184?.] Memoranda on Explosive Cotton. 179 



ed in composition or properties by immersion or even boiling in salt 

 water, insoluble in alcohol, oils, acetic acid, ammonia, weak acid and 

 alkaline solutions — such as solution of carbonate of soda or of potash 

 or lime water. When very well prepared it is entirely soluble in anhy- 

 drous sulphuric ether, and the solution when evaporated yields the 

 glass-like paper. If the ether contains alcohol or water the paper is 

 opaque and porous, like ordinary filtering paper. 



The cotton thus prepared may be exploded over gun powder without 

 igniting it. It explodes by a violent blow on an anvil with the sharp 

 ring of percussion powder, but the explosion only affects the particles 

 immediately struck, and does not ignite the rest, but if gun powder be 

 mixed with it the whole is fired. 



It does not explode by the electric spark, or by the discharge of a 

 single Leyden jar. 



It explodes on being heated to 375° of Fahrenheit. 



It does not explode by friction between wooden or metallic surfaces 

 till the temperature of these rises to 375° ; neither does it explode by 

 compression in powerful screw presses. On the contrary, compression 

 exercises some singular effects on its explosiveness and combustibility. 

 The very most explosive kind twisted into a tight cord burns like quick 

 match, and a tight ligature of wire or twine round a portion of this in- 

 tercepts the ignition. In the same way when compressed into the 

 touch-hole of a cannon it is fired with the utmost difficulty, so that it 

 cannot be used for priming; accordingly in the ordnance trials at Dum- 

 Dum the cotton charges have been always fired with quick match or 

 powder priming. 



Exploded in a loose heap its force appears to be exercised almost 

 altogether in the lines of least resistance ; thus on two occasions nearly 

 two pounds weight while being dried on a water-bath exploded acci- 

 dentally on a thin copper tray, which was not injured or displaced — and 

 on both these occasions the plaster of the roof and the loose tiles of 

 a shed within three feet of the cotton remained undisturbed. A man 

 standing close to the tray was uninjured, and several test glasses ranged 

 on a party wall within A\ feet of the explosion were not moved or bro- 

 ken or their contents spilled. 



Regarding the results obtained by my first experiments, in connexion 

 with the valuable properties ascribed by general rumour to the explo- 



2 b 2 



