ON THE APPLICATION OF GUN-COTTON TO WARLIKE PURPOSES. 21 
soluble glass, the other half being dried, as a finished product, after the im- 
mersion in distilled water/above-mentioned. 
The purified skeins to be treated with silicate of soda were first exposed to 
air until moderately dry, and then soaked for one hour in a boiling solution of 
the silicate, containing ten per cent. of that substance. When the excess of 
the liquid had been subsequently removed by means of the centrifugal ma- 
chine, the gun-cotton still retained about 80 per cent. of the solution, which, 
by evaporation, left therefore about 8 per cent. of soluble glass in the material. 
The skeins were thoroughly dried in air, and then immersed in the stream for 
about forty-eight hours, A longer period of immersion was adopted than in 
use at Hirtenberg, on account of the comparatively sluggish current of the river. 
The skeins were finally washed by hand and dried, this operation completing 
the manufacture of the gun-cotton. A comparative examination of the ash of 
a “ silicated” product with that of gun-cotton prepared at the same time, 
which had not undergone this treatment, exhibited a difference amounting to 
about one-fourth of the ash existing in the gun-cotton not treated: the latter 
furnished 1:45 per cent., the silicated left 1°85 per cent. of ash. The pro- 
portion of silica left in the gun-cotton was decidedly greater than that found 
in the Austrian specimens ; but the portion not treated with soluble glass also 
contained a very notable amount of silica, derived from suspended matter 
in the water. A portion of gun-cotton treated with soluble glass has been 
washed for a few hours only, for comparative experiment. 
(16) Artificial heat was not employed in drying any portion of the purified 
gun-cotton, This operation was accomplished by suspending the skeins 
during the day upon lines in the open air, or in a well-ventilated shed in wet 
weather and at night. 
Miscellaneous Memoranda. 
(17) 1. Samples of the products of manufacture obtained at Waltham Abbey 
have been submitted to synthetical examination, and furnished results as 
uniform as could have been anticipated, and corresponding to those demanded 
by the formula 
H, 
C,, { 9NO, } 0,,. 
In the course of the manufacture the increase of weight actually sus- 
tained by the cotton has been directly determined, and it has been found that 
100 Ibs. of cotton, purified by the treatment with alkali, furnished about 
177 pounds of gun-cotton (not silicated). The amount which theoretically 
100 lbs. of cotton should furnish, of gun-cotton of the above composition, is 
183-3 Ibs. The discrepancy between these numbers is certainly not great 
when allowance is made for mechanical loss in the various washings, and for 
the foreign matters dissolved out of the cotton by the acids. 
(18) 2. Several experiments have been instituted for the purpose of exami- 
ning the characters of the product resulting from the treatment of cotton with 
the mixed acids which have already been used once, The quantities of cotton 
treated at one time, and the various steps in the manufacture, did not differ 
in any way from those adopted in the regular system in use. The product 
obtained from the coarse yarn, by means of the once-used acid, has been ex- 
amined synthetically, and found to correspond very nearly in composition to 
gun-cotton of the formula 
H 
©. | si, | Ou» 
or the next lowest substitution-product to that obtained in the ordinary pro- 
