1 87 1.] Technology. 549 



c.c. ; the water is contained, previous to its coming into contact with the 

 sodium, in a small bulb, which is solidly fixed by means of a neck to the bulb 

 wherein the sodium is contained, which latter may be made of 50 c.c. 

 capacity. Taking 50 c.c. for the capacity of the explosion bulb, the pressure 

 of the gas generated inside will be 450 jatmospheres, equal to 6800 lbs. to the 

 square inch. 



From a lengthy memoir by Mr. P. Champion on the properties and industrial 

 manufacture of nitroglycerine, we quote the following particulars. Nitrogly- 

 cerine is absolutely insoluble in water, but soluble, in all proportions, in ether, 

 methylic alcohol, and ordinary alcohol (but, as regards the latter, only at a 

 temperature above 5o°C.) Nitroglycerine is somewhat volatile, without decom- 

 position, above ioo°, and is not liable to spontaneous decomposition when 

 pure. When exposed for several hours to a temperature of — 15% nitroglycerine 

 becomes thick, but not solid ; while a prolonged continuation of cold of only 

 — 2° freezes this body, converting it into a crystalline mass. Fuming nitric 

 acid dissolves, but also decomposes, this fluid ; and the same effect is produced 

 by concentrated sulphuric acid, and also by the mixture of sulphuric and nitric 

 acids employed for the preparation of nitroglycerine. This latter fact 

 explains the deficiency of the theoretical quantity (246) which is obtained in 

 the preparation of nitroglycerine from 100 parts of glycerine. The author's 

 experiments prove that pure nitroglycerine boils, but does not explode 

 violently, at 185 C. ; volatilises slowly at 194°, rapidly at 200 ; deflagrates 

 violently at 217 ; detonates difficultly at 241°, but violently and completely at 

 257 ; at a higher temperature the detonation is less violent, and at 287 

 is accompanied by flame. At a low red heat, nitroglycerine assumes the sphe- 

 roidal state, and is volatilised without detonation. While nitroglycerine 

 detonates with great violence by a smart blow it is not affected by electrical 

 shocks. 



The substance known as dynamite (consisting essentially of nitroglycerine 

 absorbed by any suitable inert powder) is met with in the trade made up in 

 cartridges weighing, on an average, 71 grms., and packed in boxes weighing 

 with contents, about from 25 to 30 kilos. M. P. Guyot happening to have in 

 his possession a number of cartridges containing dynamite (the body of the 

 cartridge is made of stout grey paper), found that these objects, after some 

 lapse of time, became moist and oily looking, and a cardboard box in which 

 the cartridges were kept was also found impregnated with a liquid, which, on 

 investigation, turned out to be nitroglycerine. A small piece of the paper so 

 impregnated exploded violently when brought into contact with glowing coals, 

 and the like effect was observed when a piece of the paper was laid upon an 

 anvil and smartly struck with a hammer. The author also found that the wood 

 of the boxes in which dynamite cartridges are kept becomes, by slow degrees, 

 impregnated with nitroglycerine, and thereby a most dangerously explosive 

 material, which may give rise to serious accidents in warehouses where 

 dynamite is kept. 



In a subsequent publication the same author proposes that instead of paper, 

 parchment should be used for making the cartridges filled with dynamite, so 

 that no nitroglycerine can escape by soaking the paper, parchment being 

 impervious to the liquid just alluded to. 



In a memoir on the accidental and spontaneous explosion of explosive sub- 

 stances, and on a preventative of such occurrences, Dr. Zaliwski says that the 

 explosive property of the inflammable substance depends upon the hygrometric 

 condition of the atmosphere — that is to say, that gunpowder and other 

 explosive materials may become, even without elevation of temperature, spon- 

 taneously explosive, but that the smallest trace of oxalic acid is, if mixed with 

 the explodents, sufficient to prevent spontaneous explosion due to the cause 

 alluded to, owing to a catalytic effect which precedes the loss of basic water of 

 the acid alluded to. The author further says that this fact can be readily 

 experimentally proved by adding, to a mixture of sulphur and chlorate of 

 potassa, for instance, or to any other explosive mixture, a certain quantity of 



