42 ■ Transactions of the 



cyanogen) are produced. This formerly led to the notion that 

 gun-cotton would be dangerous to employ in blasting, because it 

 would have a prejudical effect on the miners. However, by 

 further experiments it was found that, when confined, it does not 

 produce cyanogen as it does when burning freely in air, but it 

 undergoes complete combustion, so that the nitrogen of the 

 cyanogen (CN) passes off free, and the carbon is oxydised to car- 

 bonic oxide (CO) or even the higher oxide, carbonic acid (COj). 

 These latter bodies are not nearly so dangerous, especially the 

 last mentioned — carbonic acid. 



As gun-cotton will burn equally well when air is excluded, it 

 can, like gunpowder, be employed in torpedoes, which are so nnxch 

 used for blowing up vessels. To form them, iron cylinders are used, 

 closed at both ends, and filled with gun-cotton, or nitro-glycerine: 

 through the gun-cotton in the cylinder (as in these models here, 

 made of gutta-percha) a thin iron wire passes, which is turned 

 round the cotton, in order to impart all the heat possible to it at 

 once : attached to each end of the iron wire, and passing through 

 either side of the torpedo, is a long insulated copper wire, reaching 

 to the battery of the experimenter, either on land or on board 

 ship. When a ship passes over one of the torpedoes, the owner 

 of the electric battery sends an impulse along the copper wires, 

 which electric shock, as soon as it arrives at the iron wire, an in- 

 ferior conductor to copper (just as I said before with regard to 

 blasting rocks), becomes partially converted into heat, and igniting 

 the gun-cotton, bursts the torpedo, and blows up the vessel. {Ex- 

 periment toitli gutta-percha torpedoes.) 



As gun-cotton ignites much more readily, and more quickly 

 than powder, and, also, as all the products of its combustion are 

 gaseous, it is naturally much more powerful than gunpowdei', 

 weight for weight. {Experiment with pistols and bidlets, charged 

 loith an equal loeight each of powder and cotton. The superior 

 power of the gun-cotton ivas thus demonstrated.) 



Cartridges made of nitrocellulose, for cannon, &c., are always 

 composed of gun-cotton diluted with ordinary cotton, for two 

 reasons — firstly, the gun-cotton burns more quickly when kept 

 apart : if compressed tightly by itself it sometimes only smoulders 

 {experiment) ; — and secondly, in order to distribute the gun- 

 cotton through a greater part of the fire-arm, and thus avoid a 

 too sudden action, which might burst it. 



The numerous experiments shown by Blanshard and Stone were 

 very successful, and on the motion of J. G. Grenfell, Esq., a vote 

 of thanks was passed to them for the great trouble they had taken 

 in preparing them. 



