CAPTAIN NOBLE AND MR, F. A. ABEL ON FIRED GUNPOWDER. 263 
The ground portion heated but slightly, the bottom portion showing this tendency 
in the highest degree, but the heating was on the whole very abnormally low. 
During exposure the colour of the ground deposit became considerably lighter. 
Experiment 122,—Fired 5960 grs. (386'21 grins.) pebble in large cylinder. 
Density ‘4. 
On opening the cylinder observed that the deposit was lighter in colour than in the 
case of the It, L. G. The fracture was also different, being lighter and having several 
isolated portions yellow or greenish yellow. 
Divided, as in last experiment, the deposit into top and bottom, a portion of each 
being bottled with as little exposure as possible, and a portion of each being finely 
ground and exposed to the atmosphere for about 48 hours. 
The bottom part of the deposit was lighter and yellower than the top portion. 
The top ground deposit began to heat when placed on the paper, the deposit on the 
apex and in the interior, where the greatest heat prevailed, changing rapidly to a light 
sulphury yellow with a tinge of green. 
It attained its greatest heat in about 10 minutes, and in about 15 minutes later was 
not hot to the hand. 
The bottom ground portion exhibited the tendency to heat in a much higher degree 
than the top portion, commencing to heat immediately; the colour of the residue 
darkening while an orange coloured deposit formed on the surface. 
During the exhibition of heat the ground residue smoked considerably, the orange 
colour on the surface was doubtless due to this vapour. 
The smell was very peculiar, SH : was quite perceptible, but was not the dominant 
odour. 
The maximum temperature occurred at about 20 minutes after exposure, and a ther¬ 
mometer placed in the centre showed a temperature of over 600 F. (310 o- 6 C.). The 
temperature might have been somewhat higher, as the thermometer had to be with¬ 
drawn for fear of fracture. 
The paper was burned through on which the deposit was placed. After half an 
hour the deposit began to cool rapidly. 
It is to be noticed that the heat appears to play an important part in the changes 
which take place, as it was observed that the residue at the base of the cone remained 
unchanged in appearance although more exposed to the action of the air than other 
portions. 
It may also be noted that after the residue has gone through this heating process 
the physical characteristics are considerably changed. 
When taken out of the exploding vessel the residue is always difficult to pound in 
the mortar, being somewhat unctuous or greasy to the touch, but after the development 
of the heating phase it becomes crisp and powdery. 
