THE HISTORY OF EXPLOSIVE AGENTS. 
353 
(3) The transmission of detonation would not appear to have been favoured by the 
sonorosity, or the pitch, of the tube employed, as the sonorous brass tube was not 
found to favour transmission of the detonation to the same extent as the pewter tube. 
This was corroborated by some special experiments with glass tubes, of the same 
dimensions as those described in the Table. A coating consisting of two layers of 
bibulous paper was firmly attached throughout by means of gum to the exterior of one 
of the metre-tubes ; but the same result was obtained with it by the explosion of silver 
fulminate as with the uncoated tube. Another tube had pieces of tightly fitting india- 
rubber tubing placed upon the outside, until its sonorosity was reduced to a very low 
pitch ; but, when used in this condition, it transmitted the detonation, developed by 
0-6 grain of fulminate, as readily as the naked tubes. 
The principal if not the only cause of the great difference exhibited, in power of 
transmitting detonation, by these tubes composed of different materials appears to have 
been satisfactorily demonstrated by some experiments which will be presently described. 
II.— INTEEFEEENCE WITH THE TRANSMISSION OF DETONATION BY TUBES. 
Attempts have been made by me, and with some success, to demonstrate by experi- 
ment that when the limit of distance has been reached to which a tube of a particular 
diameter will transmit the force developed by a detonation, of a particular kind or 
magnitude, with sufficient completeness to induce detonation at the most distant part 
of the channel, the interposition of impediments in the path of the gas-wave, so slight 
as to be apparently incapable of opposing the transmission of force to any important 
extent, will effectually interfere with the development of detonation. Some examples 
of the experiments instituted in this direction, in which mercuric fulminate and silver 
fulminate were employed to produce the initiative detonation, are given in Table II. 
(p. 354). 
The quoted experiments with iron tubes demonstrated that the interposition of a 
small loose plug of tow, or, better still, of finely carded cotton-wool, between the 
initiative detonation and the charge of explosive substance inserted into the opposite 
end of the tube will protect the latter from detonation under circumstances which, in 
the absence of the plug of loose material, just fulfil the conditions essential to deto- 
nation. The violence of the concussion or blow sustained by the substance while 
exposed to the action of the detonation, before motion is imparted to the entire mass 
by the rush of gas, is strikingly demonstrated by the following circumstance. The 
crystals of mercuric fulminate, which were quite loosely confined in thin paper, were 
found to be more or less completely crushed or pulverized on recovering the small 
packets (which were not exploded, but only projected to a considerable distance), when 
the tuft of wool had been interposed between them and the detonation produced at the 
other extremity of the tube. 
In witnessing these experiments it was difficult to realize that the slight resistance 
JJDCCCLXXIV. 3 A 
