CYANAMID — MANUFACTURE, CHEMISTRY AND USES 23 



dicyandiamide by the Caro method, and to consider the differ- 

 ence as being equivalent to the original urea. The other 

 derivatives usually occur in such small quantities that they are 

 practically negligible. 



IDENTIFICATION OF AMIDODICYANIC ACID. 



The following is based upon the procedure given by Ulpiani^ 

 for the identification of amidodicyanic acid. 



Remove the cyanamide and dicyandiamide (Brioux's 

 method), carefully neutralize the filtrate v^ith sulphuric acid, 

 and treat with copper sulphate. In a day or two greenish 

 crystals of copper amidodicyanate separate out. Sometimes 

 there is also a slight precipitate of copper salts of cyanamide 

 and dicyandiamide, which are easily washed out by rapid de- 

 cantation, since the copper amidodicyanate is much heavier. The 

 copper amidodicyanate has the formula Cu(C2H2N30)2 .4H2O. 

 It is further identified by mixing the copper salt with ammonia 

 and treating the solution with hydrogen sulphide. The copper 

 sulphide is filtered off, and the filtrate concentrated, when a 

 white precipitate of thiobiuret is formed. This loses water at 

 100° and melts at 185°. With copper sulphate a solution of 

 thiobiuret gives a white precipitate. 



IDENTIFICATION OF AMMELINE. 



Ulpiani^ claims that ammeline can be detected in old lime- 

 nitrogen as follows : 



Extract the sample with dilute nitric acid. Filter and just 

 neutralize the filtrate with ammonia. A white precipitate of 

 ammeline is obtained, insoluble in water, soluble in alkalies or 

 mineral acids. Analysis should show the solid to have the 

 formula C3H.5N5O. 



1 Gaz Chim. Ital 1908,41 No. 4, 358-417. 

 ^ loc. cit. 



