Great improvements are yet to be made, especially in the powder used for artillery; whilst range, accuracy, and lessened recoils are points which may be determined with almost mathematical precision.
Great fame is in prospect for any one who can grasp and handle well this granulation principle; especially if he can define the sizes to be used for different varieties of guns. Artillerists who contend that a medium size grain, to suit all sizes of gun, is advantageous, might as well contend that cannon of a medium size would be preferable to so many different sizes, because, though we lose in range, accuracy, and recoil, it would be more convenient to have but one sized gun.
In making large grained gunpowder, the manufacturers defeat one of the main objects to be gained by granulation, from not subjecting it to the same amount of pressure which is necessary for the granulation of the very fine grain. In granulating very fine powder, it is necessary to subject the cake to such an amount of hydraulic pressure as shall give the mass a marble-like structure, or during the process of granulation, the whole of it crumbles into dust; but the coarser gunpowder may be granulated without subjecting it to this high degree of pressure, hence each grain is more porous and of lesser specific gravity: a difference which it is most important to avoid. It is clear, therefore, that according to the present mode of manufacturing gunpowder, the large and the fine grain are of very different kinds; the main difference being in their specific gravities. Gunpowder of less density burns with greater rapidity, because it is more open and porous; and if uniform density was observed, the diversity in the size of the grain need not be so great; whilst, at the same time, this anomaly might be avoided--that the same measure of fine and large-grained gunpowder contains a difference of the expansive element amounting to fifteen or twenty per cent. As gunpowder is now manufactured, it is highly necessary in all comparative trials to _weigh_, and not to _measure_ the charge, or the results will be deceptive and worthless. The granulation question struggles with undeserved difficulty. Gunmakers, either not understanding the question, or constructing the chambers of their guns improperly, and not using suitable nipples, decry the adoption of large-grained gunpowder; but they forget the increased range obtained in the killing from their guns, and the _éclât_ a long shot produces. In trials of guns at thirty or forty yards, the difference in the shooting with fine and large-grained gunpowder is not so apparent, and the maker exclaims, “Oh! the fine powder shoots stronger, and as close as the coarse.” I admit this to be the case, at short distances; but the great advantage of using the large grain is sufficiently evident when shooting at forty-five, fifty, and sixty yards, for then the fine grain entirely fails: simply from the oft-repeated fact, that the fine powder is more of a propulsive, while the large grain is an expellant force; so that according to the law of resistance in aëriform fluids, the one is sooner reduced to medium velocity than the other, which exerts its action more evenly. Powder of larger grain is thus more suitable for the larger sizes of shot, and would give an increased range in usual shooting, for the shot is kept better together, and is projected to greater distances. A common way of testing the quality of gunpowder is, to rub it between the hands, and observe the darkness of the stain; the darker the stain the more inferior the gunpowder is held to be. This test is, however, decidedly fallacious, because the gunpowder may be of low specific gravity, or it may have become friable from age and other causes.