1917] AGRICULTUEAL CHEMISTRY AGEOTECHNY. Ill 



The use of the centrifuge in analytical chemistry, O. Nolte (Landw. Vers. 

 Stat, 87 {1915), No. 6, pp. 449-^57, pi. i).— The use of the centrifuge for sepa- 

 rating precipitates in the determination of sodium, potassium, calcium, and 

 phosphorus is discussed and the procedures used are described. The ease of 

 manipulation and the economy of time are indicated as making its use of 

 practical importance. 



Note on the applicability of the paper pulp filter to the separation of solids 

 from liquids, S. L. .Todidi {Jour. Franldin Inst., 182 {1916), No. 1, pp. 61-67; 

 Cliem. Engin. and Manfr., 24 {1916), No. 2, pp. 79-81). — This is a short review 

 of the material previously noted (E. S. R., 34, p. 712; 3.5. pp. 204, 314). 



" Plate " forms of ultrafiltration apparatus, G. S. AValpole {Biochem. 

 Jour., 10 {1916), No. 2. pp. 254-262, figs. 3). — Tlie construction and use of two 

 patterns of an ultrafiltration apparatus, using the collodion film as previously 

 noted (E. S. R.. 35, p. G12), is described in detail. 



A note on the sulphone-phthaleins as indicators for the colorimetric de- 

 termination of hydrogen-ion concentration, H. A. Ltjbs and W. M. Clabk 

 (Jour. Wash. Acad. ScL, 6 {1916), No. 14, pp. 481-4S3) .—This article outlines 

 certain modifications in the methods of preparation of a number of sulphone- 

 phtlialeins wliich were previoxisly described by the authors.^ The color changes 

 and the approximate ranges of the various sulphone-phthaleins are given in 

 tabular form. 



The colorimetric determination of the hydrogen-ion concentration of bac- 

 teriological culture media, W. M. Clark and H. A. Lrss {Jour, ^yash. Acad. 

 Sci., 6 {1916), No. 14, pp. 4S3-489) .—ThiH is a short review of the results of 

 the work previously reported by the authors (E. S. R., 34, pp. 136, 804; 35. 

 p. 801). 



The determination of potassium in potassium salts by the perchlorate 

 method, G. Hager and .1. Kern {Landic. Vers. Stat., 87 {1915), No. 4-5, pp. 

 365-380). — From an investigation of the method, using pure potassium salts, 

 the authors found that the solubility of the potassium perchlorate in alcohol- 

 containing perchloric acid increases with decreasing strength of the acid in the 

 alcohol. Witli an increased amount of perchloric acid the solubility markedly 

 decreases. The presence of contaminating salts has the same influence on the 

 solubility. The smaller the amount of contaminating salts the more necessary 

 does the use of alcohol of not less than 96 per cent by volume strength become. 

 Potassium salts which contain considerable amounts of sulphate always yield 

 low results, as the precipitated barium sulphate carries down potassium salts. 

 This error is not only inherent in the perchlorate method but in any procedure 

 in which the sulphates are precipitated by barium chlorid. 



The estimation of potassium in presence of other substances, A. H. Ben- 

 nett {Analyst, 41 {1916), No. 483, pp. 165-168). — The author describes a pro- 

 cedure in which the potassium is first precipitated as potassium cobaltinitrite, 

 the precipitate dissolved in a small amount of hot dilute hydrochloric acid, 

 filtered into an evaporating dish and evaporated to dryness, the residue dissolved 

 in hot water, and the potassium then precipitated as perchlorate with perchloric 

 acid. 



The method is deemed applicable for the estimation of potassium in wine 

 lees, argols, and tartars, and in liquors of tartaric acid works, where it occurs 

 in the presence of free tartaric acid, sulphuric acid, phosphoric acid, iron, 

 aluminum, and organic matter. When the solution contains rather large 

 amounts of ii'on and aluminum phosphates they will be pi'ecipitated with the 



iJour. Wash. Acad. Sci., 5 (1915), No. 18, pp. 609-617, 



