But it was warm and stuffy in summer—the very time when gas is used to the greatest extent—while the chemicals in the cloth irritated the face and eyes, especially when combined with some of the poisonous gases.
Probably as a result of experience with oxygen apparatus in mine rescue work, Colonel Harrison suggested making a mask of which the principal part was a box filled with chemicals and carried on the chest. A flexible tube connected the box with a mouthpiece of rubber. Breathing was thus through the mouth and in order to insure that no air would be breathed in through the nose, a noseclip was added.
This, of course, cared for the lungs, but did not protect the eyes. Their protection was secured by making a facepiece of rubberized cloth with elastics to hold it tight against the face. The efficiency of this mask depends, then, first upon the ability of the facepiece to keep out lachrymatory gases which affect the eyes, and, second, upon a proper combination of chemicals in the box, to purify the air drawn into the lungs through the mouthpiece. (Details are given in [Chapter XII]).
Protection Against Smoke
While the charcoal and soda-lime granules furnished an adequate protection against all known true gases, they did not furnish protection against certain smokes or against minute particles of liquid gas. Since certain smokes, as stannic chloride, though not deadly, are so highly irritating as to make life unbearable, it early became necessary to devise means for keeping them from going through the masks. This was done in the first masks by adding a sufficient thickness of cotton batting. The cotton was usually placed in three layers alternating with the charcoal and granules, as it was thought the latter would be held in place better by that means.
Some time after stannic chloride came into use the Germans started firing shells containing a small quantity of diphenylchloroarsine, popularly known as “Sneezing Gas.” Protection against this is discussed in [Chapter XVIII].
Choice of Masks for U. S. Troops
When it became necessary, with the creation of a Chemical Warfare Service in France in August, 1917, to decide upon a mask for American troops, there were available for purchase two types—the British type and the French M-2. The French M-2 consisted essentially of 32 layers of cloth impregnated with various chemicals, through which the air was breathed both in and out. This mask was quite effective against ordinary field concentrations of most gases, but was utterly inadequate to care for the high concentration of phosgene obtained in the front line from cloud gas or from projector gas attacks. It was also poor against chloropicrin. The M-2 was, however, very light and easy to carry and moreover was deemed sufficient to protect against concentrations of cloud gas even, at points more than five miles distant from the front line.
Furthermore, it was felt desirable at first to have an auxiliary or emergency mask in addition to the principal one, for use in case the principal mask was worn out or damaged. Accordingly both types of masks were adopted and the day after Fries took charge of the Chemical Warfare Service, A.E.F., on August 22, 1917, 100,000 of each were purchased, although there were then only ten or twelve thousand American troops in France requiring masks. Later additional masks of both kinds were purchased to tide over the American troops until a sufficient quantity of the British type masks could be manufactured in the United States. The total of British masks purchased amounted to about 700,000.
However, within a comparatively short time after American troops got into the front line it was realized that a second mask, inferior in protection to the first, was highly undesirable. During a gas attack men seemed to acquire an uncontrollable desire to shift from one mask to the other. This shifting in nearly every case resulted in a casualty. We then came rapidly to the conclusion that one mask only should be furnished, and that one the best that could be made, and then to impress upon the soldier the fact that his life depended upon the care he took of his mask. This proved to be an entirely sound conclusion, as the number of men gassed through injuries to the mask was comparatively small. An interesting proof of the value the soldier placed upon his mask was shown by the articles of equipment thrown away by 10,000 British stragglers in the great German offensive of March, 1918. Of the articles thus thrown away the gas mask came at the foot of the list, with only 800 missing. The steel helmet is said to have come next with about 4,000 missing.