304, ME. ABEL'S EESEAECHES ON GUN-COTTON. 



74*3 upon 100 parts. The weight of the thoroughly dry product corresponded to an 

 increase of 71 upon 100. 



In another experiment, made with a somewhat higher quality of cotton, an increase 

 of 76 per cent, was obtained. 



The products of these operations were quite similar in character to those usually 

 obtained, and to the results furnished by the laboratory-experiments just now described, 

 which were conducted with samples of the same description of cotton. A difference of 

 about 9 per cent, between the latter results and the lowest number furnished by the 

 quantitative manufacturing experiments has therefore to be accounted for. The follow- 

 ing statements will show that this deficiency is not greater than would be anticipated. 



In the cotton operated upon, besides the resinous and other impurities which are 

 partly removed by solution in the acid and by subsequent extraction in the purifying 

 processes, and which also occasion a notable loss in the laboratory-experiments with this 

 kind of cotton, as already pointed out, there exists a more or less considerable propor- 

 tion of seed, of which only minute particles are here and there observed in the finished 

 gun-cotton. To this source of loss upon the weight of the cotton employed, has to be 

 added the mechanical loss of product unavoidably attending the repeated submission of 

 the gun-cotton to the expressing and long-continued washing processes. But the prin- 

 cipal loss of product, and one which alone suffices to account for the difference observed 

 between the results of the laboratory-experiments and those of ordinary manufactuiing 

 operations, occurs in boiling the gun-cotton in the alkaline bath. The brief digestion 

 of the material in the weak solution of potassic carbonate not only abstracts a con- 

 siderable proportion of the products foreign to gun-cotton, resulting from the action of 

 the acids upon the impurities which the cotton fibre obstinately retains, but also causes 

 a very notable proportion of the gun-cotton itself to pass into solution. 



A quantity of Waltham Abbey gun-cotton which had, in the ordinary course, already 

 been submitted to the treatment with alkali, was boiled for ten minutes in a solution of 

 potassic carbonate precisely similar to that usually employed (of spec. grav. 1-02). The 

 liquid became of an amber colour, and the gun-cotton, when dried, was found to have 

 sustained a loss of 3-7 per cent. The same gun-cotton was again boiled for twenty 

 minutes in the same alkaline bath, which deepened in colour considerably during this 

 second employment. The total loss sustained by the material, after this second treat- 

 ment, amounted to 12-09 per cent.* 



9*22 grms. of cotton yarn, previously purified by treatment with alkali and carefully 

 freed from seed, were converted into gun-cotton in the ordinary manner, excepting that 

 about three times the ordinary proportion of acid was used, whereby the solution of 



* The treatment of gun-cotton with a boiling solution of potassic carbonate of the prescribed strength, even 

 if greatly prolonged, does not affect the composition of the mass, but evidently acts by dissolving, and trans- 

 forming into other products, portions of the fibre, or of its surfaces. The combustion of a specimen of ordinarj- 

 gun-cotton which had been boiled for one hour in the alkaline bath furnished 24-48 per cent, of carbon (the 

 theoretical number of trinitro- cellulose being 24-24 per cent.). 



