244 
MR. ABEL’S RESEARCHES ON GUN-COTTON. 
boxes during three months’ exposure to a maximum temperature of 50° were very uni- 
form, and not the slightest indication of any development of heat in the mass of the 
gun-cotton was obtained in any one instance. The maximum temperatures within the 
boxes were always considerably below the temperatures of the air in the chamber at the 
time, the difference ranging between 6° and 11°, excepting on Mondays, when the boxes 
never reached so high a temperature as on other days. 
At the termination of three months it was decided to raise the temperature of the 
chamber to between 54° and 55°. The experiment was conducted as before, and readings 
of the thermometers were taken every two hours. The temperature of the chamber was 
generally raised to 54° by about eleven in the morning (sometimes earlier), and was main- 
tained as constantly as possible at that temperature for seven hours. On 7 9 days out of 
195, the temperature of the room reached 55 0, 5, and continued so from two to four 
hours. During three months no indication of development of heat was obtained in any 
one of the boxes ; the temperature-records within these at the close of the day were 
during this period (excluding Mondays) from 6° to 11° below that in the chamber itself, 
and the highest maximum temperature attained by the boxes up to the termination of 
that period was 49°. One of the boxes then furnished indications of some development 
of heat in its contents ; it was therefore removed, and the experiment was continued 
with the remainder of the boxes. During the last three months the maximum tempe- 
ratures recorded in the several boxes confined in the chamber, more nearly approached 
that of the air surrounding them ; the differences between the readings of thermometers 
within and outside the boxes at six in the evening ranged between 5 0, 5 and 1°. 
The following is a tabulated statement of the descriptions of gun-cotton operated 
upon, and the duration and results of their exposure to heat. In the statements given 
in this Table, of the lowest and the mean of the temperatures recorded in the several 
packages, the readings obtained on Mondays have not been included, as they were con- 
siderably below those of the other five days in the week, in consequence of the chamber 
and boxes having cooled down during Sundays. 
