520 Mr. Gladstone on the 



This cotton, which may be considered as pure lignine, was 

 steeped until thoroughly wetted in a mixture of nitric acid of 

 spec. grav. 1*502, and nearly an equal bulk of strong sul- 

 phuric acid, then well-washed with water, and dried at a 

 temperature not exceeding 212°. In one instance 38*38 grs. 

 of cotton became 66*84 grs,, being an increase'of 28*46 grs., 

 or 74*15 per cent. In a second experiment 59*3 grs. of cot- 

 ton gave an increase of 43*7 gi^s., or 73*7 per cent. The gun- 

 cotton, or pyroxyline, thus produced resembled the original 

 cotton in physical properties very closely, and exploded at 

 about 370°, producing no smoke and leaving no residue. 



The action of various solvents and reagents upon this sub- 

 stance was found to be as follows : — It is absolutely insoluble 

 in pure water, and nearly so in strong alcohol, aether, m hether 

 hydrated or anhydrous, and in a mixture of aether with y'^th 

 part of alcohol ; but acetic aether instantly destroys its fibre, 

 and dissolves it in large quantity. The solution yields on 

 spontaneous evaporation a white powder of the same weight 

 as the original pyroxyline, but I have found it very difficult 

 to drive off the last traces of the solvent. The action of sul- 

 phuric acid upon it differs from that exerted upon unaltered 

 cotton ; for, while the latter is instantly dissolved by the 

 strong acid, and charred upon a slight elevation of tempera- 

 ture, pyroxyline dissolves with difficulty unless the acid be 

 warmed, evolving at the same time nitric oxide and other 

 gases, and not being charred even upon boiling. With the 

 aid of heat it dissolves immediately in a solution of potash. 

 By means of these three last-mentioned tests I was able to 

 prove the absence of any unaltered cotton in the product 

 under examination. The action of other reagents upon gun- 

 cotton was not so decided ; it was dissolved, but not without 

 long boiling, by ammonia, the alkaline carbonates, hydro- 

 chloric acid, acetic acid, both glacial and dilute, and weak 

 sulphuric acid. These solutions, as well as the two preceding, 

 contained nitric acid; nothing could be precipitated from 

 them by dilution or neutralization; and when evaporated 

 they yielded only a dark brown amorphous matter. It is 

 evident that none of these reagents restore the lignine in its 

 original condition; and they do not afford any means of 

 ascertaining whether the compound contains the elements of 

 nitric or hyponitric acid. 



As there exists a great discrepancy in the accounts given 

 of the increase of weight in making gun-cotton, I examined 

 whether the length of time it was immersed in the acid liquor, 

 or the proportions of the acids employed, were the cause. The 

 length of immersion 1 found to produce no alteration ; but 



