CR gas or dibenzoxazepine, chemically dibenz[b,f][1,4]oxazepine, is an incapacitating agent

Incapacitating agent

The term incapacitating agent is defined by the U.S. Department of Defense asLethal agents are primarily intended to kill, but incapacitating agents can also kill if administered in a potent enough dose, or in certain scenarios....

 and a lachrymatory agent

Lachrymatory agent

Tear gas, formally known as a lachrymatory agent or lachrymator , is a non-lethal chemical weapon that stimulates the corneal nerves in the eyes to cause tears, pain, and even blindness...

. CR was developed by the British Ministry of Defence

Ministry of Defence (United Kingdom)

The Ministry of Defence is the United Kingdom government department responsible for implementation of government defence policy and is the headquarters of the British Armed Forces....

 as a riot control agent in the late 1950s and early 1960s.
CR is a pale yellow crystalline solid with a pepper-like odor. It is slightly soluble in water and does not degrade in it. CR is usually presented as a microparticulate solid, in the form of suspension

Suspension (chemistry)

In chemistry, a suspension is a heterogeneous fluid containing solid particles that are sufficiently large for sedimentation. Usually they must be larger than 1 micrometer. The internal phase is dispersed throughout the external phase through mechanical agitation, with the use of certain...

 in a propylene glycol

Propylene glycol

Propylene glycol, also called 1,2-propanediol or propane-1,2-diol, is an organic compound with formula C3H8O2 or HO-CH2-CHOH-CH3...

 based liquid.