The smoke candles employed an arsenical compound known as diphenolchlorarsine. In the laboratory this was not a new substance--in fact, none of the war gases actually used in the field was a new development; and of projected poisons, so far as is known, only the deadly Lewisite, the invention of Captain W. Lee Lewis in the Chemical Warfare Service’s laboratory in Washington, was a new chemical creation evolved specifically for use in war.[11] The other war gases had all been known to organic chemistry, some of them for many years. So with diphenolchlorarsine. It was first produced in Germany in the last century, and the Germans also originated its use as a military weapon. The Germans produced and used diphenolchlorarsine as a solid. The substance was put into glass bottles, which, in turn, were inserted in the T. N. T. filler of shell. The explosion pulverized the chemical into a fog which had the advantage of being able to pass through the cotton baffles in the canister of an ordinary gas mask. This fog was highly irritating to the membrane of the nose and throat and caused sneezing, which prevented a soldier gassed with it from putting on his mask, so that he was left a victim to more lethal gases fired simultaneously. The British secured “dud” shell containing diphenolchlorarsine and at once recognized this chemical as potentially much the most fatal substance yet brought out in chemical warfare. But it was evident that the German was not using it properly, in such a way as to release its full toxic effect. The question was how to atomize diphenolchlorarsine much more finely. British chemists and mechanical engineers eventually succeeded in producing the substance in candles which burned and cast out dense smoke. This smoke was diphenolchlorarsine so finely divided that the American gas mask, the most effective mask of all, was utterly powerless against it. The smoke particles passed freely through the baffles; and, since the particles were minute solids and not true gas at all, they were unaffected by the gas-absorbing charcoal and lime of the mask canister. Every masked experimenter gassed by this smoke declared that a mask was worse than no protection at all. It is notable, too, that every one gassed, without knowing that he was merely reiterating what others before him had said, declared that, if he had not been able to escape quickly from the concentration, he would have shot himself rather than endure the agony longer. As to the persistence and diffusibility of the smoke, at one demonstration when two candles were burned in a desolate spot in England, civilians were slightly gassed in a village several miles away.