NITRO-GLYCERINE. 



^57 



must contain 3 atoms of IST, or, if glycerine be represented by tte 

 formula : 



C. H, I 



Hs 



0. 



( ^s 



nitro-glycerine would be 



[o. 



C3 H5 



He also shewed that nitro-glycerine, when boiled with potassium 

 hydrate, was decomposed into potassium nitrate and glycerine ; 



3 5 1^0, + 3 to — ^ 5>0+3 - i O 

 3 NOj y ^^ B. \ ^ — H.^ S K S 



Nitro-glycerine is a substitution product from glycerine, obtained 

 by the action of a mixture of nitric and sulphuric acids on that sub- 

 stance. It may be described as glycerine in which three of the atoms 

 of hydrogen have been replaced by three molecules of nitric peroxide. 

 It is a colourless oily fluid of a specific gravity of 1.6, and hence 

 more than half as heavy again as water, in which it is quite insoluble. 

 It is made by dissolving glycerine in the mixed acids, and pouring the 

 resulting mixture into water, when the nitro-glycerine sepai-ates and 

 collects at the bottom of the vessel. It is necessary to keep the acid 

 mixture cool and to add the glycerine in small portions, cooling after 

 each addition. The product should be well washed with water so as 

 to get rid of the last trace of acid. Nitro-glycerine which has been 

 incompletely freed from acid has a tendency to decompose, giving off 

 red fumes of nitric peroxide, and dej)ositing crystals of oxalic acid 

 (Bloxam). On the application of an ignited substance it burns 

 quietly away without noise, and with a greenish flame. If a drop of 

 it is laid on an anvil and struck smartly with a hammer, it explodes 

 violently with a report like that of a pistol. The conditions under 

 which this explosion takes place are of great importance, and have 

 been carefully studied. All observers agree that contact with an 

 ignited body will not explode nitro-glycerine — ^under these conditions 

 it merely burns away quietly. Abel* conducted a series of investiga- 

 tions on the action of a succession of electric sparks on nitro-glycerine, 

 and he found that in no case was he able to explode it by such means, 

 until, after the discharge had been continued for a considerable 

 period, the liquid became dark -coloured from incipient decomposition. 

 Shortly after this point was reached, explosion took place. When a 



* Philosophical Trans., 15th April, 1869. 



