ME. ABEL’S EESEAECHES ON GUN-COTTON, 
237 
therefore interrupted, and the samples were again weighed. The dry specimen had sus- 
tained a loss of 34 per cent., was quite friable, and had become converted partly into 
soluble gun-cotton and partly into the products soluble in water. The sample which 
had been exposed in a moist condition had sustained a total loss of 0'89 per cent., and 
did not exhibit the slightest signs of acidity. This sample was again submitted in a 
moist state to a warm atmosphere, ranging from 55° to 65°, day and night for four 
calendar months. The total loss which it had then sustained after continuous exposure 
to heat for between seven and eight months, amounted to T47 per cent. The gun-cotton 
exhibited no acid reaction, and the moisture condensed upon the sides of the bottle gave 
only a faint indication with litmus paper. 
Careful observations have been instituted upon the storage of considerable quantities 
of the material in a wet or merely moist condition. Ordinary gun-cotton has been 
immersed in sufficient distilled water just to cover it, and has been kept in that condi- 
tion in closed vessels, with light excluded, for 2-| years. It is perhaps scarcely necessary 
to state that the material has not sustained the slightest change, and that the distilled 
water in which it has been preserved is perfectly neutral, the only impurity found in the 
latter being a small quantity of saline matter extracted from the gun-cotton. A portion 
of this sample was transferred to a large glass bottle twelve months ago, and has been 
left exposed to diffused daylight. This difference in the mode of preservation has been 
quite without effect upon the gun-cotton. 
The principal stock of gun-cotton manufactured at Waltham Abbey for experimental 
purposes, amounting to about 3000 lbs., has been preserved in a moist condition (just 
as obtained from the centrifugal hydro-extractor) in closed cases until required for use, 
some of the packages having been kept for about two years ; a few, specially set apart 
for periodical examination, have been preserved for about three years. I have to record 
no indications of the slightest change except in instances where the gun-cotton had been 
preserved in close contact with the tinned-copper linings of some gunpowder cases used 
for its storage. It was found, after some time, that the surfaces of these became oxidized 
where they were in contact with the moist material, and that this oxidation determined 
the development of an acid reaction in the gun-cotton, which, however, was, and has con- 
tinued to be, confined to the portions in immediate contact with the surface of metal*. 
Gun-cotton in the condition above referred to contains sufficient water to render it 
quite uninflammable, it may therefore be preserved with perfect safety in this convenient 
condition, and may be at any time prepared for use by desiccation. As far as can be 
* The readily oxidizable character of tin and the tendency of a metal to establish, by its own oxidation, that 
of readily oxidizable substances which are in contact with it, are well known. If gunpowder containing even 
the ordinary proportion of moisture remain in contact with a surface of tin, the metal becomes oxidized and the 
gunpowder acquires an acid reaction, sulphuric acid being detected after some time. Similarly,, some remark- 
able instances of the oxidation of iron by contact with somewhat damp gunpowder, attended by the production 
of sulphuric acid, have come under my notice. 
MDCCCLXYII. 2 K 
