Ammunition boxes must be kept closed. Vickers belts should be kept in their boxes until actually required for use. The wooden belt boxes are fairly gas-tight, but the metal belt boxes should be made gas-tight by inserting strips of flannelette in the joint between the lid and the box. Lewis magazines should be kept in some form of box, the joints of which are made as gas-tight as possible with flannelette. A recess should be made, high up in the parapet if possible, for storing ammunition and guns. A blanket curtain, moistened with water or sprayer solution, will greatly assist in keeping the gas out. (2) HAND AND RIFLE GRENADES: Unboxed grenades should be kept covered as far as possible. All safety pins and working parts, especially those made of brass, should be kept oiled to prevent their setting from corrosion by the gas. (3) LIGHT TRENCH MORTARS AND THEIR AMMUNITION: As far as the supply of oil permits, the bore and all bright parts of light trench mortars and their spare parts should be kept permanently oiled. When not in use, mortars should be covered with sacking or similar material. Unboxed ammunition should be kept covered as far as possible and the bright parts oiled immediately after arrival. Ammunition which has been in store for some time should be used up first. Sentries must be prepared to give the alarm on the first appearance of gas, as a few seconds delay may involve very serious consequences. Signals must be passed along by all sentries as soon as heard. The earliest warning of a gas attack is given: (a) By the noise of the gas escaping from the cylinders. (b) By the appearance of a cloud of any color over the enemy's trenches. If the attack takes place at night, the cloud will not be visible from a distance. (c) By the smell of the gas in listening posts. (1) ACTION TO BE TAKEN IN THE TRENCHES ON GAS ALARM: (a) Respirators to be put on immediately by all ranks (a helmet, if no box respirator is available). (b) Rouse all men in trenches, dug-outs and mine shafts, warn officers and artillery observation posts and all employed men. (c) Artillery support to be called for by company commanders by means of prearranged signals. (d) Warn battalion headquarters and troops in rear. (e) All ranks stand to arms in the front trenches and elsewhere where the tactical situation demands. (f) Blanket curtains at entrances to protected shelters to be let down and carefully fixed. (g) Movement to cease except where necessary. (2) ACTION TO BE TAKEN IN BILLETS AND BACK AREAS: (a) All men in cellars or houses to be roused. (b) The blanket curtains of protected collars, etc., to be let down and fixed in position. (c) Box respirators to be put on immediately, the gas is apparent. H. Action During a Gas Attack: (1) PROTECTIVE MEASURES: