20 rePport—1863. 
wards ; it is not submitted to any treatment with carbonate of potassa, but is 
boiled, after the first washing, in a weak solution of soluble glass, and on its 
removal from this, without any intermediate desiccation, it is immersed in the 
stream for about six days. 
The process of purification which I adopted differed from that in use at 
Hirtenberg only in the postponement of the long-continued washing until 
after treatment of the gun-cotton with alkali. At the expiration of forty- 
eight hours the skeins were removed from the stream, the water was separated 
from them in the centrifugal machine, and they were then boiled for a tew 
minutes in a solution of carbonate of potassa of spec. gray. 1°02. Having 
been returned to the centrifugal machine, for the separation of the alkaline 
liquor, they were again placed in the washing-frames and left in the stream 
for a period of fourteen to eighteen days. On subsequent removal from the 
stream, each skein was washed by hand, to separate mechanical impurities, 
and one-half of each quantity of gun-cotton prepared was finally left in soak 
in distilled water for some hours, I found that, in consequence of the very 
large quantity of salts of lime in the river-water, the proportion of mineral 
matter in the gun-cotton was notably increased (it varied from 1 to 1:5 per 
cent.); this final washing was consequently adopted (there being a good 
supply of distilled water at hand) for the purpose of reducing the propor- 
tion of mineral matter added to the gun-cotton by the long-continued im- 
mersion in the stream. The gun-cotton thus finally purified was dried in 
the open air. 
(15) e. Lhe treatment of the purified Gun-Cotton with Soluble Glass, which 
forms one of the features of the Austrian system of manufacture, was stated by 
the officials at Hirtenberg to effect two important objects,—first, a retardation 
of the combustion of the gun-cotton; and secondly, its protection from atmo- 
spheric influences, by the formation of a coating upon the fibres of the cotton. 
In my account of the results of examination of the specimens of Austrian 
gun-cotton, I have entered fully into the reasons and facts which lead me to 
the conclusion that the treatment with soluble glass, the subsequent desicea- 
tion, and the final washing of the gun-cotton for five or six hours do not prac- 
tically exert any effect upon the properties of the material, the only result 
being the addition to the mineral constituents of a small proportion of sili- 
cate of lime. 
In Gencral Lenk’s process, as described in the English patent, the soluble 
glass is applied, as already stated, to the gun-cotton which, after the removal 
from the acids, has undergone no further treatment than an immersion in 
running water for forty-eight hours or thereabouts; when removed from 
the bath of silicate, the gun-cotton is not dried, but at once immersed 
for a period of six days in running water. It is at once obvious that this 
treatment cannot exert any effect upon the cotton, beyond possibly the neu- 
tralization of a minute trace of free acid still retained by it after the first 
washing. That the treatment with soluble glass is not intended to exert any 
other than a purifying effect upon the gun-cotton, appears also to have been 
understood by Professors Redtenbacher, Schrotter, and Schneider, in their in- 
quiry into Baron Lenk’s system of manufacture ; for the only allusion which 
in their joint report they make to this point, is as follows, “the treatment 
with soluble glass has no influence on Baron Lenk’s gun-cotton, it being pre- 
viously free from acids.” 
In order to test, as nearly as possible in its integrity, the system of manu- 
facture as carried on at Hirtenberg, it was determined to submit one-half of 
each quantity of gun-cotton produced in one operation to the treatment with 
