DECOMPOSITION OF CYAN ATE. 343 



acids which are produced in the case of chlorine and the halogen 

 elements ; such compounds would have too great a tendency to 

 be converted into carbonic acid. 



The total combustion of potassium cyanate in the solid state 



i[2KCNO + 3 = K 2 C0 3 + C0 2 + N 2 ], would give off + 83*9. 



6. The facility with which potassium cyanate is converted 

 into ammonia, even by the simple fact of its prolonged contact 

 with water, is easily explained ; for 



[2KCNO (in solution) + 4H 2 = K 2 C0 3 (in solution) 

 + (NH 4 ) 2 C0 3 (in solution)], gives off + 20 Gal. 



This is again a reaction of amides. 



The well-known conversion of melted potassium cyanate, by 

 means of aqueous vapour, into melted potassium carbonate, 

 carbonic acid and ammonia gas, gives off about + 9 Cal. 



The change of potassium cyanide under the united influence 

 of oxygen and aqueous vapours at a high temperature into 

 carbonate and ammonia a change which is so pernicious in the 

 industrial preparation of the prussiates is as easily explained 

 by thermo-chemistry. In fact, we should get, at the ordinary 

 temperature 



J[2KCN (solid) + 2 + 3H 2 (gaseous) = K 2 C0 3 (solid) 

 + C0 2 (gas) + 2NH 3 (gas)] + 79-3. 



Towards a red heat this value should still keep the same, as 

 the cyanide and the carbonate are similarly fused. 



A rapid resume has been made of the more immediate 

 deductions from the new values relating to the heat of forma- 

 tion of cyanogen, hydrocyanic acid, and cyanides. It would be 

 easy to develop and extend these conclusions to innumerable 

 other reactions, the subject being most fruitful. Any one can 

 do this as far as he deems expedient or interesting. The general 

 table of the thermal formation of the cyanogen compounds will 

 be found on p. 132. 



