=Protection Against Particulate Clouds.= Just at this time, about the first of February, 1918, the danger that the Germans might devise some better method of sending over diphenylchloroarsine than by pulverizing it in high explosive shell was felt to be serious. The British had just then perfected protection against diphenylchloroarsine by employing unsized sulfate wood pulp paper—48 to 60 layers being required. This number of layers was found to be necessary as they are very thin and porous. The British had developed a method of putting this paper around a canister and yet keeping the canister small enough to fit into the knapsack by reversing its position therein; that is, putting the canister in the compartment of the knapsack made for the face piece and putting the face piece in the other compartment. Some of our own officers and enlisted men were sent to England to work with the British on this and an order given them for 200,000 of the protected canisters. They improved on the methods of the British and as it was found that sulfate paper was very scarce, investigations were made to see if any of it could be manufactured in France. Very soon thereafter such a place was located near the city of Nancy. Following this a cablegram was sent to the United States giving complete specifications for making this diphenylchloroarsine protection. From this cablegram successful samples were made though somewhat more bulky than those developed in England. Very few, however, of these were made in the United States due, we were informed, to the poor quality of the sulfate paper. Work was however begun energetically in the United States on other methods of protection against diphenylchloroarsine. =Numbers of Chemists Needed.= It was figured that out of a total force of some 1,400 gas officers there would be needed in the A. E. F., exclusive of those in regiments, approximately 200 chemists, i.e., about 15 per cent of the whole. We arranged to have a good chemist on each Division, Corps and Army Staff, and a certain number with the gas troops. It was proposed to put 20 to 40 in the laboratory in Paris and not to exceed 20 at the experimental field. This subject of personnel is touched on for the reason that a few people seem to have the idea that the Chemical Warfare Service should be made up of chemists exclusively. This is very far from being true. It was and is believed that the Chemical Warfare Service should be composed of men from every walk of life. In three positions out of every four in the field a good personality combined with energy, hard work and common sense count for more than mere technical training.