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



eisted principally of calcic carbonate and other impurities (sand, clay, &c.) deposited 

 between the fibres during the immersion of the gun-cotton in the stream. 



Proportion of the gun-cotton dissolved by ether and alcohol. — Hadow found that the 

 highest product which he obtained by the action of nitric and sulphuric acids upon 

 cotton-wool, and the composition of which agi'eed closely with the requirements of the 



"'"''' ^ Q, H; 0„ 3N 0„ or G,, U,, 0„ SN^ O5, 



was perfectly insoluble in any mixture of ether "and alcohol; but that the lower pro- 

 ducts, obtained by the action of acid-mixtures containing larger proportions of water, 

 were more or less readily soluble in ether, used alone or in admixture with alcohol. 

 Although, in operating upon small quantities of carefully purified cotton-wool with 

 a considerable proportion of the acid-mixture, the most explosive gun-cotton can be 

 obtained without difficulty in an almost pure condition (containing only mere traces of 

 matters extractable by ether and alcohol) by one single treatment of the cotton, it 

 could scarcely be expected that, in a manufacturing operation, more than a close 

 approximation to this result could be arrived at, when it is remembered that a con- 

 siderable time elapses before the action of the acids upon the entire quantity of cotton 

 with which they remain in contact is completed, and that, during the period occupied 

 by the conversion of the last portions of cotton, the acid in contact with the fibres 

 becomes diluted by the water eliminated in the reaction, and does not therefore retain 

 to the last the composition required for the production of the most explosive gun- 

 cotton. But it is remarkable how veiy close and uniform an approximation to com- 

 plete conversion of the cotton into the most explosive product is attained by properly 

 carrying out Von Lenk's instructions. 



A veiy large number of the ordinary products from Waltham Abbey have been care- 

 fully examined, with the view of determining the average percentage of soluble matter 

 in the gun-cotton. In the first experiments, the weighed gun-cotton (between 2 and 3 

 grms.) was packed closely into a tube of about 12 millims. diameter and constricted to 

 a fine opening at the lower extremity. The mixture of ether and alcohol which was 

 poured on to the gun-cotton in the tube filtered through it very slowly. When the 

 filtrate furnished what appeared an unimportant quantity of residue, the cotton in the 

 tube was dried and its loss in weight determined. Upon examining the samples of 

 gun-cotton thus treated, they were found, however, still to contain matter soluble in the 

 ethereal mixture, and it was evident that, by this mode of treatment, either the soluble 

 matter could not be separated from the insoluble fibre, or only the most readily soluble 

 portions (which furnish a tolerably limpid solution) were carried through by the liquid ; 

 while those less easily dissolved, and which were, indeed, more glutenized than actually 

 dissolved, remained in the tube. A difierent mode of operating was therefore resorted 

 to. From 8 to 10 grammes of the gun-cotton were digested in a stoppered bottle for 

 from thirty to fifty hours (according to the apparent extent of action of the solvent) 

 with from 60 to 100 centimetres of the ethereal mixture. At the expiration of this 



