Hydrocyanic Acid

HCN. Sp. gr. 0.70, bpt. 26° C. Pru ic acid; colorle liquid of bitter almond odor, prepared by the action of sulphuric acid on pota ium ferrocyanide. The pota ium cyanide is made by heating the ferrocyanide. and is also one of the most violent poisons known. A grain of anhydrous acid has produced death in 20 minutes. Discovered by Scheele, 1782. Hydro cysts. Feelers of the Physophoridæ ; curious proce es of the cœnosarc, like nematophores.