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CNS is a mixture of 23% Chloroacetophenone (CN), 38.4% Chloropicrin and 38.4% Chloroform. CN is a colorless crystal which melts at 50 degrees C (122 degrees F) and is dissolved in chloroform. CN is a powerful lachrymatory agent and irritant to the upper respiratory passages.
Old Chemical Weapons Reference Guide (1998)