical one by preference. This will produce an insoluble hard lime soap and a solution of glycerine, the latter of which may be separated by opening the top of the perforated pipe connected with MISCELLANEOUS PROCESSES. 183 the bottom of the boiler. After having washed the lime soap a little and closed the top, a certain quantity of water is added to the soap, and also a quantity of com- mercial carbonate of soda equivalent to and rather in excess of the quantity of lime used. When the ingredients are well mixed and the mixture boiled, the hard insoluble lime soap will be decomposed^ and the lime precipitated in the form of a granular car- bonate, while a soluble soda soap or potash soap (where potash is used to form a soft soap) is produced, which floats in the shape of flakes on the top of the water, more especially if sea-salt has been added. This is the reason why the shape of the truncated cone is preferred for the boiler and its bottom flat. The heat is applied only round the boiler. In this way it is said to be possible to make good soap, using fatty matter with membranes and very impure oils without incurring the expense of extracting the pure fat or oil. If cocoa-nut oil or palm-oil are to be saponified, a quantity of lime equivalent to the fifth of their weight can be used. These soaps being very soluble, even in salt water, it is necessary to use tolerably pure car- bonates of the alkali. Half-resin Soap, by Higgins's process, is produced as follows : — For a cheap laundry soap is taken prime tallow or equivalent fat, 10,000 lbs., which is saponified as usual with caustic soda of, say, 30° strength. After the first or "grease" charge an equal quantity, viz. 10,000 lbs., of clear resin is added and saponified in the usual manner. About 6,000 lbs. of caustic soda at a strength of 30° is used for the whole. Upon the completion of the saponify- ing process, and while the compound is in a hot fluid state before framing, a quantity of crystallised stearic acid of commerce, equal in amount to about 2 per cent, of the whole mass, is added, or abou.t 3 per cent, of stearine, the substance in either case being in a melted state. This is added gradually while the soap is hot and is thoroughly "crutched" into the body, which is then "framed" in the usual manner. The mass solidifies into a hard and useful soap, having in its composition equal portions of 1 84 THE ART OF SOAP-MAKING. resinous and fatty matter, instead of only one-third or one-fourth, as usual. This soap is said to preserve its quality and hardness better than ordinary resin soaps, does not become unduly dry and brittle, and also possesses the advantage that while in most laundry soaps a large portion is wasted because of their extreme solubility, which causes them to dissolve to a greater extent than is required for the strictly detersive purposes, the soap produced by the above process is said to last longer, besides being also cheaper. Mr. G. Payne's Process consists in treating fatty or oily matters and subjecting the same, under pressure, in an autoclave with lime and water. After the decomposition of the fatty or oily matter in the autoclave, the aqueous solution of glycerine is with- drawn, and instead of decomposing the lime soap with acids, as in the ordinary process of making stearine, the inventor employs for its decomposition strong caustic soda or potash leys, or a solution of carbonate of soda or potash. The hydrated or carbonate solution is used in about the proportion of 7 per cent, of the alkaline base to from 60 or 70 per cent, of the fatty acid, these proportions being varied within certain limits ; in all cases care must be taken that the alkali shall be sufficient to coinbine with or saturate the whole of the fatty acid. The decomposition of the lime soap by means of the hydrate or carbonate of soda will result in the production of a soda soap, and where the hydrate or carbonate of potash is used for such decom- position the product will be potash soap, the lime in either case being precipitated in a more or less insoluble condi- tion. The soaps obtained by this process may be finished in a soap-copper in the ordinary manner. TBx. Baukmann's Process has for its object to furnish soap in the form of thin perforated sheets or tablets, so that a single piece may be torn off for each washing of the hands or face. A number of frames are placed one above another, and are securely fastened together in such a manner that the joints are water-tight. The soap to be treated is put MISCELLANEOUS PROCESSES. 185 into these frames, and tlie sides or sections are capable of being removed so as to leave the soap projecting. Thin shavings are planed from the block of soap by a cutter passing along the surface, and the shavings or sheets are then subjected to the action of a roller which compresses and smooths them. Then a perforator divides each shaving or sheet into correspondingly small pieces. Each sheet should be about 3 inches long by 2 inches broad, and -per- forated crosswise so as to form four tablets. The sheets have then about the thickness and portability of postage- stamps. About one dozen of such sheets may be arranged in a packet in form of a pocket-book. The packet wiU then contain the material for forty-eight separate wash- ings. If desired, the soap may be impregnated with car- bolic acid, tar, or other medicinal material. Mr. W. Jeyes's Process. — The inventor introduces anthracine salt, naphthaline, or any similar crystallisable hydrocarbon into the ordinary ingredients of soap. Either of the above salts is added to and mixed with the ordinary ingredients of soap at any convenient period during the manufacture before solidification, and in various propor- tions, according to the use to which it may be intended to apply the soap. m. Varicas's Process. — " The practice now," says the inventor, " is to saponify fats with alkalies without any previous treatment of the fat, looking to the preliminary decomposition of the same. The result is a comparatively slow saponification, and all the glycerine which does not remain in the soap mechanically suspended, is carried off in the waste ley and lost. The object of this invention is to prepare fats for instant saponification, and to save all the glycerine. To effect this, the inventor first extracts the ' glycerine from fats in their neutral state by the direct action of steam and water, under a pressure of about 150 lbs., whereby a soap stock is produced susceptible of immediate saponification when combined with an alkaline ley. Besides the important advantage of saving all the glycerine, the whole process of soap-making is said to be materially hastened, and the resulting soaps are of superior 1 86 THE ART OF SOAP-MAKING. quality, all things being equal, than soaps made by ordi- nary methods. torbnry's Process consists in adding a solution of gluten in caustic alkali to soap, by which the emoUiency of the soap is said to be considerably increased. The gluten may be added to any kind of soap after the process of saponifi- cation is complete. The solution of gluten is thus ob- tained : — To a solution of caustic potassa of about 20° B. as much bran or gluten obtained from any other source is added as it will take up. After some hours' digestion the mass becomes clear and homogeneous, when it is strained through a fine sieve or coarse cloth. This solution is added to the soap to the extent of 10 per cent, more or less. Cleaver's Terebeue Soap. — Mr. Cleaver combines with soap while in a melted state the substance known as terebene, whereby a disinfectant and antiseptic soap is pro- duced. This substance is also combined with toilet creams, cosmetics, &c. The following proportions, which may, however, be varied at will, are said to give good results : — For toilet soap 4^ pints of terebene are added to 112 lbs. of soap. For household or laundry -soap, he adds 6 pints of terebene to 112 lbs. of soap. The terebene is introduced into the soap in its liquid state, and thoroughly incor- porated by stirring. The soap may be perfumed if de- sirable. The soap is known as terebene soap. Scharr's I^iqnid Soap. — For making this soap the fol- lowing complicated formula is given for one ton of the compound: — Twelve cwt. of water and 4 lbs. of starch are first boiled together for a few minutes, after which the following ingredients are introduced : — Lingeed 53 lbs. Sal amiaomac 8 „ Soda ash (52° to 54°) 44 „ Pearl asli (American) 56 „ Eussian potash. 73 ^^ Resin 52 „ Oleine 26 „ Borax 4 Spirit of turpentine 5 Liquid anunonia 10 MISCELLANEOUS PROCESSES. 187 The ingredients are placed in a vat or other suitahle vessel, and boiled by injection of stdam for two hours. The liquid, after being boiled, is passed through a sieve, to separate the solid portion ; it is then cooled down to between 90° and 122° F. The solid or third portion is put into a cask (which is provided with a tap near the bottom) and upon it is poured about 40 to 44 gallons of boiling water, which is thoroughly incorporated by stirring. It is then allowed to rest until it becomes clear, when the clear portion is run out by the tap into a suitable receiver, and brought to the boiling-point by the injection of steam. The steam is now turned off, and 152 lbs. of soft soap and 20 lbs of American pearlash are added, with stirring. The soap which had previously cooled down is now introduced and well mixed by stirring, when the compound is ready for use. Mr. Bichford introduces powdered French chalk (stea- tite, or soapstone) into soap, employing froni 4 to about 7 per cent., according to the purpose for which the soap is to be used. For a nursery soap, 4 per cent, is recom- mended, and for toilet soaps 5 per cent, of the powder. As far back as 1838 Mr. Sheridan — the original in- ventor of silicated soaps — patented a process for combining potato flour, water, and soda or potash leys (preferring the latter alkali) in the following proportions : — ^potato flour, 16 lbs. ; water, 270 lbs. ; potash leys, 100 lbs. It ■wUl be seen, as is too frequently the case with " improve- ments " in soap, that the same idea has been often patented since. Marking Soaps. — Mr. Dunn suggested marking soaps, coloured soap, or other similar material in this way : — The soap is first stamped in the usual manner, and when dry the impression is filled in with plastic soap of a different colour by means of a spatula ; or if the impression is fine and small, with dry powdered and coloured soap, by means of a spatula, with which a little of the powder is spread over the impressed surface. CHAPTEE XXIII. ALKALIMETRY. METHODS OF DETERMINING TSE PERCENTAGE OF REAL ALKALI IN COMMERCIAL SODA ASH, POTASH, AND CAUSTIC ALKALI Mohr's Alkalimeter. — Preparation of the Test-Acid. — Sampling Alkalies. — The Assay. — Normandy's Method. — Testing Commercial Pear- lashes. — To determine the Percentage of real or anhydrous Alkali. It must be obvious that in a manufacture which consumes vast quantities of materials of variable quality, some means of estimating the actual value should be at the command of the consumer. The science of chemistry, which, as we have shown, rescued the art of soap-making from the empiricism imd ignorance which ruled its operations until little more than forty years since, has shown not only the principles of saponification, but also the means by which the precise value of the various ingredients employed in the art may be determined with absolute certainty, and with com- parative ease and simplicity. It was the custom formerly for the soap-boiler to estimate the strength of his alkali by first pouring a quart of water on a pound of the ash, and then putting into the solution a lump of Dutch soap, which floated in it ; he then added more water gradually until the piece of soap sank, and the more water that was required to efiect this object, the richer in alkali was the ash supposed to be. It is needless to say that a test of this kind would be all but worthless. The first adoption of a system for estimating the relative value of alkalies by chemical agency was made by the celebrated Trench chemist Vauquelin ; this was followed by Descroizelles' important invention of the alkalimeter, by the aid of which tolerably accurate results could be obtained. ALKALIMETRY. 189 To our own countryman. Dr. Andrew TJre, however, we are indebted for the employment of a test-acid that repre- sents the absolute amount of alkali in a given cqmniercial sample of soda or potash, whether in the form of carbonate or of caustic alkali. To understand the methods of deter- mining the percentage of real alkali in a commercial sample it may be necessary to refer briefly to the laws of chemical combination defined by the atomic theory of Dr. Dalton. This great chemist discovered that all sub- stances combine in definite proportions or equivalents ; for example, 1 part by weight of hydrogen combines with 8 parts of oxygen to form water. The eqidvalent number of hydrogen, therefore, is 1, that of oxygen 8, and that of water 9. Again, 3 equivalents of oxygen combine with 1 equivalent of sulphur (16) to form sulphuric acid, thus : sulphur 16, oxygen 24, equals anhydrous sulphuric acid 40, or m.onohydrated acid (the strongest oil of vitriol) 49 ; there- fore, 40 is the equivalent or combining number of this acid, and it cannot be made to unite with alkalis or other bases in any other proportion. For example, forty grains by weight of pure sulphuric acid will neutralise exactly 63 grains of dried carbonate of soda, 31 grains of pure anhydrous soda, or 40 grains of hydrate of soda (caustic soda). This being so, it is only necessary to have exactly 40 grains of real sulphuric acid in 1,000 grains of water to form a test-acid, which, when employed to neutralise an alkaline solution, will show, by the proportion of dilute acid used to saturate the alkali, the absolute percentage present in the sample. There are two principal methods of analyzing or assaying alkalies by means of the test-acid, the first of which is mlumetric, or by measure; and the second gravimetric, or by weight. In the former, the test-acid or "standard solution" is applied by means of a glass vessel termed an alkalimeter, or burette, which holds, up to its or zero mark, exactly 1,000 grains. The scale is graduated into 100 divisions, which are again subdivided into tenths. There are several forms of the burette or alkalimeter, all more or less admirable for their ingenious igo THE ART OF SOAP-MAKING. construction, but for the ordinary purposes of alkali testing Sink's burette. Fig. 33, or Mohr's burette. Fig. 34, will be well suited to the soap-maker's laboratory. The simplicity of the former at once commends it, but the latter has the advantage of enabling the operator to add the test-liquor drop by drop, when the alkaline solution is near the point of saturation, without encumbering the hands. '"^ is7 Kg. 33. SEohr's AUEalimeter. — Mohr thus describes the con- struction and use of his very useful and ingenious apparatus.* " I have succeeded in substituting for ex- pensive glass stop-cocks, an arrangement which may be constructed by any person with ease, which remains absolutely air and water tight for an indefinite period, which may be opened and regulated at will by the * The Chemist, toI. i., New Series, p. 158. ALKALIMETR Y. 1 9 1 pressure of the fingers, and whicli costs almost nothing. It consists of a small piece of vulcanised india-rubber tube, which is closed by a clamp of brass wire (Fig. 34). The ends of this clamp, which I call a pressure-cock, are bent laterally at right angles in opposite directions, and furnished with knobs, so that when both ends are pressed the clamp is opened, and a single drop or a continuous current of liquid may be allowed to escape at pleasure. The measuring tube is a straight glass cylinder b, as uniform as possible, graduated into 0"2 or O'l cubic centi- metres, and somewhat contracted at its lower end, so as to fit into the india-rubber tube. A small piece of glass tube, inserted below the pressure-cock, forms the spout. The pressure-cock has the advantage of not leaking, for it closes of itself when the pressure of the fingers is removed. "The measure furnished with the pressure-cock is fastened upon an appropriate stand, which can be placed at any required height. When used, it is filled above the zero point with test-liquor, the cock opened for an instant, so as to let the air escape froin the spout, and the level of the solution is then adjusted. This is done by bringing the eye level with the zero point, and applying a gentle pressure to the cock until the liquid has sunk so low that the inferior curve of the liquid touches the graduation like the circle of a tangent ; the cock is then closed, and at the same moment the liquid remains at zero, and continues to do so for weeks, if evaporation is prevented. The test measure being now normally filled, the experiment may be commenced ; this is done sitting, while the filling of the measure is done standing. " The weighed sample of alkali is first placed in a ' beaker ' glass, and the test-liquor is allowed to flow into it by gently pressing the cock. Both hands are set at liberty, for when the pressure-cock is released it closes of itself. The volumetric operation may be interrupted at pleasure, in order to heat the liquid, shake it, or do what- ever else may be required. The ^ quantity of liquid used may be read ofi' at any moment, and in repeating an ex- J92 THE ART OF SOAP- MAKING. periment the limit of the quantity used before may be aproached so near that the further addition of liquid may be made drop by drop." When alkalies are analyzed gravimetrically a specific gravity-bottle (Fig. 35) capable of holding exactly 1,000 grains of distilled water is emplo5'ed, and this, when filled with teat-liquor, weighs (exclusive of the tare of the bottle) exactly i'033 grains. 1,000 grains of the test- liquor contains exactly 40 grains of real sulphuric acid. The test-acid to be used volumetricalli/, that is, with the alka- limeter, has a specific gravity of 1*032 at 60° F., Fig. 33. and 1,000 grains hy measure contain exactly 40 grains of real or anhydrous sulphuric acid. Preparation of the Test-acid or Standard Solntiou. — When making the test-liquor it is advisable to prepare a quantity sufficient for many operations, since there is necessarily a certain amount of trouble involved in its pre- paration. It may be readily made by mixing 1 part of concentrated sulphuric acid with 11 or 12 parts of distilled mater, the mixture being effected in a " Winchester " bottle, which holds rather over half a gallon. The acid solution must be adjusted or brought to the proper strength after it has cooled down to 60° F., and it should h^ faintly tinged with litmus, which will give it a pinkish hue. If the acid is of the proper strength it should exactly saturate 53 grains of pure carbonate of soda previously calcined at a red heat, or 31 grains of pure anhydrous soda. To prepare the anhydrous carbonate of soda, place a few crystals of carbonate of soda in a Berlin porcelain crucible, and heat this over a spirit-lamp or Bunsen buirner ; when all the water of crystallisation is expelled continue the calcination until the mass is at a bright red heat, when the vessel may be set aside to cool. Ifow carefully weigh out 53 grains of the calcined carbonate, and dissolve in about 2 ounces of distilled water in a beaker-glass. The alkalimeter is now to be charged with the test-acid to the level of zero, and (if Mohr's burette be used) the beaker containing the alkaline solution is to be placed upon the ALKALIMETRY. 193 stand immediately beneath the exit-tube. Now press the nobs of the pressure-cock, and allow a portion of the liquor to flow into the beaker. When the effervescence which is immediately set up subsides, make further additions of the test-liquor from time to time, until the effervescence becomes sluggish, when the acid must be added with greater caution. When the solution approaches saturation it acquires a purplish tint (due to the litmus with which the acid is tinged), which it retains until the point of saturation is reached, when it suddenly changes to pink or onion-red colour. After each addition of the acid the solution should be stirred with a thin glass rod, and before the final change from purple to piak or onion-red, the end of the glass rod should be applied to a strip of blue litmus-paper, when, if the spot touched assumes a- red colour, the saturation is complete ; if, on the contrary, the paper is unchanged, or has a violet or reddish hue, add the test-liquor, one or two drops at a time, with continued stirring, until a drop of the solution applied with the rod reddens the litmus-paper, when the saturation is finished. If any test-liquor remain in the burette this indicates that there is an excess of acid in the test-liquor ; consequently more distilled water must be added to the bulk, the burette emptied and refilled with the reduced liquor, and another 53 grains of anhydrous carbonate treated as before, xmtil 1,000 grains of the acid liquor exactly neutralise the solu- tion. Should the whole contents of the burette in the first trial be used before saturation is complete, a little more sulphuric acid must be put into the Winchester or test-acid bottle, and a 53-grain solution of carbonate of soda treated as before. A very little practice will enable the operator to adjust his test-liquor with perfect accuracy; and, in order to prevent mistakes, the bottle should be labled "Testracid," and should be kept closed with its glass stopper. Sampling Alkalies. — The ordinary soda ash of com- merce is usually packed in wooSen casks ; and in order to secure a fair average sample from a large number of these casks, which may represent one consignment, it is important 194 THE ART OF SOAP-MAKING. to take small samples, as near the centre of eacli cask as' possible, from as many of the casks as time will permit. Each sample, as drawn from the cask, should be at once placed in a wide-mouthed bottle furnished with a well- fitting cork. Each sample should be numbered and marked with the brand which cGstinguishes each cask. The soap- maker who tests or assays his own alkali should always be careful to employ a person of known intelligence and integrity to procure samples for him. "When about to analyze any given sample, first empty the contents of the bottle upon a piece of dry paper, then crush the larger lumps, and reduce the whole to a coarse powder as quickly as possible, so as to prevent absorption of moisture from the atmosphere. Now carefully weigh out 100 grains, and put them into a small flask (Fig. 36), and at once return the remainder to the bottle, and securely cork it. Pour into the flask about half an ounce of distilled water, and gently heat it, shaking occasionally to assist solution of the alkali. After a few minutes set the flask aside to enable the insoluble matter to subside, then pour the clear %Mor'into a beaker-glass, FiK 36. ^^^ wash the sediment several times with small quantities of distilled water, being care- ful to add the washings to the alkaline solution in the beaker. This washing must be performed several times, or until the last washing-liquor produces no effect upon yellow turmeric-paper. So long as the washings give a brown tint to this test-paper the presence of alkali is assured, and the washing must be continued. It is im- portant, after each washing, to pour off the last drop of the liquor, by which the process is rendered more com- plete and with less water than when this precaution is not observed. To ensure perfect accuracy every particle of the washings must be added to the contents of the beaker-glass in which the assay is to be made. The Assay.