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



Numerous researches on the composition of pyroxylin were instituted by Continental 

 and English chemists at about the period of PftLOUZE's experiments, and the following 

 are some of the formulae assigned by diflFerent experimenters to gun-cotton, in 1846 and 



1847*:— 



■p^LOUZE (1846) Ci2H,iN2 02,= CjaHy Og, 2(HON05). 



PfiLIGOT C12H., N3 024= C,2Hy O9, 3NO5. 



Von KmcHHOFF and Reuter . Cj2Hy N Oj^rr Ci2n,j O,,, NO5. 



Feiiling Ci2HioN2 02o= CjgHioOjo, 2NO5. 



PoRRET and Tesciiemacher . . C24Hj6N8 05g=2(Ci2H8 Og, 4NO5). 



Pelouze (1847) C24Hi7N5 042= C24H,;Oi7, 5NO5. 



Schmidt and Hecker . ... . C12H5 N5 03o= C,2H5 O5, 5NO5. 



Gladstone C24Hj5N5 04o= €2411,5020, 5 NO4. 



W. Crum a.H. N,0,2=|^'2H7 O7, 3NO5. 



Most of the published results of individual experimenters exhibit considerable varia- 

 tion among themselves, and in several instances the mean results are only approximately 

 represented by the formula adopted. 



The very considerable discrepancies presented by the results of independent investi- 

 gations are unquestionably due, in part, to the difficulties which have to be encountered 

 in attempts to obtain trustworthy analytical results from so highly explosive a material 

 as gun-cotton. The methods of analysis which have been adopted have been almost as 

 numerous as the formula? deduced from their results ; and in several instances the quan- 

 tity of material operated upon has been too small to permit of the attainment of satis- 

 factory results by methods in which the sources of error were not inconsiderable. 



There is no doubt, however, that the different conclusions arrived at by many talented 

 chemists with regard to the composition of gun-cotton, are to be mainly ascribed to 

 the fact that the treatment of cotton-wool with nitric acid, or a mixture of nitric and 

 sulphuric acids, has furnished, in the hands of different operators, products differing 

 considerably in composition. That such is the case is clearly indicated by the state- 

 ments made in several of the published researches with regard to the increase of weight 

 sustained by the cotton upon treatment with acid. Thus PfiLOUZE, in his first paper on 

 the composition of pyroxylin, states that he found the increase of weight constantly 

 comprised between 68 and 70 per cent. In his next publication he fixes the increase of 

 weight at between 74 and 76 per cent., the theoretical increase, according to the formula 

 which he fixed upon, being 74-9 per cent. ; and Von Kirchhoff and Reuter obtained an 

 increase of 76 per cent. Gladstone also found the increase of weight to be between 

 73 and 76 per cent. Porret and Teschemacher obtained an increase of only 54 per 

 cent. ; Tesciiemacher afterwards found the increase to be 69 per cent. Gregory and 

 Schmidt and Hecker arrived at a similar result; while W. Crum, whose experiments 



* The notation employed by the several experimenters is retained in this statement. 



