Intelligence and Miscellaneous Articles. 239 



lity and rapidity of working, as to lead temporarily, at any rate, to 

 the disuse of gunpowder, so that for the last six weeks quarries are 

 worked with nitroglycerine only. 



From the commencement we thought it necessary to prepare this 

 substance on the spot ; the carriage, whether by ship or by rail, of 

 such a substance, so explosive and of such frightful power, appeared 

 inadmissible. The great misfortunes which have occurred at As- 

 penwall and San Francisco have shown that these fears were well 

 founded, and that the carriage of nitroglycerine ought to be abso- 

 lutely forbidden. 



After studying in my laboratory, with the aid of M. Keller, the 

 various modes of preparing nitroglycerine (mixtures of glycerine with 

 concentrated sulphuric acid and nitrates of potash and soda, or with 

 nitric acids of different degrees of concentration), we have adopted 

 the following method of manufacture, which has been established in 

 a wooden cabin, constructed in one of the quarries : — 



1. Preparation of Nitroglycerine. -^~In a vessel of sandstone 

 placed in cold water, fuming nitric acid of 49° or 50° Beaume is 

 mixed with double its weight of the most concentrated sulphuric acid. 

 (These acids are prepared expressly at Dieuze, and sent to Saverne.) 

 On the other hand, glycerine of commerce, but free from lime and lead, 

 is evaporated in an iron pot until it marks from 30° to 31° Beaume. 

 This concentrated glycerine should be syrupy when quite cold. 



The workman places then 3300 grammes of the mixed acids, well 

 cooled, in a glass flask (a sandstone pot, or a porcelain or sandstone 

 basin may also be used), dipped in a bath of cold water, and pours 

 slowly, with constant stirring, 500 grammes of glycerine. The im- 

 portant point is to avoid a perceptible heating of the mixture, which 

 would occasion a tumultuous oxidation of the glycerine with pro- 

 duction of oxalic acid. Hence the vessel in which the change of 

 glycerine into nitroglycerine is effected, should be constantly cooled 

 on the outside by cold water. 



The mixture having been completely effected, the whole is left 

 for from five to ten minutes, then the mixture is thrown into cold 

 water which has been previously agitated. The nitroglycerine is 

 rapidly precipitated as a heavy oil, which is collected by decantation 

 in a tall vessel ; it is then washed once with a little water, which is 

 decanted ; then the nitroglycerine is placed in bottles, where it is 

 ready for use. 



In this condition the nitroglycerine is still a little acid and aqueous ; 

 but that is not inconvenient, for it is used a short time after its pre- 

 paration, and these impurities by no means prevent its detonation. 



2. Properties of Nitroglycerine. — Nitroglycerine constitutes a 

 yellow or brownish oil, heavier than water (in which it is insoluble), 

 soluble in alcohol, ether, &c. 



. Exposed to even a feeble degree of cold, provided it is prolonged, 

 it crystallizes in elongated needles. A very violent shock is the 

 best mode of exploding it. It is, moreover, managed easily, and 

 without danger. Spread on the earth, it is only difficultly inflamma- 

 ble by a body in combustion, and only burns partially ; a flask con- 

 taining nitroglycerine can be smashed on the stones without the 



