MILITARY USES OF EXPLOSIVES. The principal use of explosives is, of course, for military pur poses, where they are employed as propelling and as bursting charges for projectiles. An explosive for use as a propelling charge in a gun should give in that gun as low maximum pressures and as high projectile' velocity as possible. The older powders were finely pulverized. About 1860 and later, it was customary to press the powder after mixing into a cake, afterwards broken be tween rollers into irregular grains which were sorted by screens into different sizes, musket, mortar, cannon, and mammoth; the latter from 0.6 inch to 0.9 inch. At this date. 1860, Gen eral Rodman proposed cylindrical cakes, nearly the diameter of the bore and :3 inches long, pierced by holes inch apart, reason ing that the burning on the inner surfaces of these holes would give a constantly increasing surface, and therefore an increasing rate of generation of gas, a condition which lie recog nized to be desirable. At the time this form was not deemed preferable to the mammoth, and his principle was adopted only after a number of years, and was preceded by the use of other powders—as the sphero-hexagonal—molded sim ply for uniformity of size. his grain when adopted was modified to a hexagonal prism about 1 inch long and wide, pierced by one or several holes.
About 1882 the Germans introduced 'brown' or 'eneoa' powder in the same furor grains, but using charcoal not so much baked, and therefore giving a slower powder. A 'slow-burning' cocoa powder soon eame forward as an improvement. Long continued efforts were made to get a powder of more power per unit of volume, which would give in the reduced calibre small arm a higher Vvin•iiy than gunpowder, with permissible pre. sures. The high explosives were tried, espeeially guncotton, in ninny forms, pressed and mixed with other substances, but with resulting high pressures and detonations, until, about 1884, dis solved guncotton gave after evapo rathm of the sol vent n horny mass, which burned regularly without detona tion. Similar treatment of com binations of gun cotton and nitro glycerin gave sim ilar results. It had been known that these explo sives gave no smoke, their products being gas eous., but it was the desire for more power which brought them into use. The French quick ly recognized the value of smokelessness as well as of power, and soon extended the use of the only. For some years experiments in firing re cent improved high explosives from common guns have been in progress. Lyddite (used by the
English), melinite (used by the French since 1887), thorite, joveite, etc., have been tried by the United States, but none with complete satis faction. Special shells have been devised with nu merous separated compartments. The intent was to keep the charge explosion from the shock pro duced by the setting down of a long column of `pondre B' of this class to all their cannon. The Germans used `Wetteren.' and later ffiallistite.' The English later adopted cordite. Of these four powders the first two are of nitrocellulose (guncotton) and the others of this and nitroglycerin. In the United States it was not until well into the nineties that smoke less powders were adopted; for, although their advan tages were recognized and many kinds experimented with, a later aml more ad vanced stage of development was awaited. The navy adopted smokeless powder earlier than did the army. 'Nitrocellulose powders are most generally used in the United States. The forms of grain are many— long cords, spaghetti-like tubes, thin flakes, cubes, pierced prisms (generally for large guns), and others.
Until very recently the bursting charges of shell consisted of a fine-grain clack powder. Seek ing a more destructive effect, experiments were made in Germany and in Italy between 1880 and 1890 with shell loaded with guncotton and other high explosives fired from common guns. These trials met with partial success, but the solution at that time seemed to lie in the pneumatic fun. which could throw projectiles carrying 500 pounds of high explosives instead of a few pounds powder upon discharge, without interfering with complete detonation upon impact. The Gathman system, of which much was at one time hen rd. com prised a large shell carrying wet and dry guncot ton carefully packed and tired with a special fuse. The charge was expected to explode against the side of a vessel, with such force as to burst in ber armored sides. Tests made in 1901-02, how ever, failed to demonstrate the success of the system, and it was officially decided to discon tinue further experiments. Meanwhile, however, two explosives, maximite (Hudson Maxim's) and explosive D (proposed by Captain Dunn. Ord nance Department, "United States Army), had been developed which could be fired safely in armor-piereing projectiles through an I IV–inch plate of best modern Krupp face-hardened armor and detonated on the inside with most destructive effect by a delay-action fuse.