292 SOIL SCIENCE [Bot. Absts., Vol. VI, 



2024. Weir, W. W. Productive soils. 6X9 inches, 898 p., 235 fig. J. B. Lippincott 

 Co.: Philadelphia and London, 1920. 



METHODS 



2025. Hibbard, R. P., and S. Gershberg. The biological method of determining the 

 fertilizer requirement of a particular soil or crop. Michigan Acad. Sci. Ann. Rept. 21 : 223-224. 

 1919.— See Bot. Absts. 6, Entry 1419. 



2026. Lipscomb, G. F., C. F. Inman, and J. S. Watkins. The determination of borax in 

 fertilizer materials and mixed fertilizers. Amer. Fertilizer 52:57-8. 1920. — The method 

 described is similar in its general procedure to that outlined in following Entry 2027, but differs 

 in the means adopted for removing ammonia, phosphates, etc. An aliquot corresponding to 1 g. 

 of the sample is made alkaline with sodium hydroxide and boiled down nearly to dryness, and 

 then diluted with water and the same operation repeated twice. The residue is taken up in 

 dilute hydrochloric acid, the solution made alkaline with lime water, and filtered without 

 boiling. The filtrate is evaporated to dryness and ignited to destroy organic matter, the 

 residue taken up in a little dilute hydrochloric acid, made alkaline with sodium hydroxide, 

 and the addition of lime repeated to insure complete removal of phosphates. The borak 

 remains in the filtrate and may then be determined by titration. — W. H. Ross. 



2027. Pope, W. B., and William II. Ross. Qualitative method for the detection of borax 

 in mixed fertilizers. Amer. Fertilizer 52 : 65-66. 1920.— Directions are given for a simple 

 qualitative test for differentiating between fertilizers containing less than 0.1 per cent of 

 borax, the limit set by the Dept. of Agriculture for the maximum allowable in a fertilizer 

 without labeling, and those which contain in excess of this amount. The test is made on a 

 2 g. sample. This is digested with 50 cc. of 90 per cent alcohol; an aliquot of the clear solution 

 is made alkaline with sodium hydroxide and evaporated to dryness. The residue is ignited 

 to destroy organic matter and then taken up in dilute hydrochloric acid; 1 cc. of tincture of 

 curcumin added, and the mixture is again evaporated to dryness, in a porcelain dish. If borax 

 is present a pink coloration, varying in intensity with the amount, will be deposited on the 

 bottom and sides of the dish. By comparing the color given by an unknown sample with a 

 set of samples containing known amounts of borax, it is possible to apply the method quanti- 

 tatively in the analysis of samples containing in the neighborhood of 0.1 per cent of borax or 

 less. Nitrates interfere with the test and must be destroyed when present. This may be 

 done by adding sufficient sucrose to insure complete decomposition of the nitrates when the 

 evaporated residue is ignited. — W. H. Ross. 



2028. Ross, William H., and R. B. Deemer. Methods for the determination of borax in 

 fertilizers and fertilizer materials. Amer. Fertilizer 52: 62-65. 1920.— The procedure recom- 

 mended for the determination of borax varies with the nature of the material to be analyzed. 

 In the case of mineral salts free from phosphates, or iron and aluminum salts, ammonia, and 

 organic matter, it is possible to determine borax by driving off carbon dioxide from the solu- 

 tion of the salt, making neutral to methyl red and then titrating after adding phenolphthalein 

 as indicator and 1-2 g. of mannitol, with standard sodium hydroxide solution to a permanent 

 pink color. Phosphates, or iron and aluminum salts and ammonia interfere with the deter- 

 mination and the method must therefore be modified to bring about their removal when 

 present. This may be done by adding to the hot solution of the material to be analyzed 15 cc. 

 of a 10 per cent barium chloride solution and sufficient barium hydroxide to give an alkaline 

 reaction. The solution is then boiled for 15 minutes, or until any ammonia present is expelled, 

 filtered and the borax then determined in the filtrate by titration with standard alkali. Sol- 

 uble organic matter when present interferes in the determination of small amounts of borax 

 (less than 0.5 per cent) and may be removed by evaporating the filtrate from the barium 

 chloride-barium hydroxide precipitate and igniting. The residue is taken up in dilute hydro- 

 chloric acid and the addition of barium chloride and barium hydroxide repeated to insure com- 

 plete removal of phosphates, etc. In the analysis of fertilizers containing in excess of 0.5 

 per cent of borax, the removal of organic matter may be unnecessary, and the same procedure 

 may then be followed as for the determination of borax in mineral salts. — W. H. Ross. 



