47251440111 TEXAS AGRICULTURAL EXPERIMENT STATION BULLETIN NO. 165 APRIL, 1914 DIVISION OF CHEMISTRY Ammonia-Soluble Inorganic Soil Colloids POSTOFFICE College Station, Brazos County, Texas "E VON BOECKMANN-JONES co., PRINTERS, warm, TEXAS 1914 AGRICULTURAL AND MECHANICAL COLLEGE 0F TEXAS CHARLES PURYEAR, President Pro Tem. TEXAS AGRICULTURAL EXPERIMENT STATION BOARD OF DIRECTORS He: OHN I. GuioN, Vice-President, Ballinger............ . H. AsTiN, Bryan.... ...................................... .. . . HART, San Antonio ........... .. . . BENNETT, Paris ............... .. . . BATTLE, Marlin ............... .. . WILLIAMS, Paris............... LEN KYLE, Houston ...... .. “PWIIUPFI Ewmr“ € F . B. CUSHING, President, Houston ...................... .. ToN PETEET, Waco ........................................ .. ................................................... .. Term expires 1915 Term expires 1919 .. Term expires 1919 Term expires 1919 Term expires 1917 Term expires 1917 .... .. Term expires 1917 Term expires 1915 ................................. ..Term expires 1915 GOVERNING BOARD, STATE SUBSTATIONS TWiu. H. IVIAYES, President, Brownwood ............ .. P, _ emple .................... .. CHARLES RQGAN, Austin . . . . . . .. . ............................. .. L. DowNs, Vice-President, ................................................... .. Term expires 1917 .................................................... ..Term expires 1915 .................................................... ..Term expires 1915 ................. ..Term expires 1919 STATION STAFF ADMINISTRATION B. YOUNGBLOOD, M. S., Director A. B. CONNER, B. S., Assistant Director CHAS. A. FELKER, Chief Clerk A. S. WARE, Secretary DIVISION OF VETERINARY SCIENCE M. FRANCIS, D. V. S., Veterinarian in harge _ H. SCHMIDT, D. V. M., Assistant Veter- inarian DIVISION OF CHEMISTRY G. S. FRAPS, Pli. D., Chemist in Charge J. B. RATHER, M. S., Assistant Chemist WILLIAM LEviN, A. B., Assistant Chemist J. W. CREwNINc, B. S., Assistant Chemist DIVISION OF HORTICULTURE H. NEss, M. S., Horticulturistjn Charge W. S. HOTCHKISS, Horticulturist DIVISION OF ANIMAL HUSBANDRY J. C. BuRNs, B. S., Animal Husbandman in Charge , Animal Husbandman DIVISION OF ENTOMOLOGY WILMON NEWELL, M. S., Entomologist in Charge F. B. ADDOCK, B. S. E., Entomologist DIVISION OF AGRONOMY A. B. CoNNER, B. S., Agronomist in Charge A. H. LEIDIGH, B. S., Agronomist in Charge of Soil Improvement H. H. JoiasoN, B. S., Assistant Agronomist R. E. DICKSON, B. S., Assistant Agronomist DIVISION OF PLANT PATHOLOGY AND PHYSIOLOGY F. H. BLODGETT, P_h. D., Plant Pathologist and Physiologist in Charge ‘DIVISION OF FARM MANAGEMENT REx E. WILLARD, M. S., Farm Management Expert in Charge DIVISION OF FEED CONTROL W. L. BoYETr, State Feed Inspector J. H. RQGERs, Deputy Feed Inspector W. H. W001), Deputy Feed Inspector T. H. WQLTERs, Deputy Feed Inspector H. B. EHLINGER, Deputy Feed Inspector SUBSTATION NO. 1: Beeville, Bee County E. E. BINFORD, B. S., Superintendent SUBSTATION NO. 2: Troup, Smith County W. S. HOTCHKISS, Superintendent R. W. Cox, B. S., Scientific Assistant SUBSTATION NO. 3: County N. E. WINTERs, B. S., Superintendent J. W. JAcKsoN, B. S., Scientific Assistant *SUBSTATION NO. 4: County H. H. LAUDE, B. S., Superintendent SUBSTATION NO. 5: Temple, Bell County A. K. SHORT, B. S., Superintendent SUBSTATION NO. 6: Denton, Denton County T. W. BUELL, B. S., Superintendent SUBSTATION NO. 7: Spur, Dickens County I. S. YoRK, Superintendent E. W. HARRISON, B. S., Scientific Assistan SUBSTATION NO. 8: Lubbock, Lubbock County