Phosgene, the next member of the poison-gas family, is the deadliest of the lung-gases, killing almost as quickly as cyanogen. It is produced by the combination of two other gases, chlorine and carbon monoxide. The reaction is effected in iron boxes, lined with lead and filled with charcoal, into which a stream of chlorine and carbon monoxide, mixed in proper proportion, is introduced. The colorless gas which results is phosgene. It is condensed to a liquid by passing it through a condenser surrounded by brine kept cold by refrigeration and is then either stored in strong steel containers or run directly into the thirty-pound cylinders known as Livens’ drums. These drums are fired from a sort of mortar, called a projector, and are extremely effective for producing heavy concentrations of gas up to a range of 1,500 yards. The compound commonly referred to in chemical warfare as “mustard-gas” is known to chemists as dichlorethylsulphide. Its nature is as formidable as its name. It has a distinctive smell, like garlic rather than mustard. It has no immediate effect on the eyes, beyond a slight irritation, but after several hours the eyes begin to swell and inflame and practically blister, causing the most intense pain; the nose discharges freely, and severe coughing and even vomiting ensue. Direct contact with the spray causes blistering of the skin so severe that it is virtually burned. Even when protected by masks and specially made clothing, it is impossible for troops to remain for more than eight hours in an area which has been bombarded with mustard-gas. Dichlorethylsulphide, to use its correct name, is produced by blowing ethylene-gas into liquid sulphur monochloride in large iron reaction vessels. Contrary to the popular impression, this gas contains no mustard. The details of devices and methods for introducing the ethylene and sulphur monochloride into the vessels, the removal of the product, the necessary agitation and cooling of the mass, and the like, were frequently changed during the development of the process and had not reached a final form even when the Armistice was signed. Nevertheless, when the war ended, Edgewood was producing 30 tons of mustard-gas a day and a rapid increase up to 100 tons daily was practically assured.