Most studies of modern chemical warfare begin with World War I and the widespread use of poison gas by both sides in the conflict. However, as Guy R. Hasegawa reveals in this fascinating study, numerous chemical agents were proposed during the Civil War era. As combat commenced, Hasegawa shows, a few forward-thinking chemists recognized the advantages of weaponizing the noxious, sometimes deadly aspects of certain chemical concoctions. They and numerous ordinary citizens proposed a host of chemical weapons, from liquid chlorine in artillery shells to cayenne pepper solution sprayed from fire...