FROM GUNPOWDER TO HIGH EXPLOSIVES
How Explosives aid Man—From Gunpowder to Dynamite—Alfred Nobel’s Struggles and Success—Lyddite and T.N.T.
IT is on record that, in order to make a cutting three miles long to drain Lake Fucinus, the Roman Emperor Claudius employed thirty thousand men for eleven years. Many centuries later it took one hundred and fifty years to tunnel nine miles of gallery in a mine in the Harz Mountains. Again, the Spaniards, trying to drain Lake Mexico in the seventeenth century, failed to accomplish their purpose, although they had a nation of slaves upon whom to draw.
Any of these tasks would have been completed by modern engineers in a few months or, at most, years, the reason being that to-day the engineer has at his disposal a large variety of explosives which in those days were not available.
I have quoted the instances above to introduce the point that, although gunpowder was originally invented and made solely for purposes of war, in later times explosives have been used more for peaceful than for warlike purposes; without them we should not have our modern railways, our great roads, tunnels, docks, or deep mines.
We do not hear of blasting with gunpowder until the seventeenth century, and even a hundred years later the amount used for that purpose was very small. Gunpowder is made of seventy-five parts of saltpeter (or nitrate of potash), fifteen parts of fine charcoal, and ten parts of sulphur. It is not a very powerful explosive, and is both dirty and smoky. It acts best when made up into rather large grains. Yet for many centuries it was the world’s only explosive, and was not superseded until the discovery of guncotton.
So long ago as 1832 Bracon discovered that woody fiber could be turned into an explosive by the action of concentrated nitric acid; and a few years later a French inventor, Dumas, tried to make cartridges of paper treated in similar fashion. If he had succeeded these would have been the first smokeless cartridges, but he failed; and it was not until 1845 that Schönbein, a German chemist, hit upon the proper method of treating cotton wool with nitric and sulphuric acids, so as to turn it into guncotton.
In 1847 an English firm, Messrs. Hall and Son of Faversham, began to manufacture guncotton, and military experts hailed it as the new explosive which would take the place of gunpowder. But, as the slang phrase goes, "there was a nigger in the woodpile." In other words, this explosive was so terribly powerful that, when used in a gun or rifle, it blew the barrel to pieces. Worse than that, it was most dangerous to manufacture. There were several small explosions followed by a dreadful one in July, 1847, which blew part of the Faversham works to pieces and killed a number of people. The result was that Messrs. Hall not only ceased the manufacture of guncotton, but also buried their stock in hand. Many further experiments were made, however, but without much result, until the English chemist, Professor Sir Frederic Abel, then head of the Chemical Department of the British War Office, discovered a method of manufacture by which guncotton could be completely purified from free acid. It was the free acid that had caused the danger of explosion, and Professor Abel’s new product was far safer to handle than anything previously made.
Guncotton has several advantages over gunpowder. In the first place, it ignites at a temperature of three hundred degrees, while gunpowder requires a temperature of six hundred degrees to ensure ignition. In burning or exploding it leaves no solid residue, and therefore does not foul a gun barrel. Also, it is quite smokeless. Again, while gunpowder does not keep well and is ruined by damp, guncotton can be kept under water without being harmed. Nowadays guncotton can be compressed into hard cakes and handled with perfect safety, provided ordinary care is taken. Its explosive powers are tremendous. For instance, if you hang a ring of small cakes of guncotton round the trunk of a big tree and fire them, the tree comes down as if a giant hand with a single blow of a monstrous axe had chopped through it. Guncotton can be detonated, even when wet, by using a small primer of the dry material, and this fact has led to the adoption of guncotton as a charge for torpedoes or for submarine mines.
In 1847 a new explosive came into being. This was nitroglycerine, made by treating glycerine with nitric and sulphuric acids. But at first it was even more dangerous to handle than guncotton, for the least shock exploded it, and its violence was terrific. The great chemist Alfred Nobel tried to improve it by mixing it with gunpowder, but the powder did not absorb all the nitroglycerine, and accidents of the most terrible kind became more and more frequent. Yet the new explosive, being liquid, could be poured into crevices in rocks, and was so useful as a blasting agent that its manufacture went on until a large vessel carrying cases of the explosive from Hamburg to Chili blew up at sea. The ship was blown to bits and her crew killed, and the disaster caused so great a sensation that the manufacture of nitroglycerine was prohibited in Sweden, Belgium, and in England. But Nobel still continued his experiments, and at last, after trying sawdust and all other sorts of absorbents in vain, found the perfect absorbent in the shape of keiselguhr—a sort of earth made of fossil shells. The mixture is what we know to-day as dynamite; and in spite of the fact that modern chemistry has produced very many new explosives, some of terrific power, dynamite remains the safest and most widely used of all explosives.
