10 REPORT—1863. 
by exposure to desiccation in vacuo over sulphuric acid, was very uniform. 
The specimens were examined both in the condition in which they were 
found on opening the parcel containing them, and after their exposure for 
some time to a temperate and moderately dry atmosphere. The mean pro- 
portion of hygroscopic moisture found in the gun-cotton was 2 per cent. 
Further experiments, relating to the hygroscopic properties of the gun-cotton, 
will be described hereafter. 
(6) II. The composition of the specimens of Austrian gun-cotton, 7. e. the 
proportion of hydrogen-atoms which had been replaced, in the original cotton, 
by hyponitric acid, was determined by the synthetical method first employed 
by Mr. Hadow, in his examination of the substitution-products obtained by 
the action of nitric acid upon cotton*. The dried specimens of gun-cotton 
were digested in the cold, for twenty-four hours, in an alcoholic solution 
of sulphhydride of potassium (KS, HS), prepared as described by Mr. 
Hadow; and the reduced cotton thus obtained in each case was thoroughly 
washed and dried. These products, after weighing, were proved to be free 
from nitrogen-compounds, by the ignition of portions with hydrate of 
potassa, when no indications of the existence of nitrogen in the specimens 
were obtained. 
The percentage*of cotton obtained by this synthetical method from four 
specimens of the gun-cotton were as follows :— 
I. 55:20 per cent. 
II. 55-07 per cent. 
III. 55:13 per cent. 
IV. 54:97 per cent. 
These results show, as might have been predicted from the method of 
treatment of the cotton adopted, that the products obtained at the Austrian 
works consist, very uniformly, of the most highly explosive variety of gun- 
cotton, represented by the formula C,, H,, O,,, 9 NO,, as is shown by a com- 
parison of the above numbers with Mr. Hadow’s results, and with the theo- 
retical percentage number :— 
By synthesis. 
———— + —~ By analysis. By 
Cotton foundin Hadow. Hadow. calculation. 
Austrian samples. 
55°20 
55:07 59°13 54:6 55-19 54:54 
55°13 
54:97 
(7) I. The proportions of non-volatile matter or ash contained in the 
specimens of gun-cotton were determined in the following manner. The 
weighed gun-cotton was thoroughly moistened with distilled water; it was 
then cut into small fragments, and these were projected from time to time 
into a deep platinum vessel heated to dull redness. In this manner the gun- 
cotton was decomposed very gradually, the expulsion of the volatile portions 
being placed under such complete control as to exclude the possibility of any 
mechanical dispersion of portions of the ash. The heat was finally raised 
sufficiently to burn off any small quantity of residual carbon. From the 
ash thus obtained, the proportion was calculated upon the dry gun-cotton. 
Results obtained by this method from several determinations, with the same 
* Quart. Journ. Chem. Society, vol. vii. p. 201. 
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