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Nitroglycerine
| As mentioned above, nitrates were often scarce and expensive, especially in time of war, so alternatives to nitrate explosives were sought. The only real alternative was to mixes containing chlorates, which are widely used in pyrotechnics. French Cheddite was an example of such explosives, which used 60%-80% ammonium, sodium or potassium chlorate or perchlorate, with some fuel such as carbon, sulphur, aluminium or vegetable meals. |
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Some aromatic nitro compounds improved flame propagation, and paraffin or castor oil was added as a desensitizer. In Germany, a little nitroglycerine or collodion cotton was added to increase the brisance. These explosives were used in mining and quarrying, not for military purposes, for which they released scarce nitrates
Nitroglycerin, also known as nitroglycerine, trinitroglycerin, and glyceryl trinitrate, is a chemical compound, a heavy, colorless, poisonous, oily, explosive liquid obtained by nitrating glycerol. It is used in the manufacture of explosives, specifically dynamite, and as such is employed in the construction and demolition industries. It is also used medically as a vasodilator to treat heart conditions. It is colored yellow when it is decomposing due to acidic pH.
Nitroglycerine is an explosive liquid which was first made by Ascanio Sobrero in 1846 by treating glycerol with a mixture of nitric and sulphuric acid.
Early in the history of this explosive it was discovered that liquid nitroglycerin can be "desensitized" by cooling to 5 to 10 °C (40 to 50 °F), at which temperature it freezes, contracting upon solidification. However, later thawing can be extremely sensitizing, especially if impurities are present or if warming is too rapid.
It is possible to chemically "desensitize" nitroglycerin to a point where it can be considered approximately as "safe" as modern High Explosive formulations, by the addition of approximately 10 to 30 percent ethanol, acetone, or dinitrotoluene (percentage varies with the desensitizing agent used). Desensitization requires extra effort to reconstitute the "pure" product. Failing this, it must be assumed that desensitized nitroglycerin is substantially more difficult to detonate, possibly rendering it useless as an explosive for practical application.
Alfred Nobel worked hard to improve nitroglycerine as an explosive that could be used in blasting rock and in mining. He made one of his most important discoveries when he found that by mixing nitroglycerine, an oily fluid, with silica, the mixture could be turned into a paste.
This material could be kneaded and shaped into rods suitable for insertion into drilling holes. He called his paste dynamite and went on to develop a blasting cap which could be used to detonate dynamite under controlled conditions.
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