THE HISTORY OF INFERNAL MACHINES

Manawatu Times, Volume 63, Issue 48, 26 February 1938, Page 12

THE HISTORY OF INFERNAL MACHINES

MAKING OF EXPLOSIVES Knights of the Bomb

A N explosion is simply very rapid, almost instantaneous, combustion. Take, for example, a piece of cnarcoal the size of your fist; if yon burn it in a grate, it will disappear gradually: that is slow combustion. But reduce this charcoal to a fine powder and scatter it in the air of a small room and a tiny spark will be sufficient to cause an explosion. This is because the oxygen of the air, indispensable for combustion, unites into a whole the thousands of little particles and assures without delay the transformation of the carbon into carbonic gas. All the heat and all the gas engendered during the course of several hours by the piece of charcoal while burning, is thus produced in a fraction of a second. The windows of the room will be broken and you will be burned. Take the same quantity of powdered charcoal and mix it now with liquid air which contains, compressed into very small volume, a large quantity of oxygen. This time, look out! You are going to produce a powerful explosive, for the combustion will be effected even more rapidly than in the preceding case: the walls will fall down and you will be crushed.

You have got the idea: an explosion is combustion which releases instantly a Jot of heat and gas. The more rapid this release, the more violent the explosion. The com' ’stion of about two pounds of gunpowder produces about 641,000 calories and about 45 gallons of gas in a relatively long time (a ten i of a second, for example): this is a propulsive explosion. The combustion of two pounds of nitro-glycerine produces 1,320,000 colories and more than 135 gallons of gas in an extraordinarily short time (one fifty thousandth part of a second): this is a “shattering” explosion.

Because an explosion Is combustion, an explosive must necessarily contain a combustible and a comburent, for the oxygen in the air is too dispersed to be oE practical use. Thus is was found preferable to mix the combustible powder with a substance rich in oxygen, such as saltpetre, for instance. This is the old “black powder” which made its appearance in 1346.

The greatest progress realised during the six following centuries was the union in a single body of the combustible and the comburent. This has been achieved thanks to compounds of nitre having for a base nitric acid and sulphric acid.

Then it was a question of finding a support f«- tlv> cubsta T '~-' combustible and comburent combined. The first idea was that of Von Mem-ninger, a German gunsmith, who, in 1534, used oil of tar. ‘Rut after many trials glycerine proved itself most suitable. Sbrero, an Italian chemist of the last century, prepared the first nitro-glycer-ine from the followin.r formula: “Mix a litre of nitric acid with two litres of sulphuric acid, then add half a litre of glycerine, shaking continuously. Then pour the whole into 40 or 50 litres of water: the nitro-glycerine will separate itself immediately and falls to the bottom of the container.” In modern factories the fabrication is practically the same and a pale yellow liquid is thus obtained which is still one of the most powerful explosives known. Nitro-glycerine in this form, however, is now practically never used. It has been abandoned because of the catastrophes that were constantly occurring in connection with it. It is extremely sensitive to shocks and is only usable in the form of dynamite, that is to say when it is mixed with a powdered substance. Dynamite seems to have been discovered accidentally by a German miner who, chosen to make some blasting experiments, thought it would be more convenient to use dust impregnated with nitro-glycerine, than the latter in liquid form: he reported that the mixture was much more reliable than the liquid alone. Sand and cinders as a mixing agent

were later given up in favour of powdered silica: a kilogram of silica can absorb from two to three kilograms of nitro-glycerine. The oily paste obtained is cut up into sticks, just like macaroni. A stick, cut to the desired length is wrapped in paraffinised paper, and a dynamite cartridge is born. This is quit? powerful, but there is something still more effective. Instead of using an inert substance like silica, some gun-cotton, previously impregnated with, nitric acid and sulphuric acid is dissolved in the nitro-glycerine. This produces an elastic, yellow, transparent substance, the famous dynamitegum. It is much less sensitive to shock than the other ami much more shattering in its effect. To make “tolite,” the well-known explosive, instead of mixing the glycerine with nitric acid and sulphuric acid, you us? toluene, a colourless liquid extracted from coal or petroleum. You will thus obtain line crystals which reduced to powder make? colite. used for the charging of bombs, grenades, and torpedoes. During the war, France and England alone manufactured 200 tons of it a day. Anybody, it appears, then, can mane a bomb with the help of manuals, but those manufactured by novices seldom work accordin g to plan. The greater part of the effective explosives used by terrorists hav e generally been stolen from the regular makers. In some cases it is a question whether the bombs were stolen or voluntarily given by certain foreign nations to be used for political onds. Everybody lias heard of time fuses, that is, cords or the like to convey fire to an explosive. The fire travels at a fixed speed a long the cord until it finally ignites the explosive. The cord is made sufficiently long to allow the operator time to reach a place of safety. This procedure, often employed in

mines and quarries, is not in use among anarchists and other “knights of the bomb” because the latter generally desire the explosion to be considerably delayed, at least for several hours. For this too long a cord would be required, the burning of which would probably attract attention. The criminal wants to have time to get back to his den or perhaps to cross the frontier. This is possible, thanks to the infernal machine. There are two types of the latter: the passive and the retarded. The passive are those that explode only through exterior intervention, such as being turned over or by the opening of the box in which the bomb is contained.

The retarded type Is electrically worked. The important point is the liberation of the current at the hour determined upon. To-day nothing is easier. One has simply to buy for a dollar or so an automatic starter. As large as half one’s fist, this contrivance contains a clockwork movement, a wall plug and a small handle by which you can turn the hands on the dial to any time in the 24 hours of the day. The device can be used for many things, such as ringing an electric bell at a certain hour, or for turning on a radio, or the lights of a standing motor car. With this peaceable device the terrorist can arrange an explosion 24 hours ahead without fear of a misfire, and in 24 hours be far away. . . .

Are we sufficiently protected against infernal machines. It must be admitted that control at present is inadequate. How could it be otherwise. The sale of gunpowder is free. Everybody can buy as much as he wants without any formalities.

The true explosives: dynamite, tolite, melinite are only supplied to manufacturers with the reservation that a certain number of pieces must be produced. But any quarryman can obtain, if he conforms to some simple rules, tens, even hundreds of pounds of dynamite. Once a stock has been obtained the control of its use is impossible. It is therefore not necessary to go abroad to seek engines of destruction. Modern political organisations, open or secret, have sufficient funds and devoted workers enough to carry out the exploitation of mines and quarries. So the State may itself supplying those who are plotting its ruin.