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nitric acid and sulphuric acid), yet the nature of the material was then so little understood that frequent explosions occurred at his works, with some fatal results. The tendency of pure nitroglycerin to decompose, resulting in violent explosions, brought about its abandonment as a commercial explosive, but when combined with a suitable absorbent, as in the so-called dynamite, this dangerous property is removed.
Lower FLOOR OF NITRATING HOUSE. The fulminating body
Here dangerous liquids are washed to cleanse them of acids. which is required to be attached to a high explosive in cury, when exploded in contact with a order to detonate it is the only ticklish body, exerts a pressure of more than half part about a shell or a mine charged with a million pounds to the square inch. In any of the explosive materials now em other words, the fulminate used as a fuse ployed. Fulminate of mercury usually is strikes the high explosive a blow with a used for this purpose, and is made by dis- force of half a million pounds to the solving mercury in nitric acid, to which square inch. The explosive wave thus solution, when cool, alcohol is added. Ful- set up is too strong to be resisted by the minate of mercury is a powerful self-de- chemical bonds of the body, and detonatonating body, because of the weakness tion results. of the chemical bond between the mole- In a shell or a torpedo the fulminate is cules of its constituents, and also because loaded in a capsule, which is secured rigof its high specific gravity, the density of idly in position a distance to the rear of its products of combustion and their con some dry gun cotton, carried to detonate fining influences.
the shell or torpedo, and from which it is It is estimated that fulminate of mer- separated by the steel walls of its cham
ber. The projectile can then be exploded only upon receiving a certain amount of retardation (as when it strikes the side of a battleship or fort), causing the plunger body of fulminate to travel forward into the dry gun cotton chamber and explode it. This permits the torpedo or shell to penetrate to a desired depth in water or earthworks before exploding. A torpedo of this description may carry half a ton or more of explosive.
Some notable blasting operations have been
performed by explosives during re- size and eighty feet long, was driven incent years, and work accomplished which to the cliff and widened inside for the half a century ago would have been either charge of explosives. Twelve tons of wholly impossible or prohibitive on ac- dynamite were detonated at once, and count of the immense cost. The largest 78,000 cubic yards of rock removed. blast in history was the removal of Hell About five or six years ago in order to Gate rock, in the East River, New York, secure a supply of rock for the construcin 1876. This rock had an area of about tion of a dam near Teller, Colorado, a nine. acres. Twenty-four longitudinal granite mound known as Vesuvius Butte and forty-six transverse tunnels, their was blown up. A horizontal tunnel, with faces pierced with 12,561 holes three several angles to prevent the blowing inches in diameter and nine feet deep, out of the Elast, was driven to the center were excavated in its interior. In these of the mound. A transverse tunnel, drill holes were inserted, in all, 240,400 forming a T, was driven a short distance pounds of what was called rack-a-rock either way at the center, and this was powder (coarse-grain ordinary black packed with 32,000 pounds of black powblasting powder) and 42,331 pounds of der. Black powder was used instead of dynamite. Water was then admitted to dynamite because it has a less smashing the mine and the blast was fired by elec- effect, and preserved the stone in better tricity. Two hundred and eighty thous shape. The explosion opened up a crater and cubic yards of rock were removed by 72 feet deep and 150 feet in diameter, this blast.
and broke up 110,000 cubic yards of rock. In blasting out a rocky obstruction in In July, 1905, 40,000 pounds of dynathe Danube River known as "Iron mite was exploded in a single charge to Gates," a vertical cliff was removed by a break up an obstructing rock known as succession of notable blasts. For one of Henderson's Point, in the Piscatoqua these a tunnel, three feet by four feet in River, opposite Kittery Navy Yard, near
Portsmouth, N. H. Two photographs of behind the plate. A similar shell, this the commotion caused by this explosion time armed with a detonating fuse, was are reproduced herewith.
then fired at another plate, and, explodProbably the most powerful high ex- ing when about two-thirds through, shatplosive compound in use is that which has tered the plate to fragments and combeen adopted by the United States Gov- pletely demolished the supporting strucernment as a bursting charge for shells, ture. known, from the name of its inventor, as The difference between gunpowder“Maximite." This explosive is about fifty an explosive used as a propelling charge per cent more powerful than ordinary in rifles and cannon-and high explosives dynamite and somewhat more powerful employed as a bursting charge in shells, than pure nitro-glycerin. Notwith- torpedoes, et cetera, has already been exstanding its high explosive property, plained. As originally made gunpowder however, it is practically insensitive to was a loose mixture of pulverized sulshock, and will not explode from igni- phur, charcoal and saltpeter. Then it was tion even if a mass of it be stirred with actually a powder, not granulated, as is a white-hot iron. Heated in an open ves the present form of ordinary smoky black sel it will evaporate like water, and powder. The idea of granulation probshells are filled with it by the simple pro- ably arose from the admixture of bitumicess of melting and pouring. Like “Lyd- nous matter with the powder to retard dite," "Melinite," "Shimoseite," and other the combustion. The first methodical high explosives in use by foreign govern- granulation of gunpowder recorded was ments, Maximite is a compound of pic- in France, in 1825. In 1854, Gen. T. J. ric acid, but its actual composition is se- Rodman invented prismatic powder, decret. It can be detonated only by a spe- signing presses for molding the grains cial fuse, the composition of which is al- separately and giving them a uniform so a government secret.
