The manufacture of this powder has hitherto taken place in the Royal Laboratory, Woolwich, and in comparatively small quantities; arrangements will, however, soon be perfected at Waltham Abbey, which will admit of its supply to any reasonable amount. The ingredients of gunpowder are Sulphur, saltpeter, and charcoal. TheSs undergo various processes of refinement, and are then mixed in definite proportions, and incorporated in a mill for several hours. At the ) conclusion of this operation the mixture is termed mill cake, and has all the properties of gunpowder. In order to convert mill cake into granulated powder, it is necessary to pass the cake through a breaking-down machine, which crushes up all the large pieces, and reduces the powder to the form of meal, in which condition it can easily pass between the plates in the subsequent process of pressing. The powder having arrived at this stage, is ready either for granulation or being converted into pellets. To be granulated, it passes from the breaking-down machine to the press; is there converted into press cake, which is subsequently broken up by other machines into whatever size of grain is required. For pellets the meal is slightly damped with water to give the required hardness; the amount of moisture being about five per cent. It is then spread out on a molding plate, fitted with a number of small molds, each about one and one-fourth inches deep, so as to contain just sufficient meal to form a single pellet. The hydraulic piston, fitted with corresponding stops, then descends and presses the powder into the form of pellets. The next operation is drying, and the pellets are subsequently drummed, so as to round the edges, which otherwise might break off in transport and render the powder dusty. When completed, the pellets are in the form of disks, each being almost the size of a sixpence, and about half an inch thick, with a small cavity stamped in one face. They weigh from 85 to 95 grains, and their density is about 168 as compared with water. The chief advantages expected t o result from the employment of pellet powder may be enumerated as follows:—(1) Decrease of pressure in the gun; (2) greater uniformity in velocity; (3) less waste in manufacture, as the powder does not require granulation. The introduction of pellet powder is of too recent a date to enable us to speak positively of its cost of manufacture as compared with ordinary powder. It is, however, clear that we must have a largo description of gunpowder; and the j question yet remaining to be solved is, whether it is cheaper to make this in the form of pellets or of a very large grained powder. The process of manufacture is the same for both up to the stage of meal; and as the production of pellets is at tended with no waste, all the meal being xised up, we are inclined to believe that in the long run it will prove a cheaper article than a granulated powder, which yields a comparatively small amount of finished powder froman equal weight of cake, although the first cost for machinery may be greater in the case of pellet manufacture. Pellet powder is somewhat weaker than our ordinary rifle L. G., and experiments have given the proportions in the following table: i Yc i.....Zs Gun. gf 11 Bemarka. _ _J Jsfi_ _lt_ I lbs. ) lbs. feet. 12-inch rifled............I 70 ordinary 600 1.212 , ) A. short gun in Ditto C7 ordinary 600 1,18) : ,- comparison Ditto. .......... 76 Pellet 600 1.189 h with its caliber. 11-inch rifled........... 70 ordinary 530 1,255 Ditto. ...........j TO Pellet 530 1,230 lC-inch rifled............ 60 ordinary 400 1,230 Ditto. ........... (14 Pellet 400 1,800 C-inchrifled............ 43 ordinary 250 1,340 Ditto. ........... 45 I Pellet 250 j 1,340 In 1865-6 the Russian government instituted a series of experiments which resulted in the adoption of prismatic powder for their heavy ordnance. The Russian experiments were chiefly carried on by means of Rodmans pressure piston, and the results appeared to show—1. That the use of elongated cartridges is attended by a considerable reduction of pressure. 2. That with a proportional charge and diameter of cartridge, the pressure increases with the caliber or size of bore—that is to say, the same proportions which gave a pressure represented by 2,{300 atmospheres in a gun of 6-inch caliber, gave 3,000 atmospheres in an 8-inch caliber. 3. The initial pressure of prismatic powder is considerably less than that of ordinary powder. Thus in an experiment with the 8-inch B. L. rifled gun, firing shot of 174 pounds English, the initial pressures were said to be as 1 to 2 when the velocities of the shot at the muzzle were equal. On the whole, however, it was found that a larger charge of prismatic had to be used to give the same velocity as ordinary powder, and the cost per round was thus increased about 15 per cent, although the actual price of the prismatic powder was only one halfpenny per pound more than the ordinary. The Russian prismatic powder is chiefly made at Ochta, and undergoes a process somewhat similar to that followed in the case of the pellet. The broken down mill cake is first converted into an irregularly-rounded granular powder, the size j of the grains varying from one-thirteenth to one-eighth of an inch in diameter. It then receives an addition of abo at 7 per ] cent of water, and is pressed into hexagonal prisms with a force of about 2,160 pounds per square inch, each prism containing 7 holes. On issuing from this press the prisms are of sufficient density and hardness to bear any ordinary handling. The next operation is the drying process; the prisms are removed to a lofty chamber heated with hot air to the temperature of about 100 Fah.; there, arranged on shelves, they are dried for about a fortnight, by which the moisture is reduced from 7 to less than 1 per cent. The powder is then considered fit for use, and is packed in cartridges of the required size. Care is taken in packing these cartridges to fit the hex-1 agons evenly together so that the holes with which they are perforated may run parallel to the axis of the cartridge; the latter is made of cotton cloth or silk of such a size that the hexagonal prisms are all bound tightly together. The dimensions of each prism are as follows: Diagonally, 155 in.; faces, 077 in.; depth, 0% in. Seven holes of 0-2 in. diameter, arranged at a distance of 0-4 in. from centre to cen-1 ter; density, 1-66; weight, when dried, 600 grains. The prismatic powder lately adopted by Prussia is, we believe, similar to that tried in Russia.