NITRO-GLYCERINE.

Manawatu Herald, Volume XL, Issue 1792, 21 February 1918, Page 4

NITRO-GLYCERINE.

HOW IT IS MADE. ITS USE IN WAR. Nitro-glyeerine, or “explosive oil” as it used to be called, is not a substance that can be handled with impunity. Slight shocks will sometimes set it off, and when not pure it has even been known to go off spontaneously. But in the early days of its manufacture its bad habits were not so well known, and the Swedish chemist, Nobel —the first man to make it on the large scale —actually sent it in tins to various parts of the world. Many of these tins exploded either on the voyage or upon reaching their destinations. It is rather wonderful that the manufacture was continued after such accidents as this, and especially so as one of Nobel’s sons was killed by an explosion in the factory. Nobel himself, indeed, would probably have given it up, but his other son, the Alfred Nobel, who subsequently made so many great discoveries in connection with explosives, was not deterred, and resolved to go on and make the ex- - plosive safer to handle. ' In this he was quite successful. His first discovery was that nitroglycerine could be absorbed by a certain earthy substance formed from the remains of sea animalculae, and called kieselguhr. When so absorbed it became much less sensitive to shock. This mixture is now known as common dynamite. But common dynamite is not much used now, for later on Alfred Nobel discovered that a sort of jelly could be made by gently warming nitro-glyeerine with nitro-cotton (gun-cotton) —a, substance made by the action of nitric and sulphuric acids - upon ordinary cotton. This jelly is very convenient to handle, and much safer than either nitro-glycerine or dynamite. ITS USE IN WAR. We are more interested, however, just now in the explosive cordite, which is a mixture of nitro-glycer-ine, guncotton, and vaseline, worked into the form of sticks or cords, that are done up in bundles and are used to send our shells on their deadly mission to the Germans. There is a great advantage in having the explosive in this form, for the velocity imparted to the shell is regulated by the thickness and length of the sticks —the fatter (he sticks the less the velocity. The action of the vaseline is rather curious. Both nitro-glycerine and guncotton by themselves are extremely shattering in their effects. The addition of 5 per cent, of vaseline slows down their action very considerably. There is very little loss of power, but the power is exerted more slowly and regularly. There was a great discussion in the daily papers some time ago as Ito whether it was correct to say I that our high explosives depended upon glycerine for their manufacture, and there was at first a considerable amount of misunderstanding. The facts are that hitro-gly-eerino is the main ingredient in all the propelling explosives, but not in the high explosive of the shells them-eives. It would not be safe to have nitro-glycerine in the latter, because the shell ,would then probably explode in the gun. GREAT PRECAUTIONS IN MANUFACTURE.

Very great precautions have to be taken in its manufacture. The buildings are very light in character, and each is surrounded by substantial grass-covered mounds, so that if an explosion occurs the shock will be prevented to some extent from spreading to other houses, and these houses arc always placed at suitable distances from cne another. All sorts of strict rules and regulations are enforced, and inspectors visit the factories to see that they are carried out. No matches are allowed to be taken into the danger area, and in the houses the men wear special clothes and boots. Sometimes during the operations it may be noticed that red fumes are commencing to form and show-themselves through the small show-glass that is always fixed at the top of the apparatus. Then is' the time to be active, and if the man in charge finds that the thermometer in his apparatus rises ominously he opens' a special cock and lets the whole of his charge run into a drowning-tank that is generally fixed somewhere below the building- and contains a large volume of cold water. After he has turned the cock one may be pretty certain that he will remove himself as far as possible from the house, because even the running of the charge into cold water does not always prevent on explosion. But, as a general rule, things go quite smoothly. The nitroglycerine, after it is made, is separated from the acids and very carefully washed, in large lead tanks, where it is stirred up with water and carbonate of soda by means of compressed air that is made to bubble through. When the washing is finished/ the nirto-glycerine is filtered and tested, and is then ready to be sent out into other parts of the factory, after being mixed with gun-cotton or other materials. NitTo-glycerine itself is usually carried about and*measured or weighed in rubber buckets in order to lessen the chance of explosion by shock. - EASY TO FREEZE. One of the great difficulties connected with rihe manufacture is found in the easiness with which nitro-glycerine freezes. Not only is it a slow and difficult matter to

thaw it again, but the frozen material has certain properties that may lead to an explosion. For example, explosions have been known to occur through the jerking of frozen taps. In cold weather, therefore, it is necessary to surround all tanks and vessels with warm water. The men who make nitro-glycer-ine are not only exposed to great danger, but often suffer severely from headache and sickness. Most of them get more or less immune after a while, but a number are very sensitive. Some of the men will get a bad attack merely from the effect of a drop of the oil on their hands or from breathing the vapour, and a really bad attack is a thing never to be forgotten. But many of these men have the knowledge that they are doing something to help their comrades at the front, and go along quite cheerfully. — Chambers’ Journal.