Efforts were made by the enemy and by all the Allies throughout the war to invent a mechanical detector that would show when gas was present in dangerous quantities. While scores, perhaps hundreds, of these were invented none proved simple, quick, or certain enough in action to make their adoption desirable. In every case it was necessary to rely on the sense of smell. Thus it was that as the war wore on, more and more attention was given to training officers and non-commissioned officers to detect various kinds of gases in dangerous quantities by the sense of smell.
In the American Gas Defense School for officers this was done wholly by using captured German gases. This was because certain gases have quite different smells, depending upon the impurities in the gas and also upon the solvents sometimes mixed with them. Thus the German mustard gas has a mustard smell, while the Allies mustard gas, due to a slight difference in the method of manufacture, has a very perfect garlic odor. Not only must officers and men who handle gas training know the smell of the various gases, but they must know when the concentration of each is high enough to be dangerous. This is not easy to learn because the strength of the various gases in dangerous concentrations varies through wide limits. Not only does the strength of the gases vary and the sharpness of the odors accordingly, but the mingling of poisonous gases with other gases from high explosive and shrapnel tends to obscure these odors and make them more difficult of detection.
Deceptive Gases
A great deal of thought was given toward the end of the war to the subject of deceptive gases which could by powerful or peculiar odors mask the dangerous gases. This masking was to deceive the enemy when dangerous gases were present or to admit an attack without masks while the enemy was wearing his through thinking there was a dangerous gas when as a matter of fact none existed.
In gas warfare, the German, as well as the Allies, was exercising his ingenuity in devising new and startling methods of making gas attacks. A well known trick with the German was to fire gases for several days, particularly against green troops, in concentrations so slight as to do no harm. When he felt that he had lulled those troops to a sense of the ineffectiveness of his gas, he sent over a deadly concentration. In spite of the warning that this was what was happening, he often achieved too great a success. Before the war closed, however, the American was beginning to out-think and out-wit the German in this method of warfare.
Mustard Gas Burns
With the advent of mustard gas which burned the body, a new and serious difficulty in protection arose. At first it was thought mustard gas burned only when the liquid from the bursting shell actually splashed on the clothing or skin. This was unfortunately soon found to be not true. The gas itself rapidly penetrates clothing and burns the skin even when the concentration of the gas is very low. Probably the majority of burns from mustard gas arose from concentrations of gas consisting of less than one part of gas to five hundred thousand of air. Furthermore, the gas is fully fifty per cent cumulative in its effects, that is, in extremely low concentrations over a period of hours it will produce more than fifty per cent the effect that a far higher concentration would produce in a relatively shorter time.
The Allies were not long in discovering that oilcloth afforded very complete protection against mustard gas. The ordinary oilcloth, however, was too thick, too hot and too heavy for general use. Experiments soon showed that cloth thoroughly impregnated with boiled linseed oil would give protection. In order to make this protection more perfect a certain amount of paraffin was added. All this made the clothing air-tight, rather stiff and always uncomfortable. Notwithstanding these discomforts, hundreds of thousands of oiled suits, and as many pairs of oiled gloves were made and issued to artillery troops, and to troops especially charged with handling mustard gas shells, or to those employed in destroying mustard gas in shell holes by spreading chloride of lime over them.
The importance of protection against mustard gas burns led to extensive researches being made with a view to finding a cloth which would be comfortable and porous and while stopping mustard gas would yet be sufficiently durable and comfortable to be issued to infantry troops as well as to artillery and other special troops. This, it is understood, had been achieved, just prior to the Armistice. Still more desirable would be the discovery of a chemical substance which could be applied to all uniforms and Army clothing and thus protect the regulation clothing against the penetration of mustard gas, and thereby avoid carrying extra clothing for that special purpose.