In 1870 the world’s output of dynamite was only eleven tons, but by 1890 this had grown to over twelve thousand tons. To-day it is probable that nearly five times that quantity is being used in a twelvemonth. Modern dynamite is made up in sticks consisting of one part of keiselguhr to three of nitroglycerine. A stick, when touched with a match, burns with a hot flare, but does not explode. It requires a detonating fuse to set it off, and then it explodes so rapidly that the time of explosion has been calculated at only the 24,000th of a second. Used under water, it loses very little of its power, so it can be employed for blasting reefs or sea rocks.
One great advantage which it has over gunpowder is that there is no need to tamp holes in a rock to receive it. All that is necessary is to lay it upon the rock or other substance which is to be broken up, and cover it with clay. Its whole force is then exerted downward, and it will smash up a rock, a tree trunk, or a metal casting with equal ease. For quarrying purposes, dynamite is not much used, because it so completely shatters the stone, but for mining it is invaluable. Yet, if safe to handle when made, the manufacture of dynamite is still attended with considerable danger. It is necessary to keep the acids at a low temperature when run together; and if you should visit a dynamite works you will see the various processes carried out in small buildings isolated one from another by heavy banks of earth or sand. All governments have made stringent regulations for the manufacture and carriage of dynamite.
Nobel did much more than merely discover dynamite; he also invented blasting gelatine, gelatine dynamite, and gelignite, both of the latter being better suited for rock blasting than pure dynamite. Blasting gelatine was used to pierce the great St. Gothard Railway tunnel through rock so hard that without it the task could never have been accomplished. Blasting gelatine was tried in guns, but burst them, so Nobel set himself to discover an explosive less violent, yet equally clear and smokeless. By mixing nitroglycerine and guncotton he found a comparatively slow-burning powder which he called ballistite, and this, when he gave it to the world in 1888, caused a very great sensation.
Nobel, though a delicate man, had amazing courage and strength of will. In his early days he experienced all kinds of misfortune. His factory blew up, and afterward he found it almost impossible to get labor, because every one was so terrified of the power of his tremendous explosives; his younger brother, to whom he was deeply attached, died; his father became paralyzed, and his mother begged him to give up his perilous experiments. He himself suffered agonies from headache brought on by the poisonous fumes of the nitroglycerine—headaches so dreadful that at times he was forced to fling himself down on the ground in the mine or quarry where he was experimenting, and wait until the agony had somewhat abated. He was extraordinarily brave, and would allow none of his men to take risks that he would not take himself. On one occasion, when a quantity of dynamite was stuck inside a great cask and every one else was afraid to touch it for fear of explosion, he crawled into the cask on hands and knees and dug the stuff out with a knife.
Success at last crowned his efforts, and he made an immense fortune. By the terms of his will, after providing for his friends and relatives, he left over two millions sterling to provide for yearly prizes for the greatest achievements in chemistry, physics, physiology, medicine, and literature. He died in 1896, and ever since these prizes have been annually awarded. There is no distinction of nationality; the awards are open to men and women of every nation. Nobel’s name will live for ever in these prizes, which have done, and are doing, so much to help those who help the world.
Recent experiments in search of explosives which should be both powerful and safe have led to the general use of picric acid as a base. This acid is produced by the action of nitric upon carbolic acid. The French began in 1885 with what they call "melinite"—a mixture of picric acid and guncotton; and the British followed with lyddite, which was first used in Lord Kitchener’s Soudanese campaign and a little later in the Boer War. Many attempts have been made to use dynamite in guns; and the Americans at one time built some huge air guns for the purpose of firing large shells, or rather aerial torpedoes, charged with dynamite. But these guns, of which one or two were used in the Spanish-American War, were very cumbersome and slow in use. Nor could they throw a projectile to a greater distance than a mile. So they were soon abandoned in favor of rifled cannon-firing shells loaded with explosives such as cordite or lyddite.
Lyddite is one of the best known of modern explosives, and is very similar to melinite, used by the French, and shimose, the principal Japanese explosive. Lyddite is simply picric acid mixed with vaseline. It is intensely poisonous and highly explosive. Picric acid is one of the many products of coal tar. It is, in short, a mingling of carbolic, sulphuric, and nitric acids. It has many virtues as an explosive, but also some vices. Its great advantage is that it can be dropped, even thrown about, without any risk of explosion, and that it can even be lighted and burned in the open without damage. To make it explode, a powerful detonator is required, such as fulminate of mercury. The principal disadvantage of lyddite is that it is intensely acid, so that when moisture is present it attacks lead and other metals, forming explosive compounds which may go off quite unexpectedly.
An explosive of which enormous quantities were used in the Great War is that commonly called T.N.T., which is short for "trinitrotoluol." T.N.T. is somewhat similar to lyddite, and though not quite so powerful has the great advantage that it is not acid, and so is much safer to store and handle. It is not affected by water or by air, and is so difficult to explode that a rifle bullet fired through it fails to detonate a charge. T.N.T. was first used by the Germans, but afterward by the Allies, especially the British, who employed it more particularly for mines and depth charges in the anti-submarine war.