PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 503 



This analysis was made in 1857, and is one of the most skill- 

 fully executed analysis we have. 



The objections to gun cotton, urged by Prof. Seely, I think 

 unanswerable. It has been found in blasting to blow out a small 

 hole instead of large masses of rock. Gunpowder is the niost 

 obvious contribution of chemistry to the military art ; but it 

 would be difficult to say what it has not contributed, for with- 

 out chemistry we could not clothe our army, or feed them, or 

 furnish them with arms. 



Prof. Seel3^ — Was the gunpowder, in these analyses, burned 

 under pressure as in a gun? 



Prof. Joy. — It was put into a fuse on the end of a whip-stalk, 

 and so arranged as to shake down one grain at a time into a funnel, 

 so that but one grain should be exploded at a time. There was 

 an aspirator at the other end of the apparatus to draw off the gases, 

 which were immediately sealed up in tubes, and set aside to be 

 analysed. The residuum in the little bulb was analysed, and the 

 smoke was also analj^sed. 



Prof. Seely. — I conceive that this explanation very well 

 accounts for the discrepancy between the results of this analyses 

 and of our former analyses. The products of the combustion 

 of gunpowder, or anything else, will vary very much with the 

 temperature and the pressure at which combustion takes place. 

 The higher the temperature the fewer the products and the 

 simpler the constituents. In these analyses the temperature was 

 evidently low, being only sufficient to procure ignition. Cer- 

 tainly we should not find from a gun such an unstable product as 

 carbonate of ammonia. This fact of varjnng products from 

 varying temperature may account for some of the evils in the use 

 of gunpowder. 



Prof. Joy stated that if our supply of saltpetre were cut off, 

 we could manufacture it. By boiling together the chloride of 

 potassium and nitrate of soda, they would decompose each other, 

 and form common salt and nitre. 



Dr. Rowell. — The office of sulphur in gunpoAvder is to take 

 fire at a very low temperature ; and it is the office of the char- 

 coal to keep up the red heat necessary to decompose the nitrate 

 of potash. The temperature at which an ordinary friction match 

 takes fire is so low tliat it may be lighted and extinguished in 

 alcohol ; but if we wait until the brimstone takes fire, it will set 

 the alcohol on fire. It takes a temperature of 600* to set oil on 



