70 



DURATION OF EXPLOSIVE REACTIONS. 



with gas over mercury, and of there introducing the wires 

 fitted with their fuses and adjusted to the plug. This is then 

 closed by a bayonet fastening, and the detonation is effected 

 under a constant volume. 



For this purpose, the current is passed ; the fulminate goes 



off, a violent explosion is 

 caused, and a large flame ap- 

 pears in the test tube. After 

 cooling, the glass will be found 

 filled with black finely divided 

 carbon, the acetylene has dis- 

 appeared, and free hydrogen 

 remains. 1 Unscrew the cap P 

 under the mercury, remove it 

 with the capillary tube, and 

 then collect and examine the 

 gases contained in the test 

 tube. 



The acetylene is thus purely 

 and simply decomposed into its 

 elements 



C 2 H 2 = C 2 -f- H 2 . 



Scarcely a trace of the original gas 

 will be found, and, if any, it will not be 

 more than a hundredth of a cub. cm., and 

 this is doubtless some portion not reached 

 by the explosion. 



The reaction is so rapid that the small car- 

 tridge of thin paper which enveloped the fulmi- 

 nate will be found torn, but not burned, even 

 Fi S- 4 - in its thinnest fibres ; and this is explained, if we 

 note that the time during which the paper re- 

 mained in the explosion centre was about ^^^wcf f a 

 second, according to the thickness of the paper and the known 

 data relative to the rapidity of this order of decomposition. 



The carbon set free exhibits the same general conditions as 

 that obtained in a tube at a red heat ; it is mainly amorphous 

 carbon, and not graphite ; it dissolves almost totally when treated 

 several times with a mixture of fuming nitric acid and potassium 

 chlorate. ^ Nevertheless, in this way, it gives a trace of graphite 

 oxide, which proves that it contains a trace of graphite, pro- 

 duced doubtless by the transformation of the amorphous carbon 

 under the influence of the excessive temperature to which it has 

 been subjected. 



The author has, in fact, shown that amorphous carbon heated 

 up to about 2500 by electrolytic gas commences to change into 



1 Mixed with nitrogen and carbonic oxide proceeding from the fulminate. 

 and which- have been formed independently. 



