ME. ABEL’S EESEABCHES ON GTJN-COTTON. 
239 
render it liable to spontaneous heating. Comparative experiments were instituted with 
gun-cotton, and with cotton-wool in its original unpurified condition. The materials were 
prepared in two ways ; in one experiment they were exposed to an atmosphere saturated 
with moisture until about 5 or 6 per cent, of water had been absorbed ; they were then 
closely packed in boxes ; in another a small portion was moistened (the excess of water 
being expressed) and packed in the centre of a considerable quantity of dry material. 
These packages were first occasionally exposed to the sun, they were afterwards pre- 
served for several weeks in a chamber, the atmosphere of which was artificially heated ; 
but in neither instance could any indication of the development of heat be obtained, 
although the external temperature frequently reached and sometimes exceeded 50°. 
The inference drawn from these negative results is that gun-cotton is not more liable to 
spontaneous heating than ordinary cotton-wool. The latter was exposed in a damp and 
very closely packed condition, in quantities of from ten to thirty pounds, to a heated 
atmosphere for several months, in order, if possible, to establish spontaneous heating 
under conditions to which gun-cotton might afterwards be submitted, but the experi- 
ments were without result. 
The important evidence which has been collected regarding the perfect preservation 
of damp gun-cotton, when stored under ordinary conditions of temperature, has already 
been referred to. 
(b) The gun-cotton being closely packed in an ordinarily dry condition . — Large ammu- 
nition-boxes were closely packed with gun-cotton of the following kinds : — 
(1) Prepared strictly in accordance with the directions laid down by Yon Lenk (i. e. 
including the “ silicating ” treatment). 
(2) The same, made up into cartridges. 
(3) Prepared in the ordinary manner, but not “silicated.” 
(4) Not “ silicated,” and packed together with a few skeins (1^ lb.) of gun-cotton 
which had only been purified by washing in water (the treatment with alkaline water 
having been omitted). 
(5) Not “ silicated,” and packed together with some gun-cotton soluble in ether and 
alcohol. 
(6) Ordinary gun-cotton impregnated with about 0‘3 per cent, of sodic carbonate. 
Pieces of litmus paper were placed in different parts of the various packages. 
Cases containing Nos. 1, 3, and 6 were packed in July and September 1864, and 
stored in a dry locality. During the summer months The maximum temperatures 
recorded in this store room ranged from 16 0, 5 to 24°. About six months after the boxes 
were packed, one of each kind was opened for examination. All the samples had a 
faint peculiar odour like that of pine-wood, which is always developed in the closely 
packed material, and was most marked in the unsilicated gun-cotton. Some parts of 
the litmus paper enclosed in the latter had assumed a pink tinge, and where it had been 
placed between the gun-cotton and the metal surface of the packing case, it was decidedly 
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