V. L. CORY, B. S., Superintendent SUBSTATION NO. 9: Pecos, Reeves County H. C. STEWART, B. S., Superintendent J. M. TRoMsoN, B. S., Scientific Assistant SUBSTATION NO. 10: Feeding and Breeding Substation, College Station, Brazos County C. S. SCHARFF, Acting Superintendent SUBSTATION NO. 11: Nacogdoches, Nacog- doches County G. T. McNEss, Superintendent Angleton, Brazoria Beaumont, Jetfei-son CLERICAL ASSISTANTS STATION ' J. M. SCHAEDEL, Stenographer C. A. CASE, Stenographer C. L. DURsT, Mailing_Clerk —*In cooperation with Bureau of Plant Industr TResigned April 1, 1914. FEED CONTROL DAISY LEE, Registration Clerk MATriE THOMAS, Stenographer P. K. BRowNLEE, Shipping Clerk y, United States Department of Agriculture. AMMONIA-SOLUBLE INORGANIC SOIL COLLOIDS G. S. FRAPS, PH. D., Chemist. The colloidal constituents of the soil are considered as ol consider- able importance. Van Bemmerlcnl has pointed out that there is a re- lation between the power of soils t0 absorb bases and the quantity of colloid-like silicates present. His conclusion that soils which contain the most colloidal silicates and humus, are the most productive, has been emphasized by others, especially Ehrenbergx? Others have pointed out that the plasticity of clay is related to the colloidal clay. present and that any agency which increases the colloidal properties of a clay soil, also makes it more impervious, sticky, and rdifficult to work. Lime, and other substances which coagulate clayj, tend to make clay soils less sticky, miore permeable to water, and more easily worked.“ The colloidal constituents of the soil also affects the solubility of the unabsorbed salts, and also the gases present.‘ The colloidal constituents of the soil may consist of: (a) Or~ ganic substances. (b) Inorganic substances, such as aluminum hy- droxide, ferric hydroxide, hydrated silicic acid, hydrated aluminum sili- cates, and other silicates. The colloidal constituents may also be present in two forms: (1) In such forms as may enter into colloidal solution in water or other solvents. (2) In gelatinous particles which are too large to enter into colloidal solution, but which are yet in a gelatinous colloidal condition and capable of exercising colloidal properties. The condition of these gelatinous particles may also vary from a fully expanded state to a more or less shrunken condition, and the characteristics of the soil may be affected by such variations? METHODS or rnyrnsrrckrrox. Methods of study vary according as they deal with: (1) The col- loids capable of entering into colloidal solution; or (2) the total col- . loids or colloid-like substances. The only method as yet proposed tor approximatelxf estimating the total colloidsis by staining the colloidal particles, and estimating their number or quantity by means of a microscopic examinations“ Indirect methods have also been proposed such as: (a) By estimating, colorimetricallv, the absortion of soils for dye stuffs. (b) By estimating the absorbtive power of the soils for bases.“ (c) By estimating the salts made soluble by an electric current.“ These indirect methods, however, do not really estimate the colloidal constituents of the soil, but comp-are soils with respect to certain prop- erties, which may be partly dependent upon other soil constituents in addition to the colloidal particles. 4 'l‘sx-is .:\(JltlCL'l.'l.‘L'l{.