— To perfoum- the assay, the alkalimeter must first be filled with the test-acid exactly to the line or zero of the scale ; the acid must then be allowed to' ALKALIMETRY. igS flow gradually into the alkaline solution ( which should be constantly stirred with a glass rod) until the liquid assumes a purple tint, which it retains until the exact point of saturation is reached, when it suddenly changes to pink. It is commonly the practice to warm the alkaline solution so as to expel the carbonic acid which is GTolved and absorbed by the solution during the process of saturation. "When the neutralisation is complete, the alkalimeter is allowed to repose for a few moments, so that the acid liquor may drain from the interior of the glass into the bulk of the fluid, and the quantity of test- acid used is then determined by reading off the number of divisions which have been exhausted. Every alkalimeter division of Mohr's burette (Fig. 34) represents x^th part, or 1 per cent., of alkali, when 100 grains are taken for assay. " In commercial assays, when 100 grains (or some aliquot part thereof) are taken for trial, the percentage result is obtained from the number of alkalimeter divisions, or the number of grains of the test-acid consumed by the common ' Rule of Proportion.' Thus : A critdq sample of potash, having taken 90 alkalimeter divisions of test- acid to neutralise it, would contain — 100 : 47 ".(^oo :. 42-30 or nearly 42^ per cent, of pur6 potassa. If only 50, 25, or 20 grains are tested, the tesult must, of course, be double, quadrupled, &o., as the case may be. Or the third term of the proportion may be multiplied by the denomi- nator of ih.e fraction representing the aliquot part. This, in the case of 50 grains (repeating the above example), would be — 100 :' 47:: 45X2 ; 42'3og as before ; but even these easy calculations may be simplified, as is shown below. " One of the advantages, and not the least, attending the use of test-acids corresponding to equivalents is that, by means of the simple 'Rule "of Three,' the percentage 196 THE ART O-F SOAP-MAKING. quantUy of alkali may be found, whether 100 or any other number of groins have been submitted to trial. For the Tc&jgM of the sample tested (in grains) bears the same re- lation to the equivalent meiffkt of the alkali under examina- tion, that the 7mmJ>eT of alkalimeter divisions or of the grains of test-acid consumed do to the percentage of alkali sought. Thus, with a sample of 33 grains of pearlash, taHng 35 alkalimeter divisions or 360 grains (every 10 grains being = 1§) of test-acid for neutralisation. This would be — 33 : 47 : : 35 : 49-85g or nearly 50 per cent, of pure potassa. By substituting the equivalent of the dry carbonate of potassa (69) for that of 'pure potassa' used above, the quEintity of that article corresponding to the same weight of the pure alkali may be at once found. Repeating the last example this will be — 33 : 69 : : 35 : 73-iss or nearly 73j per cent. The same applies to all the alkaline bases and their carbonates." — A. J. Cooley. The following table shows the equivaUnt or combining proportions of alkalies with 40 grains of real (that is, anhydrous) sulphuric acid : — grs 40 giaiiis of anhydrous sul- phuric acid 1,000 grains of dilute sul- phuric acid (sp. gr. 1-033) 1,000 grains (water-grain measure) sp. gr. 1-032 47 Potassa (anhydrous) ■g 66 Hydrate of potassa (pure caustic pS potash) ^ $. 69 Carbonate of potassa (anhydrous) ■3^ 31 Soda (anhydrous) s 40 Hydrate of soda (pure caustic soda) S 53 Carbonate of soda (anhydrous) •^ 143 Crystallised carbonate of soda. Normandjr's Metliod.— Dr. l^ormandy gives the fol- lowing method of assaying commercial soda and potash* : — * " Commercial Handbook of Chemical Analysis." By A. Normanby. Lockwood and Co. ALKALIMETRY. 197 " Commercial Soda. — Five hundred grains are weighed out from the thoroughly powdered and mixed sample. After being dried it should be gently ignited in a porce- lain or platinum crucible, and allowed to cool without exposure to the air. "When cool it is again weighed ; the loss indicates the amount of moisture. It is then washed into a beaker, in which it is dissolved. Should any in- soluble residue remain it is filtered off, dried, and weighed; the clear filtrate is made up [with distilled water] to exactly 10,000 grain measures. The solution is well mixed together, and from it 1,000 grain measures are taken, transferred to a beaker, the solution made blue by a few drops of litmus water, heated nearly to boiling, and then tested with the normal acid [or standard test-acid] until the neutral point is reached ; the process may be repeated several times, if necessary, to be certain of the accuracy of the analysis. In order, however, to avoid aU ambiguity arising from the carbonic acid, a sufficient quantity of acid may be added to render the acid very decidedly red, and then the normal caustic alkali* added drop by drop until the liquid changes suddenly to violet-blue. The number of divisions of the burette that have been required to effect this must be deducted from the quantity of acid originally used. By this backward or residual method very sharp results may be obtained. " Example. — Suppose 850 burette divisions of the nor- mal acid have been required, the following calculation gives the amount of real carbonated alkali in the sample : — 1-000 : 850 :; 53 : x X = 45, the amount of carbonate of sodium in 53 grains of the sample. " The soda ash of commerce contains generally, besides * Tho normal caustic alkali solution is prepared by dissolving exactly ■66 grains of hydrate of potassa (pure caustic potash), or 40 grains of hydrate of soda (pure caustic soda), in 1,000 water-grain measures of dis- tilled water. The solution is applied from a buiotte. igS THE ART OF SOAP-MAKING. insoluble substances, which are removed by filtering, a greater or less quantity of chloride of sodium (common salt), and of sulphate of sodium (which, however, do not interfere with the accuracy of the result) ; but when sulphurets, sulphites, or hyposulphites are present, these substances, neutralising a certain quantity of the test- acid, would render the estimation seriously inaccurate ; wherefore it is absolutely necessary in such cases to trans- form these substances into sulphates by calcining a given quantity of the sample with 5 or 6 per cent, of chlorate of potassium, as recommended by Gay - Lussac, and Welter." The chlorate of potash is first pulverised, and then 5 or 6 grains are intimately mixed with each 100 grains of the sample, and the mixture is fusfed in a platinum crucible. When cold, the fused mass is dissolved in boiling water, filtered and washed, and the assay then conducted in the same way as before described. If, however, the soda ash contains any hyposulphites this method must not be adopted, since each equivalent of hyposulphite would be converted into two equivalents of sulphate, at the expense of the alkali or its carbonate present in the sample, and which would render the assay seriously inaccurate. MM. Fresenius and Will, in order to overcome this source of inaccuracy, recommend the addition of a small quantity of yellow chromate of potash to the alkaline solution, by which the sulphurets, sulphites, and hypo- sulphites are converted into sulphates-, sulphur, and water. Fresenius says : " It is always advisable to make it a rule, in the examination of soda, to add some chromate of Testing Commercial Fearlashes is performed in the same way as samples of soda, but it is usual to employ a separate test-acid for this purpose. The test-acid for potash should have a specific gravity of I'OTO to 1'071 ;■ 470 grains contain 40 grains of real sul- phuric acid. Of this solution 1,000 grain measures (or 100 burette divisions) exactly neutralise 113 grains of pure anhydrous carbonate of soda, or exactly 100 grains ALKALIMETRY. 199 of pure potassa. The number of measures consumed read off, by mere inspection, from tbe burette scale, gives the exact percentage of the sample of potash under examina- tion. - Or, if Normandy's method be adopted, "as the equivalent of carbonate of potassium is 69, the weight of the sample to be operated upon to make in solution 10,000 grain measures will be 690. It may sometimes be con- venient to employ a normal sulphuric acid, 1,000 grain measures of which shall be equivalent to precisely 100 grains of the anhydrous caustic alkali. For this purpose it is obvious that different standard acids will be required for soda and for potassa. That for soda must be of such a strength that 1,000 grain measures shall saturate exactly 171 grains of pure carbonate of sodium, and that for potassa must be precisely equivalent to 146"8 grains of pure carbonate of potassium. The advantage of the standard above described is its equivalency both to potassa and soda." There are many other methods of determining the per- centage of real alkali in the commercial products than those referred to, but to enter into this subject more fully would involve more space than the limits of this work would permit. Since, moreover, soap-makers are now supplied with caustic soda, as also caustic potash, the necessity for testing soda and potashes is greatly diminished. To determine the percentage of real or anhydrous alkali in a sample of caustic soda or potash, M. Barres- will recommends the following method : " A solution of chloride of barium is added in excess to a solution of the sample under examination, and the whole is filtered ; the precipitate of carbonate of baryta left on the filter is washed with a little water, and the filtrate and the reash- ings placed in a deep glass tube ; a stream of carbonic acid gas is then passed through the mixed liquor until it ceases to occasion a precipitate of carbonate of baryta. This last precipitate is separated on a filter, washed, dried, and weighed. Each grain represents '315 grains of real or anhydrous soda ; or '477 grains of anhydrous potassa." 200 THE ART OF SOAP-MAKING. TJre says : " Add the first portions of the test-acid very gradually to the sample, carefully observing the effect. When the effervescence at length commences, the Toeight or measure of the test-liquor expended shows the quantity of pure caustic alkali under treatment (nearly). The result depends upon the fact that little or no carbonic acid gas is expelled from the liquid on the addition of the test-acid until the caustic portion is very nearly netdralised." CHAPTER XXIV. METHODS OF ANALYZING OR ASSAYING SOAPS. Soap Assay. — Eampel's Method. — D'Aroet's Method. — Eiohardson and Watt'a Method. It is of the .greatest importance to tlie soap-maker that he should be able to estimate the exact proportions of fatty matter, alkali, and water ia each boil of soap when finished and ready for sale, in order that he may determine the cost of manufacture and estimate his profit. A simple method of assaying a sample of soap is the following : — Soap Assay. — I. To estimate the percentage of mater, take a fair sample, say from a recently cut bar of soap,* and weigh 100 grains. Cut this into thin slices or shavings, and put them into a small porcelain capsule, which is then to be placed over a water-bath kept boiling, or over an oil-bath heated to 350° F., until the shavings are quite free from water, in which condition they are exceedingly brittle. The shavings should be weighed from time to time, or until they cease to lose weight by continued heating. The ultimate loss in weight indicates the percentage of free or uncombined water, which, in the case of curd and mottled soap, should not exceed 35 per cent.f The loss in yellow or resin soap would be about 45 per cent., and in Castile or olive-oil soap about 14 or 16 per cent. II. To estimate the fat acids, dissolve 100 grains of the soap to be examined in 4 or 5 ounces of boiling distilled water in a porcelain capsule, then add a little muriatic * If the soap has dried on the surface, the sample should be taken from the interior of the har. t Ure gives the follo'wing analysis of London curd soap : — Fat, 62 ; soda, 6 ; water, 42 = 100. 202 THE ART OF SOAP-MAKING. acid, and stir gently. The acid, combining with the soda, will set free the fat acids, which wiU float on the surface. Now set the vessel aside to cool, and, when quite cold, make a hole in the cake of fatty matter, and allow the liquid to escape into another vessel. To hasten the solidi- fication of the fat acids, add 100 grains of white wax and a little water, and then apply heat until the whole is well melted ; again set aside to cool,- and proceed as before, washing the cake several times until no trace of acid remains in the last water when tested by litmus paper. Finally, run off all the water, remove the cake carefully, and place it upon a piece of white blotting-paper and thoroughly dry it, taking care not to allow any particles of the combined fatty matter and wax to remain in the capsule. After carefully weighing, and deducting the 100 grains of wax, the result will show the proportion of fat acids in the sample of soap under examination. If, when the soap is first dissolved in boiling water, oily matter floats on the surface, it indicates that saponification has not been complete. III. To ascertain the percentage of alkali. This may be effected roughly by simply volatilising all the fatty matter by heat, and then weighing the residuum. Having weighed out 100 grains of the soap, place them in a porce- lain crucible and apply heat either over a clear fire or a Bunsen burner until all the fatty matter has burnt off, when the residuum, which is carbonated alkali, will show, on weighing, the percentage of alkali in the sample. If the soap, however, has been adulterated with earthy matters, as silicate of soda or china clay for example, the proportion of real alkali must be determined by the alka- limetric test before described. 100 grains of the soap being dissolved in about 2,000 grains of boiling water, the solution is then neutralised with test-acid, and the quantity of this acid used will give the exact percentage of alkali present in the soap. " If the soap contain clay, chalk, silica, dextrine, fecula, pumice-stone, ochre, plaster, salt, gelatine, &c., dissolve 100 grains of the suspected soap in alcohol ; with the aid METHODS OF ANALYZING OR ASSAYING SOAPS. 203 of gentle heat the alcohol will dissolve the soap and leave all these impurities in an insoluble state. Good mottled soap should not leave more than 1 per cent, of insoluble matter, and white or yellow soap less still. All soap to which earthy or silicious matter has been added is opaque instead of being transparent on the edges, as is the case with all genuine fitted soap. The drier the soap the more transparent it is." — Normandy. There is no better test for insoluble impurities than dissolving a given weight — say 100 grains — of soap in alcohol.* After the insoluble matters have subsided, the clear solution should be poured oflF, and the residual matter washed several times with alcohol, after which it should be carefully dried and weighed. To determine the nature of the fatty matters which have been used in the manufacture of soap is a difficult and sometimes a very laborious task. An approximate result may be obtained, however, by first saturating an aqueous solution of the soap with a solution of tartaric acid ; the fatty acids which float on the surface may, when cold, be transferred .to a porcelain capsule, and heated gently over a water-bath. By applying a thermometer, the fusing point will give some idea of the nature of the fatty material, as to whether the soap was made from tallow or oils, or a combination of both. Again, if the fatty acids have been separated by dilute sulphuric or hydrochloric acid, if a little bo rubbed in the palm of the hand the odour will frequently indicate the nature of the fatty material. Soft soaps ai-e assayed in the same way as hard soaps, but the manipulation is somewhat more troublesome, and therefore involves a little extra caution. Unsaponified Fatti/ Matter. — A properly-made soap is entirely soluble in water. If, therefore, after a sample of soap has been dissolved in hot water and allowed to rest for awhile a film of fatty matter appears on the surface (and which makes a greasy stain upon paper), that portion of the fat has not been saponified. * Good methylated Bpirit answers equally well, and is mxich cheaper than alcohol. 204 THE ART OF SOAP-MAKING. Since pure soap is entirely soluble in alcoliol, any in- soluble colouring matter which may have been introduced into the soap may readily be separated, and, if desirable, examined by ordinary chemical tests. Bampel's Uethod of Assaying Soaps.-^l. The analysis of soaps does not present any more difficulty, and may be done in as little time and with as much precision as that of alkalies. 2. There is no necessity for analyzing marbled soap, for it cannot be adulterated; an excess of water would precipitate the marbling, and the introduction of foreign substances would prevent its formation. 3. For the white or unicoloured soaps, i.e. manufactured according to the Marseilles method, the quantity of water is determined by the usual process. The soap in thia shavings is submitted to a temperature of 212° F. The soap is weighed before and after drying, the difference in weight giving the proportion of water. One drachm dissolved in 2 ounces of hot water indicates, by the limpidity of the solution, if the soap has been manufactured by liquefaction. If the solution is muddy, this effect is due to the presence of resin. Liquefied soaps do not require further analysis, for they can contain neither insoluble nor inert substances. 4. Unicoloured, white, or other liquefied soaps mixed with resin, manufactured by saponification and evapora- tion, always produce muddy solutions. 5. To ascertain the presence and quantity of insoluble substances con- tained in soap, the process is simple and easy. Introduce into a small test-tube a few grains of soap, and heat it with about ten times its weight of alcohol. The solution is soon completed if there is no insoluble impurity ; if, on the contrary, a deposit is left, it is to be well washed several times with alcohol, and weighed after drjdng. Its weight indicates the quantity of insoluble substances in the soap. When the proportion of water and insoluble matter has been ascertained, the operator has approximately determined the value of the soap. Indeed, if the soap has given 30 or 34 per cent, of water, and 1 or 2 per cent, of insoluble matter, it is certain that the soap contains 6 METHODS OF ANALYZING OR ASSAYING SOAPS. 205 per cent, of alkali, and 60 per cent, of fatty acids, which are the constant proportions of the marbled and pure white liquefied soaps. If, on the contrary, the proportion of water exceeds 35 per cent., or the insoluble matter 2 per cent., it is a certain proof that the soap has been adulterated. In either case it is useless to determine the proportions of fatty and inert substances that the soap contains. By burning a small quantity of soap and assaying the residuum in the same manner as by the alkalimetric process, the real quantity of alkali and inert substances is determined at the same time. The alkalimetric assay is not necessary; indeed, when soap is burned, the residuum obtained contains all the fixed principles of the Boap, but instead of having the soda in a caustic state, as in the soap, it exists in the form of a carbonate. 6. To ascertain the value of the soap as to the pro- portions of fatty acids and base it contains the following 18 recommended : — A given weight of soap in solution is decomposed by an acid ; the fatty acids float on the surface of the liquid, and it is easy to collect them and determine their weight. When they do not collect easily, they are mixed with a known weight of white wax (previously dried) which hastens their solidification. A cake is thus obtained .which, when cold and dried, is weighed, the weight of the wax used being deducted from the gross wei^fht of the cake. To obtain the proportion of afisali, . calcine a given weight of the soap in an iron iadle ; all the soda becomes transformed into carbonate, and the real quantity of the alkali is determined by the alkalimetric test. D'Arcet's Method. — If preferred, D'Arcet's system may be adopted, which consists in dissolving 3^ drachms of soap in 2 ounces of hot water ; from 1 to 2^ drachms of pure and dried white wax are then added, and the whole boiled until the wax is melted, when the mixture is decom- posed by the normal test-acid as in the ordinary alkali- metric process. After cooling, the weight of the fatty acids is determined by deducting the weight of wax -used. By 206 ^ THE ART OF SOAP-MAKING. submitting the fatty acids to pressure, the solid and liquid acids may be recognised by their consistency, odour, &c. When the soap under examination has been made from materials rich in stearine, the addition of white wax may not be necessary, since the fatty acids will set into a hard cake. When, on the other hand, the separated acids solidify slowly, and when cold form a soft cake, it indicates that liquid vegetable oils have been employed in the manufacture. To determine the quantity of resin in soap, Dussauce suggests the following : — One ounce of soap is decomposed by an excess of sulphuric acid. The fatty acids obtained after cooling are washed with slightly acidulated water. The cake of fatty acids is divided into small equal pieces and well dried. A certain quantity is dissolved in five or six times its weight of alcohol at 90°. When the solution is made, boiling water is added to it ; the proportion of water must be largej than that of the alcohol. An imme- diate separation takes place, and the fatty acids float on the surface of the liquor, which becomes limpid if the soap does not contain resin, and, on the other hand, becomes milky if resin is present. After the solidification of the fatty acids by cooUng, the cake is divided again into pieces, dried and weighed. The difference in weight from that of the acids before the treatment by alcohol gives the proportion of resin contained in the soap. Kichardson and Watt's System. — They give the follow- ing plan for analyzing soap : — The soap is dried over a water-bath at 212° F., and is then dissolved in alcohol (100 grains require 3 ounces of alcohol), and heated to boiling' over a water-bath. The soap, resin, and free fat enter into solution, leaving the miaeral constituents, glue, starch, dextrine, &c. imdissolved. The liquid is filtered and the residue washed with alcohol. The alcohol is expelled from the filtrate by evaporation. Addition of water then sets free any resin or uncombined fat. These are collected on a filter, dried and weighed. The filtrate now only contains the fat soap and resin soap if any, and must be treated by METHODS OF ANALYZING OR ASSAYING SOAPS. 