others that followed within little more than a month found us wholly unprepared and it was not until the following September that we were able to retaliate in any way. But our immediate reply was one that did honour to Science. Due to the splendid work of English Chemists a system of defence by gas masks was established in which we were for the greater part of the war far ahead of our adversaries who only succeeded in coming up to us by learning and copying our methods. We produced for ourselves and our Allies no less than 55 millions of these masks and they were the true friend of the soldier and were felt to be such by him in spite of all the annoyance that wearing them necessarily caused. It is impossible to estimate what would have been the destruction caused by toxic gases but for these defensive measures.
The gases selected originally for this detestable warfare were well known chemical reagents of very active properties such as chlorine and phosgene. These were capable of attacking and 46
