Such is the case, however, for glycerine on being brought into contact with a mixture of sulphuric and nitric acids gives birth to nitro-glycerine, an explosive of such sensitivity, of such a furious, violent nature, that it is never allowed to remain long in its primitive condition, but is as quickly as possible changed into something less excitable. Glycerine is one of those organic compounds which is obtained from once-living matter. Arising as a by-product in the manufacture of soap, it consists, as do so many of the organic substances, of carbon and hydrogen, the atoms of which are peculiarly arranged to form the glycerine molecule. To this the nitric acid adds oxygen and nitrogen, the sulphuric acid simply standing by, as it were, and removing the surplus water which arises during the process. So while glycerine is carbon and hydrogen, nitro-glycerine is carbon, hydrogen, nitrogen and oxygen. In this state they form a compact liquid, which occupies little space. The least thing upsets them, however. The carbon combines with oxygen into carbon dioxide, commonly called carbonic acid gas, the hydrogen and some more oxygen form steam, while the nitrogen is left out in the cold, so to speak. And the total volume of the gases so produced is about 6000 times that of the original liquid. It is easy to see that a substance which is liable suddenly to increase its volume by 6000 times is an explosive of no mean order. But the fact that it is liable to make this change on a comparatively slight increase in temperature or after a concussion makes it too dangerous for practical use. It needs to be tamed down somewhat. This was first done by the famous Nobel, who mixed it with a fine earth known as kieselguhr, whereby its sensitiveness was much decreased. This mixture is dynamite.