1. AS A WHOLE

The latest type of Japanese gas mask tested by our Chemical Warfare Service does not give the all-around protection that our service mask does. The Japanese mask also will not stand the "wear and tear" that ours will although it is very well constructed. It compares very favorably with the United States mask from the standpoint of gas-tightness and effective vision. The mask is lighter than ours, weighing 3.4 pounds. Almost all the parts are made of metal except the angletube which is made of brass.

2. FACEPIECE

The facepiece and the breathing tube are made of rubber with a covering of elastic-knitted textile fabric. The tube is made with folds or furrows, much like our own. The eyepieces are made of shatterproof glass. The brass angletube contains the air inlet and outlet valves--the outlet valve is hinge-covered. There is a clamp at the junction of the breathing tube and the canister to keep out water in case the mask should be submerged. There also is a plug in the canister inlet at the bottom. The facepiece permits an interchange of optical and service lenses, and it appears to have no essential weaknesses.

3. CANISTERS

Two types of canisters are used, both oval in shape. One is 5 inches broad, 6 inches high, and 2 3/4 inches deep and the other is 5 inches broad, 4 1/2 inches high, and 2 3/4 inches deep. Each canister contains about 80 percent activated charcoal and 20 percent soda lime with a cotton filter. It differs from our canister in that the toxic fumes first pass through the filter, thus making it vulnerable to tear gas. This construction is one of the mask's major weaknesses. The canisters are good against nearly all other smoke gases and afford excellent protection against phosgene gas, a lung irritant, and chloropicrin, sometimes called "vomiting gas." However, the larger canister gives only fair protection against cyanogen chloride gas and the smaller one only negligible protection.

4. CARRIER

The carrier is a square pouch of light-weight olive drab duck--in fact, all the equipment carried in it is of this color. The equipment, which is kept in pockets, consists of a can of bleaching powder for decontamination purposes, a set of antifog plastic inserts for the lenses, and a bottle of nondimming fluid for the lenses.