THE CHEMICAL WARFARE SERVICE 165 



into at least three separate and distinct problems (a) the pro- 

 duction of ethylene, (b) the reaction between ethylene, chlorine 

 and water, to form ethylene chlorhydrin, (c) and the produc- 

 tion of mustard gas from this compound. The first problem, 

 ethylene, was successfully solved by the action of kaolin upon 

 ethyl alcohol at a temperature of 500600. A distinct develop- 

 ment was accomplished in the discovery that the reaction could 

 be controlled more uniformly and a purer ethylene obtained, 

 if steam was introduced with the alcohol vapor in the ratio of 

 one to one by weight. The British found that coke saturated 

 with phosphoric acid also provided a very suitable catalyzer for 

 the removal of water from alcohol.. The second and third 

 problems connected with this synthesis were never satisfactorily 

 solved from the commercial point of view, for in the midst of 

 this development Pope in England discovered the conditions 

 under which ethylene could be made to react with sulfur 

 chloride. Because of the simplicity of this reaction, the Meyer 

 method was entirely displaced by the sulfur chloride reaction. 

 The last word was added by the development of the Levenstein 

 " reactor." The details of these processes were communicated 

 to American chemists and adapted to American practice. The 

 success of the method is evidenced by the fact that at the signing 

 of the Armistice, the Allies were producing many times the 

 amount of mustard gas that the Germans were capable of pro- 

 ducing by their method, and also by the fact that the Germans 

 were rapidly replacing the Meyer method by the Pope method, 

 details having been captured from some Allied source. 



Another intricate field of research was found in the arseni- 

 cals. The first member of this group was diphenylchloroarsine, 

 used as a sneezing gas by the Germans. Although this was an 

 old compound (first prepared in 1885), there was no satisfac- 

 tory method of preparation on a large scale. It was finally 

 discovered that it could be prepared by the interaction of 

 triphenylarsine and arsenic trichloride. The Germans also 

 introduced a second type of arsenical, ethyl dichloroarsine. 

 Apparently they used this because there was no suitable method 



