There are many new ways of waging war that are very different to those methods used but a generation ago—weapons have become more deadly—aerial and mechanical warfare have given us a new conception of the state of war. Over and above the factors mentioned, the use of gas has been made and its usage has been probably more extensive than we have imagined it to be.
"The hazard of gas poisoning in peace time is mainly restricted to carbon monoxide, coal gas, carbon dioxide and certain risks associated with specific industries. In warfare the scope is widened very consider ably as I hope to show you later in this talk, Let us first of all have a clear understanding of what we mean by gas, when thinking of it in its war connection. The term, gas, in this connection is not limited to our us tial conception of a gas in its usual physical sense but it includes gases, liquids and even solids—in fact we may say, any chemical substance which can be dispersed in fine par-tides.
"Science has produced a number of gases that may be used for the purpose of warfare. It has been estimated that during the war of 1914 to 1918 that some three or four thou. sáhüd stibstanees were used or rather examined as to their suitability for úse as war ' gases. Out of these, of ursa, a very great many were tind for certain reasons to be of no great practical value, but fifty four different kinds were put into test use in the field. Then again, many of these, while being very efficient test tube gases, by that I mean, gases that did what was expected of them in theory, giving satisfactory results in the laboratory, yet failing in the field for various reasons. Some of these proved to be of far more danger to the manipulators than to those that they would attack. But it is interesting to note, that at the end of the great war, twelve different types of gases were in use. Much further development has taken place in the meantime, but of that I will speak later.
"Chemical warfare was initiated by the enemy in the year 1915; this was done by the liberation of ' chlorine gas from compression cylinders in the form of a cloud. This in the main has proved to be a very un satisfactory method, for the attacker may become attacked by his own weapon; and this actually proved to be the case. On a number of oe casions the gas was setoff into a favourable wind, and then for no obvíous reason the wind would turn and the gas return to the region occupied by those who had set it off. New methods had to be found and subsequently gas was liberated by the use of shells fired from trench mor. tars. And bombs and grenades became a popular method of distribution. Then certain smokes were used these were in the main made by heating certain arsenical compounds in a particular kind of generator. To these methods of distribute must now be added the development! of recent years and months—dis tribution from the air by means of bombs or sprays.
Text read from the printed page and cleaned; old type leaves the occasional error.