The sheets, when thoroughly dried, are of a uniform yellowish-grey colour, and of the characteristic colloidal consistency; they possess a perfectly smooth surface, and are free from internal blisters or cracks.  The temperature of ignition of the finished powder should not be below 172 deg.  C., and when subjected to the heat or stability test, it is required to resist exposure to a temperature of 71 deg.  C. for thirty minutes without causing discoloration of the test paper.

W.A.  Powder.—­This powder is made by the American Smokeless Powder Company, and it was proposed for use in the United States Army and Navy.  It is made in several grades according to the ballistic conditions required.  It consists of insoluble gun-cotton and nitro-glycerine, together with metallic nitrates and an organic substance used as a deterrent or regulator.  The details of its manufacture are very similar to those of cordite, with the exception that the nitro-glycerine is dissolved in a portion of the acetone, before it is added to the gun-cotton.  The powder is pressed into solid threads, or tubular cords or cylinders, according to the calibre of the gun in which the powder is to be used.  As the threads emerge from the press they are received upon a canvas belt, which passes over steam-heated pipes, and deposited in wire baskets.  The larger cords or cylinders are cut into the proper lengths and exposed upon trays in the drying-house.  The powder for small arms is granulated by cutting the threads into short cylinders, which are subsequently tumbled, dusted, and, if not perfectly dry, again placed upon trays in the drying-house.  Before being sent away from the factory, from five to ten lots of 500 lbs. each are mixed in a blending machine, in order to obtain greater uniformity.  The colour of the W.A. powder is very light grey, the grains are very uniform in size, dry and hard.  The powder for larger guns is of a yellowish colour, almost translucent, and almost as hard as vulcanite.  The powder is said to be unaffected by atmospheric or climatic conditions, to be stable, and to have given excellent ballistic results; it is not sensitive to the impact of bullets, and when ignited burns quietly, unless strongly confined.

Turning now to the smokeless powders, in which the chief ingredient is nitro-cellulose in some form (either gun-cotton or nitro-lignine, &c.), one of the first of these was Prentice’s gun-cotton, which consisted of nitrated paper 15 parts, mixed with 85 parts of unconverted cellulose.  It was rolled into a cylinder.  Another was Punshon’s gun-cotton powder, which consisted of gun-cotton soaked in a solution of sugar, and then mixed with a nitrate, such as sodium or potassium nitrate.  Barium nitrate was afterwards used, and the material was granulated, and consisted of nitrated gun-cotton.

The explosive known as tonite, made at Faversham, was at first intended for use as a gunpowder, but is now only used for blasting.