POTASSIUM CYAXATE. 341 



sufficient to keep the whole of the carbonic acid formed in solu- 

 tion, the decomposition is complete at the end of a few minutes : 



KCNO (in solution) + 2HC1 (in solution) + H 2 O 

 = C0 2 (in solution) + KC1 (in solution) + NH 4 C1 (in solution). 

 This reaction gives off, according to the experiment performed, 

 + 28-8 Cal. 



2. On the other hand, the solution of potassium cyanate, 

 KCNO (1 part of salt to 300 parts of water), absorbs - 5'2. 



3. Formation of potassium cyanate from the elements. This is 

 deduced from the above data. 



Initial system : 



K + C (diamond) + N + 2H 2 + 2 + Cl* 

 Final system : 



C0 2 (in solution) + KC1 (in solution) + NH 4 C1 (in solution). 



FIRST STEP. 



= C0 2 ......... - 94-0 



Solution ............ + 5-6 



K + Cl = KC1 (in solution) ... + 100- 8 



N + H 3 = NH 3 (in solution) ... + 21-0 



H + Cl = HC1 (in solution) ... + 39-3 



HC1 + NH 3 = NH 4 C1 (solution) .. + 12-45 



+ 273-15 



SECOND STEP. 



K+C+N+0= KCNO (solid) a 



Solution ............ 5-2 



2(H + Cl) = 2HC1 (diluted) ... + 78-6 



H 2 + = H 2 ...... + 69-0 



+ 142-4 + x 

 Reaction ... + 28-8 



+ 171-2+a; 

 x = 273-15 - 171-2 = + 102. 



Thus, the formation of solid potassium cyanate from the 

 elements, K +C (diamond) + N + O = KCNO, gives off + 102-0. 

 If the salt is in solution, + 96*8. 



This same formation, from diluted potash 



i[C 2 + N 2 + 4- K 2 (diluted) = 2KCNO (in solution)], gives 



off + 15-5. 



From gaseous cyanogen 



CN + K + = KCNO (solid) ...... +139-3 



M(CN) 2 + + K 2 (diluted) = 2KCNO (in solution)] ... +51-8 

 CN 2 + K 2 (diluted) = KCNO (diluted) + KCN (diluted) + 34-2 



4. All these values exceed the heats disengaged in the analo- 

 gous reactions of the halogen elements properly so called. 



