216 
ME. ABEL’S EESEAECIIES ON GUN-COTTON. 
Carbonic acid . . . . . . 45 - 6 per cent. 
Nitric oxide 10’8 „ 
Nitrogen 43-5 „ 
Some water had become deposited in the sides of the tube, and a small quantity of 
mercury-salt had formed. The application of heat to the tube was continued with the 
view of collecting a further quantity of gas, but the experiment was carried on uninter- 
ruptedly for a further period of nearly twelve months before a sufficient amount of gas 
(about 150 cub. centims.) could be collected for analysis. This second product con- 
tained — 
Carbonic acid 
. 55-7 i 
Hydrogen 
. 6-4 
Carbohydrogen ” 
. traces 
Nitric oxide 
. 2-1 
Nitrogen 
. 35-7 
The total volume of gas evolved during fourteen months’ exposure of the gun-cotton 
to 65° C., for seven hours daily, was about 660 cub. centims. 
On removing the specimen from the bulb-tube, it exhibited no alteration in colour, 
appearance, or explosiveness ; the strength of fibre had slightly diminished ; nitric acid 
was detected in small quantity in the aqueous extract, but no oxalic acid. A very 
slight reducing action was exerted upon cupric salts, but the proportion of matter soluble 
in ether and alcohol had not appreciably increased. At the conclusion of the experi- 
ment the specimen was washed in slightly alkaline water, dried, and exposed to strong 
daylight and occasional sunlight, in a stoppered bottle. Up to the present time (after 
nine months’ exposure) the specimen has suffered no change whatever. 
It would appear from these experiments, which were always commenced in vacuo , 
but continued after a short time in an atmosphere of the gaseous and volatile products 
formed, that gun-cotton, prepared and purified according to the system now in use, ma- 
nifests some slight but undoubted symptoms of gradual change, if maintained for several 
hours at as low a temperature as 55° C. in a confined space ; — that a very long-conti- 
nued exposure to that temperature does in some instances produce a notable alteration 
in the composition and explosive properties of the substance ; — that a similar change is 
somewhat more rapidly developed if the gun-cotton be exposed to temperatures of 60° 
and 65°; but that the exposure of the substance several hours daily, even for months, 
to the highest of those temperatures does not so seriously affect the ordinary products of 
manufacture as to prevent their being afterwards restored, by the ordinary process of 
purification from acid, to a condition differing but little, practically, from that of the 
original material. Although these experiments were instituted with comparatively con- 
siderable quantities of gun-cotton (14-20 grms.), it must be at once admitted that, if the 
material were exposed in large compactly packed masses (5-10 kilos.) to the tempera- 
tures ranging between 55° and 65° for the periods given in the preceding experiments, 
