278 ME. ABEL'S EESEAECHES ON GTJX-COTTON. 



In the manufacturing operations carried on at Waltham Abbey, where only a very slow 

 stream of water was available for the purposes of purification, the period for which the 

 gun-cotton was allowed to remain in the water, after the preliminary washing in the 

 cascade, was in some instances forty-eight hours, in others from ten to fourteen days. 

 There is no question that the latter period was excessive, especially with the improved 

 methods there adopted of exposing the gun-cotton to the purifying action of the water. 

 Indeed there can be no doubt that this first washing is of minor importance, as effecting 

 the ultimate purity of the product, compared to the treatment with alkaline liquid which 

 it receives, and Avhich, according to Von Lenk's directions, consists in boiling the gun- 

 cotton fur about fifteen minutes in a solution of potassic carbonate of specific gravity 

 1'02. The gun-cotton, manufactured nearly three years ago at Waltham Abbey, which 

 was submitted to a first washing of only forty-eight hours, but was washed for a fortnight 

 after treatment with alkali, has proved in every respect equal in permanence to products 

 of more recent manufacture which have been submitted to the long-continued first 

 washing. The curtailment of this washing operation, if compatible with perfect security, 

 would be important, not only on account of the time saved in the manufacture, but also 

 because, if the gun-cotton remains immersed in spring- or river-water in localities where 

 light cannot be perfectly excluded, vegetable growth is speedily established upon it, and 

 the perfect separation from it of extraneous organic matter becomes afterwards a very 

 difficult and time-consuming operation. But, although the perfect permanence, for a 

 period of nearly three years, coupled with very great power of resisting the destructive 

 effects of heat and light, possessed by products in the manufacture of which the long- 

 continued washing was postponed until after the alkaline treatment, warrant the belief 

 that this method of operating secures the proper purification of the product, I have 

 obtained indications, in other manufacturing operations, that a very considerable curtail- 

 ment of the total purification, by washing, which the gun-cotton receives, in addition to 

 the treatment with alkali, somewhat diminishes its power of resisting destructive influ- 

 ences. The omission of the treatment with an alkaline bath affects to a much more 

 decided extent the permanence of the gun-cotton ; indeed it is doubtful whether, even 

 if the washing were protracted considerably beyond the full time prescribed by Von Lenk, 

 the gun-cutton would be as perfectly purified as it is by being washed only for a short 

 time and then boiled for a few minutes in an alkaline solution. 



If it were possible to operate on a large scale upon pure cotton fibre, the functions of 

 the alkaline bath, used as a purifying agent, would simply be to neutralize and remove 

 from the pyroxylin any traces of acid not separated by washing. But as it is only pos- 

 sible to submit cotton to very partial purification in manufacturing operations, its treat- 

 ment with the acid must partially, or completely, convert into oxidized products the 

 small quantities of resinous and other foreign substances still retained by the tubular 

 fibre. An examination of many specimens of gun-cotton has shown that at any rate 

 some of these products, which may be comparatively unstable in character, are much 

 less readily removeable from the gun-cotton by simple washing than the acids with 



