MR. ABEL'S UESEARCHES ON GUN-COTTON. 270 



which it is impregnated ; the solvent action of the alkaline bath upon these is therefore 

 very probably one of its most important functions. 



As the difficulties attending the perfect removal of the acid with which gun-cotton 

 remains impregnated after its conversion are mainly attributable to the tubular structure 

 of the cotton fibre, and to the circumstance that the latter contracts considerably upon, 

 conversion into pyroxylin, the complete purification of the material is very greatly faci- 

 litated by reducing the gun-cotton fibre to a fine state of division, similar to that of the 

 pulp used in paper manufacture, in which form it appears likely that gun-cotton will 

 receive advantageous application. By submission to the " pulping " process, the gun- 

 cotton is divided into very minute fragments, and is at the same time violently agitated 

 for some considerable time with a very large volume of water (rendered slightly alkaline 

 if necessary), which is afterwards thoroughly expressed when the pulp is converted into 

 cylinders or other forms ; so that a more searching supplementary process of purification 

 can scarcely be conceived than this disintegration of the gun-cotton. 



The treatment of the purified gun-cotton with a solution of soluble glass, which con- 

 stituted a prominent feature in Von Lenk's system of manufacture when the latter first 

 became known in this country, has been shown by Scheotter, Redtenbacher and 

 Schneider, by myself, and more recently by PfiLOUZE and Maurt, to possess no important 

 merits. If gun-cotton, which has been thus treated, has ever been found to resist the 

 destructive effects of exposure to elevated temperatures longer than equally pure gun* 

 cotton to which no silicate has been applied, this must be ascribed to the introduction 

 between the fibres of the gun-cotton of small quantities of substances which would exert 

 a neutralizing action upon minute traces of acid not removed from the gun-cotton by 

 the purifying process, or of any acid liberated or generated by the influence of heat. 



Some hydrated calcic and magnesian silicates, produced by the decomposition of the 

 alkaline silicate when the gun-cotton is washed in spring-water after its impregnation 

 with soluble glass and desiccation, and possibly some small proportion of alkaline car- 

 bonate and silicates, which have escaped removal in the final washing, may exist in the 

 gun-cotton submitted to the silicating treatment, and may act to some extent as pro- 

 tectives, in the manner pointed out. The examination of Austrian and other specimens 

 of gun-cotton which had been submitted to the silicating process showed that some ot 

 all of those substances existed in these in small and variable quantities. But other 

 specimens, such as the general products of manufacture at Waltham Abbey, to which 

 no soluble glass had been applied, but which had remained for many days immersed in 

 somewhat hard water, were found to contain calcic and magnesian carbonates, in pro- 

 portions sufficient to exert quite as great a protective action as the substances deposited 

 in the gun-cotton by submission to Von Lejmk's " silicating " treatment. In the account 

 which I hope before long to give of the action of light and heat upon gun-cotton, it will 

 be shown that the impregnation of the material Avith small proportions of alkaline or 

 earthy carbonates is likely to prove a very important protective measure ; but it need 

 hardly be stated that there are much more simple and certain methods of distributing 



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