207 the alkalimctric test to determine the amount of potash or soda in combination with the fat acids. At the same time that the soap solution is decomposed, the fat and resin acids rise to the surface, and these are collected on a weighed filter, washed with hot water, dried in vacuo, and aeam weighed. The weight expresses the joint amount of fat and resin acids in the soap. Cold alcohol will dissolve out all the fat acid, together with a small proportion of the resin from the filter, and the filter dried in vacuo and weighed as before, gives approxi- mately the amount of resin in the soap. To determine whether the base of the soap is soda or potash, the solution of the sulphates filtered from the fat acids is concentrated and treated with tartaric acid and dichloride of platinum in the usual way. The filter containing the matter insoluble in alcohol is dried and weighed, after being thoroughly washed in alcohol. In genuine soap this insoluble matter is of very small amount, not exceeding 1 per cent, for mottled and even less for yellow soap. CHAPTER XXV. PURIFYING ANB BLEACHING OILS ANB FATS. Bleaohiag Palm-oil : "Watt's CJhrome Process. — Eecovery of the Chrome. — Bleaching P alm -nil with Chromate of Lime. — Purifying Oils. — Dunn's Method. — Justice's Method. A VERT necessary branch of the soap-maker's art is that of decolouring or bleaching oils or other fatty matters pre- vious to their introduction^ with other and superior goods, into the soap-pan. The most important of all saponifiable materials possessing a colour natural to itself is palm-oil ; but its deep orange-red colour, except for special purposes, would render it comparatively valueless as a soap-making material if there were no means of depriving it of its characteristic colour. In the early part of the present century many attempts were made to destroy, modify, or in some degree to reduce the intensity of the red colour of this oil. It was subjected to a high temperature, which changed the red to a brown tint ; nitric acid was found to change the colour from red to yellow ; it was subjected to the oxidising influence of the air, which greatly reduced its objectionable redness, and numerous other processes (including of course chlorine) were devised to render it serviceable as a partial substitute for tallow ; but it was not imtil the year 1836, when Mr. C. Watt introduced his now well-known process for bleaching palm-oil by means of chromic acid, that the useAilness of this oil as a soap material could be fully enjoyed. By all the previous processes, the colouring matter of the oil, though modified, was neither removed nor actually destroyed, for it was in- variably found that, in contact with caustic alkali, the colour more or less returned, and therefore affected the idtimate PURIFYING AND BLEACHING OILS AND FATS. 209 colour of the soap. By the " chrome process," however, the colouring matter of the oil was entirely removed and the oil rendered, as white as the finest English tallow. The importance of this process at a time when palm-oil was worth about £32 per ton and tallow about £56 can readily be imagined, and although some years elapsed before the trade fully recognised its importance, it was eventually adopted by all soap-makers in every part of the Kingdom. The process is conducted as follows : — Bleaching Falm-oil : Watt's Chrome Process. — One ton of raw palm-oil melted by steam heat and allowed to settle is placed in a wooden tub or vat, and is stirred with a wooden crutch until it has a temperature of about 120° F. or even lower in hot weather ; 28 lbs. of bichromate of potassa are then dissolved in boiling water and the solution poured into the vat and the stirring continued ; 60 lbs. of hydrochloric acid are then added, and the stirring vigour- ously kept up. In a few moments the oil assumes a dark brown colour, which in a few minutes changes first to a dark green and then quickly to a lighter green, with slight foaming, when the operation is complete. If small samples are taken from time to time and placed upon a piece of glass or porcelain, the rapid changes of colour appeaf very remarkable, and when the last stage is reached (which is sometimes the case within five minutes after the acid has been introduced) the oil upon the palette will be perfectly free from colour. If now a drop or two of the bleached oil be treated with a drop of soda ley, the mixture will be quite colourless if the operation has been properly conducted. A current of steam or a few pails of boiling wa.ter are now introduced, with brisk stirring, after which the oil is allowed to repose. In about twelve hours the " green liquor," as it is called, is drawn ofi' by a plugged opening at the bottom of the vessel, and the bleached oil is then ready for the soap-copper. The green liquor, which contains oxide of chromium in solution, is carefully preserved, and may be treated for the recovery of the chrome by a process which will be described hereafter. 210 THE ART OF SOAP-MAKING. Instead of using hydrochloric acid, 40 lbs. of sulphuric acid and 60 lbs. of common salt may be used. The sulphuric acid is diluted with about twice its bulk of water, and the salt, previously dissolved in cold water, is mixed with the solution of bichromate of potassa in the proportion given. Some persons, in bleaching palm-oil by the above process, have been known to use as much as 40 lbs. of bichromate to the ton, an excess not only extravagant but unnecessary. In bleaching palm-oil by the above process it is of great importance that the temperature of the oil should not be above 120° F., since the chemical action which takes place after the introduction of the bichromate and acid greatly augments the temperature of the oil, and when this latter stands at a higher point than we have indicated the bleached oil is liable to assume a brown or " foxy " colour. The author has most successfully bleached palm-oil when it has been almost at the point of congealing. Recovery of the Chrome — Although the recovery of the most costly ingredient employed in the process of bleaching palm-oil with chromic acid is not now, owing to the greatly reduced price of bichromate of potassa, of such paramount importance as it was formerly, there will be little difficulty in showing that even now, where this salt is used exten- sively, or even in moderate quantities, it will pay to save it from the gutter. The process, which was originated by Mr. Charles "Watt, jun., may be described as follows : — The "green liquor" resulting from the bleaching of palm- oil, and which is rich in oxide of chromium, is placed in a wooden vat or tub. A quantity of slaked lime is worked up with water into what is termed milk of lime, small quan- tities of which are added cautiously, with continual stirring, to the green liquor, until all the free sulphuric or hydro- chloric acid is saturated. ISo excess must be added, other- wise the oxide of chromium will be precipitated. When the saturation of the acid is complete the vessel is allowed to rest for an hour or two, after which the liquid is trans- ferred to another vessel, and milk of lime again added and well stirred in, until the supernatant liquor is colourless. PURIFYING AND BLEACHING OILS AND FATS. 2U After a few hours' rest the clear liquor is run off and fresh water added, which, after a further repose, is again run off', this operation of washing being continued until the clear liquor is tasteless. After ahout twelve hours' repose, the whole of the liquor is run off, and the deposit, which is a mixture of oxide of chromium and lime, after being well drained, is spread over an iron plate, with a furnace tire be- neath to the depth of about two inches. The fire being kindled, the paste is first allowed to dry, when the heat is gradually- increased. When the plate acquires, a cherry-red heat the^rey mass will gradually assume a yellow colour nearest the plate, and the mass will break up into irregular cakes. When these have become roasted about half through they must be turned over one by one, and the roasting continued until the whole assumes the yellow tint of chromate of lime. It will generally be found that the lumps will fall into a coarse powder, in which case, in order to ensure uniformity and to prevent over-heating (which must be strictly avoided) the substance should be constantly turned over by means of a trowel or shovel, a long-handled trowel being a most convenient tool for the purpose. It is advisable in prac- tice to shift from the centre of the plate those portions which are sufficiently roasted* and to replace them with those' which are less done ; the finished material may be shovelled into an iron box or barrow, and there allowed to remain until cold, when it may be put into a cask until required for use. Bleacliingf Falm-oil with Chromate of Lime. — About G^Tlbs. of the chromate of lime prepared as above are sprinkled into a vat containing a ton of melted palm-oil, and well crutched or stirred in ; and when the whole has been introduced 60 lbs. of hydrochloric acid are added, and the stirring continued until the usual reaction takes place and the oil is completely bleached. A few buckets of hot water may now be introduced with brisk agitation, and the usual time then allowed for settling. It is hardly neces- sary to say that the green liquor resulting from this opera- * It is, very important that tlie heat should he only of a dull red. Be- yond this point the product heoomes deoompoaed and useless. 212 THE ART OF SOAP-MAKING. tion may be treated as before, and the chrome again recovered. Purifying Oils. — Fish oils may be purified by first boil- ing tbem with a weak caustic soda ley — about half a pound of the alkali dissolved ia half a gallon of warm water to each ton of oil. This being well stirred into the oil, half a pound of sulphuric acid diluted with six times its weight of water is then added, the whole being boiled by steam for about a quarter of an hour. After about an hour's rest the liquid is run off from the bottom of the vat, and the operation of bleaching commenced. 4 lbs. of bichromate of potassa dissolved in hot water is first introduced, and this is immediately followed by adding 2 lbs. of sulphuric acid diluted as before ; and after steam has been blown through the oil for a short time 1 lb. of nitric acid diluted with 1 quart of water is introduced, and the boiling continued for half an hour longer. The oU is then to be well washed with boiling water, and then allowed to rest until all the liquid matters have subsided. All fixed vegetable oils and also fats may be purified and decoloured by means of chromic acid, but the opera- tion is more effective when a solution of bichromate of potassa and either dilute sulphuric acid or hydrochloric acid are mixed during the process, when the alkali, being attacked by the acid, sets the chromic acid free. Melted kitchen-stuff and other rank fatty matters may be greatly improved, both in smell and colour, by judicious treatment with small quantities of bichromate and any mineral acid, but in order to remove the traces of green oxide of chro- mium which are apt to remain in fatty matters containing a considerable amount of stearine, it is advisable to well wash the bleached fat by the free use of steam or by means of boiling water, and the vessel in which the opera- tions have been conducted should be well covered with sacking so as to retain the heat as long as possible, and thus facilitate the subsidence of the green liquor. In the purifying of fish and other oils chloride of lime, made into a thin creamy mass, has frequently been em- ployed, with the addition of dilute sulphuric acid. About PURIFYING AND BLEACHING OILS AND FATS. 213 1 per cent, of the chloride and IJ per cent, of sulphuric acid diluted with twenty times its weight of water are about the right proportions. The oil is first gently heated, the chloride of lime is then added and well stirred in, after which the dilute acid is introduced, and the agitation kept up until a sample exhibits a satisfactory appearance. Steam is then blown in or hot water applied to thoroughly wash the oil, when it is allowed to rest for some hours. The clear oil is then run ofi" into a proper receptacle. Solutions of tan, or tannic acid, followed by chloride of lime and dilute sulphuric acid have also been used in purifying fish oils. Dunn's nXethod. — Mr. Dunn purified these oils by heat- ing them with steam to a temperature of from 180° to 200° F., and then forcing a stream of hot air through the -oil, after which the oil was washed by steam or hot water and afterwards filtered. A strong solution of common salt, or a mixture of salt and sulphate of copper (both in solution), and the whole well agitated for some time, is another method of purifying fish oil which has been frequently adopted. The oil is afterwards filtered through fresh charcoal, or is allowed to clarify by resting for a few hours. Palm and other oils frequently contain foreign matter the presence of which is likely to retard the chemical action of the bleaching agent ; it is better, therefore, to remove these impurities by first heating the oil and then allowing it to rest for several hours, so that these matters may subside. Justice's method of purifying and bleaching oils and fats consists in mixing with these substances, while in a melted state, pulverised dry fuller's-earth, and then separating the earth from the oil or fat by allowing it to subside. The fatty matter to be purified is placed in any vessel suited to the. purpose, and is heated until it is perfectly liquid. The temperature required of course varies with the different kinds of oil or fat, but it is simply sufficient that the material to be treated be brought to the liquid state. When the fat is thoroughly melted a quantity 214 THE ART OF SOAP-MAmNG. of finely-powdered fuller's- earth, or an equivalent of clay, is spread over its surface and mixed vrithit by agitation, after which the fuUer's-earth is allowed to subside. The fuUers'-earth being now at the bottom of the vessel, the oil or fat, freed from impurities and colouring matter, but in other respects unchanged, is ready for use. The residuum, consisting of fuller's-earth mixed with oil, after the clear portion has been drawn off, may be put into boiling water, which separates the oil or fat from the earth and permits it to rise to the top, where it can be recovered. The refuse may then be thrown away or utilised in any desired manner. The amount of fuller's- earth to be used varies with the different kinds of fats and oils, say from 1 to 15 per cent, by weight of the fat or oil to be treated. No stills or machinery are needed, the only apparatus required being an ordinary vessel of suit- able capacity in which to warm the oil or fat, and if desired one or more settling tanks. CHAPTER XXVI. RJECOVERT OF TBE GLYCERINE FROM WASTE OR SPENT LEYS: Young's Process. — Payne's Process. — Versmann's Process. — O'FarreU'B Process. — Thomas and Fuller's Process. — Allan's Process. — Lawson and Sulmau's Process. — Clolus's Method. — Benno, Japp6, and Co.'s Method. It had always been a source of regret that the enormouB quantity of glycerine formed during the process of saponi- fication should have been ruthlessly wasted, and that no practical effort should have been made to recover this valuable product from the exhausted leys. The high price of glycerine, however, naturally turned attention, to the soap-maker's waste leys, which were known to contain large quantities of this important substance ; and to save it from its usual fate — the gutter — certain ingenious per- sons have devised various methods for its extraction. Of the several patents which have been obtained for recover- ing glycerine from spent leys, the following abstracts will prove interesting, but as these patents are of recent date they cannot, of course, be worked without the consent of the respective patentees. Mr. Benjamin Young's Process consists in first put- ting the waste ley into capacious evaporating-pans or other suitable vessels, provided with coils of pipe made of any suitable metal, through which superheated or ordi- nary steam is passed. The free and carbonated alkalies (soda or potassa) are next neutralised by adding a solu- tion of sulphuric acid in about the following proportions, namelj-, one part of water and one part of the sulphuric acid of commerce (68° B.), in about the proportion of two gallons of the diluted sulphuric acid to every forty gallons of the 216 THE ART OF SOAP-MAKING. ■waste soap-liquor. The solution of sulphuric acid is added to the waste soap-liquor in its original biilk, or when it is reduced to about one half that bulk by evaporation. Su- perheated or ordinary steam is then passed through the coils of pipe connecting with the evaporating-pans, and the waste liquor is concentrated to about one-tenth of the original volume. If any resin or fat is contained in the waste liquor it is admissible to add a slight excess of the dilute acid, and to remove the same — the resin or fat — by strain- ing the concentrated liquor through cloth or any other suitable material made into bags or otherwise, after it has been evaporated to about one-tenth of its original volume. A small quantity of carbonate of lime is then added to the strained Hquor, and it is further concentrated by evapora- tion until upon cooling it assumes the consistency of a syrup or paste, which consists of a mixture of chlorides and sidphates of soda and potassa, sulphate and carbonate of lime, and glycerine. The entire contents of the evapo- rating vessels are then placed in a centrifugal machine, such as is used for causing the separation of sugar from molasses, which is then set in motion and caused to rotate rapidly on its axis, thereby causing the removal of the glycerine. By this means the greater portion of the salts of soda, potassa, and lime are retained in the interior of the centrifugal machine, the glycerine being thrown off by the rapid rotation of the machine. As the glycerine thus obtained holds a certain quantity of salts in solution, these are separated by distillation. Mr. George Payne's Process. — The inventor takes the spent ley resulting from the manufacture of soap and saturates any free alkali present with an acid. He prefers to use sulphuric, hydrochloric, or nitric acid. He then takes a solution of tannin or tannic acid, and adds this to the spent ley after being neutralised by the acid. This solution should contain about one part by weight of tannin or tannic acid to about ten parts by weight of water. The addition of the solution to the ley is continued until it ceases to precipitate any albuminous or gelatinous matter. RECOVERY OF THE GLYCERINE. 217 The precipitate which is thus formed is separated by filtration, or is allowed to settle. The remaining liquid consists chiefly of raw or impure glycerine and chloride of sodium. The solution should be warmed, as experience shows that heat facilitates the formation and separation of the precipitate. In some instances the solution may be found to be slightly acid ; if so, it must be neutralised by the addition of milk of limo. The clear liquor, which is a mixture of glycerine and spent ley, is next heated to expel the water, thereby concentrating the mixture and removing from the same a large quantity of the salts, which will crystallise out during the process of evapora- tion. For this purpose heated air, superheated steam, or the direct heat of the fire may be employed. By this process a concentrated solution of glycerine is obtained containing about 10 per cent, of salt, and the glycerine may be separated by distillation and refined in the usual way. The inventor says that " the glycerine obtained by this process may be more easily refined by distillation than that obtained by any known process." Versmann's Process. — The object of this invention is the recovery of glycerine from soap leys, and its more or less complete separation from chloride of sodium, carbo- nate of soda, and caustic soda. A large percentage of these salts is separated by simply boiling down the soap ley and raking out the salts as they become insoluble. The concentrated solution is then allowed to cool, after which carbonic acid gas is passed through it until the whole of the carbonate and caustic soda is converted into bicarbonate of soda, which being much less soluble in glycerine than either the carbonate of soda or caustic soda, may readily be removed by filtration or other con- venient means. The inventor sometimes commences by passing carbonic acid gas through the original soap ley, but he finds it more convenient to first reduce the bulk of the liquid by boiling down, thereby separating large quantities of the salts, and then treating the liquid with carbonic acid. The liquid from which the bicarbonate of soda has been 2i8 THE ART OF SOAP-MAKING. removed is very rich in glycerine, but it still retains sensible quantities of chloride of sodium and other salts, the presence of which may act injuriously in the subse- quent applications of the glycerine to certain purposes. These salts are separated by submitting the liquor, either hot or cold, to the process of " Osmose," in an apparatus known as the " Osmogene," such as is used in the separa- tion of saline compounds from solutions of beet-root sugar. By this process nearly all the salts are separated from the glycerine. But as the latter becomes diluted with water it may be concentrated by evaporation, when it will be ready for the market as crude glycerine. OTarrell's Process. — The spent leys are evaporated immediately they are drawn off from the soap-pan by fire heat or dry steam applied by any suitable apparatus, till a saturated aqueous solution of common salt is obtained, and this saturated solution is used for the purpose of sepa- rating the glycerine from a fresh portion or second charge of soap, when the spent ley obtained from this fresh portion or second charge is evaporated, and this is again returned to the soap-copper for the purpose of separating the glycerine from a third charge, and the ley obtained is evaporated as before. The process is repeated until the quantity of glycerine present in the solution is sufficiently concentrated to be economically separated. Having by this means obtained the maximum amount of glycerine in the minimum volume of spent soap leys, the inventor proceeds to evaporate the solution till as much salt as possible crystallises out, when the glycerine is dissolved out from the residue by means of methylated spirit or other suitable liquid, or the glycerine may be separated by distillation in vacuo. Thomas and Fuller's Process. — The spent or par- tially spent leys are first evaporated until nearly all the salts are deposited; the resulting liquor, which is strongly impregnated with glycerine, is then boiled with an excels of fat or fatty acids, which readily combines with the soda salts, and removes all salts which may be in suspen- sion in the liquor. The solution is then filtered and sub- RECOVERY OF THE GLYCERINE. 