In summer the process of drying is often performed in the sun, and in winter by the steam stove, in the following way. The powder is spread about three or four inches thick on a large canvas tray, under which is an arrangement of pipes, which convey the hot air forced by a fan through a cylinder heated by steam: it is considered to be sufficiently dried in from three to four hours, during which time it is occasionally raked about. In some manufactories it undergoes a further operation of being dusted, and is then barrelled up for use. Generally the great failure in the foreign manufacture is the neglect of the principal stage of the fabrication, viz. incorporation; with the old stamping-mill, it is quite impossible that the process can be carried out to the necessary extent. The Continental powder is usually very soft in its grain, dusty, and quickly absorbs moisture from the atmosphere; its density is below the English powder, on account of its never being subjected to pressure; consequently it is not so durable, and forms a good deal of dust in transport; a great amount of residue is generally left in the gun, and its strength, as a propelling agent, is far inferior to our powders. On being flashed on a glass plate, instead of producing a sudden concussion, like the sharp rap of a hammer, it burns more like composition, throwing off a quantity of sparks. NEW RIFLE POWDER. The following mode of manufacturing rifle powder, appeared in Garrison Orders at Woolwich, 31st December, 1859: Composition in 100 parts:-- Saltpetre 75 Charcoal 15 Sulphur 10 --- 100 The charcoal to be prepared from dogwood, burned slowly in cylinders three hours. The composition to be worked under the runners for five and a half hours, and submitted to a pressure of about 50 tons to the square foot. The size of the grain to be that collected between sieves of 16 and 24 meshes. The grain to be glazed for five hours. * * * * * NOTE.--The foregoing, on the manufacture of gunpowder, is principally taken from an article in the Aide Memoire (1860), by Major Baddeley, Royal Artillery; Captain Instructor, Waltham Abbey. ON MAGAZINES. It is impossible to make powder magazines too dry, and every care should be taken to ventilate them as much as possible during dry weather, by opening all doors, windows, loopholes, &c. Magazines are generally made bomb-proof, and are furnished with lightning conductors. They are divided into chambers, and these again divided by uprights into bays. At Purfleet, which is the grand depôt for gunpowder in England, there are five magazines capable of containing 9,600 whole barrels each. Each magazine is divided into two chambers, and each chamber into 24 bays, and in each bay is placed 200 whole, 400 half, or 800 quarter barrels of powder. Total in the five Magazines, 48,000 barrels, equal to 4,800,000 pounds. LIGHTNING CONDUCTORS.