RECENT WORK IN AGRICULTURAL SCIENCE. 



CHEMISTRY. 



The determination of citric-acid soluble phosphoric acid in Thomas slag, 

 P. Wagner et al. {Die Be^timmuug der zitromnisiXiu'elodidien l'h(ii<phorsauri' hi Thomas- 

 mehlen. Berlin: I'diil P<trey, 1903, pp. VII ^ 112). — This is the first of a series of 

 contributions from the Association of German Agricultural Experiment Stations, 

 which are designed to summarize in concise form lines of investigation by the Ger- 

 man stations which have led to conclusive results of practical value. This number 

 reviews the history of the development of the German official method of determining 

 the solubility oi the phosphoric acid of Thomas slag in citric acid, explains in detail 

 the sources of error and the precautions to be observed in using the method, and gives 

 a full description of the method and of the preparation of the reagents required. 



Investigations on phosphorus and phosphoric acids, H. Giran {Ann. Chim. 

 et Phys., 7. ser., 30 {1903), Oct., pp. 203-288, figs. 6).— This article deals inasomewhat 

 exhaustive manner with the different forms, heat of combustion, and solubility in 

 bromin of phosphorus; forms and properties of phosphoric anhydrid; and preparation 

 and proi^erties of metaphosphoric and pyrophosphoric acids and the rapidity of their 

 transformation in solution. 



Solubility of magnesium ammonium phosphate in ammonium citrate, A. 

 BoLis ( ('Item. Zty., ',.'7 {1903), No. 94, p. 1151). — By treating 2 gm. of freshly precipi- 

 tated magnesium annnonium phosphate with 100 cc. of neutral ammonium citrate 

 containing 400 gm. of citric acid per liter for 24 hours in the cold, it was found that 

 the average solubility of the phosphate was 0.457 per cent. When the solution was 

 kept warm during the treatment the solubility was somewhat higher, approximately 

 0.6 per cent. 



The influence of ammonium salts in preventing the precipitation of mag- 

 nesium by means of ammonia, F. P. Treadwell {Zt.tchr. Anorgan. Cliem., 37 

 {1903), No. 2, pp. 326-331; abs. in Chem. Ztg., 27 {1903), No. 93, Repert. 21, p. 299).— 

 The author's investigations confirm Loven's conclusion that the action of ammonium 

 salts in preventing the i^recipitation of magnesium by means of anunonia is due not 

 to the formation of complex salts, but solely to the prevention of dissociation of 

 ammonium hydroxid by annnonium chloiid according to the law of mass action. 



On the quantitative separation of lime and magnesium by the indirect 

 method, A. C. Christomanos {Zt.schr. Analyt. Chem., 42 {1903), pp. 606-612; abs. in 

 ('hem.. CentbL, 1903, II, No. 20, p. 1145). — Methods applicable to mineral waters and 

 magnesite are described. These are based upon the conversion of the calcium and the 

 magnesium after the removal of silica, iron, and alumina from the solution, first into 

 carbonate and then into sulphate. A method of estimating the lime and magnesia 

 from the weights of carbonate and sulphate obtained, with proper factors to use, is 

 explained, and results of analyses of a number of samples of magnesite are reported. 



A cohtribution to the knowledge of calcium carbonate, W. Meigen {Ber. 

 Natiirf. Gesell. Freiburg, 13 {1903), Jalij, pp. 40-94, figs. 9). — A detailed and technical 

 chemical study. 



Detection and estimation of ammonia by means of sodium picrate, C. 

 Reichard {Chem. Ztg., 27 {1903), Nos. 80, pp. 979, 980; 82, pp. 1007, 1008; abs. in 

 Jour. Chem. Soc. [London'], 84 {1903), No. 493, II, p. 754)- — In the method proposed 



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