219 jeoted to distillation to recover the glycerine. Or the spent leys may be treated with quick-lime to convert the carbonate of soda into caustic soda, and after filtration boiled to concentration, and then fat or fat acid may be added to remove the soda and such salts as may be in suspension. The method described above, however, is preferred, using simply concentrated leys and a fat acid as the more effectual means of clearing the liquor of salts. Allan's Process. — The inventor first neutralises the spent leys with any mineral acid with agitation. After settling, he adds a solution of alum, chloride of lime, or crude pyroligneous acid, stirring thoroughly. If pre- ferred, he evaporates to nearly " salting point " before adding any of the substances mentioned above, and allows the precipitate to deposit. After settling he draws off the clear liquor and evaporates it to a concentrated con- dition in pans (to which the heat is only applied at the sides), or in shallow pans with sloping bottoms, to which the heat is applied. The liquor is then distilled in a glycerine retort heated by superheated steam from within, and provided with an exit pipe at the bottom, which carries off the precipitated salt as it accumulates. Lawson and Salman's Process consists in first evapo- rating the leys to a density of from 1'14 to 1'16, and allowing the solution to cool. The salt liquor being thus concentrated, the residual soapy matters remaining in solution are rendered insoluble, and, rising to the surface, may readily be removed by skimming or otherwise for further use. To remove the albuminous matters remain- ing in the liquor it is first heated, after which a salt of chromium sesquioxide is added, which is capable of tanning or rendering albumen insoluble. The quantity of the chromium salt added will depend upon the percentage of albuminous matter existing in the ley. The albuminous matters thus rendered insoluble by the addition of the salt are precipitated and removed. The removal of these matters at this stage prevents their decomposition by further evaporation, and thus a 220 THE ART OF SOAP-MAKING. purer and more concentrated glycerine of better colour than usual is obtained. The alkalinity of the liquor is at the same time neutralised by a suitable acid. The inventors remark, " A very convenient method of effecting our invention, so as to obtain these two results, i.e. the tanning of the albuminous matters and the neutralisation of the alkalinity, is to iise the waste liquor resulting from the bleaching of tallow or other fats or oils (chrome liquor ?). For a ley such as the above we may add the bleaching liquor in the proportion of, say, 1 to 3 gallons for every 100 gallons of original ley ; but this must depend entirely on the strength and colour of the ley. When treating highly-coloured leys, we add a pro- portion of free chromic acid to the waste liquor, which, by the oxidation and destruction of the colouring matters, is reduced to a salt of chromium sesquioxide capable of removing the albuminous matters as above." The quantity of chromic acid will necessarily vary, but for the above quantity of ley we should say about half a pound of bichromate of potash added to a mixture of three-quarters of a pound of sulphuric acid in 2 lbs. of water, and add this mixture in the proportion of 5 lbs. to 20 lbs. to every 100 gallons of ley, according to circumstances. "We now treat the Kquor with a small excess of calcium carbonate (say, for example, 1 to 2 gallons "cream of whiting " to 100 gallons of ley), and maintain at a boiling temperature for a short time. This precipitates the whole of the chromic salts, and neutralises any slight proportion of acid remaining. The chromic oxide contained in the resulting -precipitate can be recovered for another opera- tion in any suitable and well-known manner. The re- sultant liquor obtained by removing the precipitate by subsidence or filtration will be found clear and almost colourless. It is then concentrated by further evaporation, which causes the gradual separation of the salt, which can be again used in the manufacture of soap. The crude glycerine finally obtained is of greater purity and better colour than usual. M, Victor ClolTis's Method. — ^To effect a separation of RECOVERY OF THE GLYCERINE. 221 the various bodies for commercial purposes, and especially to extract the glycerine from spent leys, the inventor first saturates the ley, when cold, with hydrochloric acid. The solids are precipitated and collected; the neutral clear liquid is evaporated in any suitable heating apparatus. By degrees, as the evaporation proceeds, the salt is preci- pitated and is removed, subjected to the action of a tur- bine, and washed. In most cases this salt is sea-salt in a nearly pure state. The evaporation is arrested when the liquid has arrived at a density of about 32° B. At this point the glycerine contained in the ley still contains con- siderable quantities of salt in solution, the greater part of which is eliminated by the following treatment ; that is to say, the glycerine liquid, at about 32° B., is poured into any suitable vessel and hot air is blown into it, or the liquid is otherwise heated and cold air blown into it. The air so heated, or heated by the glycerine itself, gradually eliminates the last traces of water in the glycerine, and salt is constantly precipitated, as the latter is very slightly soluble in anhydroiis glycerine. To eliminate the water evaporation in vacuo might also be effected, but would be more expensive. As the final result, highly concentrated glycerine mixed with salt crystals is obtained. A tur- bine is used for eliminating the salt, which is systemati- cally washed, and the water used for the washiag is again treated. The glycerine, thus purified by one or the other of these two processes, contains only a very small quantity of sea- salt in solution, and may be distilled. The inventor also adopts another method when he desires to obtain the car- bonated or caustic salts of soda in the condition of carbonates, instead of transforming them into chlorides by means of hydrochloric acid. For this purpose he evaporates the ley and introduces into it carbonic acid, so as to convert the caustic soda into carbonate. "When the liquor indicates about 25°, he allows the ley to cool, when he introduces an excess of carbonic acid, whereby bicar- bonate of soda is formed, which is only slightly soluble, especially in a glycerine solution of salt. The greater 222 THE ART OF SOAP-MAKING. part is precipitated and is eliminated by means of a tur- bine. The bicarbonate is transformed into carbonate by calcination. The glycerine liquid which leaves the tur- bine is treated as before. If it is desired to obtain glycerine more free from salt, the operation is performed as follows : — ^The glycerine concentrated by air blown into it, or in vacuo, is treated with hydrochloric acid added in excess, either in a gaseous state or as a liquid. Sea-salt, being almost insoluble in an excess of hydrochloric acid, will be precipitated in fine crystals, and is eliminated by means of a turbine. The excess of hydrochloric acid then contained in the glycerine is eliminated either by blowing air into the same or by an excess of oxide of lead. Benno, Japp^, and Co.'s SEethod. — According to this process the inventors do not use common salt for separating the soap from the ley, but employ in lieu thereof an alkaline sulphate. The alkaline sulphates, . especially the sulphate of soda, act upon the soapy liquor in the same manner as common salt, but there will be no difficulty in subsequently separating such sulphate from the glycerine. The spent ley obtained in eliminating the soap by means of sulphate of sodium has an alkaline re- action, and is, therefore, first neutralised by the addition of hydric-sodic sulphate ; it is then filtered and ultimately evaporated. In the process of neutralising the spent ley the hydric-sodic sulphate is transformed into sulphate of soda by the caustic soda contained in the spent ley. When the liquid is evaporated the sulphate of soda sepa- rates in crystals, and is thus recovered as a bye-product. The sulphate of soda, which has been introduced for the purpose of separating the soap from the ley, is also sepa- rated, and if properly purified can be used again for eliminating soap from the ley. The liquid remaining after the crystallisation is glycerine containing a slight proportion of impurities, and can be further purified in the usual manner, as for instance by distillation. CHAPTER XXVII. MIBGELLANEOUB SOAPS. Soap to be used in. Cloth Manufactories. — White Cocoa-nut Oil Soap. — DBesden Palm Soap. — Altenburge's Eesin Soap. — Ox-gall Soap. — Scouring Balls. — Borax Soft Soap. — Borax Soap-Powder. — London Soap-Powder. Soap to be nsed in Cloth. Manufactories, &c. — Kiirten makes tlie following interesting observations on the pre- paration of soaps to be used' for milling and other similar purposes,* which will assist in guiding the soap-maker who may not be fully acquainted with the requirements of the cloth-scourers. " In preparing all soaps intended for the use of the above-mentioned establishments, great care is indispensably necessary in giving the ley its proper proportion of strength, for if the ley be too weak the stuffs cannot be properly cleansed, and also a greasy matter is communicated to them which in every case is very injurious ; on the other hand, if the ley is too strong in the soap, the stuffs are scoured too much, and retain always a dry stiffness which should be specially avoided. When the cloth is scoured or milled it is a rule to use soap of a quality corresponding with that of the stuffs, for it is proved by experience that a cloth which is really good, and which is called stout cloth, must be milled a longer time than a zephyr or light stuff for pantaloons, which only require to be washed, else they would loose the elasticity which is indispensable to them. " In executing an order for soap for milling, the maker should direct his attention to ascertain whether the pro- cess of milling was according to the ancient manner by stocks or the new method by cylinders. By the first * " Art of Manufacturing Soap." By Philip Kiirten. 224 ^^^ ^^^ OP SOAP-MAKING. method the milling requires longer time and the em- ployment of a soap which does not dissolve too quickly, whilst by the latter method a soap is wanted which does not congeal too quickly. Among the soaps which do not dissolve quickly we reckon those which are prepared from tallow or palm-oil with soda ley, from which it is after- wards separated. A soap which dissolves the quickest is that which has been boiled from olive-oil, with an addi- tion of tallow, then some olein soap ; in a word, the genuine soap. It is, however, true that green or brown soap always dissolves quickest ; nevertheless it is not fit for milling heavy cloth with the stocks, because on that account they do not thicken sufficiently. Although the manufacturers of cloth will not easily decide on using any other sort of soap, yet the soap-boiler should not be led away by the opinion that every maker of the same artide can make use of the same sort of soap, because, as we have already observed, not only the different qualities of cloth and the method employed in their manufacture should be taken into consideration, but also the different pro- perties of the water used. It is, therefore, the duty of every soap-boiler to supply each manufacturer with the kind of soap which, in that manufacturer's own opinion, is the best adapted for his purpose and for the quality of his material. We will for that reason more fully describe the preparation of the different sorts of soap. "Hard and Unsalted Soap for Milling Cloths of Superior quality. — This kind of soap is made either of tallow or cocoa-nut oil, or whitened palm-oil with an addition of cocoa-nut oil, and in the following manner : — The palm-oil or the tallow should be boiled into a firm- grained soap with a caustic soda ley,* which is added till the soap shows a strong grain and bears a good pressure of the hand, and the sample shows a sufficient firmness when cool, and when the ley, which still remains im- salted in the soap, leaves a sharpish taste on the tongue. "We have then a soap, it is true, but it is not fit for milling, because it does not yet possess a sufficient scouring * Mr. Kiirten is in error in recommending soda soaps for these purposes. MISCELLANEOUS SOAPS. 225 quality, therefore will not cleanse the cloth from its dirt, glue, and grease. To give the soap the necessary power to effect that purpose an addition of cocoa-nut oil is requisite, and for that reason the unsalted ley which remains in the soap must be got rid of, and the soap poured again into the boiler, but without any ley. For every 100 lbs. of palm-oil or tallow used for this soap 25 lbs. of cocoa-nut oil must be added, which is mixed with the soap when cold in small quantities, or, which is more advisable, when in a state of solution, and then made to boil afresh. When it is intended to make a soap of a superior quality and to diminish the ley, in order to saponify cocoa-nut oil a caustic ley of soda of 38° or 30° is required. The ley is added till the soap has acquired a good firmness, and, when tried, a taste rather strong of ley remains on the tongue. As soon as this is foufld, then the soap must be allowed to boil for half an hour to ascertain whether the same taste yet remains ; if not, a little more ley musl; be added till the taste returns. "When the soap is not yet separated from the ley, to effect that purpose some salt must be used, and continued till the soap on the spatula separates from the ley. The soap will remain some hours in the boiler to cool, and be after- wards poured into the frame. "When it is desired to obtain a larger produce, although with the conviction that the quality will not be so good, instead of a ley at 28° or 30° for the saturation of the cocoa-nut oil, one 22° to 24° must be used, and the soap poured into the frame in the state of paste, and not unsalted ; but in this case care must be taken that the soap is not brought to a higher degree of heat than 25° Reaumur (152°), otherwise the soap from the cocoa-nut oil would stick to the bottom of the boiler." White Cocoa-nut Oil Soap. — Cristiani gives the fol- lowing directions for making this soap in a simple and quick way: — To prepare 100 lbs. of >this soap, introduce into a kettle* holding from 200 to 250 gallons, 200 lbs. * The term " kettle " is generally used in America in preference to soap-pan or copper. 226 THE ART OF SOAP-MAKING, of pure white cocoa-mit oil ; afterwards add 200 lbs. of colourless and perfectly limpid ley at 30°. All being ready, heat the kettle, and to accelerate the combination of the substances stir weU from time to time. Under the influence of the heat the material, which was at first in the form of grains, softens and becomes liquid. Contiaue the heat gently and gradually until the combination of the oil and alkali is efiected, which generally takes place when the ebullition begins. When properly made, the soap has the appearance of a fluid, homogeneous, and syrupj' paste of an amber-white colour. It is useless to boil it ; stop off the heat, and run the soap into the frames. If, when the mixture begins to boil, a certain quantity of oil swims on the surface of the paste, it may be com- bined with the saponified mass by adding 10 lbs. to 12 lbs. of cocoa-nut oil soap ; or, the same result may be obtained by adding from 2 to 2\ gallons of pure water. After stirring a few minutes the homogeneity of the soap is re- established and the combination perfected. The heat is then withdrawn, and the soap transferred to the frames as usual. After five or six days the soap is firm enough to cut. By the above process the soap is very white, does not contain any excess of alkali or oil, and may be employed for toilet uses. From the quantities given from 396 to 400 lbs. of soap are obtained, according to the quantity of water added. The operation lasts about one hour. Dresden Palm Soap. Cocoa-nut oil 3,520 Its. Palm-oil (crude) 1,100 „ Eesin '.'."..: 880 „ Soda ley, 28» 353 „ Melt together the fats and saponify the resin separately, taking care to add the resin soap before it becomes too thick to stir. Alteubnrge's Besin Soap. Cocoa-nut oil 220 Its. Resin 220 ,, Soda ley, 28° B 297,, Make by the cold process, and cut with a salt ley of 24° B. before framing. MISCELLANEOUS SOAPS. 227 Ox-gall Soap. Purified ox-gall 1 part. White curd soap 2 parts. The soap is cut into shavings and melted in the ox-gall at a moderate heat, evaporating until of proper consistency. The ox-gall is prepared by boiling it with 10 to 12 parts of wood spirit and straining. Sconring-Balls. White curd soap 33 lbs. 2 ozs. Pearlash 6 „ 6 ,, Oil of juniper 3 „ 3 „ Mix together, having previously added a little water to the soap and pearlash to dissolve them by a moderate heat ; add the oil of juniper and mould into balls. Borax Soft Soap. White fats 100 Ihs. Soda ley, 15° B 100 „ Potash ley, 10° B 60 „ Solution of horax, 10° B IS „ The soda ley is added to the melted grease and heated till it forms a clear liquid or is combined, when the potash ley and borax solution are added. It should be a semi- solid translucent paste, and is usually sold in quart cans. Borax Soap-powder. Curd soap in powder S parts. Soda ash 3 „ Silicate of soda 2 „ Borax, crude 1 part. Each ingredient is thoroughly dried and all mixed together by sifting. London Soap-powder. Yellow soap 6 parts. Soda crystals : 3 „ Pearlash 1| part. Sulphate of soda 1 J „ Palm-oil 1 ,, These ingredients are combined as well as possible without any water, and they are spread out to dry and then ground into a coarse powder. Thus in an infinite degree can the variety of soap-powders be multiplied. They are adapted for hard waters, as their excess of alkali neutralises the lime. — Gristiani. CHAPTEE XXYIII. USJEFUL N0TJE8 AND TABLES. Pickling Soap. — The •Oleometer. — Aluminate of Soda. — betermination of Eesin in Soap.- — Detection of Kesin in Soap. — Cheap Almond Soap. — Analyses of Soft Soaps. — Potato-flour in Soft Soap. — Saponi- fication of Neutral Fatty Bodies ty Soap. — JeUifying. — TwaddeU's Hydrometer. — Causticising Soda. — Soda Soft Soap. — Half-palm Soap. — ^Adulteration of Commercial SUioate of Soda Soaps for Calico- printers. — Fulling Soaps. — Table showing the Percentage of Soda in" Caustic Ley. — Tahle showing the Percentage of Anhydrous Caustic Potash in Caustic Ley. — Comparative French and English Ther- mometer Scales. — Table showing the Specific Gravity corresponding with Baume's Hydrometer (Liquids denser than Water). — Table showing the Specific Gravity corresponding with the Degrees of Baumfe's Hydrometer (Liquids lighter than Water). — Table of Essential Oils. — Fusing and Congesting Points ot Fats and Oils. — Kiirten's Table. — Boiling-points of some Volatile Oils. — Boiling- points of Caustic Alkaline Leys. — Table showing the Quantity of Caustic Soda in Leys of different Densities (Water 1000). — ^Table of the Mechanical Power of Steam. PicMiug Soap. — Under this attractive Leading we may state that some very competitive soap-makers have occa- sionally adopted a plan of artificially hardening the surface of soap containing an infinitesimal proportion of fatty matter by soaking it for a few hours in a strong solution of common salt. The soap hars (which require careful handling !) are gently deposited in the strong brine, where they are allowed to remain until the surface is sufficiently indurated, after which they are qvdckly rinsed and then submitted to the drying-room for a short time. By this method the soap assumes a virtue which it does not possess. The Oleometer. — This very useful instrument, for ascer- taining the density of fixed oils, is thus described by Mr. Cooley : — "A delicate areometer or hydrometer, so weighted and graduated as to adapt itself to the densities of the leading fixed oils. As the difiierences of the specific USEFUL NOTES AND TABLES. 229 gravities of these substances are inconsiderable, to render it more susceptible the ball of the instrument is pro- portionately large and the tube or stem very narrow. The scale of the oleometer in general use (Gobby's) is divided into 50 degrees, and it floats at or zero in pure poppy oil ; at 38 or 38 j in pure almond oil, and at 50 in pure olive-oil. The standard temperature of the instru- ments made in this country is now 60° ; those m^de on the Continent 54*5° F. The oil must therefore be brought to this normal temperature before testing it, by plunging the glass cylinder containing it into either hot or cold water, as the case may be ; or a correction of the observed density must be made. The last is done by deducting 2 from the indication of the instrument for each degree of the thermometer above the normal temperature of the instrument, and adding 2 for every degree below it. Thus : suppose the temperature of the oil at the time of the experiment is 60° F. and the oleometer indicates 60°, then — 60"0° Actual temperature. 