Mercury fulminate is a detonator widely used in explosives. Explosives commonly used in detonators include mercury fulminate, lead azide, lead styphnate, tetryl, and DDNP. Percussion cap systems relied on small copper caps that were filled with mercury fulminate. Early primers used the same mercury fulminate used in 19th century percussion caps. He discovered mercury fulminate, a powerful primary explosive. The primers contained also, as detonators, fuses holding each twenty grains of fulminate of mercury. Well known detonators are lead azide [Pb(N)], silver azide [AgN] and mercury fulminate [Hg(ONC)]. Mercury fulminate slowly decomposed in storage until the remaining energy was insufficient for reliable ignition. Today, mercury fulminate has been replaced in primers by more efficient chemical substances. When the cracker is pulled, the abrasive detonates the silver fulminate. He was also involved in the invention of mercury fulminate. Along with mercury fulminate, it is the only fulminate stable enough for commercial use. Another way to make silver fulminate is to react silver carbonate with ammonia in solution. Silver fulminate (AgCNO) is the highly explosive silver salt of fulminic acid. Sodium cyanate is isostructural with sodium fulminate, confirming the linear structure of the cyanate ion.