296 MK. ABEL'S RESEAKCHES ON GUN-COTTON, 



cotton which contained only small proportions of matter soluble in ether and alcohol. 

 From 4-0G4 grms. to 4-898 grms. of substance were employed. 



In conducting experiments on this method of examination, a liability to mechanical 

 loss was observed when a very strong solution of the potassic sulphhydrate was employed, 

 in 'consequence of the fibre becoming to a considerable extent disintegrated during the 

 digestion ; but this can be easily avoided by employing the reagent in a more dilute 

 form. The solution best adapted for effecting the complete reduction of gun-cotton by 

 digestion in the cold without breaking up the fibre, was obtained by preparing a satu- 

 rated solution of potassic hydrate, completely saturating this with sulphhydric acid, and 

 diluting the liquid thus obtained with half its volume of alcohol. 



A small loss of product occurs generally, even when the sulphhydrate-solution is not 

 stronger than just described, in consequence of a feeble solvent action exerted by the 

 liquid upon the reduced cotton*. In one experiment a sample of cotton obtained from 

 ■gun-cotton sustained -a loss of 0-6 per cent, by digestion in the cold for forty-eight 

 Iiours with the sulphhydrate. 



A slight excess (about 0-5 per cent.) is sometimes exhibited by the weight of the 

 reduced cotton over the amount which should be furnished, theoretically, by pure tri- 

 nitro-cellulose. In order to ascertain how far this might be ascribed to the retention 

 of sulphur by the cotton under treatment, a very careful examination of several specimens 

 was instituted. A faint odour of sulphurous acid was sometimes observed when the 

 reduced cotton was burned, and in two or three instances the cotton sustained a slight 

 loss (from O'l to 0-3 per cent.) upon being digested and washed with carbonic bisul- 

 phide ; but in other instances the proportion present was only very minute, and the 

 cotton was generally found to be quite free from sulphur. 



A comparison between the ash existing in the gun-cotton operated upon, and the 

 quantity remaining in the reduced cotton, showed that no proportion of an excessive 

 result can be ascribed to an accumulation of that constituent. Although the amount of 



* Cotton, in the original form of carded -wool, is not dissolved by the potassic sulphhydrate. 



