THE CHEMICAL WARFARE SERVICE 155 



tally, of course, the methods used did not differ from those of 

 the individual sciences. But here there was a combination of 

 all sciences practically ; the results of one set of tests decided 

 whether other tests should be made and the combined results 

 decided whether the " gas " was suitable for military purposes. 

 The material in question may be one that was already used by 

 the Germans, it may have been found from a search of the 

 literature, or it may be the result of analogy or pure inspiration 

 The substance was prepared by the Offense Section, research 

 ability being used to secure the cheapest and most efficient 

 laboratory method. The first test is to determine the toxicity, 

 if the material is simply a lethal gas, or if a special gas, its 

 lachrymatory power, blistering power, etc. If this report is 

 favorable, then real research work begins. Methods of analysis 

 are worked out, both for the pure material and for air mixtures. 

 These methods are used in testing the efficiency of the standard 

 respirator against varying concentrations of the gas in air. 

 The stability when fired in shell is determined, and, if the mate- 

 rial is a solid, methods of dispersing it as a cloud or mist. If 

 the canister does not furnish sufficient protection, changes are 

 made in the proportion of the present ingredients, or new 

 mixtures or compounds are tested until satisfactory protection 

 is afforded by the canister. The results of all the tests so far 

 are then critically analyzed, and a decision reached as to the 

 probable suitability of the material as a poison gas. If this 

 decision is favorable, then more work is undertaken. First of 

 all it becomes necessary to work out a commercial process of 

 preparing the substance. Large firing trials are made to deter- 

 mine whether the boosters are suitable to secure the maximum 

 effect from each shell. The pharmacological effect of the 

 material is carefully studied, and the animals that have been 

 " gassed " are studied by pathologists. These results are then 

 used to ascertain, if possible, the therapeutic measures to heal 

 the lesions caused by the " gas." If the results of all these 

 tests still point to the success of the material, it is then ready 

 to be launched as a new poison gas. 



