Reflecting over the processes for making gunpowder, it suggested itself that the chemical reactions would necessarily have the most favorable conditions, when there should be the most intimate approximation of the component molecules. That, as the charcoal by its combustion with the oxygen of the saltpetre, supplied the expanded gases which produced the explosive force, it was of the first consideration that there should be the most perfect mixture practicable between these two ingredients. Under the microscope a fine particle of charcoal was seen to be a mass of carbon penetrated by numerous pores, hence it became necessary to completely fill these minute pores with the saltpetre to have the best condition. This might be accomplished by the usual processes, as the charge is kept moistened when stamped or rolled, but as it will not answer to have the mass wet during the incorporating operation, only moist or damp, the completion of the process was necessarily delayed. If this mass of material could be made into a semi-liquid condition by the action of steam, the hot solution of saltpetre would speedily penetrate the minute pores of the charcoal, and thus the desired end would be rapidly attained. Accordingly, the following process was devised: The moistened sixty pounds charges, roughly mixed and moistened with water, were introduced into horizontal cylinders of sheet copper thirty inches long by eighteen inches in diameter. These cylinders revolved slowly on a common axis, consisting of a heavy brass tube three inches in diameter, perforated with holes. High pressure steam was introduced through the tube raising the temperature to the boiling point while the water produced by condensation, added to that originally used to moisten the materials, reduced them to a semi-liquid slush, which was run out of the cylinders after about eight minutes rotation. On cooling, this mud became a damp solid cake, the saltpetre which in the state of boiling hot saturated solution had entered the minutest pores of the charcoal, now crystallizing. The cake as produced was transferred to the incorporating mills, and under the five ton rollers was in an hour brought to the condition of finished mill cake, ready to be cooled and granulated, while without the steaming process, four hours incorporation in the mills had previously been necessary to produce powder of the same first-class character. The capacity of the work of the mills was thus practically quadrupled, the thorough saturation of the charcoal with saltpetre being accomplished by the steaming, while it remained for the rollers merely to complete the incorporation of the whole mass and give the required density to the mill cake.