54'5 Normal temperature. 5-5 Difference. Indication of the oleometer 61'0 The difference 5-5X2= 11-0 Eeal density 60'0 Suppose the temperature observed at the time of the experiment is 52° and the oleometer indicates 45°, then — 54'5 Normal Temperature. 52'0 Actual Temperature. 2-5 Difference. Indication of the oleometer 45"0 The difference 2-5x2= 5-0 Eeal density 50-0 The oil is therefore" presumed to be pure. Alnmiuate of Soda. — It has been proposed to employ this salt as a substitute for caustic soda in the manufac- ture of soap. Aluminate of soda is prepared from bauxite, an aluminate of iron, and from cryolite, a double fluoride 230 THE ART OF SOAP-MAKING. of sodium and aluminum. Bauxite is calcined with soda ash, whereby an aluminate of soda is formed, and the oxide of iron is separated by lixiviation, the resulting liquors being evaporated until a dry commercial alumi- nate of soda is obtained, the composition of which is — soda, 43 ; alumina, 40 ; water and impurities from the soda ash employed, 9. Cryolite (powdered) is mixed with six equivalents of lime and boiled with water, when an insoluble fluoride of calcium is formed and the alumina becomes dissolved in the excess of caustic soda. If an excess of lime is used, the alumina will be precipi- tated, leaving caustic soda alone in solution. We under- stand that soap is made in the United States to a con- siderable extent from aluminate of soda. For making soap from aluminate of soda, about equal parts of lard and tallow are preferred, and these should not be heated to a greater extent than is just necessary to liquefy them. The materials are not boiled in the usual way, but the combination is effected at the lowest tem- perature at which they can be intimately mixed. To determine the Qnantity of Besin in Soaps. — Mr. Sutherland recommends the following process, which is said to give very satisfactory results : — 300 grains of soap cut into small pieces are introduced into a capsule and covered with concentrated hydrochloric acid, the contents are gently boiled till the soap is dissolved and entirely decomposed ; 4 ounces of hot water are added, and the capsule is set aside to cool. When cold, the cake of fatty acids and resin is removed and washed several times with warm water. After cooling it is dried and gently remelted, and kept for a few minutes at 212° to evaporate all traces of water. This cake containing the fatty acids and the resin is carefully weighed. 100 grains of the mixture are placed in a capsule and covered with strong nitric acid and the temperature raised to the boiling-point; a powerful reaction takes place with violent evolution of nitrous vapours. The heat is withdrawn till the violence of the action subsides, and is USEFUL NOTES AND TABLES. 231 again applied to maintain a gentle ebullition for a few minutes. Small portions of nitric acid are successively added till no further distinctly appreciable quantity of nitrous acid is given off. The fatty acids are now allowed to cool, and are removed from the acid solution strongly coloured by terebic acid. The cake is then washed by melting it in a further quantity of nitric acid. When cold it is dried and melted at a gentle heat till acid fumes cease to be given off. The resulting cake is the pure fatty acid freed from resin, the latter being indicated by the loss. It will be observed that a correction must be made to obtain the exact relative proportions between fat and resin originally put into the soap-pan, as fats on being decomposed lose about 4 J per cent, of their original weight. Hence, in making the calculation a proportionate addition must be made to the fatty acid before dividing its weight by that of the resin indicated. This process may be also used to determine resin in bees' -wax. Detection of Besin in Soap, — Mr. C. Barford decom- poses the soap with hydrochloric acid, and washes the mass thus obtained with water. He then treats it with a caustic soda ley of the specific gravity of Tl diluted with 6 volumes of water, avoiding excess. He then evaporates it to dryness over a water-bath, grinds up the residue, and dries in stove at 100°. One portion of this powder is utilised for the determination of the fatty acids, and another portion is put into a very dry bottle, and from 5 to 6 per cent, of absolute alcohol are added for every gramme of soap. It is heated at 80°, to dissolve the soap of the fatty acids and of resin, and allowed to cool again while well stoppered. The alcoholic liquid, when cold, is mixed with 5 times its volume of ether. The :whole is well shaken up and left to settle. The resin soap is entirely dissolved, whilst the soap of the fatty acids is deposited almost entirely. After standing for 24 to 48 hours the ethereal liquid is decanted, and the residue is treated with hydrochloric acid. This method is based upon the slight solubility of a soda soap of the fatty acids in the above mixture of alcohol and ether. 232 THE ART OF SOAP-MAKING. Cheap Almond Soap. — To impart the odour of bitter almonds to soap, nii/ro-benzol has been much employed. It is exceedingly powerful as a perfume, and must there- fore be used in moderation. It is largely used in some parts of England for scenting cheap tablet soaps. In small quantities it has also been employed to disguise the dis- agreeable odour of cocoa-nut oil. Analyses of Soft Soaps, — The following analyses may be useful as showing the composition of several well-made soft soaps : — Good soft soap of London make : Potash 8'5 -f oil and tallow 45 + water 46-5 in 100 parts. — Ure. Thenard gives the composition of soft soap as : Potash 9-6; oil 44-0; water 46-5 = 100. Belgian soft or green soap : Potash 7 -f oil 36 -h water 57 = 100.— Ure. Scotch soft soap : Potash 8 -|- oil and tallow 47 + water 45 = 100.— Z7re. Another well-made soap : Potash 9 -1- oil and fat 34 + water 57 = 100. An olive-oil (Gallipoli) soft soap from Scotland con- sisted 'of potash with a good deal of carbonic acid 10, oils 48, water 42 = 100.— C/re. A rapeseed oil from Scotland consisted of potash 10 + oil 61-66 -I- water 38-33. A semi-hard soap from Verviers, for fulling cloth, called savon iconomique, consisted of potash 11-5 -|- fat (solid) 62 + water 26-5 = 100.— C/re. M. Juncmann proposes to make a soap by dissolving 28 parts of soda ash in 100 parts of molasses, and stirring in 100 parts of oleic acid. Fotato Flour in Soft Soap. — In the year 1838 Sheridan (the original inventor of silicated soap) obtained a patep.t for making soft soap with potato flour. The proportions were : potato flour, 16 lbs. ; potash leys, 100 lbs. ; water, 270 lbs. How many times has the same process been, with slight modifications, re-patented ! " Liquored soaps " are such as have water (with or without silicate of soda) added to them after removal from USEFUL NOTES AND TABLES. 233 the pan. Watered, or " run " soaps are those which have water or weak leys added and mixed with the soap in the soap-pan. Saponification of STeutral Fatty Bodies by Soaps: By M. J. Pelouze. — One of the oldest and most skilful candle-makers in France, M. de Milly, made a series of important experiments on the saponification of fatty matters, and especially suet, by lime, in which he demon- strated that a much smaller percentage of lime than was ordinarily employed would effect the complete saponifi- cation of the fatty matter. Having reduced the per- centage of lime from 15 to 8 or 9 per cent., he subse- quently reduced the proportion to 4 per cent, of the fatty matter operated upon, the condition being that of sub- jecting the lime, water, and fatty matter to an elevated temperature. The operation was performed in a metallic boiler, which was maintained for several hours at a tem- perature corresponding to a pressure of 5 to 6 atmospheres. It is easy to understand the economy of an operation which enables us to diminish to one half the quantity of sulphuric acid necessary for' the decomposition of the lime soap. It appeared to me interesting to subject to an attentive examination a saponification performed with so small a quantity of a base as one twenty-fourth part of the acidified fatty matter. I prepared a lime soap by double decompositioiijjjllf^ pouring a solution of chloride of calcium into an aq^jreous solution of commercial soap. The precipitate, wbren well washed, was introduced into a small Papin's digester, with nearly its own weight of water and 40 per cen^- of olive oil. The vessel was kept for nearly three hour^ ii ^^ oil bath at a temperature of from 311° to 329° \F. The water above the precipitate was evaporated, an^ left a syrupy residue presenting all the properties of glycsrine. The precipitate, when boiled in water acidulated^ ^ith hydrochloric acid, furnished a completely acidified fatty, matter ; for it was directly and entirely soluble in alcohol \ and the alkalies. In one word, the reaction showed all \ the characters of the ordinary decomposition of the neu- 234 THE ART OF SOAP-MAKING. tral fatty matters by tlie free alkalies. The difference in hardness of the new lime soap being set aside (it was not so hard), one might have supposed that the saponification had been performed with caustic lime. Another experiment was made by mixing Marseilles soap with its weight of water and one quarter of its weight of olive-oil. The temperature and operation were the same. The matter, after the reaction, had all the properties of an acid soap : it was soluble in cold alcohol and in an aqueous solution of potassa or soda. Acids separated from it a fatty substance likewise entirely soluble in cold alcohol and alkaline solutions. It results from the double experiment, which has just been described, that soaps are as capable as alkalies of decomposing fatty bodies into glycerine and fatty acids ; it will thus be understood why I have given to this note the apparently paradoxical title, Sapomfication of Neutral Fatty Matters by Soaps. I have, moreover, ascertained that at the temperature of 329° F. water does not act on oils. To decompose them it is necessary that the mixture of fatty matters and water should attain and be maintained for a long time at the temperature of 428° F. assigned by M. Berthelot for this latter saponification. In England, where Price's, house manufactures immense quantities of stearine candles, the saponification is per- formed by the action of superheated steam at a stni highe^ temperature. Thence result fatty acids and free glycerih*a which is nearly pure, and whence arts, manu- factures, and medicine have already drawn great advan- tages, and which will, probably, be much increased. In the new reactions of which we speak it will be understood that water, at a temperature of from 311° and 329° F., decomposes a neutral soap into an acid soap and very basic soap, and that the latter acts in a secondary manner on a fresh quantity of fatty matter in the same manner that a free alkali would do. The observations of M. Chevreul, relative to "the action of water on soaps, accord with this explanation. USEFUL NOTES AND TABLES. 235 The experiment of M. Milly, which served as a founda- tion for my work, may be explained in an analogous manner. It must be admitted that the saponification of suet by means of 4 per cent, of its weight of lime presents several distinct phases in which a basic or neutral soap is formed at first and is'then changed into a relatively acid soap. The observations of which I have been giving a sum- mary find a simple interpretation in M. Chevreul's works on fatty bodies. They lead us to look forward to fresh developments in this class of numerous and important substances. "When the elements of water alone cause the decomposition of neutral fatty bodies into fatty acids and glycerine, we may expect that science and industry will multiply and vary the phenomena of saponification. Jellifying is a term applied to soap which, after being dissolved in a certain quantity of water, sets into a jelly when cold. Soap-makers frequently test the jellifying property of their soaps in this way : — After having care- fully weighed 1 ounce of soap, this is cut up into thin shavings, and these are placed in a porcelain capsule ; 7^ ounces of water (by measure) are then added, and the whole gently boiled over a spirit-lamp, constantly stirring with a glass rod until the soap is all dissolved. Cold water is then added to make up 16 ounces, and the solu- tion of soap is then set aside to cool. If the soap is of good quality it should gelatinise in half an hour. In cloth factories, and large laundries also, the character of soap is determined by its congealing or jellifying pro- perties. For this purpose 1 cwt. of soap is boiled by steam heat in 80 gallons of water. When thoroughly dissolved, cold water is added to make up 170 gallons in all. At the end of twelve hours or so the solution of soap will have set into a jelly if the soap has been of good quality. Twaddell's hydrometer is used in England for liquids heavier than water. Its degrees are converted into specific gravities by multiplying them by 5, adding 1,000, and dividing the sum by 1,000. Thus : — 20 Tw. = 20 X 5--H 1000 1000 = 1100 236 THE ART OF SOAP-MAKING. Twaddell's figures advance 5° in each number, thus : — 1000 specific gravity is No. 1005 „ „ 1 1010 „ „ 2 1015 „ „ 3 1020 „ „ 4 and so on. Cansticising Soda. — Mr. Parnell's plan for causticising soda liquor under pressure appears to have proved very- successful in practice and to have effected a considerable saving in fuel. The operation is conducted in horizontal cylinders about 7 feet in diameter and 30 feet long, pro- vided with a revolving shaft or agitator and " cages " for holding the lime. Each charge is about 400 cubic feet of soda liquor, and takes about three and a half to four hours to causticise under a pressure of from 50 to 60 lbs. to the square inch. It is stated that 90 or 92 per cent, of the soda is causticised by this method, and the caustic liquor comes out up to 32° Twaddell. The " mud " contains from 3 to 4 per cent, of free lime. Each ton of 70 per cent, caustic soda requires 15 or 16 per cent, of lime. One apparatus turns out about 70 tons weekly. The patentee says : — " 1. I treat the alkaline carbonates, or alkaline carbonates mixed with caustic lime, under a pressure greater than the ordinary atmospheric pressure, so as to obtain a sufficiently high temperature to cause the alkaline carbonate and the caustic lime to react upon each other. Thus it is possible, under pressure of 50 lbs. per square inch, to efiiect the reaction with a solution of 1*200 specific gravity or over. 2. I agitate, the mixed alkaline car- bonates and lime during treatment in the manner above described in order to facilitate the reaction and hasten its completion. 3. After the reaction has taken place I maintain the pressure upon the products, and keep the temperature constant until I have separated the caustic soda or potassa, or both, from the carbonate of lime pro- duced, in order that the reaction may not be reversed by a reduction of temperature taking place whilst the caustic alkalies and the carbonate of lime are in contact. Soda Soft Soap may be made from a mixture of soda USEFUL NOTES AND TABLES. 237 and potash leys, but the leys must be quite free from salt. Tie proportions recommended are : Soda ley, 1 part ; potash ley, 4 parts ; oleic acid, 100 lbs. ; tallow, 50 lbs. ; hempseed-oil, 3,750 lbs. This is said to make a good soft soap. Half-palm Soap may be made from either of the fol- lowing formulae : Wiite tallow 900 Its. Palm-oil 400 „ Cocoa-nut oil 200 „ Yellow resin 100 „ 1600 TaUow 700 „ Palm-oil 300 „ Cocoa-nut oU 200 „ Cotton-seed oil 400 „ 1600 Lard 550 lbs. TaUow 400 „ Cotton-seed oil , 450 ,, Eesin 200 ,, 1600 The following formulae, recommended by Ott*, may prove useful : — Palm-oil 300'lliS. TaUow 200" „ Eesin 20 „ 520 Tallow 500 „ Palm-oil 300 „ Eesin 200 „ 1000 Palm-oil 450 lbs. Cocoa-nut oil ..... 50 „ 600 Lard 550 „ Palm-oil 150 „ Coooa-nut oil 60 „ Clarified resin 50 „ 800 Adulteration of Commercial Silicate of Soda. — The sample in question gave on analysis, according to M. F. Jean — Soda combined with. sUica 8'54 Carbonate of soda 6'36 Soda soap 2-00 silica ■. 21-40 Perric oxide, alumina, and traces of lime 0-74 Alkaline chloride and sulphates 0-66 Water 60-05 Matter not determined, and loss 0-25 The sample of silicate of soda contained, therefore, 2 per cent, of anhydrous soap, but as such a solution * " Art of Manufacturing Soap," &o. By Adolphe Ott. 238 THE ART OF SOAP-MAKING. forms a jelly on cooling, tKe object of its introductioi^ was evidently to thicken the silicate, giving it the appear; ance of a very concentrated product, and to prevent its strength being taken with the hydrometer. Soaps for Calico-printers. — The soap used by calico-' printers for clearing alizarine work must be very neutral, the alkali being not only kept down in quantity, but its thorough combination with the fatty acids secured by very careful boiling. The superiority of the madder purples for which the firm of Hoyle and Sons were long famous was due to their practice of re-melting the best soaps procurable with an additional quantity of palm-oil. Fulling Soaps. — For use in woollen manufacture a genuine potash oil-soap has been found in practice supe- rior to all others. Resin gives harshness to the fibre of wool, so must not therefore on any account be used. Soda also injures the suppleness of the wool, so in discarding it the manufacturer follows the teachings of Nature. The natural lubricant of wool, called mint, is a kind of potash soap, containing a bare trace of soda. SiKcates also must not be used ; if present they are decomposed in the pro- cess of fulling, &c., and deposit free silica, which grates on the fibre and injures its lustre. To prevent the boiling-over of the Copper, a piece of machinery called a "fan" is used at some soap-works. This consists of a revolving paddle furnished with blades which touch the top of the boiling matter. Small jacket-pans may be made from the alloy of aluminium and bismuth of the Crown Aluminium Com- pany, instead of silver, which possesses the advantage of being cheaper, harder, and less fusible than the more costly metal. USEFUL NOTES AND TABLES. 239 Tablb showino the Peboentaob or Soda in a Oaubtio Let, at the Tempbuatuke op 60° Fahrenheit, and the. Quantity op Mixed Fats whioh mat be baponipied by this Ley. — Tiinnermann. Speoifio Degiees For oent. itity of Mixed which may be lified by lOO of these Leys. Speoiflo Degrees Per oent. ■§.288 Gravity. Baumd. of Soda. Gravity. Baum(S. of Soda. 16-11 1'4285 43 30-22 379 1-2392 27 139 1-4193 42-6 29-616 274 1-228 26 14-606 134 1-4101 42 29-011 270 1-2178 25 13-901 128 1-4011 41 28-407 263 1-2058 24-6 13-297 122 1-3923 45-6 27-802 267 1-1948 23 12-692 117 1-3836 39-7 27-2 251 1-1841 22 12-088 111 1-3761 39 26-694 246 1-1734 21 11-484 106 1-3668 38-6 26-489 240 1-163 20 10-879 100 1-3686 33 26-886 286 1-1628 19 10-276 95 1-3505 38 24-78 229 1-1428 18 9-67 89 1-3426 36-7 24-176 224 1-133 17 9-066 83 1-3349 36 23-672 217 11233 16 8-462 78 1-3273 36 22-967 212 1-1137 16 7-857 72 1-3198 34-6 22-363 206 1-1042 13-5 7-253 66 1-3143 34-2 21-894 202 1-0948 12 6-648 61 1-3126 34 21-768 201 1-0855 11 6-044 66 1-3053 33-6 21-154 195 1-0764 10 5-44 50 1-2982 33 20-66 190 1-0676 9 4-836 44 1-2912 32-4 19-946 184 1-0687 7 4-231 39 1-2843 31-6 19-341 179 1-05 6 3-626 33 1-2775 31 18-73 173 1-0414 6-6 3-022 28 1-2708 30-6 18-132 167 1-033 4-2 2-418 22 1-2642 30 17-618 162 1-0246 3 1-813 16 1-2678 29 16-923 166 1-0163 2 1-209 11 1-2615 28-0 16-319 161 1-0081 1 0-604 5-6 1-2453 28 16-714 146. 240 THE ART OF SOAP-MAKING. Taslb showing the Pekcentage op Anstdrous Caustic Potash m A Let at 60° Fahs., and the Quantity of Mixed Fats which KAT BE SAPONIFIED BT XT. — Tunnermann. Appmximate "Pav f^an4- n-F A n _ Quantity (in weight) of Specific Gravity. Valneiix Degrees bydrooE Caustic Potash. Mixed Fats, which may be saponified by lOO parts Bailing : (in weight) of these leys. 1-3300 36 28-290 170 1-3131 34 27-158 163 1-2966 33 26-027 156 1-2803 32 24-895 150 1-2648 30 23-764 142 1-2493 28 22-632 136 1-2342 27 21-5 129 1-2268 26 20-935 125 1-2122 25 19-803 119 1-1979 23 18-671 112 1-1839 22 17-54 105 1-1702 21 16-408 98 1-1568 19 15-277 92 1-1437 18 14- 145 85 1-1308 17 13-013 78 1-1182 15 11-882 71 1-1059 14 l'&-750 64 1-0938 12 9-619 58 1-0819 11 8-487 51 1-0703 10 7-355 43 1-0589 7 6-214 37 1-0478 6 5-022 30 1-0369 5 3-961 24 1-0260 3 2-829 17 1-0153 2 1-697 10 1-0050 1 0-5658 3-4 COHPABATITB FbEKCH AND EnGUSE TeEBMOMETER ScALES. French, or Centigrade. __^,- English, or Fahrenheit. Cent, or C. eqnals 32 Fahr. or F. s jj 41 j> 10 )) 60 }, 15 59 ij 20 68 3} 25 77 ,f 30 86 », 35 95 ij 40 104 45 „ 113 >, 50 122 )} 6a 131 60 140 i> USEFUL NOTES AND TABLES. 241 Comparative Frbnoh and Enghsh Theemombtbr Scales — [continmS). English, 01 Fahrenheit. 149 Pahr. or P. French, 01 Centigrade- 65 Cent, or 0. equals 70 , 158 75 167 80 , 176 85 , 186 90 , 194 95 203 , 100 200 , (Water boils) }} 212 392 , , (Water boils). 300 , 572 , 356 , (Mercury boils) )> 662 , , (Mercury boils) Table showinq the Specific G-batity corresponding with the- Degrees op BAUMfi's Htdromeiek. Liquids denser than Water. De- Specific De- Specific De- Specific grees. Gravity. grees. Oiavity. grees. Gravity. 1-0000 26 1-2063 52 1-6200 1 1-0066 27 1-2160 63 1-5363 ■ 2 1-0133 28- ; 1-2258 54 1-5610 3 1-0201 29 1-2358 55 1-5671 4 1-0270 30 1-2459 56 1-5833 5 1-0340 31 1-2562 57 1-6000 6 1-0411 32 1-2667 68 1-6170 7 1-0483 33 i-2773 69 1-6344 8 1-0556 34 1-2881 60 1-6622 9 1-0630 35 1-2992 61 1-6705 10 1-0704 36 1-3103 62 1-6889 11 1-0780 37 1-3217 63 1-707& 12 1-0857 38 1-3333 64 1-7273 13 1-0935 39 1-3451 65 1-7471 14 1-1014 40 l-3o71 ' 66 1-7674 15 1-1095 41 1-3694 67 1-7882 16 1-1176 42 , 1-3818 68 1-8095 17 1-1259 43 1-3945 69 1-8313 18 1-1343 44 1-4074 70 1-8537 19 1-1428 45 1-4206 71 1-8765 20 ■ 1-1515 46 1-4339 72 1-9000 21 1-1603 47 1-4476 73 1-9241 22 1-1692 48 1-4616 74 • 1-9487 23 1-1783 49 1-4758 75 1-9740 24 1-1875 60 1-4902 76 2-0000 25 1-1968 51 1-4951 K 242 THE ART OF SOAP-MAKING. Table showing the. Specific Gkavitt correspondino with the Deosees of Bauii£'s Htdsometee. Liquids lighter tlian "Water. Degrees. Specific Gravity. Degrees. Specific Gravity. 