Hydrogen cyanide [74-90-8], hydrocyanic acid, prussic acid, formonitrile, HCN, M r 27.03, is a colorless liquid with the characteristic odor of bitter almonds. Hydrogen cyanide in aqueous solution was first prepared by SCHEELE in [22]. The acid occurs naturally in combination with some glucosides, such as amygdalin.Hydrogen cyanide is currently produced by direct reaction of alkanes with ammonia, and indirectly as a byproduct of the manufacture of