Gun-Cotton is now manufactured in England to an amount exceeding 100 tons per annum. The cotton fibre is reduced to a pulp, as in paper-making, in which condition the excess of acids is readily removed. The pulp is compressed into disks, under a pressure of 18 tons to the inch, and then dried. These disks are ⅞ inch to 7 inches in diameter, and ½ inch to 2 inches thick. In the open air this compressed cotton burns intensely, but without explosion; but when properly exploded under close confinement, its strength is from 2 to 5 times that of the same weight of gunpowder. If accidentally wetted, this form of gun-cotton can be re-dried by exposure to the sun, or even by a gentle heat, without risk of explosion or deterioration.—Journ. Frankl. Inst., August, 1871.