388 
MR. F. A. ABEL’S CONTRIBUTIONS TO 
There would appear to be some indication of a falling off in the rapidity of trans- 
mission in this experiment towards the end of the tube, but this was not borne out by 
other results with tubes of the same length. 
In one experiment, with a tube of T5 inch ('037 m.) diameter, charges of only 
1 ounce of gun-cotton were placed in the tube at intervals of 2 feet. The results 
obtained in the first 6 feet of the tube corresponded with those furnished by tubes of 
the same dimensions, when charges of T5 ounce (46 - 8 grms.) were employed; but the 
fourth and succeeding charges, though they exploded, did not detonate, no destructive 
effect being produced upon the tube ; the wires were, however, severed by the explo- 
sions, and the records obtained indicated that the rate at which the explosion was 
transmitted from charge to charge, through the last three intervals of 2 feet each, was 
only between 1500 and 1800 feet (450 m. and 540 m.) per second. 
It appears from the experiments with tubes that, when the relations between the 
amount of explosive agent, the diameter of the tube, and the space or length of tube 
intervening between the charges are such as to ensure the transmission of detonation , 
the rate of its transmission is about one third of that at which it travels, in open air, 
along a continuous mass, or row of masses, of the same material in the same condition. 
VIII.— ON CIRCUMSTANCES WHICH INFLUENCE THE BEHAVIOUR OF EXPLOSIVE AGENTS 
WHEN EXPOSED TO HIGH TEMPERATURES. 
In my former memoir on explosive agents I discussed* incidentally the influence of 
an accumulation of heat in a mass of gun-cotton in promoting violent explosion or deto- 
nation, if through any cause the materials become ignited, an influence which equally 
affects other explosive agents. This point has acquired much additional importance 
since the publication of that Paper, in consequence of its probable bearing upon the 
violent explosions which occurred at the Gun-cotton Works at Stowmarket in August 
1871, and of the possibility thereby rendered manifest that violent explosions of gun- 
cotton, or other substances of analogous properties, may occur under circumstances 
which until lately were not considered to involve hazard. 
The fact that the previous application of heat to an explosive agent increases the 
violence with which this will explode when flame, or a sufficiently powerful source of 
heat, is applied, admits of ready demonstration by simple experiments. Thus, if a 
small quantity of gun-cotton, wool, or thread be inserted and lightly pressed down into 
a test-tube, and ignited by application of a hot wire to the gun-cotton, or of a sufficient 
source of heat to the exterior of the tube, it will simply flash into flame rapidly, with 
but little indication of explosive violence; but if it be previously exposed to a heat of 
90° to 100° C., until it has attained that temperature throughout, its ignition, while at 
that temperature, will be attended by decided evidence of greater explosive energy. 
* Phil. Trans. 1869, yol. clix. pp. 495-6. 
