POISON GAS 286 POISON GAS first, the gas, either liquified or highly compressed, was brought in cylinders, as near to the enemy's trenches as possible, and sent over in a cloud, favoring winds being necessary to carry the cloud in the right direction; by the second, the gas was introduced into a shell of special type, which was fired at the enemy, and, on exploding, spread the gas among his troops. Both methods were first used by the Germans on April 22d, 1915, against the French, on a frontage of four miles, N. of Ypres salient. The cloud method of attack, however, was too un- certain in'its results, and was practically abandoned in the later years of the war in favor of the gas shell, the last exten- sive German cloud attack occurring in the summer of 1916. Chlorine was the gas first used in cloud attacks, a mixture of chlorine and phosgene (q. v.) being used later. The early gas shells con- tained chlorinated ketones or chlorinated xylene (both lachrymatory or "tear" gases), but they were largely ineffective owing to the fact that they were charged with too much high explosive, leading to too great a dispersion of the gas. The development of the gas shell into a more deadly weapon was brought about by the French, who saw the necessity for a thin-walled shell, containing a compara- tively small charge of high explosive. As finally developed, the gas shell con- sisted of a thin-walled chamber, fitted with a fuse connected with an inner tube containing high explosive. The gas, frequently in liquid form, was often placed in a glass or lead container, the rest of the space being filled with cement. The shells were sent over either by artil- lery proper, or by smaller guns or types of trench mortars. The area covered by shells averaged five hundred yards in depth, although with a favoring wind the effects of gas have been felt at a dis- tance of 3,000 yards from the explosion. Poison gases, as used in the World War may be classified into (1) Arsenic poisons; (2) Asphyxiating gases; (3) Lethal lachrymatory, and (4) Lachry- matory. Mustard Gas (q. v.) may be considered as in a class by itself. Of the first class, two types are used — liquid filled and solid filled. The liquid filled shell contained ethvldichlorarsine, C^HsAs CI2, while the solid filled con- tained fused arsenic compounds, diphe- nylchlorarsine being first used, diphenyl- cyanarsine being later substituted for it. When the latter tjrpe exploded, the solid poison was blown into the air as a very fine dust. These shells seldom, if ever, produced fatal results, the chief effects being a burning of the nose and throat, with pains in the neck, chest and stom- ach, sometime followed by dizziness, nausea and vomiting. They had some value owing to the property these com- pounds possess of producing a tickling of the nose followed by an overpowering desire to sneeze. A group of men af- fected in this way would be tempted to remove their gas masks, thus exposing themselves to the deadly action of a gas of a more toxic character. The most commonly u:ed asphyxiating gases were phosgene and diphosgene (trichlor- methylchloroformate). Chlorpicrin was also used. The persistence of these gases was slight, but the percentage of deaths to casualties was probably higher in this group than in any of the others. Trench mortar bombs usually contained phosgene. The commonest lethal lachmi- matory gases were mixtures of bromi- nated ketones, or brominated xylene. Like all lachrymatories, these gases affected the eyes, producing excessive watering, and sometimes temporary blindness. Opinions differ somewhat re- garding the toxic effect of these gases, but the number of actual deaths caused by them was probably small. The gases were very persistent, effects lasting for as long as six hours, even with a breeze. Lachrymators, or tear gases, affect the eyes only. The most commonly used were benzyl bromide and phenyl carbyla- mine chloride, the latter first appearing as late as September, 1917. These gases produce temporary blindness when suffi- ciently concentrated. They are very per- sistent and effects will be felt for as long as twenty-four hours. Mustard gas or dichlorethylsulphide (CH2CI CHs): S, is a water-white liquid, boiling at 219 °C. It was first used by the Germans at Ypres on July 20th, 1917, and came to be the most widely used of all the poison gases. The liquid had a corrosive action on the skin, while the vapor attacked the eyes and lungs and any other moist surface. It was very persistent, from two to seven days being required to clear a position shelled with mustard gas. (See Mustard Gas). A device connected with the use of poison gas was invented late in 1916 by Major W. H. Livens, of the British army, and was known as the Livens pro- jector. It enabled a large number of bombs to be fired simultaneously at any desired spot, thus producing high concen- tration, with practically no warning. Statements have appeared in the press that the United States Chemical Warfare Service had, at the time of the Armistice, developed a gas far more deadly than mustard gas, but detailed information on this subject has never been given by the authorities.