10 1-0000 36 0-8488 11 0-9932 37 0-8439 12 0-9865 38 0-8391 13 0-9799 39 0-8313 U 09733 40 0-8295 15 0-9669 41 0-8249 16 0-9605 42 0-8202 17 0-9542 43 0-8156 18 0-9480 44 0-8111 19 0-9420 45 0-8066 20 0-9369 46 0-8022 21 0-9300 47 0-7978 22 0-9241 48 0-7935 23 0-9183 49 0-7892 24 0-9125 50 0-7849 25 0-9068 51 0-7807 26 0-9012 52 0-7766 27 0-8957 53 0-7725 28 0-8902 54 0-7684 29 0-8848 55 0-7643 30 0-8795 56 0-7604 31 0-8742 57 0-7656 32 0-8690 58 0-7526 33 0-8639 59 0-7487 34 0-8588 60 0-7449 35 0-8538 61 0-7411 Taele of Essentiai, Oils. C Name. » Coloor Oil of absinthe (worm- wood) green „ dill yellow „ anise 1* „ ache, or parsley »» Name. Colour. il of mugwort yellow , , elecampane white „ badlane yeUow „ angelica ,. Portugal j» USEFUL NOTES AND TABLES. 243 Table of Essential Oils — (continued). Name. Coloui. Kame. Colour. il of oinnamou yellow Oil of yarrow blue and „ chamomile blue green „ oajeput green marjoram yellow „ cascaiilla yellow mustard deep brown „ caraway >j nutmeg yellow „ cherril lemon yel- neroli orange low pennyroyal yellow „ lemon yellowish rosemary white „ cocUearia j» sage green „ coriander white saffron yellow „ cumin yellow sassafras »» „ dittany brown turpentine white „ fennel white thyme yellow or „ galangal yellow pale green „ genista »» rose white „ juniper green valerian green „ ginger yellow pimento slightly „ cloves tt yellow „ hyssop rhodium yellow „ lavender it savin limpid „ cherry laurel >t tansy yellow ,, crisp mint white rue yellow- „ peppermint It green yellow „ balm mint )i bergamot „ motherwort blue serpolet (lemon thyme) lightbrowu Fusing and Congealinq Points op Fats and Oils. Substance. Degrees Fahrenheit. Castor and poppy oils freeze at or Zero. "Walnut-oil freezes , 15° Oil of beechnuts freezes 29° Almond-oil congeals • „ 30° Olive-oil freezes , 36° Horses' fat fuses „ 55° Cocoa-nut oU solidifies „ 70° Lard fuses , 74°'5 Oil of roses and oil of cedar-wood solidify at 79° Lard melts at 97° Spermaceti fuses ,, 107° Palm-oil melts , 117J° Margarine fuses „ 120° Tallow fuses , 127° Bees' -wax fuses ,, 150° Stearine melts „ 158° Eesin becomes soft „ 160° Dammara resin fuses „ 164° 244 THE ART OF SOAP-MAKING. KTJRTEN'S TABLE Showing the Composition and Pboduct of Soap by thb Cols Pbo- CKSS PBOM OONOENTEATED LeT AND ]yllXT0BE OP CoOOA-NDT On. WITH Palm-oil, Labd, and Tallow. Soap. 1 30 h go i Ley. 1 1| fi iS 1 1 Cocoa-nut oil No. 1 J» 100 j» 56 36 }l 153 Facia toilet, round 20 30 8 31 36 5 36 87 f) 25 75 50-62 36 »» 1> 150 Windsor, square 66 34 »» 77 30 13 30 185 66 34 J> ,, >» » jr >J n jT »» Shaving No. 1 or or »» JJ 120 27 }' Jt ft 214 ii3 34 33 1) a »» Shaving No. 2 ii3 34 33 )J 120 27 12 12 i> 224 Washing No. 1 6U 40 „ JJ >» n 3* »» ») J» or or >» »» 125 27 25 12 »» }> 244 3U 40 30 ,, -•» )J ]) J) >, „ No. 2 4U 60 or jj >» 135 27 .If 50 16 J> 278 ' )> 100 j> » ,, J* )» 31 if 31 II or or jj » >i »» »J ,, t1 ft )» Ordinary ooooa-oil i 10 90 3> » 225 21 75 12 »» i9 400 or »» J) ,, J) » » ;> JJ • j> ^ 90 10 J» )> J) ))' » J) » Boiling Points op some Volatile Oils. Snlistaiice. ^ Degrees EaJuenlieit. Oil of sassafras hegins to hoil at 223 „ tar (creosote) begins to boil at .... ; 280 „ amber boUs at 284 „ hyssop „ 289-4 „ grass „ 297 „ garlic „ 302 „ coriander „ 302 „ elemi , 345 „ bitter almonds boils at 350 „ thyme boils at 356 „ orange-peel boils at 356 USEFUL NOTES AND TABLES. 24s \S BoiLiNO Points of Caustic Alkaline Lets. Alkaline Ley. Specific Gravity. Pcroentoge of Alkali. Boils at Degrees Fahrenheit. Soda 1-18 13 217 Potash.... 1-23 19-5 220 Soda .... 1-23 16 220 Potash.... 1-28 23-4 224 Soda .... 1-29 19 224 Soda .... 1-32 23 228 Potash.... 1-33 26-3 229 Soda .... 1-36 26 235 Soda 1-40 29 242 Potash.... 1-42 34-4 246 Soda .... 1-47 34 255 Potash.... 1-44 36-8 255 Soda .... 1-5 36-8 265 Potash.... 1-.52 42-9 276 Potash.... 1-6 46-7 290 Soda .... 1-63 46-6 300 Potash.. .. 1-68 51-2 329 Tablb shotino the Quantity op Caustic Soda in Lets op DippERENT Densities (Watek 1000). Specific Soda Specific Soda Gravity. Per Cent. Gravity. yer Cent. 1-00 0-00 1-22 20-66 1-02 2-07 1-24 22-58 1-04 4'-02 1-26 24-47 1-06 5-89 1-28 26-33 1-08 7-69 1-30 28-16 110 9-43 1-32 29-96 1-12 11-10 1-34 31-67 1-14 12-81 1-35 32-40 1-16 14-73 1-36 33-08 1-18 16-73 1-38 34-41 1-20 18-71 " « ^46 6 THE ART OF SOAP-MAKING. Tablb op the Mbchanicai. Powek of Steam. Fiessoies. TempeTa- tnieiu Degrees of I'ahreDheit. Pressures. Tempera- ture in Decrees of Fahrenheit. Atmo- sphere. Founds pers^ Atmo- sphere. Pounds per^square 1-00 1-25 1-50 1-76 2-00 2-25 2-60 2-75 3-00 3-25 3-50 3-75 4-00 14-70 18-38 22-05 25-72 29-40 3308 36-75 40-42 44-10 47-78 51-45 55-12 58-18 212-00 223-88 234-32 242-78 250-79 257-90 263-93 269-87 275-00 279-86 284-63 288-66 292-91 4-50 6-00 6-00 7-00 8-00 9-00 10-00 12-50 15-00 17-60 20-00 25-00 30-00 66-15 73-50 88-20 102-90 119-60 132-30 147-00 183-75 220-50 257-26 294-00 367-50 441-00 300-27 307-94 320-00 331-56 340-83 361-32 359-60 377-42 392-90 406-40 418-56 499-34 457-16 INDEX. A BSINTHE, oil of, 241 -c*- Ache, or parsley, oil of, 241 Acid, arsenious, 174 benzoic, 175 boracic, 181 carbolic, 124, 175 carbonic, 8 chromic, 27 cocinic, 8 elaiodic, 27 hydrochloric, 203 hyponitrous, 27 margaric, 8 margaritic, 27 muriatic, 92 nitric, 2@ nitrous, 230 oleic, 8 palmitic, 8 pyroligneous, 219 ricinic, 27 salicylic, 175 stearic, 10 sulphuric, 29 tannic, 175 tartaric, 203 terebic, 231 test, 189 thymic, 124 Acids, fatty, 8 Adulterations of commercial silicate of soda, 237 Albumen, 219 Alcohol, 9 Alizarine, 121 Alkali, 10 carbonated, 28 caustic, 9, 44 Alkalies, 29 samples of, 193 Alkalimeter, 188 Sink's, 190 Mohr's, 190 Alkalimetry, 188 Alkaline ley, 9 leys, boiling-points of, 244 to prepare, 33 Alkanet root, 172 Almond cream, 165 oil soap, 152 Almonds, bitter oil of, 166 Altenburge's resin soap, 226 Alum, 69, 94 Alumina, 41 silicate of, 109 sulphate of, 69 Aluminate of soda, 229 soap, 230 Alumino-ferruginous soap, 41 Allan's process for recovery of gly- cerine, 219 Amberette^ lard with, 159 Ambergris, 159 oU of, 150 soap, 159 American potash, 128 Ammonia, liquid, 177 and camphor soaps, 176, 180 Analyses of soft soaps, 231 Analysing or assaying soaps, 201 Anderson's process for treatment of nigers, 72 Angelica, oil of, 241 Anhydrous soda, 189 Aniline, fast red, 158 Animal oil, 130 soap, 125 tissues, 124 Anise, oil of, 241 Anthracene salt, 185 248 INDEX. Antlinonial soap, 173 Antimony, golden sulphniet of, 173 Apparatus and appliances, 16 barring, 23 for re-melting the soap, 140 Archil, tincture of, 170 Areometer, 228 Arsenical soap, 174 Arsenjous acid, 174 Ash, black, 41 soda, 29, 93 Assay, of soap, 201 alkalies, 194 Assaying alkalies, 194 B'Arcefs method, 205 Bampel's method, 204 Bichardson and Wattes met' o 206 soaps, 201 Assays, commercial, 195 Australian tallow,. 26, 53 BADIANE, oil of, 241 Balm mint, oil of, 242 Balsam of Peru, 162 Tolu, 162 Balling, 156 Balls, sand, 164 scouring, 227 wash, 161 Bankmann's process, 184 Barilla, 2, 29, 93 Barium, chloride of, 199 Barring apparatus, 23 Baryta, carbonate of, 199 Bauxite, 229 Beech-nut oil, 28, 242 Beef marrow, 83 Bees'-wax, f using-point of, 242 Belgian soap, 136 soft or green soap, 231 Benzoic acid, 175 soap, 175 Benzoin soap, 153 tincture of, 153 Benzole, nitro, 86 Bennett and Cribbs's process, 117 Benno, Japp£, and Co.'s method of re- covering glycerine, 222 Bergamot, essential oil of, 149, 242 Bernardet's process, 124 Besson and Remy's process, 182 Bicarbonate of potassa, 176 soda, 93 Bichford's process, 187 Bichromate of potash, 26, 92 potassa, 200 Bink's alkalimeter, 190 Binoxalate of potash, 139 Bitter almond soaps, ISO almonds, oil of, 150 Black ash, 41 garden poppy oil, 44 ivory, 167 resin, 177 soap, 172, 174 Bleached palm-oil, 49 Bleaching, Watfs chrome process, 208, 209 palm-oil with chromate of lime, 211 powder, 112 soap in the pan, 115 Blue, Prussian, 52 Boiling, 56, 64 over, to prevent, 238. points of caustic alkaline leys, 243 points of some volatile oils, 224 to "strength," 72 Bole, 163 Bone-fat, 123 grease, 28 Boracic acid, 181 Borax, 139 soap, 180 soap-powder, 227 soft soap, 227 toilet soap, 175 Bordhardt's herb soap, 174 Bran, 69, 175 soap, 175 Bromine, 175 Brown ochre, 157 oil, 85 soap from, 85, 139 Spanish, ISO Windsor soap, 150 Burette, 189 " Bink'e, 190 Mohr's, 190 Burnt sienna, 153 Butter, cocoa, 73 pACAO, oil of, 166 ^ Cadmium yellow, 158 Cajeput, oil of,"242 Calcined flint, 98 quartz, 98 soda. 111 Calcium carbonate, 220 Caldron, 81 Camphine, 180 Camphor, 162 and ammonia soaps, 180 INDEX. 249 Camphor, savonnettes of, 162 I ice soap, 175 t Caramel, 151 Carbolic acid, 124, 175 soap, 173 Carbonate of batyta, 199 lime, 23 potash, 100 1 soda, 28 ' Carbonated alkali, 28, 92 leys, 121 of potassa, 12 Carbonic acid, 8 Caraway, oil of, 150, 242 Cascarilla, oil of, 242 Castile soap, 8, 36, 161 Castor-oil, 27 oil soap, 175 Cassia, 86 powdered, 151 Caostic alkali, 9, 44 alkaline leys, boiling-points of, 244 ley, strong, 82 leys, 32, 121 lime, 233 potassa, 12 soda, 8, 29 Causticising soda, 236 Cedar wood, oil of, 242 Cerates, 36 Chalk, 29 French, 180 prepared, 173 Chamomile, oil of, 242 Charcoal, ground, 100 Cheap almond soap, 231 Cheapened soaps, 96, 105 Chervil, oil of, 242 Cherry laurel, oil of, 242 Chevreul's discovery, 3 theory, 7 China clay, 31, 105 in soap, 109 Chlorate of potash, 181 potassium, 198 Chloride of barium, 199 lime, 112 potassium, 13 soda, 85, 112, 114 sodium, 13 Chloridised sanitary soap, 112 Chlorinated soap, 113 Chromate of lime, 208 bleaching palm-oil with, 211 Chrome, recovery of, 210 Chromic acid, 27, 208 Chromic oxide, 220 Chromium, oxide of, 210 sesquioxide of, 219 Cinnamon, essential oil of, 149, 242 soap, ISO tincture of, 162 Citronella, oil of, 157, 242 Clarified resin, 237 Clay, China, 31, 105 pipe. 111 Cleansing, 60 Cleaver's process, 186 > Clolus's method of recovering glycerine, 220 Cloth manufacture, soap used in, 223 Cloves, essential oil of, 149, 242 powder of, 150 Cochlearia, oil of, 242 Cocinic acid, 8 Cocoa butter, 73 nut oil, 27, 73, 75 soaps, 71, 74, 75, 77 oU, 75 Cocos nucifeira, 27 Coction, 43 leys of, 63 Coke, ground, 100 •Cold process (Hawes's), 79 soap, 133 soft ley, 46 Coleseed oil, 42, 130 Colophony, 28, 177 Colza oil, 28, 130 Combined soaps, 115 Commercial assays, 195 soda, 197 Common salt, 10 Comparative French and English thermometer scales, 239 Composition of pure olive-oil soap, 50 Continental method of making yellow soap, 62 Continental soaps, 135 Cooling worm, 68 Copper or soap-pan, 17 Copperas, green, 41 Coriander, oil of, 242 Corn-meal soap, 175 Corrosive sublimate, 172 Cotton-seed oil, 28 Cream, almond, 165 of whiting, 220 Creams, soap, 166 Creme' ambroisie, 166 de cacao mousseuse, 166 Creosote, 124 Crevel's process, 126 250 INDEX. Crisp mint, oil of, 242 Croton oil, 175 soap, 175 Crude glycerine, 218 soda, 43 soft soda, 43 Cratch, steam, 16, 20 Crutches, 16, 20 " Cratehed in," 20 Crntching-pot, 20 spindle, 21 Crysolite, 229 Crystals, soda, 88 Cumin, oil of, 242 Curb, 17 iron, 132 Curd soap, 39 white, 53 stiff, 101 Cutting machine, 24 soap, 127, 146 into shavings, 156 « Cutting the pan," 38 TVALTON'S theory, 189 -L' Dammara resin, 242 D'Arcet's method of assaying, 205 Davis's process. 111 Descroizelle's invention of the alkali- meter, 188 Detection of resin in soap, 232 Detergent mixture, 98 Dextrine, 160, 174 Diachylon plaster, 8 Dill, oil of, 241 Disinfecting mixture, 112 soap, 112, 124 Dittany, oil of, 242 Douglas's Improvements, 109 Dresden palm soap, 226 Dry white soap, 170 Dunn's method of purifying oils, 213 process, 105 of marking soaps', 187 EARTH-NUT oil, 42 Effloresced soda, 93 Elaine, 25, 27 Elaiodic acid, 27 Elais guineaensis, 27 melanococca, 27 Elder-flower soap, 160 Elecampane, oil of, 241 English soft soap, 135 tallow, 209 Essence de savon Corinthe, 170 de savon Vienne, 169 Essence of soap, 1C9 Essential oil of bergamot, 149, 242 oil of cinnamon, 149, 2^ oil of cloves, 149, 242 oil of rose, 149, 242 oils, table of, 241 Ether, 232 FANCY soaps, 140 Farina, 161 Farriers' soap, 174 Fat acid, 87 bone, 123 hogs', 26 horses', 242 Wakefield, 86 Yorkshire, 28 Fats, 26 and oils, Justice's method of puri- fying, 213 Dunn's method, 213 fusing and congealing points of, 242 Fatt^' acids, 8, 41 FeciiJa, 202 Felspar, ground, 100 Fennel, oU of, 162, 242 Ferric oxide, 237 Finishing the soap, 39, 61 First ley, 129 soap patent, 2 Fish-oils, 8, 28, 212 Fitted soaps, 14, 61 Fitting, 55, 64, 71 the soap, 91 Flint, calcined, 98 Floating soaps, 11 savonnettes, 163 FIoccuIk, gelatinous, 11 Flour, potato, 187 Foam or fob, black, 47 Frames, 19 iron, 16, 19 soap, 20 wooden, 16, 19 Free alkali, 34 French chiQk, 180 cocoa-nut oil soaps, 77 formulse for soaps, 49 marbled soaps, 42 system of making toilet soaps, 154 toilet soaps, 154 Fresh vat, 32 Fuller's earth soap, 109 Fulling soap, 138, 238 Fusing and congealing points of fats and oils, 242 INDEX. 251 n ALANGAL, oil of, 242 'J Gall, ox, 227 Gamboge, 153 Gauging stick, 24 Gelatinous floccalffi, 11 Genista, oil of, 242 Gentsle's process, 137 Geranium, oil of, 157 Gilliflower, powder of, 150 Ginger grass, oil of, 162 oil of, 242 Glass liquor, 114 soluble, 30 Glauber's salt, 31 Gluten, 122 in soap, 122 Glycerine, 7, 10, 14 Allan's, 219 Benno, Japp6, & Co.'s, 222 CIolus's, 220 crude, 218 Lawson and Sulman's, 219 O'Farrell's, 218 Payne's, 216 recovery of, 215 soap, 160 Thomas and Fuller's, 218 Versmann's, 217 Young's process, 215 Glyceryl, oxide of, 10 Golden sulphuret of antimony, 173 Goose-fat, 8 Gossage's processes, 99 Grain, soap, 11 Gravimetric assaying, 189 Grease, bone, 25, 28 horse, 25, 28 recovered, 28 soap, 69 Green copperas, 41 vitriol, 44 Ground charcoal, 100 coke, 100 felspar, 100 suet, 161 Gum tragacanth, 158 Guppy's process, 106 TTALF-resin soap, 176, 183 -'-'- Hampel's shaving soap, 178 Hand pumps, 22 Hard soaps, 8, 29, 36, 58, 71 or unsalled soaps for milling cloth, 224 Hawes's system (cold process), 79 Hempseed oil, 28, 130 Higgins's process, 183 Hogs' fat, 26 lard, 151 Holland soft soap, 134 Honey, 163 savonnettes, 162 Horse-grease, 28 OH, 8 Horses' fat, fusing-point of, 242 Hydrate of potassa, 196 soda, 189 Hydrochloric acid, 203 Hydrometer, Baum^'s, 37, 240 Twaddell's, 235 Hyponitrous acid, 27 Hyssop, oil of, 242 TCELAND moss, 139 J- Indigo, 134 Instantaneous soap, 94 Intestines^ soap made from, 124 Iodine, 174 soap, 175 Irish moss soap, 175 Iron curb, 132 frames, 19 oxide, 45 pans, 17 peroxide of, 41 pumps, 16 rake, 51 salts of, 46 sulphate of, 41 sulphuret of, 41 Ivory black, 157 JACKET-PANS, 238 " Jacobson's process, 137 Jasmine pomade, 169 Jeyes's process, 185 Jennings's processes, 176 Juice, lemon, 178 Juniper, oil of, 242 tar, 173 Justice's method of purifying and bleaching oils and fats, 213 EAOLIN, 31, 109 Kelp, 29, 93 Kettle, 17, 225 Kitchen-stuff, 28 waste, 28 Kottula's soaps, 94 Kurten's table, 243v T ADLES, 16 -L', Lard, hogs', 26, 161 soap by cold process, 83 with amberette, 159 252 INDEX. Laid with lettnce, 159 raniUa, 1S8 Laundry soaps, 82 Lavender, oil of, 150, 242 water, 169 Lawson and Salman's process for re- covering glycerine, 219 Lead, margarate of, 8 oxide of, 8 red, 145 Leblanc's process for making soda, 3 Lemon grass, oil of, 160 juice, 178 oil of, 153,242 soap, 160 Lettuce, lard with, 159 soap, 159 Levafs process, 178 Lewis's process, 179 Ley, alkaline, 9 caustic, 9 cold soft, 46 potassa, 13 soda, 33 soft, 44 strong, 129 tank^ 16, 19, 32 Leys, caustic, 32, 121 of coction, 63 potash, 128 salted, 46 soda, 33 spent, 38, 215 waste, 22 Lichen, 178 Liebig's researches, 10 Lime, 8, 33 carbonate of, 23 chloride of, 112 chromate of, 208 liquor, 94 milk of, 129 slaked, 23, 33 soap, 84, 116 „ Lunge's method of making, 116 sulphate of, 84 waste, 23 Liniments, 36 Linseed oil, 28, 130 Liquid ammonia, 177 glycerine soap, 173 soaps, Schar^s, 186 Liquor, lime, 94 Liquored soaps, 232 Litharge, 8 Litmus, 197 London " Crown soap," 133 mottled, 50 soap-powder, 227 tallow, 26 Lumbarton'a process, 124 MACHINE, barring, 23 cutting, 24 for slicing soap, 142 for stamping soap, 147 Magnolia, oil of, 174 Maize flour, 175 Making oleic soaps, 93 Manganese, oxide of, 94 Manufacture of hard soaps, 36, 58, 71 of soft soaps, 128, 136 of toilet soaps, 140 Marble savonnettes, 163 Margarate, 10' of lead, 8 Margaric acid, 8 Margarine, 25, 37 Marine soap, 73 Marjoram, oil of, 162, 242 Marrow, beef, 83 Marseilles soap, 36 Marsh's, Sir H., sulphur soap, 171 Marshmallow soap, 153 Materials used in soap-making, 25 Matters, membranous, 124 Meat, residuum of, 125 Medicated soaps, 172 tar soap, 173 I Medicinal soft soap, 172 Meinicke's process, 68 Membranous matters, 124 Mercurial ointment, 175 soap, 172, 175 Mercury, 105 bath, 119 Metallic soap, 8, 40 Methods of analysing and assaying soaps, 201 D'Arcet's, 205 of preparing leys, Tennant h Co.'a, 33 Rampel's, 204 Richardson and Watt's, 206 Methylated spirit, 203, 218 Milk of lime, 129 Mineral, orange, 153 Minium, 159 Mint, oil of, 153 Miscellaneous processes, 176, 223 Bastetfs process, 181 Besson and Bemy's process, 182 Bichford's process, 187 INDEX. Cleaver's process, 186 Cooper and Smith's process, 180 Sunn's process, 187 Hampel's process, 178 Higgins's process, 183 Jennings's processes, 176 Jeyes's process, 185 Levat's process, 178 Lewis's process, 179 Lorbury's process, 186 Macltay and Sellers's process, 181 Marriott's, Mrs., process, 179 Payne's process, 184 Eowbottom's process, 180 Scharr's process, 186 Symons's process, 124 Tardani's process, 182 Varicas's process, 185 Violefs process, 178 Waller's process, 179 M. Loch's soft soap, 139 Mohr's alkalimeter, 190 Molasses, 232 Morfit's steam series, 16 system of soap-making, 86 Moss, Iceland, 139 soap, Irish, 125 Motherwort, oil of, 242 Mottled soap, 8, 50 Mottling, 47 notes on, 48 Mrs. Marriott's process, 179 Mugwort, oil of, 241 Muriatic acid, 92 Musk soap, 150 . tincture of, 158 Mustard, oil of, 242 Mutton tallow, 160 Myrtle, oil of, 162 NAPLES soap, 165 Naphthaline vellow, 160 Neroli, oil of, 162,"242 savonnettes of, 162 Neutral fatty bodies, saponification of, 232 Neutral soap, 88, 233 New process of saponification, 120 Niger, or Nigrp, 40 Nigers, treatment of, 71 Nitric acid, 26, 178 Nitro-benzol, 86 Nitrous acid, 130 Notes on mottling, 48 useful, and tables, 228 Normandy's method of assaying, 196 process, 96 Nut, cocoa, oil, 8, 27 palm, oil, 8, 25, 26 Nutmeg oil, 242 OATMEAL soap, 175 Ochre, 202 brown, 150, 157 yellow, 157 O'Farrell's process for recovering' gly- cerine, 218 Oil, almond, 242 animal, 130 lieechnut, 28 black garden poppy, 44 bleached palm, 49 brown, 84 castor, 27 cocoa-nut, 8, 27, 75 cod, 130 coleseed, 42, 130 colza, 28, 130 cotton-seed,- 28 croton, 175 earth-nut, 42 fish, 8, 28 hempseed, 130 horse, 8 linseed, 28, 130 olive, 8, 25, 130 palm, 8, 25, 26 palm-nut, 161 petroleum, 175 poppy, 28, 130 rapeseed, 26, 130 raw palm, 75 red, 83 seal, 130 sesame, 26, 161 sesamum, 28 sperm, 133 taUow, 25, 161 turpentine, 68 vegetable, 130 volatile, 243 walnut, 242 whale, 130 yellow cocoa-nut, 158 of absinthe, 241 of ache or parsley, 241 of ambergris, 150 of angelica, 241 of anise, 241 of badiane, 241 of balm mint, 242 of beechnuts, 242 of bergamot, 242 of bitter almonds, 150 of cacao, 166 254 INDEX. Oil of cajeput, 242 of caraway, 152, 242 of cascarilla, 242 of cedar-wood, 242 of chamomile, 242 of cheny laurel, 242 of cherril, 242 of cinnamon, 242 of citronella, 157 of cloves, 2^ of cochlearia, 242 of coriander, 242 of crisp mint, 242 of cumin, 242 of dill, 241 of dittany, 242 of elecampane, 241 of fennel, 162, 242 of galangal, 242 of genista, 242 of geranium, 157 of ginger, 242 of ginger grass, 162 of hyssop, 242 of juniper, 242 of lavender, 150, 242 of lemon grass, 160 of magnolia, 174 of marjoram, 242 of mint, 153 of motherwort, 242 of mugwort, 241 of mustard, 242 of myrtle, 162 of neroli, 149, 242 of nutmeg, 242 of orange-peel, 160 of pennyroyal, 242 of peppermint, 242 of pimento, 242 of Portugal, 241 of rhodium, 242 of rose, 242 of rosemary, 242 of rue, 242 of saffron, 242 of sage, 242 of sassafras, 242 of savin, 242 of serpolet, 242 of sweet almonds, 152 of tansy, 242 of thyme, 242 of turpentine, 242 of valerian, 242 of verbena, 153 of wild thyme, 162 of wormwood, 162 Oil of yarrow, 242 Oils and fats, 25 congealing-points of, 243 essential, table of, 242 fish, 212 purifying, 212, 213 Oleate of soda, 7, 84 Oleic acid, 8, 50 soaps, 93 Oleine, 8, 28 Oleometer, 228 Olive-oil, 8, 25, 130 Orange mineral, 153 flower soap, 149, 150 powder, 162 soap, 160 Orangine, 178 Origin of soap-making, 1 Orris root, 158, 161 Osmogene, 218 Otto of roses, 172 Ox-gall soap, 227 Oxide, chromic, 220 ferric, 237 of chromium, 210 of glyceryl, 10 of iron, 45 of lead, 8 of manganese, 94 Oxidising agent, 181 PALE soap, 60 Palmine, 27 Palmitic acid, 8 Falmitine, 7 Palm-oil, 26, 130 bleaching, by C. Watt's process, 209 Palm soap, 157 Violef s, 178 Pans, iron, 16 jacket, 238 , soap, 17 Papin's digester, 62, 233 Paraffin soap, 175 Parchment, vegetable, 139 Paris toilet soaps, 156 Paste, lime, 32 shaving, 168 Pasting, 129 Payne's process, 84 process for recovery of glycerine, 216 Pearlash, 111 Pearlashes, testing, 198 Pearl soap, 166 Pennyroyal, oil of, 242 Peppermint, oil of, 242 INDEX. 