Emily Dickinson Lexicon

PHOS'GEN, a. [Gr. φως, light, and γενναω, to generate.]

Generating light. Phosgen gas is generated by the action of light on chlorine and carbonic oxyd gas. It is composed of one equivalent of carbon, one of oxygen, and one of chlorine; and is now called chloro-carbonic acid, the name of phosgen gas having fallen into disuse. – Silliman.