240 Intelligence and Miscellaneous Articles. 



liquid detonating ; it may be volatilized without decomposition by 

 a regulated heat ; but if the ebullition becomes brisk, explosion 

 ensues. 



A drop of nitroglycerine falling on a moderately hot plate vola- 

 tilizes quietly ; if the plate is red-hot the drop inflames immediately, 

 and burns like a grain of powder without noise ; but if the plate, 

 without being red, is hot enough to make the nitroglycerine boil 

 immediately, the drop decomposes suddenly with a violent explosion. 



Nitroglycerine, especially when it is impure and acid, may decom- 

 pose spontaneously at the expiration of a certain time, with disen- 

 gagement of gas, and production of oxalic and glyceric acids. 



It is probable that to some such cause are due the spontaneous 

 explosions of nitroglycerine of which we read in the papers. The 

 nitroglycerine being enclosed in well -stoppered bottles, the gaseous 

 products of decomposition, not being able to escape, exert a very great 

 pressure on the nitroglycerine ; and under these circumstances the 

 least shock and the slightest motion may bring about an explosion. 



Nitroglycerine has a taste at once saccharine, piquant, and aro- 

 matic ; it is a poisonous substance ; in very small doses it provokes 

 strong headaches. Its vapour produces similar effects; and this 

 circumstance might be an objection to its use in the deep galleries of 

 mines, where the vapour cannot escape as easily as in the open air. 



3. Mode of using Nitroglycerine. — Suppose it is desired to detach 

 a layer of rocks. At a distance of from 2*5 to 3 metres from the 

 outside, a mine-hole is dug of about 5 to 6 centimetres diameter, and 

 2 to 3 metres depth. 



After having cleaned this of dirt, water, and sand, 1500 to 2000 

 grammes of nitroglycerine are introduced by means of a funnel. 



A small cylinder of wood, of cardboard, or sheet iron about 4 

 centims. in diameter, and 5 to 6 centims. in height, is then introduced 

 filled with ordinary powder. This is fixed to a wick or ordinary 

 mine fuse, which penetrates into it to a certain depth, to assure the 

 inflammation of the powder. By means of the match on the fusee 

 the cylinder is lowered ; and by the feel the moment can easily be 

 judged at which the cylinder reaches the surface of the glycerine. 

 The match being then held firmly, fine sand is run into the hole until 

 it is quite full. It is useless to compress or tamp the sand. The 

 match is cut a few centimetres above the orifice, and set fire to. In 

 eight or ten minutes, the burning of the wick having reached the 

 cylinder, the powder inflames. A violent shock ensues, which in- 

 stantaneously explodes the nitroglycerine. The explosion is so sudden 

 that the sand has no time to be projected. 



The mass of the rock is seen to rise, become displaced, and settle 

 down quietly without any projection ; a dull sound is heard. 



It is only on reaching the places that an idea is formed of the 

 great force developed. Formidable masses of rock are displaced 

 and fissured in all directions, ready to be worked mechanically. 



The principal advantage consists in the fact that the stone is but 

 slightly bruised, and that there is little waste. With the charges 

 mentioned, 40 to 80 cubic metres of very resisting rock can be de- 

 tached. —Cowptes Rendus, July 23, 1866. 





