Properties of Pure Substances : Nitrogen. 3 



they used pure nitrogen without giving details of its method 

 of preparation. 



Name. 

 J. S. Stas . 



Neuman 



Olzewski . . 



Wroblewski 

 Lupton .... 



H. Deslandres. 

 W. Gibbs 



JN T . W. Fisher. 



Regnault 

 Wullner .... 



Huggins 

 Warburg 



Reference. 

 Bull de V Acad, de 

 Belgique, vol. x. 

 p. 254. 



J. fur prk. Chemie, 

 [2] xxxvii. p. 342. 



Wien. Anzeiger, 

 March 1884. 



C. R. xcviii. p. 982. 



C. S. J. 1876; 

 Ohem. News, 

 xxxiii. p. 90. 



C.R. ci. p. 1256. 



Ber. 



1887. 



Method. 



By passing purified air over hot 

 copper turnings and gauze, 

 which are previously reduced 

 by hydrogen. Copper oxide at 

 end of tube (?) ; ordinary ab- 

 sorbent reagents to help purify 

 the gas after leaving the hot 

 copper. 



From chloride-of-lime cubes (made 

 by Winkler's method) and 

 aqueous ammonia (see C. S. J. 

 1887, p. 442). 



Hot copper and air. 



Hot copper and air. 



Air and ammonia over hot copper ; 

 claims to get pure N with a 

 short tube. 



Hot copper and air ; no precaution 

 mentioned. 



Sodium nitrite, ammonium sul- 

 phate, and potassium dichro- 

 mate in excess. If there is a 

 trace of chloride present, im- 

 purities are introduced. 



Uses cuprous chloride as an ab- 

 sorber of oxygen from air. 



Hot copper and air. 



Burning phosphorus in air over 

 mercury and removing traces of 

 oxygen by incandescent iron 

 wire. 



Purified air over hot reduced 

 copper. 



Hittorf's method. Dust-free air 

 over hot white phosphorus, then 

 over potassium permanganate, 

 solid potash, and phosphorus 

 pentoxide. Special drying in 

 some cases followed by exposure 

 (Wied. Ann. xl. p. 1) to nascent 

 sodium obtained by the electro- 

 lysis of glass. 



It is clear that the most popular way of making nitrogen is 

 to absorb the oxygen from air by means of red-hot copper. 

 There are a great many objections to this method, however, 

 even when precautions are taken against the possibility of the 

 formation of oxides of nitrogen. In the first place, a satis- 

 factory method of making connexion to the porcelain tube is 

 unknown to me ; indiarubber stoppers are undesirable in any 



B2 



Pogg. Ann. xvii. 



p. 137. 

 C. R. t. xx. p. 975. 

 Pogg. Ann. cxlvii. 



p. 325. 



Phil. Trans. 1860. 



Ann. der Chem. und 

 der Phys. 1887, 

 p. 548. 



