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MR. ABEL’S RESEARCHES ON GUN-COTTON. 
The results of these experiments were as follows : — 
(1) Gun-cotton closely packed in metal-lined cases, of considerable size, in two of 
which some imperfectly prepared gun-cotton was purposely included, sustained uniformly 
a daily exposure for twelve hours during three months to a heated atmosphere, the 
temperature of which generally ranged from 49° to 51° for a period of seven hours, 
without furnishing any indication of the development of heat within the mass of the 
gun-cotton, consequent upon chemical change. 
(2) The further exposure of these packages for another period of three months to a 
heated atmosphere, the temperature of which generally ranged during seven hours daily 
between 64° and 55°, resulted only in one instance in the development of heat in the 
gun-cotton ; and the particular box which, at the expiration of the six months’ treat- 
ment, furnished this indication that its contents were undergoing decomposition, was 
filled with gun-cotton in the condition which all previous experiments had indicated as 
least capable of resisting the effects of prolonged exposure to heat ; being, namely, 
almost free from substances (carbonates) which would exert a neutralizing action upon 
any acid generated by decomposition of the comparatively unstable impurities existing 
in the gun-cotton. 
(3) The box which next furnished very slight indications of the development of heat, 
after exposure for 6^ months, contained gun-cotton through which a small proportion 
of earthy carbonates had been distributed by its submission to the so-called “ silicating 
process,” but in the centre of which a specimen of imperfectly purified gun-cotton had 
been packed. There is no question that this box would have furnished much earlier 
indications of the occurrence of chemical change in its contents, if the gun-cotton prin- 
cipally composing the latter had not been protected for a considerable period by the 
presence of carbonates from the destructive effects of acid liberated from the imperfectly 
purified gun-cotton which was packed in the centre of the box. 
(4) A box of “ silicated ” gun-cotton containing a small quantity of soluble gun-cotton 
not silicated, was the next to exhibit symptoms of decomposition, after having been ex- 
posed to heat for seven months. Numerous experiments have shown that the soluble 
gun-cotton is not more prone to decomposition than the most perfectly converted mate- 
rial ; but the sample packed in the centre of this box was not protected by carbonates, 
and therefore doubtless sustained change considerably sooner than the chief portion of 
the contents of this box, promoting an alteration in the latter, after the lapse of some 
time, when the protective effect of the carbonate had become neutralized. 
(5) The box which was entirely filled with gun-cotton, prepared strictly according to 
Yon Lena’s system, including its submission to the “silicating” process, only exhibited 
a slight indication of internal development of heat after having been exposed for eight 
months to a heated atmosphere. The protective effect exerted by the small proportion of 
earthy carbonate deposited in the gun-cotton as a result of the “silicating” treatment 
was, in this instance, not diminished by the presence of any gun-cotton not thus treated, 
and consequently the contents of this box resisted change for a longer period than the 
