3^62 NITRO-GLYCfiRiNie. 



liitro-glycerine was enclosed in tin cases from eiglit to fifteen inclieis 

 long and about an inch in diameter, and holding from four to eight 

 ounces of nitro-glycerine. The nitro-glycerine was generally ex- 

 ploded by a small confined charge of gunpowder. 



The use of nitro-glycerine is attended with great danger, and a 

 iiumber of melancholy accidents followed its introduction into the 

 arts. Some of these accidents will be alluded to subsequently. In 

 consequence of this danger, and of the inconvenience of the liquid 

 form of the compound, owing to which it could not be used in any 

 but downward bore holes, various attempts Were made to obtain a 

 compound of which nitro-glycerine should be the base, but which 

 should have a solid form. These attempts resulted in the introduc- 

 tion by Mr. Nobel of dynamite, which consists of a siliceous earth 

 called Kieselguhr, impregnated with nitro-glycerine. This Kiesel- 

 guhr is a siliceous earth found in large quantities only in one place 

 ■■ — near Luneburg in. North Germany. It consists chiefly of silica, 

 although there are traces of alumina, ferric oxide and lime. It is 

 a deposit consisting of the remains of the shells of by-gone genera- 

 tions of infusoria. It is of a light red colour, and is very absorbent, 

 so that the dynamite may be made up in paper cartridges and kept 

 without appreciable loss; although Girard, Millot and Yogt* have 

 shewn that it loses strength on exposure to the air, and Guyot f has 

 pointed out that paper will absorb nitro-glycerine, and that its 

 absorption by the paper of the cartridges in which it is enclosed, is a 

 possible source of accident. The paper is sometimes soaked in paraf- 

 fin, which will obviate the danger from this cause. 



M. Champion| concludes that dynamite is not exploded by a blow; 

 but Girard, Millot and Vogt§ found, by experiments conducted with 

 the apparatus already described, that a mixture of equal parts of 

 nitro-glycerine and silica is exploded easily by a weight of 4 kDos 

 700, falling through 1.65 metres. Indeed it is easy to explode a 

 small fragment of dynamite by laying it on an anvil, and striking 

 it smartly with a hammer. The contact, however, must be between- 

 iron and iron, or rarely, between iron and stone. 



There is ample testimony to the value of dynamite in blastings 



* Comptes Kend., quoted in Am. Chem., i, 79. 



t Dingler's Pol. Jouru. in Am. Chem., ii, 234. 

 t Monit. Scient., xiii, 91 ; Q. J. Chem. Sdc., ix, 7T1. 

 § Monit. Scient., xiii, 58 ; Q. J. Chem. Soc, ix, 769. 



