Here are the many types of gas which were used or tested in World War One
 
 

Acrolein Gas

Acrolein Gas was used by the french under the code name of 'Papite'.

Benzyl Bromide

Blue Cross Gas

Bromacetone Gas

Bromo-Benzyl-Cyanide Gas

Chlorine Gas

Chlorocpicrin Gas

Cyanogen Bromide Gas

Cyanogen Chloride Gas

Dimethyl Sulphate Gas

Diphenylchorarsine Gas

Ethyldichlorarsine

Green Cross Gas

Mustard Gas

Phenyldichlorarsine Gas

Phosgene Gas

Xylyl Bromide Gas