GUNPOWDER. Gunpowder is a very intimate mixture of potassium nitrate (nitre), charcoal, and sulphur, and generally consists of the following proportions: Nitre, 75 parts; charcoal, 15 parts; sulphur, 10 parts. The following processes are used in its manufacture: (1) Mixing the ingredients; (2) incorporating or "milling"; (3) breaking down the mill-cake; (4) pressing; (5) granulating; (6) dusting; (7) glazing; (8) second dusting; (9) stoving or drying; (10) finishing. Good gunpowder should be composed of hard angular grains which do not soil the fingers, and should have a perfectly uniform dark-gray color. When new, it should be free from dust, and a gramme of it flashed on a copper or porcelain plate should leave no residue or foulness. It should give the required initial velocity to the projectile, and produce not more than the maximum strain upon the gun. When exposed to air of average dryness, it should not absorb more than 0.5 to 1.5 per cent of water. In damp air it absorbs more and deteriorates. Its exploding-point is 560° F. DYNAMITE. Dynamite is composed of a particularly porous siliceous earth (Keiselguhr) impregnated with about 70 or 75 per cent of nitro-glycerine. True dynamite resembles in appearance moist brown sugar. It takes fire at 350° F., and freezes. MATERIALS IN USE FOR BLASTING. =Cartridges.=--The regular sizes are from four to eight inches long and from three fourths of an inch to two inches in diameter. They are furnished to order of any required size, packed in boxes containing 25 or 50 pounds, the layers of cartridges being separated by sawdust. To use a small cartridge in a large hole, slit it on the side and press it down into the drill-hole with a wooden tamping-rod. Cartridges may be readily cut into desired lengths. _In tamping powder or explosives always use a wooden rammer, never an iron or steel bar._ =Caps.=--The regular cap or exploder is employed. It consists of a hollow copper cylinder about ¼ inch in diameter and from one to two inches long, and contains 15 to 20 per cent or more of fulminate of mercury mixed with other ingredients into a cement, which fills the closed end of the cap. =Fuzes.=--The double-tape fuze is the best. Single-tape fuze may be used when the ground is only a little wet. =Nippers and Pincers.=--For cutting the fuze, and after it is inserted in the cap for squeezing the cap tightly around the fuze. =Funnel.=--Used in charging with loose powder. DRILL-HOLES. As a general rule drill-holes and charges for dynamite should be comparatively small. In heavy work the holes should be large in size and less in number, and the amount of dynamite should be in proportion to the work done.