255 Peroxide of iron, 41 Peru, balsam of, 162 Petroleum oil, 175 soap, 175 Bastet's process, 181 Pickling soap, 228 Pigment, yellow green, 159 Pimento, oil of, 242 Pipeclay, 111 Plaster, diachylon, 8 . Plasters, 36 Plastic soap, 11 Platinum, diohloride of, 207 Pomade, rose, 158 Poppy oil, 25, 28 Portugal, oil of, 241 Potash, 30 American, 128 bichromate, 92 binoxalate, 139 carbonate, 100 chlorate of, 181 ley, preparation of, 128 leys, 128 Eussian, 186 silicate of, 100 soap, 13, 128 soaps, 8, 99 stearate of, 132 Potassa, 13 bicarbonate of, 176 bichromate of, 220 carbonated, 12 caustic, 12 ley, 13 silicate of, 30, 96 Potassium, chlorate of, 198 chloride, 13 Potato-flour, 187 in soap, 108 in soft soap, 232 Pot, crutching, 21 Powder, bleaching, 112 borax soap, 223, 227 London soap, 223, 227 orange, 162 of cloves, 150 of gilliflower, 150 of pale roses, 150 Powdered cassia, 151 orris-root, 158 resin, 69 soap, 168 Preparation of soda ley, 33 potash ley, 100 resin soap, 64 silicate of soda, 100 Preparation of silicate of potash, 100 test-acid or standard solution, 192 Prepared chalk, 173 Process, cold, 79 Processes for the recovery of glycerine, 215 Allan's, 219 Benno, Japp6, and Co.'s, 222 Ololus's, 220 Lawson and Sulman's, 219 O'Farrell's, 218 Payne's, 216 Thomas and Fuller's, 218 Versmann's, 217 Young's, 215 Prussian blue, 52 Pumice, 164 Pumps, iron, 16 Punner, 129 Pure olive-oil soap, 36 Purifying and bleaching fats and oils, 213 Pyroligneous acid, 219 Pyroxylic spirit, 174 QUANTITY of resin in soap, to de- termine, 230 Quartz, 30 calcined, 98 Quicklime, 33 EAMPEL'S method of assaying soaps, 204 Kancid tallow, 58 Eapeseed oil, 26, 130 Eaw palm-oil, 75 Kecovered grease, 28 Becovery of chrome, C. Watt, junior's, process, 210 glycerine, 215 Eectified spirit, 172 Bed lead, 145 oil, 83 Ee-melting the soap, 144 Eendered tallow, 53 Eesin, 8, 28 black, 177 clarified, 237 Dammara, 242 in soap, detection of, 232 powdered, 69 soap, 58 preparation of, 64 soft soap, 134 yellow, 28 Eesinous soap, 62 Eogera's process, 120 256 INDEX. Rose, essential oil of, 149 leaf soap, 158 oil of, 242 soap, 77, 149 water, 163 Rosemary, oil of, 242 Eoses, otto of, 172 powder of, 150 Bhodium, oil of, 158 Bicinic acid, 27 Kicinus communis, 27 River-sand, 164 Root, alkanet, 172 orris, 158 Rouge, 163 Rue, oil of, 242 Runnings, first, 33 second, 33 Russian potash, 186 soft soap, 137 tallow, 26 SAFFRON, 169 oil of, 242 8age, oil of, 242 Salad-oil, virgin, 25 Sal ammoniac, 94 Salicylic acid, 175 soap, 175 Saline ley, 40 Sal soda, 93 Salt, anthracine, 185 common, 10 Glauber's, 31 of sorrel, 139 truck, 39 Salted leys, 46 soda, 42 Salting point, 219 Salts of iron, 40 sulphur, 40 Sampling alkalies, 193 Sand-balls, 164 river, 164 Sanitary soap, 112 Saponaria officinalis, 139 Saponification explained, 7 new process of, 120 of neutralfatty bodies by soap, 233 under pressure, 117 Saponifying, 9 Sassafras, oil of, 242 Savin, oil of, 242 Savon a la cannelle, 152 a la MarSchale, 159 a la rose, 149 au bouquet, 152 Savon aux fleurs d'ltalie, 157 d'amandes ameres, 150 , de Corinthe, essence de, 170 de Crimie, 157 de gnimauve, 166 de palme, 157 de Vienne, essence de, 169 vert, 135 Savonnettes or Washballs, 161 a la vanille, 162 au miel, 163 floating, 163 marble,. 163 of camphor, 162 of neroli, 162 of sweet herbs, 162 Sawdust in soap, 179 Scented soaps, 140 Scharr's process, 186 Scotch soft soap, 231 Scouring balls, 227 Screw press, 148 Seal oil, 130 Second ley, 129 runnings, 33 Seed, cotton, oil, 28 Semi-hard soap, 231 Separation, 43 Serpolet, oil of, 242 Sesame oil, 26, 161 Sesamum oil, 28 Sesquioxide, chromium, 219 Shaving paste, 168 soap, Hampel's, 178 Shoots, 23 Sienna, burnt, 153 Silica, 105 Silicate of alumina, 109 of potash, 100 preparation of, 100 of soda, 30, 98 preparation of, 30, 100 adulteration of, 237 Silicated soaps, Sheridan's process, 98 Gossages processes, 99, 101, 103 Skin soap. 111 soaps, 175 Slaked lime, 23, 33 Sliced soap, 146 Soap, almond-oil, 152 alumino-ferruginous, 41 ambergris^ 159 ammonia and camphor, 180 analysing, 201 animal, 125 antimonial, 173 apparatus for re-melting, 140 INDEX. 257 , arsenical, 174 assay, 201 assaying, 201 Belgian, 136 soft, or green, 231 benzoic, 175 benzoin, 153 bitter almond, 150 black, 174 bleaching in the pan, 115 Iborax, 180 soft, 227 toilet, 175 Bordhardt's herb, 174 bran, 175 brown oil, 85, 139 Windsor, 151 camphor, 180 ice, 175 carbolic acid, 173 Castile, 8, 161 or olive oil, 36 Castor-oil, 175 cheap almondj 231 cheapened, 96, 105 chloridised sanitary, 112 chlorinated, 113 cinnamon, 150 cocoa-nut oil, 73 cold, 133 Continental, 135 copper or pan, 17 corn-meal, 175 creams, 166 croton oil, 175 cutting, 1?7, 146 disinfecting, 112 Symons's, 124 Dresden palm, 226 dry white, 170 elder-flower, 160 essence of, 169 factory, its apparatus and ap- pliances, 16 fancy, 140 farriers', 174 fitted, 14 frames, 19 French marbled, 42 formulae for, 49 fuller's earth, 109 fulling, 138 gluten in, 122 glvcerine, 160 half-palm, 237 half-resin, 183 hard, manufacture of, 36, 58, 71 Soap, household, 82 instantaneous, 94 iodine, 175 Irish moss, 175 lard, by cold process, 83 laundry, 82 lemon, 160 lettuce, 159 lime, by Lunge's method, 116 Iiquid,"Schar?s, 186 glycerine, 173 liquored, 75 London " crown," 133 mottled, 50 grey mottled, 113 machine for slicing, 142 marine, 73 Marseilles, 36 marshmallow, 153 medicated tar, 173 medicinal soft, 172 mercurial, 172 metallic, 8, 48 mottled, 50 musk, 150 Naples, 165 neutral, 88 oatmeal, 175 oleic acid, 88, 93 orange, 160 orange-flower, 150 ox-gall, 227 palm, 157 Dresden, 226 Violet's, 178 pans, 17 paraffin, 175 patent, the first, 2 pearl, 166 petroleum, 175 Bastet's process, 181 pickling, 228 potash, 8, 13, 128 potato-flour in, 108 powder, London, 227 powdered, 168 pure olive-oil, 36 composition of, 50 re-melting, 144 resin, 58 Altenburge's, 226 preparation of, 64 resinous, 62 rose, 77, 149 rose-leaf, 158 Eussian soft, 137 salicylic, 175 258 INDEX. Soap> sawdust in, 179 Scotch soft, 132 shaving, Hampd's, 1TB silicated, 96, 98, 101, 103 skin, 1T5 soda, S borax, 227 English, 135 medicinal, 172 M. Loch's, 139 potato-flour in, 232 resin in, 134 Russian, 137 Scotch, 132 soft, 236 • toilet, 166 stamping, 146 sulphur. Sir H; Marsh's, 172 tallow, 53 tannin, 175 tar, 174 terebene, Cleaver's, 186 thymol, 124, 175 toilet, 140 tooth, 173 transparent, 8, 9, 170 turpentine, 174 unsalted, 224 used in cloth manufactories, 223 vanilla, 153, 158 violet Windsor, 151 (yeUow), 158 A^olers palm-oil, 178 wax, 175 white and rose, 77 - cocoa-nut oil, 225 curd, 53 soft, toilet, 166 to prepare, 82 Windsor, 150 brown, 151 yellow, or resin, 58 for silks and printed goods, 138, 238 for washing dogs, 174 from recovered grease, 84, 85 Soaps, camphor and ammonia, 180 cheapened, 96, 105 combined, 115 French cocoa-nut oil, 77 hard, manufacture of, 36, 58, 71 Kottula's, 94 made from animal refuse, 124 marking, 187 medicated, 172 potash, 8, 128 Soaps, saponification of neutral fatty bodies by, 233 scented, 146 silicated, 98 soda, 128 soft, analysis of, 231 manufacture of, 128, 136 toilet, French system of making, 154 [154 toilet, manufacture of, 140, 149, soft, 165 French formulae for, 156 yellow, to make with cocoa-nut oil, 75 Soap-making by cold process, 79 materials used in, 25 origin of, 1 Soapstone, 187 Soapwort, 139 Soda, aluminate of, 222 anhvdrous, 189 ash," 29, 93 bicarbonate of, 93 calcined. 111 carbonate of, 28, 93 caustic, 8, 29 causticising, 236 chloride of, 85, 112, 114 crude, 2, 43 soft, 43 crystals, 88 effloresced, 93 hydrate of, 189 oleate of, 9, 84 sal, 93 salted, 42 silicate of, 30, 98 adulteration of, 237 mi^ng with soaps, 101 preparation of, 100 soaps, 8, 128 soft, 42 stearate of, 7 sulphate of, 31, 96 Sodium, chloride of, 13 Soft borax, 227 English, 128, 135 ley, 44 medicinal, 172 M. Loch's, 139 potato-flour in, 232 resin in, 134 Bussian, 137 Scotch, 132 soap, Bel^um, 136 toilet, 166 Soft soaps, analyses of, 231 INDEX. 259 Soft soaps, manufacture of, 128, 136 lesin in, 134 toilet, 166 Soluble glass, 98 Sorrel, salt of, 139 South American tallow, 26, Spanish brown, 150 Specific gravity bottle, 192 tables, 240, 241 Spent leys, 38, 218 Sperm-oil, 133 Spermaceti, 151, 159 Spirit, methylated, 203, 218 pyroxylic, 174 rectified, 172 wood, 227 Stamping the soap, 146 Starch, 161 Steam crutch, 20 series, Morfit's, 17 Steaming tub, 26 Stearate of potash, 132 of soda, 7 Stearates, 10 Stearic acid, 10 Stearine, 7 Steatite, 187 Stick, gauging, 24 Stiff curd, 101 Still-head, 68 Stirrer, 16 Stockholm tar, 174 " Strength," boiling to, 72 Strong caustic ley, 82, 129 Stuff, kitchen, 28 Sturtevant's process, 74 Sublimate, corrosive, 172 Sublimed sulphur, 172 Sud oil, 85 Suds of fulling miUs, 28 Suet, ground, 161 Sugar, burnty 151 Sulphate of alumina, 69, 177 of iron, 41 of lime, 84 of soda, 31, 96 Sulphur, 172 salts, 40 • soap. Sir H. Marsh's, 172 sublimed, 172 Sulphuret of iron, 41 sodium, 45 Sulphuric acid, 26 Sweet almonds, oil of, 83 Swimmer, 22 Symons's disinfecting soap, 124 Syphon, 34 rpABLE, Kiirten's, 243 L of fusing and congealing points of fats and oils, 242 of essential oils, 241, 242 of the mechanical power of steam, 246 showing percentage of an- hvdrous caustic potash in ley, 239 showing percentage of soda in caustic ley, 238 showing the quantity of caustic soda in leys of different densi- ties, 245 Tables showing specific gravity cor- responding with the degrees of Baum^'s hydrometer, 240, 241 Tables, useful notes and, 228 Tallow, 8, 26 Australian, 26 English, 209 London, 26 mutton, 160 rancid, 58 Kussian, 26 South American, 26 " town," 26 ' white, 49 Tank, ley, 19, 32 Tannic acid, 175 Tannin, 216 soap, 175 Tansy, oil of, 242 Tar, juniper, 173 soap, 174 medicated, 173 Stockholm, 174 Tardani's process, 182 Tartaric acid, 203 Terebene, 186 soap. Cleaver's, 186 Terebic acid, 231 Test-acid, 189 acid or standard solution, pre- paration of, 192 Testing commercial pearlashes, 198 Thermometer scales, comparative French and English, 239 Third ley, 129 Thomas and Fuller's process for re- covering glycerine, 218 Thomas's process, lb7 Thyme, oil of, 242 Thymic acid, 124 Thymol, 175 soap, 124, 175 Tincture of archil, 170 ■260 INDEX. Tincture of benzoin, 153 of cinnamon, 162 of musk, 158 of vanilla, 153 Tissues, animal, 124 To determine the quantity of resin in soap, 230 Toilet soap, fuller's earth, 110 soaps, French, f ormulie for, 154 soaps, French system of making, 154 manufacture of, 140, 149, 154 soft soaps, 165 Tolu, balsam of, 162 Tooth soap, 173 Town tallow, 26 Transparent soap, 170 Turmeric, yellow, 170 Turpentine, oil of, 68 Venice, 174 white, 68 ' Twaddell's hydrometer, 228, 235 ULTRAMARINE, 94 Umber, 151 Uncombined soap, 39 Unsalted soap, 224 Unsaponified fatty matter, 203 Useful notes and tables, 228 ■yALERIAN, oil of, 242 ' Vanilla, lard with, 158 soap, 153, 158 tincture of, 153 Varicas's process, 185 Various processes, 123 implements, 22 Vauquelin's system of estimating the value of alkalies, 188 Vegetable oils, 130 parchment, 139 Venice turpentine, 174 Verbena, oil of, 163 Vermilion, 145 Versmann's process for recovering glycerine, 217 Villacrose's process, 126 Villart's process, 125 Violet soap, yellow, 158 washballs, 161 Windsor soap, 151 Violefs palm-oil soap, 178 Virgin salad-oil, 25 Vitriol, green, 44 Volatile oils, boiling-points of, 243 Volumetric analysis, 189 WAKEFIELD fat, 86 '^' Walnut-oil, 242 Washballs, 161 violet, 161 Waste leys, 22 leys, recovery of glycerine from, 23, 215 lime, 23 Water, lavender, 169 rose, 163 Watt's fuller's earth soap, 109 process for bleaching palm-oil, 209 sanitary soap, 1 12 process for recovering chrome, 210 Wax, 158 bees', 242 soap, 175 white, 158 Whale-oil, 130 White cocoa-nut oil soap, 225 cocoa-nut oil soap, to make, 74 curd soap, 36, 53, 162 soap, 82, 77, 160 soft, toilet soap, 166 tallow, 49 tallow soap, 157 turpentine, 68 wax, 158 Whiting, cream of, 220 Wild thyme, oil of, 162 Windsor soap, 150 Wood spirit, 227 Wooden frames, 19 Wormwood, oil of, 162 YARROW, oil of, 242 ' Yellow, cadmium, 158 cocoa-nut oil, 158 soap, 75 green pigment, 150 naphthaline, 160 ochre, 145 or resin soap, 58 resin, 28 turmeric, 170 violet soap, 158 Yorkshire fat, or recovered grease, 28 Ypung's process for recovering gly- cerine, 215 I'RINTED BY J. S. VIRTDE AND CO., LIMITED, CITY BOAD, LONDON. London, Dtcmkr, 1883. INCLUDING MANY NEW AND STANDAKD WORKS IN ENGINEERING, ARCHITECTURE, AGRICULTURE, MATHEMATICS, MECHANICS, SCIENCE, ETC. PUBLISHED BV CROSBY LOGK^WOOD & CO., 7, STATIONERS'-HALL COURT, LUDGATE HILL, E.C. ENGINEERING, SURVEYING, ETC. 1 Number's Work on Water-Supply. A COMPREHENSIVE TREATISE on the WATER-SUPPLY of CITIES and TOWNS. By William Humber, A.-M. Inst. C.E., and M. Inst. M.E. Illustrated with 50 Double Plates, I Single Plate, Coloured Erontispiece, and upwards of 250 Wood- cuts, and containing 400 pages of Text. Imp. 4to, 6/. 6^. elegantly and substantially half-bound in morocco. List of Contents ;— I. Historical Sketch of some of the means that have been adopted for the Supply of Water to Cities and Towns.<^ II. Water and the Foreign Matter usually associated with it. — III. Rainfall and Evaporation.— IV. Springs and the watei> bearmg formations of various districts. — V. Measurement and Estimation of the Flow of Water.— VI. On the Selection of the Source of Supply.— VII. WeUs.— VIII. Reservoirs.— IX. The Purification of Water.— X, Pumps. — XI. Pumping Machinery.— XII. Conduits.- XIII. Dis- tribution of Water.— XIV. Meters, Ser- vice Pipes, and House Fittings. — XV. The Law and Economy of Water Works.— XVI. Constant and Intermittent Supply. — ^XVII. Description of Plates. — Appen- dices, giving Tables of Rates of Supply, Velocities, &c. &c. , together witli Specifi- cations of several Works illustrated, among which will be found : — Aberdeen, Bideford, Canterbury, Dundee Halifax, Lambeth, Rotherham, Dublin,, and other?. * The most systematic and valuable work upon water supply hitherto produced in English, or in any other language .... Mr. Humber's work is characterised almost throughout by an exhaustiveness much more distinctive of French and German than «f English technical treatises."— .£'*^>*^^n Humbef^s Work on Bridge Construction, A COMPLETE and PRACTICAL TREATISE on CAST and WROUGHT-IRON BRIDGE CONSTRUCTION, including Iron Foundations, In Three Parts — Theoretical, Practical, and Descriptive. By William Humber, A.-M. Inst. C.E.,andM.Inst, M.E. Tldrd Edition, with 115 Double Plates. In 2 vols. imp. 4to, 6/. i6f, 6^. half-boimd in morocco. **Abook — and particularly a large and costly treatise like Mr. Humber's— which ha^ reached its Uiird edition may certxunly be said to have established its o^'n reputation," — En^neering, B WORKS IN ENGINEERING, SURVEYING, ETC., Humbers Modern Engineering. A RECORD of the PROGRESS of MODERN ENGINEER- ING. First Series. Comprising Civil, Mechanical, Marine, Hy- draulic, Railway, Bridge, and other Engineering Works, &c. By William Humber, A.-M. Inst. C.E., &c Imp, 4to, witi 36 Double Plates, drawn to a large scale, and Portrait of John Hawkshaw, C.E., F.R.S., &c., and descriptive Letter-press, Speci- fications, &c. 3/. 3J. half morocco. List of the Plates and Diagrams. Victoria Station and Roof, L. B. & S. C. R. (8 plates); Southport Pier (2 plates); Victona Station and Roofj L. C. & D. and G. W. R. (6 plates) ; Roof of Cremome Music Hall ; Bridge over G. N. Railway Roof of Station, Dutch Rhenish Bail (3 tlates) ; Bridge over the Thames, West London Extension Railway (^ plates) ; Ar- mour Plates ; Suspension Bridge, Thames (4 plates) : The Allen Engine ; Suspension Bridge, Avon (3 platesj; Railway (3 plates). Underground HUMBER'S RECORD OF MODERN ENGINEERING. Second Series. Imp. 4to, with 36 Double Plates, Portrait of Robert Ste- phenson, C.E., &C., and descriptive Letterpress, Specifications, &c. 3/. 3J. half morocco. List of the Plates and Dia^ams. Birkenhead Docks, Low Water Basin (15 plates}; Charins Cross Station Roof, C, C. 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To which is added a Chapter on Wind Pressures. By R. Hudson Graham, C.E. With numerous Examples, many taken from existing Structures. 8vo., l6j.cloth. "Mr. Graham s book will find a place wherever graphic and analytic statics are used or studied."— £«fJ««er. " This exhaustive treatise is admirably adapted for the architect and engineer, and 'will tend to wean the profession from a tedious and laboured mode of calcula- tion. To prove the accuracy of the graphical demonstrations, the author compares them with the analytic formulae given by Rankine."— 5«z7i^?»^ News. Strength of Girders. GRAPHIC TABLE for FACILITATING the COMPUTA- TION of the WEIGHTS of WROUGHT-IRON and STEEL GIRDERS, &c., for Parliamentary and other Estimates. By J. H. Watson Buck, M. Inst. C. E. On a Sheet, 2s. td. Strains, Formulce & Diagrams for Calculation of. 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AID TO SURVEY PRACTICE : for Reference in Surveying, Levelling, Setting-out and in Route Surveys of Travellers by Land and Sea. With Tables, Illustrations, and Records. By Lowis D'A. Jackson, A.-M.I.C.E. Author of " Hydraulic Manual and Statistics," &c. Large crown 8vo, \2s. 6d., cloth. " Mr. Jackson has had much and varied experience in field work and some know- ledge of bookmaking, and he has utilised both Acse acquirements with a viity useful result. The volume covers the graund'it occupies very t\uaQ\i^y."—Engi>ieemtg. '* A general text book was wanted^ and we are able to speak with confidence of Mr. Jackson's treatise. , . . We cannot recommend to the student who knows something of the mathematical principles of the subject a better course than to fortify his practice in the field under a competent surveyor with a study of Mr. Jacksons useful manual. The field records illustrate every kind of survey, and will be found an essential aid to the student." — Building News. 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Second Edit, revised. i2mo, S^- cloth. *' A book which every borough^ surveyor and engineer must possess, and of consi- derable service to architects, builders, and property owners." — Building News. PUBLISHED BY CROSBY LOCKWOOD & CO. Locomotives. LOCOMOTIVE ENGINES, A Rudimentary Treatise on. Com. prising an Historical Sketcli and Description of the Locomotive Engine. By G. D. Dempsey, C.E. With large additions treat- ing of the Modern Locomotive, by D. Kinnear Clark, M. Inst. C.E. With Illustrations. l2mo. 3j. dd. cloth boards. " The student cannot fail to profit largely by adopting this as his preliminary text- book." — Iroil and Coal Trades Review. Field-Book for Engineers. THE ENGINEER'S, MINING SURVEYOR'S, and CON- TRACTOR'S FIELD-BOOK. By W. Davis Haskoll, C.E, Consisting of a Series of Tables, with Rules, Explanations of Systems, and Use of Theodolite for Traverse Surveying and Plotting the Work with minute accuracy by means of Straight Edge and Set Square only; Levelling vrith the Theodolite, Casting out and Re- ducing Levels to Datum, and Plotting Sections in the ordinary manner; Setting out Curves with the Theodolite by Tangential Angles and Midtiples with Right and Left-hand Readings of the Instrument ; Setting out Curves without Theodolite on the System of Tangential Angles by Sets of Tangents and Offsets; and Earth- work Tables to 80 feet deep, calculated for every 6 inches in depth. With numerous Woodcuts. 4th Edition, enlarged, Cr. 8vo. I2J. cloth. " The book is very handy, and the author might have added that the separate tables of sines and tangents to every minute will make it useful for many other purposes, the genuine traverse tables existmg all the same," — Athenaum, Earthwork, Measurement and Calculation of. A MANUAL on EARTHWORK. By Alex, J. S. Graham, C.E, With numerous Diagrams. iSmo, 2s, dd. cloth. " As a really handy book for reference, we know of no work equal to it ; and the railway engineers and others employed in the measurement and calculation of earth- work will find a great amount of practical information very admirably arranged, and available for general or rough estimates, as well as for the more exact calculations required in the engineers' contractor's ofiSces." — Artisan. Drawing for Engineers. THE WORKMAN'S MANUAL OF ENGINEERIN.G DRAWING. By John Maxton, Instructor in Engineering Dravidng, Royal Naval College, Greenwich, formerly of R. S. N. A., S outh Kensington. Fifth Edition, carefully revised. With upwards of 300 Plates and Diagrams, l2mo, cloth, strongly bound, 4J. " A copy of it should be kept for reference in every drawing ofl&ce." — Engiwering, " Indispensable for teachers of engineering drawing," — Mechanics^ Magazine. Wealds Dictionary of Terms. A DICTIONARY of TERMS used in ARCHITECTURE, BUILDING, ENGINEERING, MINING, METALLURGY, ARCH/EOLOGY, the FINE ARTS, &c. By John Weale. Fifth Edition, revised by Robert Hunt, F.R.S., Keeper of Mining Records, Editor of " Ure's Dictionary of Arts." l2mo, 6x. cl. bds. " The best small technological dictionary in the language," — Architect. " The absolute accuracy of a work of this character can only be judged of afler extensive consultation, and from our examination it appears very correct and very complete," — Mining youmal. 10 WORKS IN MINING, METALLURGY, ETC., MINING, METALLURGY, ETC. — t — Metalliferous Mining. BRITISH MINING. A Practical Treatise on the Metalliferous Mines and Minerals of the United Kingdom, dealing comprehen- sively with the Theories of Mineral Deposits, the History of Mines, their Practical Working, and the Future Prospects of British Mining Industry. Super royal 8vo. Fully Illustrated. By Robert Hunt, F.R.S., Keeper of Mining Records ; Editor of " Ure's Dictionary of Arts, Manufactures, and Mines," &c. [/» the press. Coal and Iron. THE COAL AND IRON INDUSTRIES OF THE UNITED KINGDOM : comprising a Description of the Coal Fields, and of the Principal Seams of Coal, with returns of their Produce and its Distribution, and Analyses of Special Varieties. Also, an Account of the occurrence of Iron Ores in Veins or Seams ; Analyses of each Variety ; and a History of the Rise and Progress of Pig Iron Manufacture since the year 1740, exhibiting the economies intro- duced in the Blast Furnaces for its Production and Improvement. By RiCHAijD Meade, Assistant Keeper of Mining Records. With Maps of the Coal Fields and Ironstone Deposits of the United Kingdom. 8vo., ;^i %s. cloth. Metalliferous Minerals and Mining. A TREATISE ON METALLIFEROUS MINERALS AND MINING. ByD. C. Davies, F.G.S. With Numerous Wood Engravings. Second Edition, revised. Cr. 8vo, \2s. 6d. cloth. " Without question, the most exhaustive and the most practically useful work we have seen ; the amount of information given is enormous, and it is given concisely and intelligibly." — Mining journal. Earthy Minerals and Mining. EARTHY AND OTHER MINERALS, AND MINING. ByD. C. Davies, F.G.S. Uniform with, and forming a com- panion volume to, the same Author's " Metalliferous Minerals and Mining." With numerous Illustrations. \In the press. Slate and Slate Quarrying. A TREATISE ON SLATE AND SLATE QUARRYING, Scientific, Practical, and Commercial. By D. C. Davies, F.G.S. Illustrated. Second Edition, revised. 3J. dd. cloth. Mining, Surveying and Valuing. THE MINERAL SURVEYOR AND VALUER'S COM- PLETE GUIDE, comprising a Treatise on Improved Mining Surveying, with new Traverse Tables ; and Descriptions of Im- proved Instruments ; also an Exposition of the Correct Principles of Laying out and Valuing Home and Foreign Iron and Coal Mineral Properties. By William Lintern, Mining and Civil Engineer. With four Plates of Diagrams, Plans, &c.,l2mo,4T. cloth. *,,* Also, bound witli Thoman's Tables. 7j. dd. (See page 20.) PUBLISHED BY CROSBY LOCKWOOD & CO. ii Metallurgy of Iron. A TREATISE ON THE METALLURGY OF IRON : con- taining Outlines of the History of Iron Manufacture, Methods of Assay, and Analyses of Iron Ores, Processes of Manufacture of Iron and Sted, &c. By H. Bauerman, F.G.S. Fifth Edition, Revised and Enlarged. Illustrated. Sj. 6d, cloth boards. PUBLISHED BY CROSBY LOCKWOOD & CO. I J Handbook of Specifications. THE HANDBOOK OF SPECIFICATIONS; or, Practical Guide to the Architect, Engineer, Surveyor, and Builder, in drawing up Specifications and Contracts for Works and Constructions. Illustrated by Precedents of Buildings actually executed by eminent Architects and Engineers. By Professor Thomas L. Donald- son, M.I.B.A. New Edition, in One large volume, 8vo, with upwards of looo pages of text, and 33 Plates, cloth, \l. lis. 6d. "In this work forty-four sijecifications of executed works are given. . . . Donald- son's Handbook of Specifications must be bought by aU aj:chitects."