MR. F. A. ABEL’S CONTRIBUTIONS TO 
340 
The employment of the iodide of nitrogen in experiments of the kind carried out by 
MM. Champion and Pellet appears to me open to objection : first, because it is of 
uncertain composition, and consequently varies very considerably in sensitiveness and 
stability; secondly, because the quantities employed in experiments can only be ap- 
proximately estimated, and hence experiments instituted with small quantities cannot 
possess great accuracy ; thirdly, because it is so very readily exploded by vibrations im- 
parted to the air by concussions of all kinds, that its use can scarcely afford much scope 
as a means of investigating the character and effects of different vibrations. 
Hence, in carrying out a series of experiments on the transmission of the concussion 
or vibration developed by explosions, I have preferred to operate with explosive agents 
of thoroughly constant composition, and more readily and accurately applicable because 
less highly susceptible of explosion. 
I.— ON THE TRANSMISSION OE DETONATION. 
In describing the experiments instituted by them on the detonation of iodide of 
nitrogen at considerable distances through the medium of tubes, MM. Champion and 
Pellet allude to an analogous experiment made by M. Barbe with dynamite. I have 
been unable to find a description of this particular experiment ; but Captain Trauzl, of 
the Austrian Engineers, has made numerous experiments on the transmission of de- 
tonation of a cartridge of dynamite by means of tubes to charges separated from it by 
considerable distances. A cartridge of dynamite, between 2 and 3 ounces in weight, 
was inserted into each extremity of an iron tube (a gas-pipe) 6 feet (1*82 m.) long 
and l - 25 inch (-031 m.) diameter; by the explosion of one of these charges with a 
detonating fuse, the detonation of the charge at the opposite extremity of the tube was 
accomplished, the two explosions being apparently simultaneous. A similar result was 
obtained by employing a much wider tube ; and the practically simultaneous detonation 
of several charges, connected with a long tube by short branch-pipes at a distance of 
2 feet from each other, was accomplished by inserting dynamite-cartridges into this long 
tube over the opening of each branch-tube, and detonating a charge of the material at 
one extremity of the tube. These interesting results induced me to institute a series of 
experiments, with the view of more closely examining into the transmission of detonation 
to widely separated masses of different explosive agents through the medium of tubes. 
The following is an account of the principal results obtained. 
a. Experiments with compressed gun-cotton. 
The first experiments were made with wrought-iron tubes (gas-pipe), T25 inch 
(•0317 m.) in diameter. One ounce (31-2 grms.) of gun-cotton, in the form of a 
1-inch disk, was placed against each opening of the tube ; the disk at one extremity was 
exploded by means of an electric detonating fuse. The length of tubes experimented 
with was gradually reduced from T92 metre (6 feet 3 inches) to *91 metre (3 feet) 
before any transmission of detonation was obtained; the mass of gun-cotton at the 
