cyanogen bromide

Tear gas used by all sides during World War I. Its prime effect is as a lachrymatory agent and irritant, although it is lethal at higher concentrations.

It was introduced by the Austrians September 1916 and subsequently adopted by the British and Italian armies. However it is highly corrosive and decomposes in contact with metal, and is also unstable in storage, losing its effect and becoming inert. Hence its use as a war gas was short, and it was soon replaced by more stable compositions.