ME. ABEL'S EESEAECHES ON GUN-COTTON. 305 



foreign matters in the acid was promoted. The product, after long-continued wash- 

 ing in distilled water, was dried and weighed. The increase sustained by the cotton 

 amounted to 78-14 per cent, (a number closely corresponding to the laboratory-results 

 previously described). The gun-cotton was then boiled for eleven minutes in a solution 

 of potassic carbonate of the usual strength. When washed and again dried, it was found 

 to have lost considerably in weight, and the finished product showed an increase of 

 weight upon the original cotton equivalent to 69'8 upon 100, which was therefore 

 1'2 per cent, less than the lowest result obtained in the manufacturing operations. It 

 is easily conceivable that, in the smaller operations, the gun-cotton, though submitted 

 only for exactly the usual period to treatment with an . alkaline bath of the ordinary 

 strength, should sustain a somewhat greater loss than a large compact mass of the 

 material, such as is always operated upon. But the results of these experiments esta- 

 blish a source of loss in the usual process of manufacture, which fully accounts for 

 the discrepancies exhibited between the yields of usual manufacturing operations and 

 of laboratory operations conducted with the same description of cotton, in which the 

 treatment with boiling alkaline water has been omitted. 



Comparison between analytical and synthetical results. — The relative proportions of 

 carbonic acid and nitrogen furnished by the complete oxidation of gun-cotton, afibrd the 

 means of instituting a comparison between the analytical and synthetical results, of 

 which the details have been given, and, it is believed, of demonstrating beyond dispute 

 the correctness of the conclusion, that the product of the complete action upon cotton- 

 wool of the mixture of strongest acids prescribed by Von Lenk is most correctly repre- 

 sented by the formula 



GgHyNg Gij, 



of which the expression 



appears to be the most rational interpretation. The method of determining the relative 

 proportions of the two gases furnished by gun-cotton has been already described. The 

 following results were furnished by four samples of gun-cotton : — 



Volume proportions of carbonic acid and nitrogen. Proportions required by 



>v_ 



€,H,N,0„. 

 80 

 20 



C24H36 0,85Nj©,. 



82-8 

 17-2 



* A sample of guu-cotton which had been left in contact with acids for five days, and a second sample, 

 which had been twice submitted to the ordinary treatment with acids, furnished the following results : — 



5 days in acid. Twice dipped. Trinitro-cellulose. 



Carbonic acid . . . 80-.574 80-37 80 



Nitrogen 19-426 19-63 20 



