CYANAMID — MANUFACTURE), CHEMISTRY AND USES 1 7 



N 



/// 

 CaCN, + CO2 -f H,0 — Cv /Ca 



\N<( I 5H,0. 



Calcium cyanamide carbonate is somewhat insoluble in water, 

 and insoluble in alcohol and ether. On standing in dry air 

 it slowly loses 4 molecules of water of crystallization, and at 

 the same time decomposes to dicyandiamide and calcium car- 

 bonate. The same change takes place rapidly when heated : 



N 



/// 

 2C\ /Ca.5H,0 •-- (CN.NH,), + 2CaC03 + 8H,0 

 \N< I 



Silver Cyanamide, CN.NAg2. — Obtained on treating an 

 ammoniacal solution containing cyanamide with very dilute 

 (i: 150) solution of silver nitrate.^ More concentrated solu- 

 tions yield a mixture of this salt and double or basic silver 

 salts, containing, however, all the cyanamide. 



Silver cyanamide is an amorphous, yellow substance, almost 

 insoluble in dilute ammonia or caustic potash at ordinary tem- 

 peratures, soluble in hot ammonia solutions, easily soluble in 

 dilute nitric acid. It is easily soluble in alkali cyanide solution, 

 but if an excess of silver nitrate is added, a white, crystalline 

 double salt of silver cyanide and silver cyanamide is precipi- 

 tated. 



When potassium hydroxide is added to a cyanamide solution 

 containing silver nitrate in excess an insoluble mixed precipi- 

 tate of silver cyanamide and brown silver oxide is formed, 

 which contains all the cyanamide nitrogen. 



y 



NH, 



Dicyandiamide,' NH : C<^ .—Obtained by extract- 



\NH.CN 



ing lime-nitrogen with boiling water, concentrating the solu- 



^ Caro, Schiick, Jacoby, loc cit. 

 2 Beilstein, loc cit. 