\I. EXPERIMENT SJTXIION. Schloesing’ has prepared the colloidal constituents which enter into aqueous solution. He brought the clay in suspension with water as in the mechanical analysis of a soil, and precipitated it with a small amount of acid, collected. it in a filter, and washed with distilled water. The residue on the filter was treated with ammonia, and diffused in a considerable quantity ol‘ distilled water. 'J_‘his was allowed to stand until particles no longer settled out, wr'hicl1 required several months. Particles of visible dimensions could then no longer be detected in the solution by means of the microscope. The liquid was then decanted off, and the colloidal clay precipitated by the addition of a small quan- tity of acid. It dried to a translucent, horn-like mass. According to Schloesing, even the stiitest i1atural_ clays seldom contain over 1.5 per cent of such soluble colloidal clay. G-edroitz” has done some work on the colloids in aqueous extracts of the soil. METHOD or ESTIMATION. This article deals with the soluble colloidal soil substances, and not with the total, or insoluble, colloitls. It has been shown by Smiths that when a mixture of soil and ammonia water is poured in a filter, it the mixture is shaken thoro- ughly, and the soil also put upon the filter, a clear filtrate may easily be secured. This method he proposes for securing a clear filtrate in the estimation of the ammonia-soluble organic matter of the soil. It has been, found in this laboratory, however, that when ammonium car- bonate is added to the clear ammoniacal filtrate, a precipitate is formed which is composed largely of inorganic material. The use of ammonium carbonate, for precipitating the clay, is the method proposed by Rather“ for purifying the ammoniacal humus filtrate. The method used for estimating the soluble colloidal material of the soil is based upon these observations, and is describes as follows: Meth0d.——Digest 100 grams of the soil with 2000 c.c. of fifth-normal hydrochloric acid at room temperature for twenty-four hours. Filter and wash thoroughly. Wash back into the bottle with 2000 c.c. of 4 per cent ammonia. and let digest at room temperature for twenty-four hours, shaking every half hour for four hours. Filter on a large folded filter, getting as much of the _soil as possible on the filter, and continue to pour back the filtrate until it comes through clear, as per the Smith method. Discard the residue. Take 1500 c.c. of the filtrate, coagulate with the ammonium carbonate (and heat. if necessary), let settle, col- lect on ash-free filter, ignite. and weigh. Fuse the precipitate with sodium and potassium carbonates; dissolve in hydrochloric acid and evaporate to render silica. insoluble. Filter ofl’ and weigh silica. it pure; it contaminated with iron, purify. Pre- cipitate the iron and eiluminzi in the filtrate with ammonia, ignite, and weigh precipitate. Fuse with potassium acid sulphate and dissolve, reduce the iron with zine and titrate with permanganate. The methods as used above was intended onlv tor soils low in lime. and for this reason onlv one extraction ivith hydrochloric acid was made. lf the soils ctvntaiii much lime, several extractions must be made in order to remove all the lime. and, it the soil is high in lime. the acid must be made (lecidedlv stronger. AMMONIA——SOLUBLE INORGANIC‘ 501i Uorroins. AMMONIA-SOLUBLE INORGANIC COLLOIDS. The percentages of colloidal inorganic material in the soils studied is given in Table N0. 1. Thesoils are divided into tour groups, ar- ranged according to their total content of amlllOllltl-SOlllblé’ inorganic colloids: (l) .00-.050 per cent; (2) 0.051-.101 per cent; (3) 0.101- .200 per cent; (4) 0.201-.600 per cent. For the purposes of com- parison, the total nitrogen, the acid-soluable iron and alumina, and the acid-soluble lime, are also given in the table. Pnncmvraon OF TOTAL COLLOIDAL (Inoneanrc) MATTER IN THE SorLs. E n; i g ,__ __ A __. a A g; ‘fin: d é a»? as e -..