RECENT WORK IX AiiRICULTURAL SCIENCE. 



CHEMISTRY. 



Kjeldahl method and platinochlorids, C. Van Dam {Rec. Trav. 

 Chhn. Pai/.s-Ikis, li {18!)5), pp. 217-2fJ6; ahs. in Jour. Chem. Soc, 1896, 

 Mar., p. 218). — The results of tlie author's investigations confirm those 

 of others in showing that the Kjeldahl method fails to show the total 

 amount of nitrogen present in certain platinochlorids, and that the 

 error is not eliminated by prolonging the heating or by using Gunning's 

 method. On platinochlorids of certain amins Wilfarth's method (addi- 

 tion of mercury) gave more satisfactory results. However, it failed to 

 recover the total amount of nitrogen in ammonium platinochlorid. 

 Both the platinochlorids of the amins and ammonium platinochlorids 

 yield theoretical amounts of nitrogen when zinc dust is used in the 

 digestion. Ethylamin aurocblorid and ethylamin niercurochlorid give 

 good results by botli (Tunning's and Wilfarth's methods. "The author 

 has demonstrated that the whole of the nitrogen is evolved as such 

 when ammonium platinochlorid is heated with concentrated sulphuric 

 acid for 5 hours." 



The rapid determination of organic nitrogen, Leonard {Rev. 

 Chim. analyt. et appJ., 3 (1895), p. 285; ahs. in Chem. Ztg., 20 {1896), JS'o. 4, 

 Repert.jp. 5). — For the determination of nitrogen in milk and urine the 

 author uses tbe following modification of the Kjeldahl metbod: To 

 10 cc. of the solution in a long neck 300 cc. flask add 1 gm. each of 

 water-free copper sulphate and disodium phosphate and 10 cc. of con- 

 centrated snlj)huric acid. Heat the flask, inclosed in a sheet-copper 

 covering, until its contents are clear and slightly green. When cool, 

 wash into a 100 cc. flask, add an excess of alkali, and allow the copper 

 precipitate to dissidve. Add 20 cc. of alkaline Eochelle salt solution 

 and fill to tbe mark with water. Ammonia may be determined in an 

 aliquot part by distillation in the usual way and by titration with 

 sodium hypo-bromite. 



The determination of nitrogen in Peruvian guano, Heiber 

 {Landw. Vers. Stat, 46 {1895), pp. 407, 408). — The author compared the 

 Jodlbauer method with that proposed by E. Haselhoft' ^ on G different 



• Landw. Vers. Stat., 43 (1894), p. 289 (E. S. R., 6, p. 609). In this method the siib- 

 stanie is (extracted with water, the nitrogen being determined in the extract by 

 Ulsch's method, in the. residue by the Kjeldahl nietliod. 

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