390 
ME. F. A. ABEL’S CONTEIBI7TIONS TO 
composing the heap was coated with tar and covered with wood shavings, these being 
afterwards set fire to, furnished a similar result ; no explosion followed the eventual 
ignition of the gun-cotton contained in this and another box. These results were con- 
sidered at the time to afford satisfactory proof that if even considerable quantities of 
gun-cotton, in the form of compactly compressed, homogeneous masses, were ignited 
when confined in strong wooden boxes, no explosion would occur, the gun-cotton 
merely burning rapidly; and that if such packages of compressed gun-cotton were 
exposed to the effects of fire from without, some portion must be inflamed by access of 
fire, and the combustion of the mass thus brought about before it can be raised to the 
temperature of explosion. Subsequent experiments, however, clearly demonstrated that 
the results above described must be considered in relation to the quantity of gun-cotton 
by which they are furnished, as well as to the degree of its confinement w T hen subjected 
to the action of heat or fire. In the experiments just described, the largest quantity of 
gun-cotton employed was 224 lb. (contained in eight pakages) ; but some very different 
results were obtained in somewhat similar experiments conducted in each instance with 
three times that quantity (viz. 672 lb.) of gun-cotton. That amount of material, packed 
in 24 boxes of the kind used in the preceding trials, was, in the first instance, placed 
upon two tables in a light wooden shed ; a heap of shavings and wood chips was then 
kindled immediately beneatlfithe two piles of boxes, of which two were left partly open. 
The gun-cotton inflamed after the lapse of eight minutes, and continued to burn with 
increasing violence for about six seconds, when a powerful explosion occurred, the shed 
being blown to pieces and a deep crater formed in the ground. It was estimated, from 
comparative experiments with packages of gun-cotton purposely detonated, that the 
explosion occurred when only a small proportion had burned. In a second similar 
experiment the nature of the building only was varied, the 672 lb. of gun-cotton being 
placed (in boxes upon tables, and surrounded by inflammable material) in a strongly 
built brick magazine. In this instance also a violent explosion occurred after the 
gun-cotton had been burning, with increasing fierceness, for nine seconds. A third 
periment, conducted with an equal quantity of gun-cotton, was made for the purpose 
of ascertaining whether the result would be influenced by confining it less strongly. 
The 672 lb. were therefore packed in twenty-four deal boxes of lighter construction 
than those before used (f inch instead of finch deal, and more lightly fastened together), 
and these were placed in light wooden sheds, the other details of the experiment being 
as before. The gun-cotton became inflamed about 36 minutes after the fire had been 
kindled in the hut, and burned fiercely for about 15 seconds ; having subsided for a 
short time, there was a second burst of flame, and the gun-cotton was entirely burnt 
about 48 minutes after the first ignition, there being no explosion in this instance. 
A repetition of the experiment furnished the same negative result. 
An experiment, similar to the first of the foregoing, was made some time afterwards 
with Nobel’s dynamite (the mixture of nitroglycerine and Kieselguhr). 672 lb. of this 
material (containing about 500 lb. of nitroglycerine), enclosed in twelve stout wooden 
