introduction of the percussion cap, which exploded the charge by a blow,

in the place of the old flint lock, was, however, a notable advance. Alexander John Forsyth, a Scotch clergyman, was the first to apply a percussion or detonating compound, as set forth in his British patent No. 3,032, of 1807. The embodiment of such compounds in the little copper caps was made about 1818, and has been claimed by various parties. Manton’s British patent No. 4,285, of 1818, describes a thin copper tube filled with fulminate and struck sidewise by the hammer to explode it. Joshua Shaw took a United States patent on a percussion gun, June 19, 1822, and the copper percussion cap was said to have been introduced in the United States by him in 1842. The embodiment of the charge of powder and ball in brass and copper shells was done in France by Galay Cazalat as early as 1826. Drawn metallic shells were made by Flobert and Lefaucheux, in 1853, and Palmer, in 1854. Drawn copper cartridges with center fire were introduced in the United States, and patented by Smith & Wesson August 8, 1854, No. 11,496, and solid headed shells by Hotchkiss, August 31, 1869, No. 94,210. [Illustration: FIG. 283.--SUBMARINE MINE. CHARGE, 250 POUNDS DYNAMITE.] In 1846 a new and distinct development in explosives was made in the discovery of gun cotton by Schönbein, and of nitro-glycerine in 1847 by Sobrero. The former is made by the reaction of nitric acid, aided by sulphuric acid, on ordinary raw cotton, which, while changing the physical aspects of the cotton but little, gives to it a terrific explosive energy. Nitro-glycerine is made in a somewhat similar way by treating glycerine with nitric and sulphuric acids. At first it found no practical applications, except as a homœopathic medicine for headache, but about 1864 Nobel commenced its manufacture for explosive uses, and since that time nearly all the great blasting operations have been performed through its agency. Its most familiar form is _dynamite_, or giant powder, Nobel’s patent, No. 78,317, May 26, 1868, which is simply nitro-glycerine held in absorption by some inert granular solid, such as infusorial earth, and is thus rendered safer to handle and more convenient to use. A suggestive application of the terrible power of these explosives is in submarine mines. The instantaneous and dastardly destruction of our battleship, “The Maine,” with 250 of her crew, in Havana harbor, February 15, 1898, by one of these agencies, is a harrowing illustration. Fig. 283 represents one of these submarine mines carrying 250 pounds of dynamite, and Fig. 284 is an instantaneous photograph at the moment of explosion. [Illustration: FIG. 284.--EXPLOSION OF A MINE. BASE OF WATER COLUMN, 100 FEET WIDE, HEIGHT, 246 FEET.] _White gunpowder_, or wood powder, was invented by Captain Schultz, of the Prussian army. It is made by treating granulated wood with a mixture of nitric and sulphuric acids, which, acting upon the cellulose of the wood, convert it into an explosive something of the nature of gun cotton. The grains are afterward saturated with saltpetre. This was patented in the United States June 2, 1863, No. 38,789, and in Great Britain, No. 900, of 1864. Dittmar’s powder is another of the same general nature, covered by United States patents No. 98,854, January 18, 1870; No. 99,069, January 25, 1870, and No. 145,403, December 9, 1873. Among the high explosives of more recent date may be mentioned: _Tonite_ (gun cotton and barium nitrate), British patents No. 3,612, of 1874, and No. 2,742, of 1876. _Rack-a-rock_ (potassium chlorate and nitro-benzene), United States patent No. 243,432, June 28, 1881; British patent No. 5,584, of 1881. _Bellite_ (ammonium nitrate and nitro-benzene), United States patent No. 455,217, June 30, 1891; British patent No. 13,690, of 1885. _Melinite_ (picric acid and gun cotton), British patent No. 15,089, of 1885. _Lyddite_, not patented, but believed to be substantially same as melinite, and containing for its active ingredient picric acid, which is a compound formed by the reaction of nitric acid on carbolic acid. _Cordite_ (nitro-glycerine, gun cotton, and mineral jelly or oil), British patent No. 5,614, of 1889; United States patent No. 409,549, August 20, 1889. _Indurite_ (gun cotton and nitro-benzene, indurated), United States patent, No. 489,684, January 10, 1893; British patent, No. 580, of 1893. In recent years smokeless powders have largely superseded all others. These contain usually nitro-cellulose (gun cotton), or nitro-glycerine, or both, made up into a plastic, coherent, and homogeneous compound of a gluey nature, and fashioned into horn-like sticks or rods by being forced under pressure through a die plate having small holes, through which the plastic material is strained into strings like macaroni, or else is molded into tablets, pellets, or grains of cubical shape. Prominent among those who have contributed to this art are the names of Turpin, Abel and Dewar, Nobel, Maxim, Munroe, Du Pont, Bernadou and others. In the recent years of the Nineteenth Century great activity has been manifest in this field of invention. In the United States more than 600 different patents have been granted for explosives, the larger portion of them being for nitro-compounds, which partake in a greater or less degree of the qualities of gun cotton or nitro-glycerine. The influence exerted by them has been incalculable. Subtile as is the force imprisoned in inter-atomic relation, it has been the power behind the boom of the cannon; it has lent itself to the driving of great tunnels through the solid rock; it has lifted the coal and ore from the solid embrace of the mountain, and the building stone from its sleep in the quarry; it has opened up channels to the sea, canals on land, and in both war and peace has been one of the great agencies of civilization.