A colorless liquid which boils at 26 degrees C (79 degrees F). Its American equivalent is hydrogen cyanide or AC. Its vapor is 0.93 times heavier than air. It is considered a non-persistent blood agent. It interferes with the utilization of oxygen by the body, inhibiting the enzyme cytochrome oxidase. It causes a marked increase in the individual’s breathing rate. In this form, it is stabilized from decomposition by the addition of a small quantity of arsenic trichloride or stannic chloride.