MR. ABEL'S EESEAECHES ON GUN-COTTON. 298 



The majority of results obtained in each of the above experiments are concordant 

 among themselves, and agree closely with the percentage proportions (by volume) of 

 carbonic acid and nitrogen which should be furnished by trinitro-cellulose (namely 80 

 of carbonic acid to 20 of nitrogen). But in each experiment somewhat discordant 

 results were obtained, and therefore this method of determining the relation between 

 the carbon and nitrogen in gun-cotton was abandoned as not sufficiently trustworthy. 

 It should be observed, however, that even the' mean of the several results obtained 

 in each experiment corresponds much more closely with the volume-proportion which 

 should be furnished by trinitro-cellulose, than with that demanded by the formula which 

 Pelouze and Mauey adopt, as the following comparison shows : — 



Theory. Experiment. 

 /V . /^ 



Nitrogen . . 17-2 20 21-28 19-88 



Several determinations of the relative proportions of carbonic acid and nitrogen have 

 been made by Bunsen's method. The mode of operating was as follows : into a very 

 stout wide Bohemian glass tube, about 22 centimetres long and sealed at one end, were 

 introduced, first some reduced copper, then about 0-1 to 0-15 grm. of the dry gim-cotton, 

 and afterwards sufficient oxide to fill about 4 centimetres of the tube. The open 

 extremity of the latter was constricted, and sealed when air had been exhausted. The 

 gun-cotton was then decomposed by applying the flame of a lamp for a short time to 

 the tube. After the oxide of copper had been distributed over the surface of the tube 

 (to the interior of which it adhered, in consequence of the deposition of water from the 

 exploded gun-cotton upon the glass), the latter was introduced into a vessel of wrought 

 iron, within which it was compactly surrounded on all sides by very fine sand. The 

 vessel consisted simply of a piece of gas-pipe about 25 centimetres long and of 3 centi- 

 metres internal diameter, closed at one end by means of a plug welded into it, and 

 provided at the other extremity with a screw-cap. A few small perforations were drilled 

 into the sides of the pipe. The glass tube was exposed in this envelope to a red heat 

 for about one hour ; when cold, it was opened imder mercury, and the gas transferred 

 and examined in the usual manner. The results thus arrived at, which will be quoted 

 presently, were very concordant, and stood in close relation to the results obtained 

 by the separate determinations of carbon and nitrogen in gun-cotton. 



The reproduction of cotton from pyroxylin by Hadow's method has been made the 

 subject of many experiments, with the view of controlling by its means the analytical 

 and synthetical results obtained. It was found that by submitting purified insoluble 

 gun-cotton to the action of an alcoholic solution of potassic sulphhydrate, as directed by 

 Hadow, the amount of cotton obtained corresponded closely to the theoretical proportion 

 to be furnished by trinitro-cellulose. 



The following results may be quoted as examples. They were obtained with gun- 



2s2 