~ e <3 e55 s e5“ B - —'2 "*3 ‘Pg 7” £5 51-43 2~Q ._ou.> ._.:-- 3.1-: we; "r: 32 @155 3:8 3313f, E32 2.113 Igoufstfinfiblack ccllay, 13124” . . . . . . . . . . . . . .003 .882 oro n an,su ace . . . . . . . . . . . . . .. . .004 . 3 . . . 860 Orangeburgiafine sand, 0"—24" . . . . . . . . . .. .017 .010 .003 .001 .020 1.01 08 312 Norfolk sand, 0"-10" . . . . . . . . . . . . . . . . . . . .035 .020 .006 .002 .030 .. .54 28 4231 Black clay, upland S. S . . . . . . . . . . . . . . . . . . .039 .024 .006 .003 .055 13.51 43 348 Norfolk fine sand . . . . . . . . . . . . . . . . . . . . . . . .047 .024 .006 .003 .020 1.13 09 316 Norfolk fine sandy loam, 0”—20” . . . . . . . .. .049 .028 .007 .005 .030 .82 09 Average (8) . . . . . . . . . . . . . . . . . . . . . . . . . . .028 .015 .004 .002 .034 5.36 0.26 3662 Orangeburg clay, 0" --18" . . . . . . . . . . . . . . . . .052 .025 .010 .006 .132 17 .95 .26 318 Lufkin fine sand, 0 ”—12” . . . . . . . . . . . . . . . . .058 .032 .007 .007 .030 .89 .15 937 Orangeburg fine sandy loam, 0"—12 . . . . . . .065 .035 .007 .007 .0304 1.61 .12 172 Norfolk sand . . . . . . . . . . . . . . . . . . . . . . . . . . . .070 .037 .007 .011 .030 .83 .05 3663 Orangeburg clay, 18”—30 " . . . . . . . . . . . . . . .093 .048 .017 .011 .112 17.94 .30 1202 Victoria clay, 0"—10" . . . . . . . . . . . . . . . . . . . .096 .054 .007 .026 .063 13.81 2.35 Average (7) . . . . . . . . . . . . . . . . . . . . . . . . . . .072 .039 .009 .011 .066 8.82 0.54 4380 Red clay “Post Oak Land," ”0—8” . . . . . . . . .102 .053 .011 .025 .072 16.70 .64 4998 Post Oak upland, 12”—24" . . . . . . . . . . . . . .. .106 .053 .011 _ .028 .079 16.30 .23 819 Norfolk fine sandy loam, 0"—22" . . . . . . . .. .133 .065 .014 .042 .020 1.29 .07 4543 Post Oakland, S. S . . . . . . . . . . . . . . . . . .143 .083 .013 .041 .067 15.21 .30 180 Orangeburg fine sandy loam . . . . . . . . . . . . . ‘.145 .074 .017 .046 .040 52 .02 4327 Oranburg fine sand, 5"—18" . . . . . . . . . . . . . . .180 .088 .024 .066 .058 14.12 .21 Average (6) . . . . . . . . . . . . . . . . . . . . . . . . . . .135 .069 .015 .041 .054 10.69 .24 112 Lufkin fine sandy loam . . . . . . . . . . . . . . . . .. .212 .122 .017 .064 .040 1.19 .91 823 Orangeburg fine sandy loam,'12”—36”. . . . . .230 .109 .031 .090 .090 29 22 .49 3423 Black Musquite land, 9"-21" . . . . . . . . . . .. .233 .118 .020 .072 .034 1.24 .19 4343 Sandy upland, 12”—24” . . . . . . . . . . . . . . . . .. .241 .117 .028 .102 .050 23.03 .17 875 Norfolk fine sandy loam, 22"—36" . . . . . . . . . .276 .127 .039 .101 .030 6.76 .05 3366 Laom upland, 6"—18" . . . . . . . . . . . . . . . . . .. .313 .140 .047 .121 .062 19.58 .13 3368 Light red sandy loam, 7"-19" . . . . . . . . . . . . .590 .224 .104 .243 .055 19.60 .25 Average (7) . . . . . . . . . . . . . . . . . . . . . .. .299 .137 .041 .113 .052 14.36 .31 There is an average relation between the acid-soluble iron palnd alumina of the soil, and its total soluble inorganic colloids. On an average, the iron and alumina increase as the percentages of ammonia- SOl11l)l(? colloids increase. However. there are very striking instances WhGTC a high iron and alumina content is accompanied by a low colloid content, and also other instances where a high soluble colloid content is accompanied bvlovr iron and alumina. The results are not sufficient to trace a relation. (3 