276 MR. ABEL'S EESEAECHES ON GUN-COTTON. 



In the treatment of the cotton with the mixed acids, the following precautions, viz. 

 the immersion of uniform quantities of the perfectly dry cotton in the bath of acid, 

 the adherence to a fixed proportion in weight between the cotton and the acid with 

 which it is left in contact, and the regular replacement of the acids removed from the 

 bath at each successive immersion of cotton, by a corresponding quantity of fresh mix- 

 ture, combine to exert no unimportant influence upon the uniformity of the product. 

 That such is the case has been established by manufacturing experiments. For example, 

 on one occasion some hanks of cotton were immersed in the bath of acids without addi- 

 tion to the latter of the quantity of fresh acid proportionate to the amount removed in 

 the previous operation of immersion. The resulting product, which was in aU other 

 respects treated as usual, exhibited a decided difference, both in its composition and its 

 explosive powers, when compared with gun-cotton previously produced, strictly according 

 to rule, in the same bath of acids. 



As regards the period during which the cotton is allowed to remain immersed in the 

 acids, the precise time fixed upon by Lenk (forty-eight hours) appears to be arbitrary, 

 but there is good reason for prolonging for several hours the contact between the acids 

 and the product. That a few minutes' immersion of a small quantity of cotton may be 

 sufficient to convert it into a highly explosive and even to a great extent into the 

 most explosive product, is indisputable ; but a considerable period elapses before the 

 cotton, especially when it is spun and when at least 6 oz. are operated upon at one 

 time, is converted, as comjyletely as possible by one single treatment, into the most 

 explosive product. 



In operating upon small quantities of cotton, when the proportion of acids employed 

 is always considerably in excess of that prescribed by Von Lenk, an immersion of the 

 cotton for two hours has been found to furnish results quite as perfect as those obtained 

 by protracting the immersion for forty- eight hours. Even when the proportion of acid 

 to cotton was reduced, in small experiments, as nearly as possible to that employed in a 

 manufacturing operation, the results of twelve and twenty-four hours' immersion were 

 quite equal to those produced by treatment for the full period ; indeed, decided evidence 

 was obtained that the very long-continued contact of gun-cotton with the acids gave rise 

 to a slight loss, a small proportion of the product being eventually dissolved by the acids. 

 But when the duration of the treatment of even small quantities of cotton (between 

 three and four grammes) with a large excess of acid was limited to ten minutes, the 

 conversion was comparatively very imperfect, and the products contained considerable 

 proportions of soluble gun-cotton. 



upon the cotton-wool exhibited no difference as regards its insolubility, from the ordinary products furnished 

 by the cold mixture. Neither was insoluble gun-cotton rendered at all soluble by being submitted to treatment 

 with the warm mixture. Hadow has shown that a more dilute mixture of acids which, when cold, furnishes 

 an almost insoluble product, wUl, if employed at a temperature of 55° C, yield perfectly soluble gun-cotton, 

 giving a fluid transparent collodion. 



