“The first 20,000 masks sent over to England were completed by the Research Division in record time. As compared with the French masks, they were far superior, giving greater protection against chlorine, phosgene, superpalite, prussic acid, xylyl bromide, etc. The French mask was of the cloth type, conforming to the face, and consisting of twenty layers of cheesecloth impregnated with sodium phenate and hexamethylenetetramine. Chloropicrin went through this like a shot. Just before the masks were sent abroad, we received disturbing rumors of the contemplated use of large quantities of chloropicrin. The French, apparently, had no intention of changing the design of their mask, and did not do so for months to come. We therefore released the masks, they were sent abroad, and an anxious research group on this side of the water waited expectantly for the verdict. It came. A brief cablegram told us what our English cousins thought of us. It was a subject they had been wrestling with for two years and a half. They had had battlefield experience; they had gone through the grief of developing poor masks into better ones, knew the story better than we did, and after a thorough test ‘hammered’ the American design unmercifully. “This experience put the Research Division on its mettle. Our first attempt had given us the necessary preliminary experience; cablegrams and reports traveled back and forth; an expert or two eventually came to this country from England in response to previous appeals for assistance, and we turned with adequate information to the development of a real mask.” The story of mustard gas is given later. It probably occupied more time and thought on the part of the Research Division, as well as that of Edgewood Arsenal and the Development Division, than any other gas. Diphenylchloroarsine led to the preparation of a series of arsenic compounds, some more easily prepared and more or less effective. Cyanogen chloride and cyanogen bromide, reported by the Italians as having been used by the Germans, were extensively studied. The Inorganic Section was early interested in special incendiary materials which were developed for bombs, shells, darts and grenades, and which were later taken over by the Pyrotechnic Section, and finally adopted by the Ordnance Department.