TEXAS AGRICULTURAL EXPERIMENT Srarrox. COMPOSITION OF THE TNORGANIC COLLOIDAL PREOIPITATE. Table No. 2 shows the percentage conipositon of the inorganic col- coidal precipitate. The soils_in this table are likewise arranged in groups, ascending to the total colloidal precipitate secured from the soil. The quantity of the precipitate secured from the soils of the first group was so small that the analytical error is very large. This applies particularly to the first four soils. The average composition of the {our groups is as follows: Per cent Group. Silica. Iron Alumina. Difference. Oxide. 0.00-.05 per cent colloids... 59.7 24.3 8.7 7.3 0.051-.10 per cent coliloids.. 53.3 12.6 16.9 17.2 0.101-.20 per cent colloids. 51.5 11.0 29.9 7.6 0.201—.60 per cent colloids. 17.5 12.6 36.9 3.0 The most striking fact about these averages is the decrease in per- centage ot silica, and the increase in percentage of alumina, as the soluble colloid content of the soil increases. The molecular ratio of the constituents is as follows: 0.00-.05 per cent colloids: 12SiO._,:2Fe2O,., A120,, 0.051110 per cent colloids: 11SiO2:2Fe2O_.._:2Al._.O_... 0101-920 per cent colloids: ]2SiO.-_,:F2O3:/-LAl._,O_... 0201-110 per cent colloids: 10SiO2:l1‘e2O_.,:4i/1l2O;.. PERCENTAGE COMPOSITION OF COLLOIDAL PRECIPITATES. >4 é a5 A a.“ ea-Q 3? "O P’ E2 c» 5% 3 gs gs as 4880 Redel “P to kl d’.',0”—8" ....................................... .. 4298 Post oaail upl):nd,a12';a—l24” ............................................. .. i018 810 Norfolk finesandy loam, 0"-22" ........................................ .. 48.9 10's m 454s Post Oak land, s.s .................... .. 58.0 9'1 28": 180 Orangeburg fine sandy loam . . . . . . . . . . . . .. 51.0 11.7 31-7 4827 Orangeburg fine sand, 5"-18" .......................................... .. 48.0 1313 3017 Average (6) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 51.5 11.0 29.9 . 112 Lufkin fine and lo . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. . 823 Orangeburgsfineliandililloam, gig 13'? ggi 242s Black Mesquite land, 9"-12" .......................................... .. 50.8 8'0 s00 484s Sandy upland, 12"-24" ............................................... .. 48.5 11'4 42's 875 Norfolk finesandyloam.22"-36" ...................................... .. 40.0 141 35's 3380 Loam upland, 6"-18" ................................................. .. 44.7 150 38'? 8808 Light red sandy clay, 1110" ........................................... .. 88.0 1110 4112 Average (7) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .' . . . . . . . . . . . . . . . . . . . . . . 47.5 12.6 36.9 AMMONIA-——SOLUBI.E INORGANIC Sort CoLLoms. 7 PERCENTAGE COMPOSITION OF (‘OLLOIDAL PRECIPITATl-IS. 5.- 1 .1 n d n 5% gs gs : _ -- a - 5 z é Ea 352E 3634 Houstoniblack clay, 12”—24" . . . . . . . . . . . . . . . . . . . . 75.0 50.0 0.0 287 Probably Laredo silt loam, 12”—20” . . . . . . . . . . . . . . 50.0 16.7 33.3 981 Norfolk fine sand surface, S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 66.7 50.0 0.0 860 Orangeburg fine sand, 0”—24'l . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58.8 17.7 5.9 312 Norfolk sand, 0"—10" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57.1 17.1 5.7 4231 Black clay, upland S . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.5 15.4 7. 7 348 Norfolk fine sand . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 51.1 12.8 6.4 316 Norfolk fine sandy loam, 0”—20” . