Chemistry and Physics. ^99 



reaction was thus obtained with as little as 0.0000004g. of 

 gaseous ammonia, and the reaction is even more delicate than 

 that of Nessler. 



In order to apply the reaction for detecting nitrogen in organic 

 compounds a small quantity of the substance is mixed in a por- 

 celain crucible with a mixture of two parts of well-dried soda- 

 lime and one part of finely divided metallic copper, prepared 

 electrolytically. The copper facilitates the formation of ammo- 

 nia from compounds in which the nitrogen is directly combined 

 with oxygen. The crucible is then heated upon a hot plate and 

 the resulting ammonia is detected by means of the reagent on 

 a watch-glass covering the crucible according to the method 

 already mentioned for testing the vapors from a test-tube. It 

 seems probable that the ignition with soda-lime and copper could 

 be carried out in the bottom of a test-tube and the tube satisfac- 

 torily made in this way. — Gomptes Bendiis, 175, 153 and 

 308. H. L. w. 



2. The Quantitative Separation of Arsenic, Antimony and 

 Tin. — F. L. Hahn and P. Philippi have adopted for quantitative 

 use a qualitative process that was described about six years ago 

 by the former author. As the method is a simple one and as it 

 varies essentially from the usual processes, it deserves attention. 

 A mixture of the three sulphides is dissolved in the least possible 

 measured quantity of 10 per cent sodium sulphide solution, the 

 same volume of 20 per cent sodium hydroxide is added, the liquid 

 is diluted to 50 or 100 c.c. and strong peroxide (10-30 per cent) is 

 gradually added to complete decolorization. The liquid is then 

 heated to boiling, cooled, 1/3 volume of 80 per cent alcohol is 

 added, and after twenty-four hours the precipitated sodium pyro- 

 antimonate is filtered and washed with alcohol of increasing 

 strength. The precipitate is dissolved in hydrochloric and tar- 

 taric acids in order that antimony may be determined by one of the 

 usual methods, for instance, as SbgSg or volumetrically. The fil- 

 trate is evaporated in a porcelain or platinum dish until the alco- 

 hol has been removed, the liquid is diluted to about 300 c.c. and 

 the same volume of 50 per cent ammonium nitrate as that of the 

 20 per cent sodium hydroxide previously used is added, the liquid 

 is boiled until the odor of ammonia has disappeared and the tin 

 precipitate is filtered off and washed with hot, dilute ammonium 

 nitrate solution. The precipitate is ignited and SnOg is weighed. 

 The filtrate is concentrated and ammonium magnesium arsenate 

 is precipitated as usual. This should be dissolved in hydrochloric 

 acid and re-precipitated with ammonia. 



The authors have carried out as many as fifty-three test- 

 analyses by this method. The results of many of these are given, 

 including those that gave the least accurate results. The agree- 

 ments with the amounts taken are astonishingly close. — Zeitschr. 

 anorgan. u. allgem. Chem., 116, 201. h. l. w. 



