AGRICULTURAL CHEMISTRY AGROTECHNY. 709 



" Uric acid is decomposed in part by tin* autoclave treatment witli hydro- 

 chloric acid aud, moreover, it is still further decomposed into ammonia by dis- 

 tillation with 20 cc. of 10 per cent sodium hydroxid solution. 



" Tlie hydrolysis-aeration method ijives practically the same urea nitrogen 

 values as does the Folin method but the Renedict-CJephart method gives higher 

 results than does the Folin method. . . . 



" The hydrolysis-aeration method requix'os much less time and attention than 

 does the Folin method and it does not require the expert manipulation and 

 training necessary to get concordant results which the Folin method re- 

 quires." 



The estimation of phosphorus in urine, G. C. Mathison (Bio-Chon. Jour.j ^ 

 (1909), Xo. 7-7, pp. 2SJ-.2J9). — According to the author's investigations the 

 total phosphorus in urine is most conveniently estimated by the Neumann 

 method as modified by Plimmer and Bayliss. 



" Inorganic P2OB is best estimated by precipitation with magnesium citrate 

 mixture, incineration, and calculation from the weight of the ash, Mg-PsO?. 

 This method is shown to precipitate inorganic phosphates completely. 



" Magnesia mixture gives incorrect and variable results, partly owing to the 

 precipitation of calcium, partly to precipitation of a portion of the organic 

 phosphorus. 



** Organic P2O5 can be determined either by subtracting the inorganic from 

 the total P^Os, or directly by applying Neumann's method to the filtrate after 

 precipitation of inorganic phosphates by magnesium citrate or barium chlorid. 



" The uranium acetate method is unsuitable for accurate work. Statements 

 as to the existence or nonexistence of organic phosphorus in the urine based 

 on uranium acetate estimations are valueless. 



" It is important to make the determinations of organic P-Ob in fresh samples 

 of urine, as the organic compound is partially or completely decomposed in 

 the course of a few weeks, or, if ammonia be present, in a few days. 



" The organic phospliorus compound is readily dialyzable, and is not precipi- 

 tated by reagents that precipitate traces of protein." 



A comparison of the methods for the estimation of total sulphur in urine, 

 S. RiTSoN (Bio-Chem. Jour., 4 {1909), Xo. S, pp. 337-3.',2).—The author con- 

 cludes from comparative studies that the sodium peroxid method carried out 

 accox'ding to Asboth-Modrakowski gives the highest figures in the estimation 

 of total sulphur in urine, " aud must therefore be considered to be the most 

 trustworthy of the methods at present in use." 



The use of barium peroxid in the estimation of total sulphur in urine, 

 S. RiTsoN {Bio-Chcm. Jour., h (1909), Xo. 8, pp. 3 4 3-3. ',5). —From his investi- 

 gations it follows, according to the author, " that the estimation of total sul- 

 phur in urine by means of a mixture of barium and sodium peroxids gives the 

 highest results and possesses the further advantage of being carried out 

 rapidly." 



Chemical tests for blood, J. H. Kasti.e ( I'lih. Health and Mar. Iloftp. Srrv. 

 U. *S'., Ili/fj. Lab. Bui. .51, pp. 62). — Phenolphthalein was studied in regard to its 

 action toward the peroxydases, with particular reference to its employment for 

 the detection of blood. 



It was found that on the whole it was more sensitive for various substances 

 containing blood than the other reagents used for the purpose. In the case 

 of milk it was necessary to coagulate either with an acid or spontaneously in 

 order to carry out the test, the peroxydases or reacting bodies being retained 

 or dissolved by the whey. 'With l)oiled milk the test was as sensitive as the 

 benzidin test. It was further found possible to determine the amount of blood 

 by color comparison. 