shape. He also made multi-perforated As showing the insensitiveness of this powder grains to insure progressive comexplosive to all ordinary forms of shock bustion. some elaborate tests have been made at The granular black powder of the presSandy Hook by government officials. In ent day is made by thoroughly incorpoone of these a 12-inch armour-piercing rating the moistened ingredients—sulprojectile was charged with seventy phur, saltpeter and charcoal—in a wheel pounds of Maximite and fired, without a mill. This mixture is then subjected to fuse, through a seven-inch Harveyized high pressure, and what is known as press nickel steel plate, the projectile being re- cake is formed. This cake then is passed covered intact from the sand abutment between crushing rolls, which break it up States Government is pyro-nitro-cellulose, . in which no nitro-glycerin is used, and which contains so little oxygen that a grain burned in the air leaves a large quantity of unconsumed carbon. Burned in a gun, however, under service pressures, most of the carbon combines with the oxygen to produce cartonic oxide, (carbon monoxide) instead of carbonic acid, (carbon dioxide.) The products of the combustion of these materials are practically all gaseous, and
therefore smokeless, and Still, Wherein an Explosive MATERIAL is Distilled like Water. consist mainly of car
bonic oxide, free nitrointo irregular fragments, or grains. These gen and free hydrogen. are then "tumbled," to round the edges British cordite is a smokeless powder, and corners and to glaze the surfaces containing the greatest percentage' of niwith graphite, when the grains are sepa tro-glycerin—58 per cent—and conserated according to size and the rapidity quently develops the highest temperature of combustion desired. This form of and the greatest amount of energy. It granulation is chiefly employed for blast- would require one-third more pyroing purposes and small arms. The simp- nitro-cellulose compound to develop the lest form of grain for cannon is made by same energy behind a projectile. Notbreaking the press cake into rectangular withstanding this, the greater erosive fragments.
action of cordite at high pressures is so A smokeless powder is one which destructive to guns as to more than balleaves no ash when burned, but is con- ance the additional expense of using verted wholly into gases. The smoke greater charges of the American powder. from common black powder is the pro It would be impossible to use so hard duct of its combustion, which consists of and dense a material as smokeless powmore than half solid matter, or ash. It der, and one that burns through such a was not until 1888 that anything like a small thickness, without its being multipractical smokeless powder was made. In perforated. This is owing to the enorthat year the French government de- mous initial areas presented to the flame, veloped, by a secret process, a smokeless with the resultant high pressures depowder for small arms, which, being veloped by full charges if granulated sufused in the Lebel rifle, became known as ficiently fine or made thin enough to burn the Lebel powder. It is now known that in the gun without perforations. this powder was simply a soluble variety As many as nineteen perforations may of gun cotton dissolved in a volatile sol- be made in a single grain of smokeless vent, dried in a thin sheet and then cut powder, though the usual number is up into small laminae.
about seven, the diameter of the cylinder All smokeless powders now made con and the distances between the perforasist either of nitro-cellulose of some spe tions being governed by the size of the cial degree of nitration, or of a mixture gun in which the grain is to be used. In of different grades, whether with or with the air this smokeless powder will burn out the addition of nitro-glycerin. The with comparative slowness, but under smokeless powder in use by the United pressure its action is greatly quickened.
The Opportunity the Small
Farmer is Missing
OW the small farmer of 'that land's own people, thousands of
the United States is let- small farmers of worked-out and barren
cently there landed in South Carolina found it necessary to esCharleston a ship-load of immigrants tablish her Department of Immigration, from Northern Europe, the advance and send agents to Europe to secure deguard of many thousand expected at no sirable settlers; an example which will distant date. These were not the kind of shortly be followed by Georgia and other immigrants who may be seen at Ellis Southern States. Island, but carefully selected laborers and While it is true that there is some emismall farmers invited by South Carolina gration from the crowded Eastern States to become citizens. Many of them to the South, it is astonishingly small brought sufficient money to purchase when considered in connection with the small farms, and when they have done opportunities there afforded, particularly so, there will be presented the somewhat to the small farmer. Undoubtedly this remarkable spectacle of aliens, not even is mainly due to a misconception of the speaking the language of the land of their conditions which exist—a misconception adoption, seizing an opportunity which arising from a belief in the continuance