12 Mr. J A. Harker and Mr. H. B. Dixon on tin 



On the Decomposition by shock of Endothermic Com- 

 pounds. By J. A. Harker, Dalton Chemical Scholar, 

 and H. B. Dixon, F.R.S., Professor of Chemistry 

 in the Owens College. 



{Received October 20th, 1891.) 



In his work " Sur la Force des Matiercs Explosives," 

 published in 1883, M. Berthelot described some experiments 

 on the decomposition by shock of certain bodies formed 

 with absorption of heat. Most of his experiments were 

 made on gases. He exploded a charge of o - i grm. of 

 fulminate of mercury in a strong glass tube holding about 

 25 cc. of the gas. With acetylene the experiment always 

 succeeded, only about - oi cc. gas remaining undecomposed, 

 and a deposit of very finely divided amorphous carbon 

 being left on the walls of the vessel. Cyanogen was some- 

 times wholly decomposed, sometimes not at all. The other 

 gases he succeeded in breaking up were nitric oxide and 

 arseniuretted hydrogen. The decomposition, started by 

 the fulminate, is, according to Berthelot, a detonation pro- 

 pagated from layer to layer with extreme rapidity, and is 

 of the same nature as the ' explosion-wave.' 



In the Journal of the CJiemical Society for 1889, Prof. 

 Thorpe stated that he had discovered accidentally that 

 carbon bisulphide could be detonated with a bright 

 flame in the same way, yielding a mixture of carbon 

 and sulphur. No explosive, he says, would cause the 

 decomposition except fulminate of mercury, and the 

 brown powder, obtained by the action of a fluid alloy of 

 potassium and sodium on carbon bisulphide. The explosion 

 •of one-twentieth of a gram of mercury fulminate will de- 



