PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 391 



into a hard string, it will burn but little faster than ordinary cotton. In 

 loading a cannon with it, if it is put in loosely, it will explode like gun- 

 powder, but if it is rammed down hard, with a tight-fitting wad on the top 

 of it, it will not explode at all — it will not burn any more than dirt. 

 Several accidental explosions of gun cotton that have occurred within my 

 knowledge, prove that although the force is great, it is generated slowly. 

 At the place which I now occupy, 244 Canal street, a very careless opera- 

 tor was drying ten pounds of gun cotton over a hot furnace, when it 

 exploded. The man was standing in the same room and within a few feet 

 of the furnace; his hair was singed, but he was not otherwise injured, 

 while the windows of the front room, some forty feet distant, were blown 

 out. Mr. Janes, who was three stories above, said that he did not hear 

 much noise, but he felt himself lifted about eighteen inches. Last winter 

 a building was blown up in Fifty-first street, and I examined the premises, 

 very carefully the next morning. It was said that there was 300 pounds 

 of gun cotton in the building, and the destruction was certainly not as 

 great as would be produced by 300 pounds of gunpowder. The roof was 

 lifted and the walls were thrown down, but the materials were not thrown 

 any considerable distance. In July last Mr. Dornbach was killed in 

 Williamsburgh by an explosion of gun cotton. He was filling a barrel 

 intended to hold sixty pounds, and had got it nearly filled when it went 

 off". His hands and face were burned, but he was not injured otherwise 

 than by the burning. 



Mr. Butler. — How was the cotton fired ? 



Prof. Seely. — Gun cotton explodes by percussion, and it was either per- 

 cussion or friction which set that on fire. The cotton had become very 

 warm in the bright July sun, and then the violence used in driving it into 

 the barrel with a stick set it off", by either percussion or friction. If it had 

 been sixty pounds of gunpowder it would have blown Mr. Dornbach to 

 pieces. This is the article which was made by Schonbein, the discoverer, 

 and is known as "gun cotton." It differs from ordinary cotton in contain- 

 ing more oxygen, but it does not contain enough to burn it. It has been 

 discovered since that by varying the manipulation a little, a larger 

 quantity of oxj'gen may be introduced. Gunpowder contains sufficient 

 oxygen to eff"ect its complete combustion; it will burn in a close chamber 

 or under water, but tliis is not the case with gun cotton; it will not burn 

 imless supplied with oxygen. By adding chlorate of potash or niter, the 

 oxygen is supplied and a compound is produced which explodes with great 

 violence, and it is possible that in this wa}'^ a practical substitute for gun- 

 powder may be produced. 



Mr. Stetson. — It may be well, as we are on the subject, to consider the" 

 difference in the different kinds of explosive compounds. When fulminat- 

 ing mercury is fired it shatters everything in its immediate neighborhood, 

 but it does not seem to follow up the fragments and send them to a distance; 

 while the force of gunpowder is less violent in its close vicinity, but fol- 

 lows the fragments further, and consequently throws them to a greater 

 distance. 



Gun cotton may be burned up cleaner and make a greater expansion 

 than gunpowder, under proper conditions. 



