“PREPARATION OF ETHYLDICHLOROARSINE—The compound was prepared by treating ethylarsenous oxide with hydrochloric acid. The reaction is as follows: C₂H₅AsO + 2HCl = C₂H₅AsCl + H₂O. The operation was carried out in an iron kettle lined with lead, which was cooled externally by means of water and which was furnished with a lead covered stirrer. To the kettle, which contained from 500 to 1000 kg. of hydrochloric acid left over from the previous operation, were added 4000 kg. of ethylarsenous oxide. The gaseous hydrochloric acid was next led in. The kettle was kept under slightly diminished pressure in order to assist in the introduction of hydrochloric acid. The temperature during the reaction must not rise above 95°. When the hydrochloric acid was no longer absorbed and was contained in appreciable quantities in the issuing gases, the operation was stopped. This usually occurred at the end of from one to two days. The product of the reaction was drawn off by means of a water pump and heated in a vacuum until drops of oil passed over. The residue was passed over to a measuring tank and finally to tank-wagons made of iron. The yield of the product was practically the theoretical. On account of the volatility of the compound and its poisonous character, the apparatus in which it was prepared was surrounded by an octagonal box, the sides of which were fitted with glass windows. Through this chamber a constant supply of air was drawn. This was led into a chimney where the poisonous vapors were burned. The gases given off during the distillation of the product were passed through a water scrubber.” “LEWISITE” The one arsenical which created the most discussion during the War, and about which many wild stories were circulated, was “Lewisite,” or as the press called it, “Methyl.” Its discovery and perfection illustrate the possibilities of research as applied to Chemical Warfare, and points to the need of a permanent organization to carry on such work when the pressure of the situation does not demand such immediate results.