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:
(1a) Chlorine is fairly toxic, though its lethal concentration (2.5 milligrams per liter of air) is very high when compared with some of the later gases developed. This figure is the concentration necessary to kill a dog after an exposure of thirty minutes. Its effects during the first gas attack showed that, with no protection, the gas was very effective.