280 MR. ABEL'S KESEARCHES ON GUN-COTTON. 



such substances uniformly through a mass of gun-cotton than the treatment with soluble 

 glass and subsequent washing. Thus, considerable quantities of gun-cotton have been 

 uniformly impregnated at Waltham Abbey, for experimental purposes, with sodic car- 

 bonate (in the proportions of 0"5 and 1 per cent.), simply by soaking the finished gun- 

 cotton in solutions of that substance, of definite strength, expressing the excess of liquid 

 in the usual manner, and then drying the skeins. 



It will be seen from the foregoing observations on the Austrian system of manufacture, 

 which are almost exclusively based upon the results of experience in the manufacture of 

 considerable quantities of the material during the last three years, that General Von 

 Lenk has not actually initiated any new principle as applied to the production of gun- 

 cotton, but that he has, by long experience and persevering investigation of the subject, 

 so perfected the process of converting cotton-wool into the most explosive form of gun- 

 cotton and of purifying the product, as to render a simple attention to clear and defi- 

 nite regulations alone necessary to ensure the manufacture of a very uniform material, 

 which is unquestionably much more perfect in its nature than the products obtained in 

 the earlier days of the history of gun-cotton. Such being the case, too much stress 

 cannot be laid upon the fact that deviations from the prescribed process, which at first 

 sight may appear very trivial (such as a slight reduction of the strength of the acids, 

 the neglect of proper cooling arrangements, &c.), are certain to lead to variations in the 

 products of manufacture affecting their explosive characters, or their permanence, or 

 both. In discussing the composition of gun-cotton manufactured by Lenk's system, I 

 shall have to refer to several samples of the material, produced at Hirtenberg and 

 at Stowmarket, which differed widely in their composition and properties from the 

 normal product of manufacture. I have obtained abundant and most conclusive proof 

 that these exceptional variations are solely ascribable to the neglect of a uniformly 

 strict adherence to the prescribed process of converting the cotton ; and I am strongly 

 of opinion that their occurrence has almost always been due to the employment of 

 nitric acid which exhibited a fictitious specific gravity, from the presence either of 

 considerable quantities of peroxide of nitrogen, or of some other impurity (such as 

 sulphuric acid). A searching examination of the ordinary products of manufacture 

 obtained at Waltham Abbey, where the quality of the nitric acid employed received 

 uniformly strict attention, has shown that, without any exception, the variations in their 

 composition were embraced within very narrow limits. 



II.— COMPOSITION OF GUN-COTTON. 



The researches instituted by me into the composition of gun-cotton have been con- 

 ducted partly with ordinary products of manufacture, obtained from Waltham Abbey 

 and from the gun-cotton factories at Hirtenberg and Stowmarket, and partly with pro- 

 ducts prepared in the laboratory with purified and very finely carded cotton-wool. The 

 latter was more particularly employed in experiments instituted for the purpose of 

 accurately ascertaining the maximum increase of weight which cotton-wool will sustain 



