164 THE NEW WORLD OF SCIENCE 



did not lead very far at first, and besides, years of research and 

 chemical reading had given the German an advantage. The 

 best results came from individual fields of research. Here, 

 again, we must acknowledge our debt to our Allies, for all their 

 experimental results were freely placed at our disposal. 



The preparation of chloropicrin and superpalite was first 

 considered. Chloropicrin was soon placed on a manufacturing 

 basis, the well-known reaction between bleaching powder and 

 picric acid being used. The logical method of preparation 

 should be from an aliphatic compound, but no research revealed 

 the proper conditions. The English later found that chlorine 

 gas could be substituted for bleaching powder with a great 

 economy of chlorine, but the method was never used in Ameri- 

 can practice. 



Superpalite was a favorite poison gas with the Germans and 

 was extensively used in the first gas shell. American chemists 

 could never discover any economy in its preparation, and never 

 used the material. It was found that chlorination of methyl 

 chloroformate in steps in ultraviolet light gave the substance 

 in fair yields but with a very great waste of chlorine. After a 

 great many fairly successful trials the matter was permanently 

 dropped. 



One of the large tasks followed the introduction of mustard 

 gas ( dichloroethyl sulfide). The British were able to identify 

 the new shell filling without difficulty, because they had previ- 

 ously suggested its use. Their analysis indicated that the 

 material had been prepared by the academic method of Victor 

 Meyer, through the action of sodium sulfide on ethylene chlor- 

 hydrin, followed by the action of hydrochloric acid. The 

 logical method seemed to be the action of ethylene upon 

 sulfur chloride. Several American chemists tried this reaction, 

 but were unsuccessful in obtaining mustard gas, because of 

 their lack of information regarding its chemical properties. It 

 seemed necessary, therefore, that attention should be concen- 

 trated on the method as used by the Germans and that very 

 rapid progress should be made. This method resolved itself 



