Metafulminuric acid

The unsaturated nature of fulminic acid accounts for its tendency to polymerize and suggests that polymers constitute the brown impurity produced in the manufacture of mercury fulminate. The ability of fulminic acid to polymerize is also proved by the formation of cyamelide (I). It has also been established that an ether solution of fulminic acid is converted into metafulminuric acid on standing ... 

An aqueous solution of chloroformoxime reacts with sodium hydrate and with ammonia, forming metafulminuric acid treated with ferric chloride it gives an intense red coloration. 

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