ME. ABEL'S EESEAECHES ON GUN-COTTON. 



29a 



because cellulose, by conversion into a substance having the percentage-composition 

 which that formula demands, should sustain an increase of weight of 77*78; a number 

 which is very slightly below the maximum result obtained in their experiments. 



It should be stated that they describe the acids employed by them in all their expe- 

 riments as follows : the sulphuric acid had a density of 66° BAUMfi (which corresponds 

 to a specific gravity of 1*767), and the nitric acid had a specific gravity of 1-50 at 9°C. 



It will be observed that these acids, but more especially the sulphuric acid, are very 

 notably inferior in strength to those prescribed by Von Lenk, which have been used in 

 all the experiments now described, and are always employed in the manufacture of gun- 

 cotton at Waltham Abbey; namely, sulphuric acid of specific gravity 1-833 to 1'84 

 (somewhat above 69° BaumS), and nitric acid of specific gravity 1*52 at 15° C. It appears 

 most probable, from many of the experimental observations included in these researches, 

 that such discrepancies as exist between the results arrived at by PjSlouze and Maury, 

 and by Hadow, the German chemists and myself, are to be mainly ascribed to the difier- 

 ences in the strength of acids employed. 



The subjoined results of very numerous experiments will, I believe, be admitted not 



only to establish satisfactorily the correctness of Hadow's statement, that cotton-wool 



may be made to sustain an increase in weight above 81 per cent., but also to show that 



the results of other experimenters who have found the increase sustained by cotton not 



to exceed 78 per cent., are in perfect harmony vdth the conclusion that the product of 



the complete action, upon cotton-wool, of certain mixtures of the strongest nitric and 



sulphuric acids, is the substance 



€eH;N3 0„, 

 in a nearly pure condition. 



The following statement shows the increase of weight which finely carded cotton- 

 wool of very high quality, previously purified by treatment with alkali and washing, has 

 sustained by single and successive digestions, for different periods, with the prescribed 

 acid-mixture. The products were always purified by careful washing with distilled 

 water. 



