AGEICULTUEAL CHEMISTEY — AGROTECHNY. 317 



first precipitation, and allowing unusual duration of time for this precipita- 

 tion gave apparently perfect results, as judged by recovery of added phosphates, 

 in certain cases, but unsatisfactory results in others. Incompleteness of re- 

 covery of added phosphates was shown not to be due to retention of phosphates 

 by the solid substance of the sample. We are unable to recommend this method, 

 or any other, as reliable for the estimation of inorganic phosphorus in vege- 

 table substances generally. 



" The acid-alcohol extraction of the method of R. C. Collison is either incom- 

 plete in 3 hours or else causes a cleavage of organic compounds of phosphorus 

 with the liberation of inorganic phosphate." 



The studies on the estimation of water-soluble inorganic phosphorus in ani- 

 mal substances were in the nature of comparisons of the neutral molybdate 

 method of Emmett and Grindley, the barium chlorid method of Siegfried and 

 Singewald, and the magnesia mixture method of Forbes and associates. Ex- 

 perimental data presented showed that the methods usually checked by the re- 

 covery of known amounts of added phosphate. Outlines for the preparation 

 of cold water extract of desiccated flesh for the determination of inorganic 

 phosphorus, and of hot water-ammonium sulphate extracts of blood, liver, 

 and brain are given in detail, as well as tabular data on the determination of 

 inorganic phosphorus in muscle, blood, and brain. 



The authors' conclusions from their work done in 1914 follows: 



"The magnesia mixture method gives satisfactorily agreeing results on 

 blood, brain, liver, and flesh, with a recovery of 96 to 100 per cent of added 

 phosphates. 



" Neither ammonium sulphate nor boiling and ammonium sulphate to- 

 gether, as used in the magnesia mixture method, were found to cause a splitting 

 off of inorganic from organic phosphorus in blood. 



" The use of heat and ammonium sulphate, as in the magnesia mixture 

 method, gives lower results than are obtained without heat and ammonium 

 sulphate, though the recovery of added phosphates is perfect; and evidence 

 was obtained that these lower results were due not to inclusion of phosphates 

 in the coagulum obtained by the use of heat and ammonium sulphate, but to 

 the precipitatin of water-soluble organic phosphorus compounds which, with- 

 out the use of heat and ammonium sulphate, yield up their phosphorus as 

 inorganic phosphate, under the influence of the nitric acid used in the subse- 

 quent steps of the inorganic phosphorus estimation. 



" It was found advisable to wash the coagulum with 3.33 per cent ammonium 

 sulphate rather than with hot water. A more concentrated solution was 

 shown not to be necessary. 



" In the case of blood, the filtration of the extract through paper was found 

 preferable to the filtration through sand on linen, which is necessary in the 

 case of brain." 



The calculation of the specific gravity of milk, O. von Sobbe {Molk. Ztg. 

 [Hildesheim], 28 (1914), No. 32, p. 602; abs. in Zentbl. Agr. Chem., U (1915), 

 No. 1, pp. 52). — The specific gravity of curdled milk is determined with difficulty 

 and only after treating the milk with ammonium hydroxid. This entails the 

 use of formulas in which the quantity and specific gravity of the ammonium 

 hydroxid used must be known, and also the quantity of milk used. The author 

 has therefore estimated the specific gravity of curdled milk by means of the 

 formula of Mayerhofer-Hoybergsche for the determination of solids other than 

 fat, rearranging it as follows: S'=4Xr— /, where )S'=specific gravity, r=solids 

 other than fat, and /= the fat content. By determining the fat and the solids- 

 not-fat the specific gravity can thus be easily calculated. 



