16 REPORT—1863. 
description of cotton were successively submitted for equal periods (forty- 
eight hours) to treatment with one and the same quantity of the mixed acids. 
The specific gravity of the latter, at the commencement of the experiment, 
was 1°82. The acid was separated from each quantity of the cotton at the 
expiration of the above period, by means of a small centrifugal machine. 
After two quantities of cotton had been immersed in the acid, its specific 
gravity was reduced to 1°81. The original mixed acids were examined by 
means of a standard solution of carbonate of soda; a known quantity of the 
mixture neutralized 148-3 measures of the solution. After immersion of the 
first quantity of cotton, 147-5 measures were neutralized by an equal quantity 
of the acid, and 146°3 measures after immersion of the second quantity of 
cotton. The reduction in the strength of the acid appeared therefore to be 
very uniform. The four products successively obtained were carefully purified 
and dried. The volumes of gas which they furnished upon ignition cor- 
responded very closely with each other and with that obtained from a specimen 
of the Austrian gun-cotton. 
In a second similar experiment, five different quantities of cotton were 
submitted successively to treatment for forty-eight hours with one and the 
same mixture of acids. The first three products furnished, upon comparative 
examination by the exploding method, almost identical results; the fourth 
and fifth afforded indications of less complete conversion. Examined syn- 
thetically, there was a difference of not quite 1 per cent. between the amount 
of recovered cotton obtained from the first and the fifth products. 
The results of these experiments indicated, therefore, that products cor- 
responding closely in composition can be obtained by the treatment of even 
more than two quantities of cotton successively with the same acid. It 
should be observed, however, that the above results were obtained with 
cotton in the unspun condition, and that the proportion borne by the mixed 
acids to the cotton was higher than that prescribed in the Austrian system 
of manufacture, 
Experiments instituted upon a manufacturing scale at the Royal Gunpowder 
Works, Waltham Abbey. 
(10) Very considerable difficulties were experienced in procuring the small 
quantity of cotton (two to three ewts.) required for these experiments, in a 
condition resembling sufficiently closely that employed at Hirtenberg, as its 
production in the form of the thick and the thin loose rovings, or yarn, ne- 
cessitated some deviation from the ordinary method of spinning, which it 
was difficult to induce manufacturers to attempt without the promise of an 
extensive order. Eventually I succeeded, through the kind assistance of Mr. 
Whitworth, in obtaining the requisite quantity of coarse and fine yarn or 
roving, resembling closely in character, and quality of cotton, the specimens 
obtained from Hirtenberg, though in the subsequent operations with the 
coarse or thicker kind no ineonsiderable proportion of it was found to be in 
a much less compact or more lightly twisted form than the Austrian samples. 
The comparatively open condition of this portion, and the impossibility of 
placing it under a sufficient strain to wind it compactly into cartridges, in 
consequence of the weakness of the yarn, must exert considerable influence 
upon the rapidity of its combustion in its employment in ordnance (as a few 
rough experiments at Waltham Abbey have indeed already shown); the 
gun-cotton prepared from these portions will therefore be carefully separated 
from the remainder, and will doubtless furnish instructive comparative re- 
