200 
ME. ABEL’S EESEAECHES ON GUN-COTTON. 
Experiment 40. — Three specimens, each of one grm., were exposed side by side in 
small long-necked flasks to 100° C., in three different conditions. The one was air-dry 
(and contained therefore about 2 per cent, of water), the second was dried immediately 
before the experiment by sufficient exposure to 50° C., and the third was saturated with 
water and pressed between bibulous paper. The dry sample showed signs of decompo- 
sition in ten minutes, the air-dry sample began to decompose in forty-five minutes, and 
the moistened specimen exhibited no acidity after exposure to 100° C. five hours daily for 
three days (further experiments on the protective power of water will be presently de- 
scribed). In all subsequent experiments upon the comparative effects of exposure of dif- 
ferent samples to elevated temperatures, the gun-cotton was employed in a dry condition. 
The discrepancies noticed above in the behaviour of different samples of gun-cotton 
under exposure to 100° C., led to a searching investigation into the composition of pro- 
ducts of manufacture obtained from Waltham Abbey, Stowmarket, and Hirtenberg, the 
results of which were laid before the Royal Society last year. 
It was established by this inquiry that gun-cotton manufactured at those establish- 
ments contains variable proportions of the following substances foreign to the most 
explosive gun-cotton, trinitrocellulose , or € 6 0 5 . 
O JN V72 
(1) Hygroscopic moisture, the proportion of which amounts very uniformly to about 
2 per cent., except in special instances, when mineral impurities in the material exert 
an influence upon its hygroscopic properties*. 
(2) Mineral matters, varying in amount with the character of water used in purifying 
the material, with the duration of its treatment with water, and with the circumstance 
whether the purified gun-cotton has been submitted to the treatment with soluble glass, 
recommended by Von Lenk. These mineral matters include calcic and magnesian carbo- 
nates, silica, clay, and occasionally small quantities of sand and alkaline salts. 
(3) Products of the less complete action of nitric acid upon cellulose, the nature of 
which has been investigated by Hadow. These products, which are less explosive than 
trinitrocellulose, and are more or less readily soluble in mixtures of ether and alcohol, 
were found to exist in very considerable proportion in some samples obtained from Hir- 
tenberg and Stowmarket, and have also been found to the extent of about 2 per cent, 
in the most perfect products of manufacture. Their formation may be due to insuffi- 
ciently protracted treatment of the cotton with the mixed acids, to the employment of 
acids of insufficient strength, and to the presence of hygroscopic moisture in the cotton 
at the time of its conversion. An elevation of temperature during the treatment of the 
cotton with the acids would also give rise to the production of soluble gun-cotton. 
(4) Products of the partial oxidation, by nitric acid, of organic impurities existing in 
the cotton, even after the preliminary purification to which it is subject. These products, 
* Several of the earlier products of manufacture obtained at Stowmarket were found to absorb from the atmo- 
sphere, under ordinary conditions, from 0-5 to l - 5 per cent, more moisture than the average proportion (2 per 
cent.) contained in Yon Lenk’s gun-cotton. 
