Protective clothing was an additional feature of the general program of protection. As far as factory protection is concerned, the use of protective garments was more or less of a temporary expedient and they were abandoned as fast as automatic machinery and standard practice made their use less necessary. It is likewise a question regarding their value at the front. It is very certain that the garments developed needed to be made lighter and more comfortable to be of much value to the fighting unit. The first development of protective clothing was along the lines of factory protection. The large number of casualties in connection with the manufacture of mustard gas made it imperative that the workmen be protected not only from splashes of the liquid mustard gas, but also from its vapors. The first suit developed provided protection to the entire body. The ordinary clothing materials and even rubberized fabrics offered little protection but it was found that certain oilcloths were practically impermeable to mustard gas. The suit was a single garment, buttoning in the back, with no openings in the front, no pockets and with tie-strings at wrists and ankles. The head was protected by means of an aluminium helmet, supported by means of a head band resting on the head like a cap and slung from the inside of the helmet; this permitted slight head motions independent of the helmet. In order to provide cooling and ventilating and pure air breathing, the suit was inflated by pumping a considerable volume of air into the suit through a flexible hose long enough to permit considerable freedom of movement. This suit had the very great disadvantage of limiting the range of motion to the length of the hose. Because of this, a Tissot type mask was used in place of the helmet and hose connections. The hood was made of the same special oilcloth as the suit, enveloped the head and neck and extended a short distance down the back and over the chest. The canister was slung on the left hip by an oilcloth harness and was kept from swinging by an oilcloth belt around the waist. The canister was much larger than the standard box respirator, had a much longer life with lower resistance and weighed about 3.5 lbs. [Illustration: FIG. 80.—Impervious Overall Suit for Mustard Gas.] Another type of impervious overall suit was developed which protected against mustard gas for over 100 minutes. The material was a cotton sheeting which was impregnated with linseed oil containing a suitable non-drying material, which was thoroughly oxidized in the fabric. These suits proved to be very uncomfortable, especially in warm weather, because they entirely prevented the escape of perspiration from the body.