CHEMICAL HISTORY AMD APPLIANCES OF GUN-COTTON. 
73 
facture of gun-cotton, and upon its chemical constitution and stability. In the autumn 
of that year, General Sabine directed the attention of the British Association to the re¬ 
sults obtained with gun-cotton in Austria, and a combined committee of engineers and 
chemists was appointed to inquire into the subject. At the meeting of the Asso¬ 
ciation in 1SG3, this committee presented a report, which was based upon infor¬ 
mation received partly from General von Lenk, who had been permitted by the Austrian 
Government to visit this country for the purpose of communicating fully with the 
British Association on the subject, and partly upon the results already arrived at in the 
experiments instituted by the lecturer, under the direction of the Secretary of State for 
War. Subsequently, a committee of investigation was appointed by the latter, under 
the presidency of General Sabine, composed of scientific men connected with the Royal 
Society and British Association, and of military and naval officers of considerable ex¬ 
perience; and this committee has been entrusted with the. full investigation of the pro¬ 
perties of gun-cotton, as improved by Baron von Lenk, with reference to its application 
to military, naval, engineering, and industrial purposes. 
The chemical constitution of gun-cotton, concerning which the opinions of chemists 
were divided until 1854, has been conclusively established by the researches of Hadow. 
In the formation of substitution-products, by the action of nitric acid upon cotton or 
cellulose, three atoms of the latter appear to enter together into the chemical change, 
and the number of atoms of hydrogen replaced by peroxide of nitrogen in the treble 
atom of cellulose, C )3 H 30 0 )5 = 3 (C G H 10 O s ), may be nine, eight, seven, or six, according 
to the degree of concentration of the nitric acid employed. 
The highest of these substitution-products is triuitrocellulose, pyroxylin, or gun-cotton; 
f TT 1 r XT Y 
C 1S [ 9 NO j" 0 15 = 3C G o j- 0-; this being the substance first produced 
by Pelouze in an impure condition, in 1836, by the action of very concentrated nitric 
acid upon paper, or fabrics of cotton or linen ; and afterwards obtained in a purer form 
by Schonbein, who employed a mixture of concentrated nitric and sulphuric acids for the 
treatment of cotton-wool, the object of the sulphuric acid being to abstract water of hy¬ 
dration from the nitric'acid, and also to prevent the action of the nitric acid from being 
interfered with by the water which is produced, as the chemical transformation of the 
cotton into gun-cotton proceeds. The formation of trinitrocellulose is represented by the 
following equation:— 
C 0 H,„O 5 + 3 { } o = C 6 { 3 ^ } 0 5 + 3 g } 0 
Cotton. Nitric acid. Gun-cotton. Water. 
The lowest substitution-product from cotton, of those named above, appears to have the 
same composition as the substance which Braconnet first obtained in 1832, by dissolving 
starch in cold concentrated nitric acid and adding water to the solution, when a white, 
highly combustible substance is precipitated, to which the name of Xyloidin was given. 
The substitution-products from cotton, intermediate between the lowest and highest, are 
soluble in mixtures of ether and alcohol, and furnish by their solution the important 
material collodion , so invaluable in connection with photography, surgery, experimental 
electricity, etc. 
According to Schoubein’s original prescription, the cotton w r as to be saturated with a 
mixture of one part of nitric acid (of specific gravity 1*5) and three parts of sulphuric 
acid (sp. gr. 1*85), and allowed to stand for one hour. In operating upon a small scale, 
the treatment of cotton with the acid for that period is quite sufficient to effect its com¬ 
plete conversion into the most explosive product, pyroxylin or trinitrocellulose ; but when 
the quantity of cotton treated at one time is considerable, especially if it be not very 
loose and open, its complete conversion into pyroxilin is not effected with certainty, un¬ 
less it be allowed to remain in the acids for several hours. This accounts in great 
measure for the want of uniformity observed in the composition of gun-cotton, and its 
effects as an explosive, in the ealier experiments instituted; and it is, moreover, very 
possible that the want of stability, and consequently even some of the accidents, which 
it was considered could only be ascribed to the spontaneous ignition of the material, 
might have been due to the comparatively unstable character of the lower products of 
substitution, some of which existed in the imperfectly-prepared gun-cotton. 
The system of manufacture of gun-cotton elaborated by General von Lenk is founded 
