14 REPORT—1863. 
water from a moist atmosphere, which it continues to exert until it actually 
becomes pasty. Moreover gunpowder, when once damp, cannot be restored 
to a serviceable condition without being again submitted to the incorporating 
and subsequent processes, 
TII.—Memorandum with reference to Experiments in progress bearing upon the 
Manufacture of Gun-cotton. By F. A, Anrt, F.RS, (Received Aug. 23, 
1863). 
Experiments of a preliminary character. 
(9) The experiments on a manufacturing scale, instituted on the Austrian 
system of preparing gun-cotton for military purposes, were preceded by an 
examination into some of the regulations laid down for the treatment of the 
cotton—the objects of these preliminary experiments being partly the attain- 
ment of direct proof of the necessity of a strict adherence to certain details 
(relating to the strength of the nitric acid, the duration of the treatment of 
the cotton with the mixed acids, and the rejection of the mixture after being 
once used), and partly the acquirement of experience in the treatment of 
the cotton. 
It was important, before proceeding with these experiments, to determine 
upon some method, both expeditious and trustworthy, for submitting the 
products of the numerous experimental preparations of gun-cotton to compara- 
tive examination with the highest substitution-product, 7. e. the Austrian gun- 
cotton. 
Mr. Hadow’s synthetical method of examination, which had been success- 
fully employed in determining the composition of the Austrian gun-cotton, 
though valuable for finally controlling the composition of any particular pro- 
duct, is not sufficiently expeditious for the particular object in view, 7. e. the 
examination of small samples from products of manufacture before their 
entire bulk is submitted to the final (purifying) processes *. 
The first method tried for submitting the products of manufacture to com- 
parative examination was as follows :—The weighed gun-cotton was soaked 
in water, the excess being afterwards expressed ; and it was then placed in 
a glass tube about 18 inches long and open at both ends. Into one extre- 
mity was fitted a delivery-tube, dipping into mercury or water; the other 
was connected with a gas-holder containing nitrogen; the communication 
between the latter and the tube could be cut off by means of a stopcock. 
Air was expelled from the tube by means of the nitrogen, and the wet gun- 
cotton was then heated as quickly as possible by an Argand flame, the tube 
being slightly inclined. The gun-cotton was rapidly decomposed, though not 
with explosive violence; the gases isstiing from the tube were collected and mea- 
sured. The volume of gas furnished by different specimens of the Austrian 
* Many experiments were instituted with this method of examination, and it was found 
that although the results obtained corresponded closely to theoretical requirements, when 
the starting-point in the examination was the gun-cotton, results of similar precision were 
not furnished by it when the original cotton itself was taken as the starting-point. That 
is to say, in commencing with a known weight of dry cotton, submitting it to proper treat- 
ment with the mixed acids, washing the product as carefully as possible, so as to avoid 
mechanical loss, drying the pure gun-cotton, digesting it with sulphhydride of potassium 
solution, and proceeding, with all possible care, exactly according to the prescriptions 
given by Mr. Hadow, the reduced cotton is always somewhat lower in amount than the 
cotton originally employed, the deficiency varying within the limits of 1 per cent. This 
deficiency is unquestionably due to the abstraction, by the mixed acids, of portions of 
the mineral constituents and of small proportions of organic matter from the cotton, and 
also, to a slight extent, to mechanical logs in the washing operations, which it appears im- 
possible to guard against altogether. : 
