1866.] 



Mr. Abel on Gun-cotton. 



103 



manufacture of very uniform products, which are unquestionably much 

 more perfect in their nature than those obtained in the earlier days of the 

 history of gun-cotton. Great stress is laid upon the fact that deviations 

 from the prescribed process, which at first sight may appear trivial (such 

 as a slight modification in the strength of the acids used, the neglect of 

 proper cooling-arrangements), are certain to lead to variations in the pro- 

 ducts of manufacture, affecting their explosive characters, or their perma- 

 nence, or both. A considerable deviation from the normal composition, 

 due evidently to some accidental irregularities in the course of manufac- 

 ture pursued, has been exhibited occasionally by gun-cotton obtained 

 from the manufactories at Hirtenberg and Stowmarket. 



The composition of gun-cotton has been made the subject of a very 

 extensive series of experiments, both analytical and synthetical. The ma- 

 terial employed in the analytical researches consisted of ordinary products 

 of manufacture, prepared at Waltham iVbbey, and obtained from Hirten- 

 berg and Stowmarket. The general analytical results are as follows : — 



Air-dry gun-cotton contains very uniformly about two per cent, of 

 water, which proportion it reabsorbs rapidly from the atmosphere after 

 desiccation. If exposed to a moist confined atmosphere, it will gradually 

 absorb as much as six per cent, of water ; but it rarely retains more than 

 two per cent, upon re-exposure to open air. 



The mineral constituents of gun-cotton vary according to the quality 

 of the water employed in its purification. The average proportion of ash 

 furnished by gun-cotton prepared at Waltham Abbey, where the water 

 used is hard, amounts to one per cent. It should be observed that the 

 process of silicating" the gun-cotton, which is prescribed by Von Lenk, 

 but the value of which is not admitted, has been applied at "Waltham 

 Abbey only in special experimental operations. Its use naturally adds to 

 the mineral constituents contained in the finished products. 



The proportions of matters soluble in alcohol alone, and in mixtures of 

 alcohol and ether, were found to be remarkably uniform in products of 

 manufacture obtained by strictly following Von Lenk's directions. In the 

 ordinary products from Waltham Abbey, the matter extractable by alcohol 

 amounted to between 0*75 and 1 per cent., and consisted of a yellowish 

 nitrogenized substance possessed of acid characters, and evidently produced 

 from matters foreign to cellulose (which are retained by cotton fibre after 

 its purification), and the products of oxidation which escape complete 

 removal when the gun-cotton is submitted to purification in an alkaline 

 bath. The average proportion of matter extractable by ether and alcohol 

 after the alcoholic treatment is from 1 to 1*5 per cent. This consists of 

 one or more of the lower products obtained by the action of nitric acid 

 upon cotton-wool, the existence of which was established by Hadow. The 

 causes of the invariable production of small proportions of these substances 

 in the ordinary manufacturing operations, and of their existence in larger 

 quantities in exceptional instances, have been carefully examined into. 



VOL. XV. K 



