WHAT HAS HAPPENED to gas warfare? Will gas be used before the war ends? These questions have been asked for the past two year and it is more important than ever now for us to know the answers. If gas is to be used, we must be prepared for it. If there is little chance of chemical warfare, we need not worry about gas masks, decontamination materials and all the complicated and expensive business of gas defense, but may use our energy for other important work. Until Japan entered the war the question, “Why hasn’t gas been used?” was a good one.