Any man wounded during a gas attack must not be placed in a dugout or on the bottom of a trench, and even if considerable shell fire be going on it is far better that he be laid out in the open on the top of the ground, where he will have a far better chance than lying in the bottom of the trench or in a dugout. After gas has passed through a trench system, and before the officer thinks that it is safe to remove the helmets, the trenches must be sprayed with a machine known as Vermeral Sprayer. A man with this sprayer on his back and wearing his helmet, slowly traverses the trench working the spray. This small tank on his back is charged with nothing more or less than “hypo” (sodium hyposulphite), about 6 pounds of which is dissolved in a bucket of water and a handful of ordinary washing soda added. Garden syringes and buckets may be used if sprayers are not available, but their effect is not so quick. When the officer thinks that the trench has been sprayed sufficiently and all gas has gone, he may then allow the men to take off their helmets, but not to reënter their dugouts until they have been thoroughly cleaned. This is sometimes done by fanning the gas out, sometimes by building a fire and smoking it out, and by the use of the sprayer. Great care must be taken that no one enters until every last vestige of gas is gone, and it is generally well that the medical officer should inspect infected dugouts before allowing the men to return. GAS MASKS OR RESPIRATORS The Box Respirator at present in use on the Western Front is the latest improvement, and proof against any gas that so far has been used, but should such a thing happen that a man be caught without his box respirator, any of the following improvised methods are good: 1. Wet and ring out any woolen article, such as a stocking, muffler or cap comforter, so as to form a thick pad large enough to cover the nose and mouth, and press firmly over both. 2. Place in a scarf, stocking or handkerchief, a pad of about three handfuls of damp earth, and tie firmly over the nose and mouth. 3. A wet cap comforter will be found useful as additional protection, especially against certain gases other than chlorine. 4. A cap comforter wetted with water and soda solution or tea, folded into eight folds and firmly held over the nose. 5. A sock folded fourfold similarly wetted and held or tied. If the sock or comforter has been soaked in soda solution it will act efficiently when dry, though, if possible, it should be moist. The spare tapes from puttees may be used for tying on the sock or cap comforter. 6. Any loose fabric, such as a sock, sandbag, woolen scarf or comforter, soaked in urine, then wrung out sufficiently to allow of free breathing and tied tightly over the nose and mouth. In the absence of any other cloths, the flannel waistbands issued for winter use could be used for this purpose.