14 CYANAMID manufacture:, CH]E:MISTRY AND USEJS 



NagCN^ on fusion with carbon yields sodium cyanide: 

 Na^CN, + C — 2NaCN. 



/NCa 

 Calcium Cyanamide, CaCN, or C^ , can be made by the 



fusion of calcium cyanate:^ 



Ca (CNO)^ — > CaCN, + CO, 



or by fusion of cyanamide or its polymers with calcium oxide. 

 Calcium cyanamide forms colorless crystals which sublime 

 at about 1,090° C. at atmospheric pressure. It is insoluble in 

 alcohol, but easily soluble in water (about 2.5 g. in 100 cc. 

 water at 25° C). Upon solution of the calcium cyanamide in 

 water it is directly hydrolyzed into the acid calcium cyanamide 

 and calcium hydroxide. 



2CaCN2 + 2H,0 — Ca(CN.NH)2 + Ca(OH),. 



That such hydrolysis takes place as indicated by the equa- 

 tion is shown by the relative amounts of lime and nitrogen 

 existing in solutions of calcium cyanamide. C. Ulpiani^ inves- 

 tigated the relation of lime to nitrogen in a solution of calcium 

 cyanamide kept at a constant temperature for several weeks. 

 At intervals of several days determinations were made of 

 total nitrogen, nitrogen in the form of cyanamide, and calcium 

 in solution. It was noted that crystals of pure calcium 

 hydroxide, as determined by analysis, were deposited on the 

 walls of the vessel after a day or two. The quantities of 

 lime and nitrogen found in the solution are shown in Fig. i. 



Since the solubility of calcium cyanamide is much greater 

 than that of calcium hydroxide, a concentrated solution of 

 calcium cyanamide is, after hydrolysis, saturated with respect 

 to calcium hydroxide. In addition, there is present lime as 

 a calcium compound of cyanamide. If this compound is cal- 

 cium acid cyanamide, Ca(CN.NH)2, there will be in solution 

 one atom of calcium to four of nitrogen, or 56 parts by weight 



^ Beilstein loc cit. 



' Rend. Soc. Chim. di Roma, n. 4 (1906). 



