294 ME. ABEL'S EESEAECIEES ON GmST-COTTON. 



substance having the composition more recently assigned to pyroxylin by PfiLOUZE and 

 Mauey, viz., 



^24 H.sfi ©185 5 Ng ©5 . 



The analytical results of gun-cotton manufactured at Waltham Abbey according to 

 Von Lenk's directions confirm, therefore, the correctness of the conclusions that the 

 most explosive known variety of gun-cotton is trinitro-cellulose or trinitric cellulose ; and 

 that cotton-wool is converted into this substance by the complete action upon it, in the 

 cold, of a mixture of one part by weight of nitric acid of specific gravity 1'52, and three 

 parts of sulphuric acid of specific gravity 1'84. 



In addition to the data furnished by the analytical experiments described in the fore- 

 going, others, bearing upon the composition of gun-cotton, have been furnished by 

 different systems of experimental inquiry. 



The relation between the nitrogen and carbonic acid obtained by oxidation of gun-cotton 

 has been determined. For this purpose, Liebig's method of operating was adopted in 

 the first instance ; the gun-cotton being prepared and arranged for combustion as in the 

 case of the nitrogen determinations, and the mixed gases collected in successive propor- 

 tions and examined*. A few experiments rendered it evident, however, that this 

 method, when applied to the examination of gun-cotton, did not furnish trustworthy 

 results. In the decomposition of this substance, when distributed through a very large 

 proportion of oxide of copper, the oxidation of the carbon does not proceed uniformly ; 

 small portions of that element evidently escape oxidation in the first instance, and are 

 only subsequently burned when the nitrogen has already been in great proportion 

 liberated. The proportion which the carbonic acid bears to the nitrogen in the gases 

 successively collected varies therefore, frequently, as the combustion proceeds; and it 

 would consequently be necessary to collect the entire quantity of gases furnished by the 

 gun-cotton operated upon, in order to arrive at a correct result. 



The following statement of the relative proportions by volume of the gases collected 

 successively in two operations of this kind, will serve to illustrate the variable compo- 

 sition of the gas collected at successive stages of one and the same operation. In both 

 experiments the gas had been allowed to escape for some time, before the first collection, 

 for expulsion of the air in the combustion-tube. 



* This method of examination appears, from the description given in their report, to have been the one 

 adopted by PfiLorzE and Maitky in their determinations of the relative proportions of carbonic acid and nitrogen 

 furnished by gun-cotton. 



