DENSITY – 4.00 g per ml @ 137,900 kPa (20,000 psi)
NORMAL STATE – Crystalline solid
PHYSICAL APPEARANCE/COLOR – White to grayish yellow solid
INITIATION – Flame or impact
SENSITIVITY – Very sensitive to shock, friction, and sparks when dry
STABILITY – Relatively stable when stored underwater, rendered inert when stored above 35o C
DETONATION VELOCITY – 5,000 m/s (16,404 fps)
RE FACTOR (BRISANCE) [TNT=1.0] – 0.46
TOXICITY – Toxic, the material should not be handled directly or inhaled
MELTING POINT – 160o C.(320o F.)
IGNITION POINT – Explodes at 180o C. (356o F.)
SOLUBILITY – Slightly soluble in water
APPLICATIONS – PRINCIPLE USES – Percussion caps, primers, and detonators
Mercury fulminate is one of the oldest explosives, as well as being one of the most influential and important. As such, Mercury fulminate can be considered second in historical importance only to Black Powder. It is the first Primary explosive, those used to initiate other explosives. Mercury fulminate qualified as a primary explosive because of its sensitivity to initiation by shock (impact), crushing, or flame. Within a few years of its discovery, Mercury fulminate was used by the Reverend Alexander John Forsythe of England in 1806, to produce a percussion-fired, sealed, ignition system for firearms. Improvements to the original percussion ignition system were patented by Joshua Shaw in 1822. The improvement basically consisted of a metallic cap that contained a priming mixture made up primarily of Mercury fulminate among other ingredients. The soft metal priming cap fitted over a nipple that would be struck by a hammer when the weapon it was fitted to was fired. The crushing of the primer (percussion) cap would create a flash of flame that would be guided through the central hole of the nipple and into the Black Powder charge held in the barrel of the weapon. The flash would ignite the powder charge very quickly, even in the pouring rain. That was something a flintlock mechanism could not do well. It was not until the introduction of the metallic (brass) cartridge case later in the 1800s that a problem with Mercury fulminate primers was found. It was not until nearly 1900 that Mercury fulminate was being replaced for primer cap use when it was found that the mercury salts would cause the brass cartridge cases to become brittle, damaging them for reloading.
One of the next most important uses for Mercury fulminate, besides its use in percussion caps, was the inclusion of the material in the blasting cap invented by Alfred Nobel in 1865, improved from his original Black Powder design in 1863. The 1865 improvement included a charge of Mercury fulminate in a slim, soft metal capsule that could be crimped to the open end of a fuse. The flash of fire from the burning fuse would be sufficient to initiate the explosion of the Mercury fulminate. The shock of the detonating blasting cap was first used to set off Nitroglycerine charges, but quickly found an application in detonating dynamite, another invention of Alfred Nobel.
