268 M. L. v. Karolyi on the Products of 



in which P is the quantity of combustible gases, P x the carbonic 

 acid produced in combustion, P 2 the oxygen used in combustion. 

 Hence the gases from gun-cotton contain in 100 parts, 





By volume. 



By weight. 



Carbonic oxide . . , 



28-55 



28-92 



Carbonic acid . 



19-11 



30-43 



Marsh-gas . . . 



11-17 



6-47 



Binoxide of nitrogen , 



8-83 



959 



Nitrogen 



, 8-56 



8-71 



Carbon .... 



1-85 



1-60 



Aqueous vapour . . 



21-93 



14-28 



10000 10000 



The gun-cotton used had the average composition C 24 H 17 N 5 38 , 

 from which, after subtracting the results of the analysis, the 

 separated carbon is obtained which is included in the above 

 analysis. 



This simple and apparently faultless method has repeatedly 

 shown that, by using a somewhat large quantity of gun-cotton 

 under the same circumstances, when therefore the combustion 

 takes place under comparatively greater pressure, the quantities 

 of the products of combustion change, and the quantity of bin- 

 oxide of nitrogen diminishes as the pressure increases. Hence 

 the deoxidation of nitrogen-compounds during the combustion 

 takes place the more completely the greater the work which the 

 gun-cotton has to perform during its combustion. 



This circumstance suggested to me the idea of exposing the 

 gun-cotton during its combustion to a determinate resistance, 

 and regulated so that it just gives way at the moment gun-cotton 

 is completely burnt away. This condition led me to the experi- 

 ment of placing a vessel filled with gun-cotton which offered the 

 necessary resistance, in a 60-pound mortar, which was then ex- 

 hausted and the gun-cotton exploded by galvanism. 



The detailed plan of this apparatus is seen from the 

 diagram. In the touchhole of the mortar a strong iron nut, «, 

 is screwed, which by the aid of a good stuffer, e, enables the 

 mortar to be made air-tight. The screw is provided at b with a 

 short tube closed by a cock, by which the vacuum is obtained in 

 the subsequent operations. At d' a copper wire, well insulated 

 by gutta percha, passes through the nut, while at d is a small 

 hook; to this and to the insulated copper wire the vessels 

 filled with the gun-cotton intended for explosion are fixed, and, 

 as the figure shows, allow the ignition of the charge to be effected. 

 In the experiment the mortar is exhausted, the tap closed, and the 

 platinum wire in the charge ignited by the current from six 

 Smee's elements, and thus the vessel burst. It is readily seen 



