~The effect of granulating gunpowder.~ A piece of pressed cake weighing 1·06oz., was put into a mortar, and a globe of some light substance, placed upon it, and the powder being consumed after ignition without ejecting the ball from the bore of the piece. When an equal quantity was divided into seven or eight pieces, the globe was thrown out of the mortar; breaking the cake into twelve pieces; the ball ranged 3·3 yards; being further increased to fifty grains, it ranged 10·77 yards; and when the ordinary powder was used, the ball was projected 56·86 yards. ~Action depends upon size and form of grain.~ It will appear from the above remarks, that the force generated from the charge of powder in a gun, will be greatly influenced by the size and form of the grains composing it. ~Density of gunpowder.~ In order to obtain a gunpowder which shall possess a proper amount of force, it is necessary that the ingredients should be thoroughly incorporated, and the process of incorporation will in great measure affect the density of the grains. After going through the process, it is subjected to a certain pressure, in order that the substance in travelling may not be reduced to a fine powder, which would cause the velocity of transmission of inflammation to be diminished. But there is a certain point beyond which it would not be advantageous to increase the density, and this seems to vary with the size of the grain. With large-grain powder the action in a musket, or in guns with small charges, is greatest with a low density; while with very small grain, the highest velocities are obtained generally with the gunpowder of great density; but in heavy guns with ordinary charges, the large-grained powder should be of considerable density in order to obtain the greatest effect, though still it must not be too great. ~Advantages of glazing.~ The principal advantages of glazing are; first, that the powder so prepared, will in travelling, owing to the smaller amount of destructive force consequent on friction, produce less mealed powder; and secondly, that in a damp country like England, the glazing imparts a preserving power to the powder, as the polished surface is less likely to imbibe moisture than the rough. ~Disadvantages of glazing.~ ~Experiments as to glazing.~ ~Glazing less hurtful to fine grains.~