ME. ABEL'S EESEAECHES ON GUJf-COTTON. 892 



gun-cotton operated upon is about double that of the cotton recovered, the latter was 

 found to contain the smallest proportion of ash. Thus, 



It is evident that the mineral impurities which, during the washing operations, have 

 attached themselves to the gun-cotton fibre, become partially detached during the 

 digestion in potassic sulphhydrate, and the subsequent washing. 



Some combustions made of the reduced cotton furnished proportions of carbon and 

 hydi-ogen which, though according fairly with the requir.ements of pure cellulose 

 (allowance being made for the ash in the specimens analyzed), were somewhat below 

 the theoretical numbers : — 



The specimens analyzed were carefully examined for nitrogen, and very small quan- 

 tities were detected. The deficiencies of the carbon obtained from them may, therefore, 

 be to a slight extent ascribable to minute portions of the nitro-product having escaped 

 reduction. A still greater influence upon the results must, however, be exerted by the 

 invariable existence of small quantities of foreign organic substances in the samples 

 operated upon. 



The slight excess obtained, in many instances, above the theoretical amount of cotton 

 may, it appears, be occasionally due to some extent to accidental causes, but it is mainly 

 to be ascribed to the presence in the specimen examined of a proportion of material 

 r.esulting from the less perfect action of nitric acid upon some portions of the cotton 

 fibre. Unfortunately, however, the fluctuations in the results which may be furnished 

 by different examinations of the same specimen of gun-cotton by this method, though 

 they might be regarded as not very important in an ordinary analytical process, may be 

 equivalent to diflferences which would be caused by very considerable variation in the 

 amount of soluble gun-cotton present in the substance. 



The proportions of cotton which should be furnished by pure trinitro-cellulose, and 

 by the lower products which Hadow has examined, are as follows : — 



Cotton. 

 GgHjGj, 3NO2, o'* ^18^210155 9NG2 furnishes 54'54 per cent 

 Compounds . . CigHa^Gij, 8N Og „ 57-45 



Compound C*. . CigHgaGij, 7N©2 „ 60-67 



• A product possessing the properties of compound C, described by Hadow, and agreeing closely in its com- 

 position with the requirements of the formula assigned to that body, has been manufactured in considerable quan- 

 tities at Waltham Abbey, for experimental purposes, by submitting cotton-yam to digestion for the customary 



