In the working of ores of gold and silver the old method of comminution of the rock and the separation of the gold and silver by amalgamation with mercury has given birth to thousands of inventions in stamp mills, amalgamators, ore washers, concentrators and separators. In the treatment of iron ores, and especially those of low grade, the magnetic concentrator is an interesting and striking departure. This method goes back to the first half of the Nineteenth Century, an example being found in the patent to Cook, No. 6,121, February 20, 1849. Edison’s patent, No. 228,329, June 1, 1880, is however, the basis of the first practical operations in which magnets, operating by attraction upon falling particles of iron ore, are made to separate the particles rich in iron from the sand. In [Fig. 263] is shown the Edison magnetic concentrating apparatus. The ore, in masses of all sizes up to boulders of five or six tons weight, is dumped between the giant rolls, and these enormous masses are crunched and comminuted more easily than a dog crunches a bone. These gigantic rolls are six feet in diameter, six feet long, and their surfaces are covered with crushing knobs. They weigh with the moving machinery seventy tons, and when revolved at a circumferential speed of 3,500 feet in a minute, their insatiable and irresistible bite soon chews the rock into fragments that pass into similar crushing rolls set closer together until reduced to the desired fineness. The sand is then raised to the top of the concentrating devices, shown in [Fig. 264], and is allowed to fall in sheets from inclined boards in front of a series of magnets, of which four sets are shown in the figure. These magnets deflect the fall of the particles rich in iron (which are attracted), while the non-magnetic particles of sand drop straight down. A thin knife-edge partition board, arranged below the falling sheets of sand, separates the deflected magnetic particles from the straight-falling sand. These magnetic particles are then collected and pressed into little bricks, which are now so rich in iron, by virtue of concentration, as to make the final reduction of the iron in the blast furnace easy and profitable. More recent developments in this art are shown in patents to Wetherill, No. 555,792, March 3, 1896, and Payne, No. 641,148, January 9, 1900.

In the production of copper the well-known Bessemer process for refining iron is now largely used, as shown in patent to Manhes, No. 456,516, July 21, 1891, in which blasts of air are forced through the melted copper to remove sulphur and other impurities. Electrolytic processes of refining copper are also largely used, as described in Farmer’s patent, No. 322,170, July 14, 1885.

The production of metals, other than iron, in the United States for the year 1897, was as follows:

[CHAPTER XXX.]
Firearms and Explosives.

[The Cannon the Most Ancient of Firearms]—[Muzzle and Breech Loaders of the Sixteenth Century]—[The Armstrong Gun]—[The Rodman, Dahlgren and Parrott Guns]—[Breech Loading Ordnance]—[Rapid Fire Breech Loading Rifles]—[Disappearing Gun]—[Gatling Gun]—[Dynamite Gun]—[The Colt and Smith & Wesson Revolvers]—[German Automatic Pistol]—[Breech Loading Small Arms]—[Magazine Guns]—[The Lee, Krag-Jorgensen, and Mauser Rifles]—[Hammerless Guns]—[Rebounding Locks]—[Gun Cotton]—[Nitro-Glycerine and Smokeless Powder]—[Mines and Torpedoes].

Strange as it may appear, the evolution of an enlightened civilization and the deadly use of firearms have developed in parallel lines. What relation there may be between the adoption of the teachings of Christ to men to love one another, and the invention of increased facilities among men for killing one another, is a problem for the philosopher. Is it because killing at long range is less brutal, or does the deterrent influence of this increased facility operate as a check appealing to the fear of the individual, or is the cannon one of God’s missionaries in working out the great law of the survival of the fittest? Whatever it may be, there does seem to be some relation of cause and effect between the two factors, and doubtless all three of the causes have exercised a contributory influence. In the olden days the wage of battle was almost universally decided by the strength of brawn, and the higher qualities of mind were subservient. The advent of firearms has changed all this. It has made the weakest arm equal to the strongest when supported by the same or a superior mental equipment, and this has made a great step toward the supremacy of the intellectual against the attack of the physically strong. In the fifth century the great civilization of Rome fell under the ruthless attack of the northern barbarian. Could such a thing have been possible with the gates defended by Gatling guns, magazine rifles, and dynamite shells? On the contrary, we find to-day a handful of trained soldiers equipped with modern firearms putting to flight a horde of ignorant savages. The history of modern wars is filled with illustrations of the shifting of the contest among men from an issue of brute force to a contest of brains, and of the support rendered the latter by firearms. But is war really necessary, and may we not hope that it shall cease? We can only say that the ideal sentiment of beating the sword into the plowshare is as yet the dream of the optimist, for man has gone right along in perfecting the arts of war and raising the execution of firearms to such a deadly efficacy, that the Nineteenth Century in a paramount degree has been conspicuously notable for its advances in this art. Invention after invention has followed in such rapid succession, even to the last years of the Nineteenth Century, until war now assumes the conditions of suicide and annihilation.

No coherent history of firearms and explosives is possible in any short review. The cannon, bombard or mortar, musket, pistol and petard, all belong to former centuries, and in one form or another extend back to the most ancient times, but they have grown in the Nineteenth Century into such accuracy and distance of range, into such rapidity of action, into such multiplied efficiency in repeating systems, into such energy of explosives, and such convenient embodiment and penetration of projectile, that these subjects must needs be considered in separate divisions.