RECENT WORK IX ACiRlCUETlRAE SCIENCE. 



CHEMISTRY. 



Comparative methods of determining nitrogen in nitrates, L. 



VON WissELL {Jviii-. Landu'., J^S {19u0}, jVo. '2^ pp. 10'>-llo,jig. i).— 

 Comparative tests of the following- methods are reported: (1) The 

 Mockern method^ (rediu'tioii in alkaline solution with zinc and iron 

 powder), (2) the Ulsch method," (3) the Devarda method (reduction 

 in alkaline alcoholic solution with ammonium-copper-zinc alloy — E. S. 

 R., tt, p. 67B), and (i) Forster's modification of the Kjeldahl method, 

 using sidphuric acid containing salicylic acid. The Devarda method 

 gave in all respects the most satisfactory results. Of the other three 

 methods the Ulsch and the Forster methods gave equally good results, 

 while the results ])y the Mockern method were too low. The author 

 considers the Devarda method the quickest and most convenient of the 

 methods tested. 



The determination of perchlorates in potassium and sodium 

 nitrates, N. Blattner and J. Brasseur {C'hem. Ztg., 2.!f (1900), JVb. 

 72, J). 767; ah.s. /// 0/>e)n. CenthL, 1900, If, N'o. U, 2U>- '''^0, 781).— 

 The authors' method (E. 8. K., 10, p. 4-10) is modified as follows: Heat 

 5 gm. of the dried and finely powdered nitrate with T to 8 gm. of pure 

 calcium hydrate (5 gm. of water and 100 gm. of caustic lime) in a plat- 

 inum or porcelain crucible for 15 minutes over a Bunsen flame, cool 

 and wash into a 125 cc. flask, and allow to stand for 1 hour for the 

 complete diflusion of the soluble salts. Fill to the mark, allowing 3 

 cc. for the volume of the undissolved lime, shake and Alter, neutral- 

 ize 100 cc. of the Altered solution with dilute nitric acid, using methyl 

 orange as an indicator, and titrate according to Mohr Avith potassium 

 chromate and decinormal silver solution. 



Method of determining chlorid, chlorate, and perchlorate in the 

 presence of each other, X. Blattner and .]. Hhasseli{ {CJk-ik. Zt(j., 

 2J^ {1900), j>. 793; ahs. Jn. Che in. CeiifhJ., 1900, II, No. 15, j). 820)'.— 

 The method is as follows: Dissolve 20 to -tO gm. substance in 200 cc. 

 of water. Determine chlorln in 50 cc. of this solution l)y titration 

 with decinormal silver solution. Conduct sulphurous acid through 

 another 50 cc. of the solution or add 50 cc. of a saturated solution of 



' Landw. Vers. Stat., 1892, p. 165. -Ztschr. Analvt. C'lieiii., 1891, j). 175. 

 510 