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 57.2 14.3 10.2 Average (8) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59.7 24.3 8.7 3662 Orangeburg clay, 0”—18" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 48.1 19.2 11.5 31S Lufkin fine sand, 0”~12" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 55.2 12.1 12.1 3270 Black waxy upland, l2”-22" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55.2 10.4 29.2 937 Orangeburg fine sandy loam, 0”—12” . . . . . . . . ., 53.8 10.8 10.8 172 Norfolk sand . . . . . . . . . . . . . . . . . . . . . . . . . . 52.9 10.0 15.7 3663 Orangeburg clay, 18”—30" . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.6 18.3 11.8 1202 Victoria clay, 0"—10 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56.3 .73 27.0 Average (7) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 53.3 12.6 16.9 In kaolin the ratio of silica to alumina is 2SiO,:Al._.O_.,:2H,O. If We assume that. all the alumina is present as kaolin, then there is an excess of five-sixths of the silica in the first group, seven-elevenths in the second group, one-third of the silica in the third group, and one- fifth of the silica in the fourth group. However, there were other bases present in the precipitate which were not estimated. It appears prob- able that he soluble colloidal material consists of hydrated silica, hjy- drated oxides of iron, hydrated silicates of alumina with other bases, and possibly hydrated silicate of alumina.‘ ACKNOWLEDGMENT. The analytical work reported in this bulletin uras done by Mr. J. B. Rather. ' REFERENCES. 1. Van Bernmerlen, Landw. Versuchsstat, 1878, p. 135; 1879, p. 265; 1888, p. 69. 2. Ehrenberg, Zeitschr. f. Ghent. d’: Ind. d. Colloids, 1908, pp. 193- 24-1. Abstract Experiment Station Record, 22, 610. 3. Fraps, “Principles of Agricultural Chemistry,” pp. 88-89. 4-. Findlay and Creighton, “Colloid,” Zeiischia, 3, p. 169. 5f Endell, “T\'olloid,” Zeitschvz, 1909, p. 244.; Sjollema, Exp. Sta. Record, 17, p. 119. from J. Landau, 53, p. 70. 6. Koenig, HaGsenbaumer 8r Hassler, Landw. Versuchstat, 1911., p. 377. 7. Schloesing. (Fizemie Agricola, 1885. 8. Smith, Proc. Ass. of Agr. Chem, 1912. 9. Rather, Bull. 139, Texas Experiment Station.- 10. List of articles on Colloids by Ehrenberdg, Mitt. Tiandu’. Inst, Breslau, (S, p. .1. . 11. ltohlantl, Lmz/Zrc‘. JaFzrZM/ch, 39, p. 369. 8 Texas Acunci'i.*i'1i1:.u. EXPERIAIICNI.’ STATION. 12. Gedroitz, lluss. Jan. ljlxpt. L-andun, 13, p. 363; Exp. Sta. Record, 28, p. 516. SUMMARY AND CONCLUSIONS. 1. When a soil, previously extracted xvith acid, is digested with ammonia, and tl1e soil and ammoniacal solution poured ona filter, as suggested by Smith, a clear filtrate is secured Which contains inorganii: substances that are precipitated by ammonium carbonate. 2. Colloidal inorganic matter is dissolved from the soil by ammonia. 3. The maximum quantity present in the soils examined was 0.59 per cent. Al. The average of seven soils rich in colloidal matter was 0.299 per cent inorganic colloidal material. ~ 5. The colloidal precipitate contains from 4'7 to 59 per cent silica, from 11 to 24 per cent oxide of iron, and from 8 to 36 per cent aluminum oxides. 6. The quantity of iron oxide is, on an average, fairly constant. The quantity of aluminum was found, on an average, to increase with the quantity of total inorganic colloidal matter in the soil. '7. It is probable that the ammonia-soluble colloidal material con- sists of hydrated silica, hydrated oxides of iron, hydrated silicate of aluminum With other bases, and possibly hydrated silicates of aluminum. 8. The method given is not supposed to estimate the total colloidal constituents of the soil.