| Cyamelide, (CONH)n, a polymer of cyanic acid of unknown molecular weight, is formed from this acid at 0° C. by spontaneous polymerisation with evolution of heat and light, and may also be prepared by gently heating a mixture of equal parts of potassium cyanate and oxalic acid. It is a white amorphous powder, which, in accordance with high molecular weight, is insoluble in water and other solvents; its density at 0° C. is 1.974; its heat of formation per gram is 1362 calories; and its heat of combustion 1630 calories. The heat of transformation of cyamelide into cyanuric acid is - 9600 calories. Cyamelide dissolves in alkalis, forming cyanates; it dissolves in sulphuric acid unchanged, whence it may be precipitated by water, but when warmed with the concentrated acid it passes into cyanuric acid, and eventually into carbon dioxide and ammonia. |