The Medical Section, through its intimate knowledge of what was going on in the Chemical Warfare Service as well as what was contemplated and being experimented with, was enabled to work out methods of handling all gas cases far in advance of what could have been done had there been no such section. One instance alone illustrates this fully. It became known fairly early that if a man who had been gassed with mustard gas could get a thorough cleansing and an entire change of clothing within an hour after exposure, the body burns could be eliminated or largely decreased in severity. This led to the development of degassing units. These consisted of 1,200 gallon tanks on five-ton trucks equipped with a heater. Accompanying this were sprinkling arrangements whereby a man could be given a shower bath, his nose, eyes and ears treated with bicarbonate of soda, and then be given an entire change of clothing. These proved a very great success, although they were not developed in time to be used extensively before the war closed. There is an important side to the Medical Section during peace, that must be kept in mind. The final decision as to whether a gas should be manufactured on a large scale and used extensively on the field of battle depends upon its physiological and morale effect upon troops. In the case of the most powerful gases, the determination of the relative values of those gases so far as their effects on human beings is concerned is a very laborious and exacting job. Such gases have to be handled with extreme caution, necessitating many experiments over long periods of time in order to arrive at correct decisions. CHAPTER V CHLORINE Chlorine is of interest in chemical warfare, not only because it was the first poison gas used by the Germans, but also because of its extensive use in the preparation of other war gases. The fact that, when Germany decided upon her gas program, her chemists selected chlorine as the first substance to be used, was the direct result of an analysis of the requirements of a poison gas. To be of value for this purpose, a chemical must satisfy at least the following conditions: (1) It must be highly toxic. (2) It must be readily manufactured in large quantities. (3) It must be readily compressible to a liquid and yet be more or less easily volatilized when the pressure is released. (4) It should have a considerably higher density than that of air. (5) It should be stable against moisture and other chemicals. Considering the properties of chlorine in the light of these requirements, we find: