The bracelet grenade and the German grenade just described have to be made in a factory. Attempts have been made to construct similar missiles with the explosives which are at hand at the front, cheddite and melinite. Several kinds have been made: a primed cartridge and a primed hand petard, fitted on a wooden paddle, a preserved meat tin can filled with explosive, etc. The Germans have hand petards similar to those of the Allies but with different explosives. These missiles are primed by a detonator and a slow match and can be thrown about 30 meters. The discharge takes place either automatically or by tinder. They are made on the spot and very rapidly. The assaulting troops carry them in baskets or strung on a circle of wire carried on the shoulder. [Illustration: PLATE 41d.—Throwing hand grenades.] Grenades and petards constitute a terrible weapon. These projectiles exert considerable moral effect owing to the violence of their explosion and the awful wounds they occasion, and they make it possible to reach the enemy at points where it is impossible to use the rifle and bayonet. CHAPTER IX Gas Warfare Germany first made use of poisonous and asphyxiating gases on the field of battle. It has become an accepted element in the present war. Every soldier should, therefore, have a knowledge of the various ways in which gas is employed in the attack, as well as the measures to be taken to counteract its effect in the defense. The two methods of disseminating the gas over the battlefield are by emanation and grenades charged with it. [Sidenote: Emanation] This method has for its object to create a poisonous or irritant atmosphere. This is accomplished by means of the arsenic and phosphorous gas being forced through tubes in the direction of the enemy or by means of liquefied chlorine, bromide, phosgene and sulphuretted hydrogen gas stored in cylinders under high pressure. To be successful the gas attack must be attended by the following conditions. 1. The weather must be comparatively calm with a wind blowing in the direction of the enemy at about 5 miles an hour. If the wind is too strong the gas will be carried over the enemy’s trenches so rapidly that it will not settle in them. If the wind is too light the gas will be carried up into the air and disseminate or may even be blown back into our own trenches, in which case chloride of lime scattered about freely will disperse them. 2. There must be no rain, for that would quickly disseminate the gas and negative the effect. 3. The attack must come as a surprise. If the elements of surprise are missing and the enemy has time to take protective measures, the effect is lost. If the surprise is complete, the enemy trenches should be emptied very quickly.