THE CHEMICAL WARFARE SERVICE 153 



usually mixed with phosgene. This was almost as toxic as 

 phosgene and had the advantage of being more persistent, since 

 its boiling point was very much higher. The manufacture of 

 this material, however, wasted tremendous quantities of chlorine 

 and its use gradually decreased. 



With the summer of 1916, we see the introduction of special 

 gases. The first of these was chloropicrin. While not quite 

 as toxic as superpalite, chloropicrin possessed the peculiar 

 physiological property of causing vomiting. It was used very 

 effectively in connection with other lethal gases, the chloropicrin 

 causing the men to remove their masks in the poisonous atmos- 

 phere, and thus producing many casualties. With the increas- 

 ing degree of protection, chloropicrin lost its great military- 

 value. Then the Germans sprung their Sneezing Gas 

 (diphenylchloroarsine). This was used in shells carrying a 

 high bursting charge. The explosion of the shell scattered the 

 Sneezing Gas in the form of a very fine cloud of particles. 

 While the charcoal of the mask will remove most poisonous 

 gases, it has no protective power against clouds or mists. The 

 Sneezing Gas passed through the best canister, and through its 

 peculiar physiological effect caused great discomfort to the 

 men and numerous casualties through forcing the men to re- 

 move their masks. Lachrymators were also used extensively, 

 especially in territory where neutralization alone was desired. 

 Because of the low concentrations in which lachrymators are 

 effective, they are very economical as far as the amount of gas 

 used, and very valuable from the military point of view, because 

 they cause the wearing of masks and thus reduce the efficiency 

 of the men. 



The crowning achievement of gas warfare was the introduc- 

 tion of mustard gas. The name '* blistering gas " indicates its 

 peculiar physiological property. This is a high boiling sub- 

 stance which is very persistent. It has been known to cause 

 casualties seven to ten days after the firing of the shell. It 

 produces a severe burn and the casualties are usually out of 

 action from three weeks to three months or even longer. A 