-^^7«7rf«'. Specifications for Practical Architecture. SPECIFICATIONS FOR PRACTICAL ARCHITECTURE : A Guide to the Architect, Engineer, Surveyor, and Builder ; with an Essay on the Structure and Science of Modem Buildings. By Frederick Rogers, Architect. 8vo, iSj. cloth. %* A volume of specifications of a practical character being greatly required, and the old standard work of Alfred Bartholomew being out of print, the author, on the basis of that work, has produced the above. — Extract frotn Preface. Designing, Measuring, and Valuing. THE STUDENT'S GUIDE to the PRACTICE of MEA- SURINGand VALUING ARTIFICERS' WORKS; containing Directions for taking Dimensions, Abstracting the same, and bringing the Quantities into Bill, with Tables of Constants, and copious Memoranda for the Valuation of Labour and Materials in the re- spective Trades ot Bricklayer and Slater, Carpenter and Joiner, Painter and Glazier, Paperhanger, &c. With 8 Plates and 63 Wood- cuts. Originally edited by Edward Dobson, Architect. Fifth Edition, Revised, with considerable Additions on Mensuration and Construction, and a new chapter on Dilapidations, Repairs, and Contracts. By E. Wyndham Tarn, M.A. [In the press. '* Well fulfils the promise of its title-page. Mr. Tarn's additions and revisions have much increased the usefulness of the work."~~Sn£zneerin^. Beaton's Pocket Estimator. THE POCKET ESTIMATOR FOR THE BUILDING TRADES, being an easy method of estimating the various parts of a Building collectively, more especially applied to Carpenters' and Joiners' work. By A. C. Beaton, Second Edition. Waistcoat-pocket size. l.r, ftd. Beaton' sBuilders' and Surveyors' Technical Guide. THE POCKET TECHNICAL GUIDE AND MEASURER FOR BUILDERS AND SURVEYORS; containing an Expla- nation of the Terms used in Building Construction, Directions for Measuring Work, Useful Memoranda, &c. By A. C. Beaton, is.6d. The House-Owner's Estimator. THE HOUSE-OWNER'S ESTIMATOR ; or, What wiU it Cost to Build, Alter, or Repair? A Price-Book for Unprofes- sional People, Architectural Surveyors, Builders, &c. By the late James D. Simon. Edited by F. T. W. Miller, A.R.I.B.A. Third Edition, Revised. Crown 8vo, 3J. 6d., cloth. " In two years it will repay its cost a hundred times over,"— Field- i6 WORKS IN CARPENTRY, TIMBER, ETC., CARPENTRY, TIMBER, ETC. — »— Tredgold's Carpentry, new and cheaper Edition. THE ELEMENTARY PRINCIPLES OF CARPENTRY ; a Treatise on the Pressure and Equilibrium of Timber Framing, the Resistance of Timber, and the Construction of Floors, Arches, Bridges, Roofs, Uniting Iron and Stone with Timber, &c. To which is added an Essay on the Nature and Properties of Timber, &c., with Descriptions of the Kinds of Wood used in Building ; also numerous Tables of the Scantlings of Timber for different purposes, the Specific Gravities of Mateii^s, &c. By Thomas Tredgold, C.E. Edited by Peter Barlow, F.R.S. Fifth Edition, cor- rected and enlarged. With 64 Plates, Portrait of the Author, and Woodcuts. 4to, published at 2/. 2x., reduced to l/. 5^'. cloth. " A work whose monumental excellence must commend it wherever skilful car- pentry is concerned. The Author's principles are rather confirmed than impaired by timet The additional plates are of great intrinsic value."—* ^»2^i»^ News, Grandy's Timber Tables. THE TIMBER IMPORTER'S, TIMBER MERCHANT'S, & BUILDER'S STANDARD GUIDE. By R. E. Grandy. 2nd Edition. Carefully revised and corrected. i2mo, 3^, 6d. cloth. "The best work yet printed on its subject for a reasonable price." — yewelUr. ** Essentially a practical manual, well adapted to the wants of amateurs and apprentices, containing trustworthy information that only a practical man can supply." — Enzlish Mechanic. Silver and Silver Working, THE SILVERSMITH'S HANDBOOK, containing full In- structions for the Alloying and Working of Silver. Including the different Modes of Refining and Melting the Metal, its Solders, the Preparation of Imitation JUloys, &c. By G. E. Gee. l2mo, y. td. " The chief merit of the work is its practical character. The workers in the trade will speedily discover its merits when they sit down to study it," — English Mechanic. Hall-Marking of Jewellery. THE HALL-MARKING OF JEWELLERY PRACTICALLY CONSIDERED, comprising an account of all the different Assay Towns of the United Kingdom ; with the Stamps at present employed ; also the Laws relating to the Standards and Hall- Marks at the various Assay Offices ; and a variety of Practical Suggestions concerning the Mixing of Standard Alloys, &c. By George E. Gee. Ci-own 8vo, 51. cloth. Electro-Plating, &c. ELECTROPLATING: A Practical Handbook. By J. W. Urquhart, C.E. Crown 8vo, S^. cloth. "Any ordinarily intelligent person may become an adept in electro-deposition with a very little science indeed, and this is the book to show the way." — Builder. Electrotyping, &c. ELECTROTYPING : The Reproduction and Multiplication of Printing Surfaces and Works of Art by the Electro-deposition of Metals. By J. W. Urquhart, C.E. Crown 8vo, 5^. cloth. "A guide to beginners and those who practise the old and imperfect methods." — Iron. Electro-Plating. ELECTRO-METALLURGY PRACTICALLY TREATED. By Alexander Watt, F.R.S.S.A. Including the Electro- Deposition of Copper, Silver, Gold, Brass and Bronze, Platinum, Lead, Nickel, Tin, Zinc, Alloys of Metals, Practical Notes, &c., &c. Eighth Edition, Revised, including the most recent Pro- cesses. i2mo, 3^. f)d., cloth. " From this book both amateur and artisan may learn everything necessary for the successful prosecution of electroplating."— /ra«. -" A practical treatise for the use of those who desire to work in the art of electro- deposition as a business."— £«g/w/4 Mechanic. 22 WORKS IN SCIENCE AND ART, ETC., Dentistry. MECHANICAL DENTISTRY. A Practical Treatise on the Construction of the various kinds of Artificial Dentures. Com- prising also Useful Formulae, Tables, and Receipts for Gold Plate, Clasps, Solders, etc., etc. By Charles Hunter. Second Edition, Revised ; including a new chapter on the use of Celluloid. With over loo Engravings. Crown 8vo, "Js. 6d. , cloth. " An authoritative treatise, whicn we can strongly recommend to all students."— Dublin Journal of Medical Science, Electricity. A MANUAL of ELECTRICITY ; including Galvanism, Mag. netism, Diamagnetism, Electro-Dynamics, Magneto-Electricity, and the Electric Telegraph. By Henry M. Noad, Ph.D., F.C.S. Fourth Edition, with Joo Woodcuts. 8vo, l/. 4r. cloth. _ *' The accounts |;iven of electricity and galvanism are not only complete in a scientific sense, but, which is a rarer thing, are popular and interesting."— ZawtA Text-Book of Electricity. THE STUDENT'S TEXT-BOOK OF ELECTRICITY. By Henry M. Noad, Ph.D., F.R.S., &c. New Edition, Revised. With an Introduction and Additional Chapters by W. H. Preece, M.I.C.E., Vice-President of the Society of Telegraph Engineers, &c. With 470 Illustrations. Crown 8vo, \2s. €d. cloth. "A reflex of the existing state of Electrical Science adapted for students."— W. H. Preece, Esq., vide " Introduction." " We can recommend Dr. Noad's book for clear style, great range of subject, a good index, and a plethora of woodcuts. Such collections as the present are indis- pensable." — Athenavm. " An admirable text-book for every student— beginner or advanced— of electricity. " ^EngineeriTtg. " Recommended to students as one qf the best text-books on the subject that they can have. Mr. Preece appears to have introduced all the newest inventions in the shape of telegraphic, telephonic, and electric-lighting apparatus." — Enelisk Mechanic, " Under the editorial hand of Mr. Preece the late Dr. Noad s text-book of elec- tricity has grown into an admirable handbook." — Westminster Review, Electric Lighting. ELECTRIC LIGHT ; Its Production and Use, embodying plain Directions for the Treatment of Voltaic Batteries, Electric Lamps, and Dynamo-Electric Machines. By J. W. Urquhart, C.E., Author of "Electroplating." Edited by F. C. Webb, M.LC.E., M.S.T.E. 2nd Edition, Carefully Revised, with Large Additions and 128 Illustrations. Cr. 8vo, ']s. dd, cloth. * ' The book is by far the best that we have yet met with on the subject." — A thenaunt, " An important addition to the literature of the electric light. Students of the subject should not fail to read it." — Colliery Guardian, Lightning. THE ACTION of LIGHTNING, and the MEANS of DE- FENDING LIFE AND PROPERTY FROM ITS EFFECTS. By Major Arthur Parnell, R.E. 'i2mo, 7j. dd, cloth. ' Major Pamell has written an original work on a scientific subject of unusual inte- rest ; and he has prefaced his arguments by a patient and almost exhaustive citation of the best writers on the subject m-the English language." — A ihenteum, " The work comprises all that is actually known on the subject." — Land. " Major Parnells measures are based on the results of experience. A valuable repertoire of facts and principles ananged in a scientific iarm, —Buililine News, PUBLISHED BY CROSBY LOCKWOOD & CO. 23 The Alkali Trade — Sulphuric Acid^ &c. A MANUAL OF THE ALKALI TRADE, including the Manufacture of Sulphuric Acid, Sulphate of Soda, and Bleaching Powder, By John Lomas, Alkali Manufacturer. With 332 Illus- trations and Working Drawings, and containing 386 pages of text. Super- royal 8vo, 2/. I2j. 6d, cloth. This work provides (i) a Complete Handbook for mietiding Alkali and Sulphuric Acid Manufacturers^ and for those already in the field who desire to improve their plants or to become practically acquautted with the latest Processes and developments of the trade ; {2) a Handy Volume which Mamtfacturers canput intoihe hajtds 0/ their Managers and Foremen as a useful guide in i/ieir daily rounds of duty. Synopsis of Contents. Chap. I, Choice of Site and General Plan of Works— II. Sulphuric Acid— III. Recovery of the Nitrogeu Com- pounds, and Treatment of Small Pyrites —IV. The Salt Cake Process— V. Legis- lation upon the^ Noxious Vapours Ques- tion — ^VI. The Hargreaves' and Jones' Processes— ^VI I. The Balling Process — VIII, Lixiviation and Salting Down — IX. Carbonating or Finishing — X. Soda Crystals — XI. Refined Alkali — XII. Caustic Soda — XIII. Bi-carbonate of Soda — XIV. Bleaching Powder— XV. Utilisation of Tank Waste— XVI. General Remarks — Four Appendices, treating of Yields, Sulphuric Acid Calculations, Ane- mometers, and Foreign Legislation upon the Noxious Vapours Question. "The author has given the fullest^ most practical, and, to all concerned in the alkali trade, most valuable mass of mformation that, to our knowledge, has been published in any language." — Engineer. " This book is written by a manufacturer for manufacturers. The working details of the most approved forms of apparatus are given, and these are accompanied by no less than 232 wood engravings, all of which may be used for the purposes of con- struction. Every step in- the manufacture is very fully described in this manual, and each improvement explained. Everything which tends to introduce economy into the technic^ details of this trade receives me fullest attention." — Athenteum. ** The author is not one of those clever compilers who, on short notice, will ' read up' any conceivable subject,' but a practical man in the best sense of the word. We find here not merely a sound and luminous explanation of the chemical principles of the trader but a notice of numerous matters which have a most important bearing on the successful conduct of alkali works, but which are generally overlooked by even the most experienced technological authors." — Chemical Review. Soap-making, THE ART OF SOAP-MAKING,'A Practical Handbook of the Manufacture of Hard and Soft Soaps, Toilet Soaps, &c. Including Descriptions of many New Processes and a Chapter on the Recovery of Glycerine Irom W^aste Leys. By Alexander Watt, Author of" Electro-Metallurgy Practically Treated," &c. \Nearly ready. Chemical Analysis, THE COMMERCIAL HANDBOOK of CHEMICAL ANA- LYSIS ; or Practical Instructions for the determination of the In- trinsic or Commercial Value of Substances used in Manufactures, in Trades, and in the Arts. By A. Normandy. New Edition, Enlarged, and to a great extent re-written, by Henry M. Noad, Ph.D.,F.R.S. With numerous Illustrations. Cr. 8vo, i2j.6^.cloth. "We recommend this book to the careful perusal of everyone; it maybe truly af&rmed to be of universal interest, and we strongly recommend it as a guide, alike ndispensable to the housewife as to tibe pharmaceutical practitioner." — MedicalTimes, "Eaential to the analysts appointed under the new Act. The most recent results 5ire given, and the work is wpjl edited imd carefully written."— iV«A*ri', 24 WORKS IN SCIENCE AND ART, ETC., Dr. Lardnef's Museum of Science and Art. THE MUSEUM OF SCIENCE AND ART. Edited by DiONYSlus Lardner, D.C.L., fonnerly Professor of Natural Phi- losophy and Astronomy in University College, London. With up- wards of 1200 Engravings on Wood. In 6 Double Volumes. Price £l IS., in a new and elegant cloth binding, or handsomely bound in half morocco, 31^. 6c/. OPINIONS OF THE PRESS. " This series, besides aiFording popular but sound instruction on scientific subjects, with which the humblest man In the country ought to be acquainted, also undertakes that teaching of ' common things ' which every well-wisher of his kind is anxious to promote. Many thousand copies of this serviceable publication have been printed, m the belief and hope that the desire for instruction and improvement widely pre- vails ; and we have no fear that such enlightened faith will meet with disappoint- ment" — Times. "A cheap and nteresting publication, alike informing and attractive. The papers combine subjects of importance and great scientific knowledge, considerable induc- tive powers, and a popular style of treatment." — Spectator. "The 'Museum of Science and Art' is the most valuable contribution that has ever been made to the Scientific Instruction of every class of society." — ^'iV David Brewster in the North British Review. . " Whether we consider the liberality and beauty of the illustrations, the charm of the writing, or the durable interest of the matter, we must express our belief that there is hardly to be found among the new books, one that would be welcomed by people of so many ages and classes as a valuable present." — Examitier, ** Separate books formed from the above, suitable for IVorimen's Libraries, Science Classes, &'c, COMMON THINGS EXPLAINED. Containing Air, Earth, Fire, Water, Time, Man, the Eye, Locomotion, Colour, Clocks and Watches, &c. 233 Illustrations, cloth gilt, 5/. THE MICROSCOPE. Containing Optical Images, Magnifying Glasses, Origin and Description of the Microscope, Microscopic Objects, the Solar Microscope, Microscopic Drawing and Engrav- ing, &c. 147 Illustrations, cloth gilt, 2s. POPULAR GEOLOGY. Containing Earthquakes and Volcanoes, the Crust of the Earth, etc. 201 Illustrations, cloth gilt, 2s. 6d. POPULAR PHYSICS. Contaming Magnitude and Minuteness, the Atmosphere, Meteoric Stones, Popular Fallacies, Weather Prog- nostics, the Thermometer, the Barometer, Sound, &c. 85 Illus- trations, cloth gilt, zs. ()d. STEAM AND ITS USES. Including the Steam Engine, the Lo- comotive, and Steam Navigation. 89 Illustrations, cloth gilt, 2s. POPULAR ASTRONOMY, Containing How to Observe the Heavens. The Earth, Sun, Moon, Planets. Light, Comets, Eclipses, Astronomical Influences, &c. 182 Illustrations, ^. 6d. THE BEE AND WHITE ANTS : Their Manners and Habits. With Illustrations of Animal Instinct and Intelligence. 135 Illus- trations, cloth gilt, 2s. THE ELECTRIC TELEGRAPH POPULARISED. To render intelligible to all who can Read, irrespective of any previous Scien- tific Acquirements, the various forms of Telegraphy in Actual Operation, 100 Illustrations, cloth gilt, is, 6d, PUBLISHED BY CROSBY LOCKWOOD & CO. 25 Dr. Lardne^s Handbooks of Natural Philosophy . •*• The following Jive volumes^ though each is Complete in ttselj, and io bepitr- chased separately^ form A Complete Course of Natural Philosophy, and are intended for the gefieral reader who desires to attain accurate knowledge of the various departments of Physical Scietice^ ivittwut pursuing them according to the more profmtnd methods of mathematical investigation. The style is studiously popular. It has hetft the author's aim to supply Manuals such as are required by the Student^ the Engineer^ the Artisan, and the superior classes in Schools. THE HANDBOOK OF MECHANICS. Etilarged and almost rewritten by BENJAMIN LoEWY, r.R.A.S. With 378 Illustra- tions. Post 8vo, 6s, cloth. ** The perspicuity of the originfd has been retained, and chapters which had become obsolete> nave been replaced by others of more modern character. The explanations throughout arc studiously popular, and care has been taken to show the application of the various branches of physics to the industrial arts, and to the practical business of life." — Mining yo7imal. THE HANDBOOK of HYDROSTATICS and PNEUMATICS. New Edition, Revised and Enlarged by Benjamin Loewy, r.R.A.S. With 236 Illustrations. Post 8v6, .5J. cloth. " For those * who desire to attain an accurate knowledge of physical sdence with- out the profound methods of mathematical investigation,' this work is not merely in- tended, but well adapted." — Chemical News, THE HANDBOOK OF PIEAT. Edited and almost entirely Rewritten by Benjamin Loewy, F.R.A.S., etc. 117 Illustra- tions. Post 8vo, 6j. cloth. " The style is always clear and precise, and conveys instruction without leaviog any cloudiness or lurlung doubts behind.*' — Engineering, THE HANDBOOK OF OPTICS. New Edition. Edited by T. Olver Harding, B. A. 298 Illustrations. Post 8vo, ^s. cloth. "Written by one of the ablest English scientific writers; beautifully and elaborately illustrated." — Mec/uinics' Magazine. THE HANDBOOK OF ELECTRICITY, MAGNETISM, and ACOUSTICS. New Edition. Edited by Geo. Carey Foster, B.A., F.CS. With 400 Illustrations. Post 8vo, ss. cloth. " The book could not have been entrusted to anjr one better calculated to preserve the terse and lucid style of Lardner, while correcting his errors and bringing up his work to the present state of scientific knowledge." — Popular Science Review. Dr. Lardner's Handbook of Astronomy. THE HANDBOOK OF ASTRONOMY. Forming a Com- panion to the "Handbooks of Natural Philosophy." By Diony- sius Lardner, D.C.L. Fourth Edition. Revisedand Edited by Edwin Dunkin, F.R.S., Royal Observatory, Greenwich. With 38 Plates and upwards of .100 Woodcuts. In l vol., small 8vo, 550 pages, gs. 6d., cloth. " I^bably no oUier book contains the same amount of information in so com- pendious and well-arranged a form — certainly none at the price at which this is offered to the public." — Aihetueitm, " We can do no other than pronounce this work a most valuable manual of astro- nomy, and we strongly recommend it to all who wish to acquire a general — but at the same time correct — acquaintance with this sublime science." — Quarterly Journal of Science. Dr. Lardner's Handbook of Animal Physics. THE HANDBOOK OF ANIMAL PHYSICS. By Dr. Lardner. With 320 Illustrations. New edition, small 8vo, cloth, 732 pages, "Js. td. " We have no hesitation in cordially recommending it." — Educational Titnes." 26 WORKS IN SCIENCE AND ART, ETC., Dr. Lardney's School Handbooks. NATURAL PHILOSOPHY FOR SCHOOLS. By Dr. Lardner, 328 Illustrations. Sixth Edition. I vol. J,s. 6d. cloth. " Conveys, in clear and precise terms, general notions of all the principal divisions of Physical Science." — British Quarterly Review. ANIMAL PHYSIOLOGY FOR SCHOOLS. By Dr. Lardnbr. With 190 Illustrations. Second Edition, i vol. 3^. 6d. cloth. "Clearlywritteniwel! arranged, and excellentlyillustra ted."— G«»-ife>M«'C/iWH(W^ Dr. Lardnev's Electric Telegraph. THE ELECTRIC TELEGRAPH. By Dr. LarDner. New Edition. Revised and Re- written, by E. B. Bright, F.R. A. S, 140 Illustrations. Small 8vo, is. 6d. cloth. ' ' One of the most readable books extant on the Electric Telegraph,"— ^^. Mechanic, Mollusca. A MANUAL OF THE MOLLUSCA ; being a Treatise on Recent and fossil Shells. By Dr. S. P. Woodward, A.L.S. With Appendix by Ralph Tate, A.L.S., F.G.S. With numer- ous Plates and 300 Woodcuts. 3rd Edition. Cr. Svo, 7^. td, cloth. Geology and Genesis. THE TWIN RECORDS OF CREATION ; or, "Geology and Genesis, their Perfect Harmony and Wonderful Concord. By George W. Victor le Vaux. Fcap. Svo, 5^ . cloth. " A valuable contribution to the evidences of revelation, and disposes very conclu- sively of the arguments of those who would set God's Works against God's Word. No real difficulty is shirked, and no sophistry is left unexposed." — The Rock, Geology. GEOLOGY, PHYSICAL AND HISTORICAL; Consisting of " Physical Geology," which sets forth the Leading Principles of the Science ; and " Historical Geology," which treats of the Mineral and Organic Conditionsof the Earth at each successive epoch, especial reference being made to the British Series of Rocks. By Ralph Tate. With more than 250 Illustrations. Fcap. Svo, 5^. cloth. Practical Philosophy. A SYNOPSIS OF PRACTICAL PHILOSOPHY. By Rev. John Carr, M.A., late Fellow of Trin. Coll., Camb. iSmo, ^s, cl. The Military Sciences. AIDE-M£M0IRE to the MILITARY SCIENCES. Framed from Contributions of Officers and others connected with the dif- ferent Services. Originally edited by a Committee of the Corps of Royal Engineers. 2nd Edition, revised ; nearly 350 Engravings and many hundred Woodcuts. 3 vols, royal Svo, cloth, 4/. lOf. Field Fortification. A TREATISE on FIELD FORTIFICATION, the ATTACK of FORTRESSES, MILITARY MINING, and RECON- NOITRING. By Colonel I. S. Macaulav, late Professor of Fortification in the R. M. A., Woolvidch. Sixth Edition, crown . Svo, cloth, with sep^rat? Atlas of 19 Plates, \2s, complete, PUBLISHED BY CROSBY LOCKWOOD & CO. 27 Clocks, Watches, and Bells. RUDIMENTARY TREATISE on CLOCKS, and WATCHES, and BELLS. By Sir Edmund Beckett, Bart., LL.D., Q.C., F.R.A.S. Seventh Edition, revised and enlarged. Limp cloth (No. 67, Weale's Series), 4J. 6d.; cl. bds. ^s. dd. "The best work on the subject extant. The treatise on bells is undoubtedly the best in the language." — Engineeriitg. "The only modem treatiseonjilock-making." — Horological jfoumal. The Construction of the Organ. PRACTICAL ORGAN-BUILDING. By W. E. 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