190 Atomic Matter and Luminiferous Ether. (April, 
weight of about 100 tons to produce the same effect by 
dragging the glass tube asunder against its attraction of © 
cohesion. 
The vibrations, due entirely to the elasticity of the glass, 
passed to and fro the length of the tube, and were reflected 
from the ends and from any intermediate ‘‘nodes.”; SA — 
series of reflected vibrations thus met a dire&t and distin&, 
and not coincident, series of vibrations; and this jarring or 
interference of vibrations, themselves dependent upon the ~ 
elasticity of the glass, sufficed to overcome, simultaneously, 
the attraction of cohesion of its substance at many different . 
points of its length, thus showing that cohesion and elasticity — 
are intimately related, and that the form of the motion 
governs much of its effects. This latter fact is also 
exemplified in many other ways. Amongst these are Abel’s 
experiments on exploding gun-cotton by detonating powder. 
A small portion of common fulminating powder produces a 
most powerful explosion of the cotton, under conditions 
where a much larger quantity of the more violent explosive, 
chloride of nitrogen, simply disperses the cotton, and will 
drive some of its unaltered fibres into oak, &c., without 
producing any remarkable explosion of any part of it. 
Amongst other instances are Professor Reynolds’s bursting 
of the glass tube by an ele¢tric spark, and the difference of 
fracture in a pane of glass by a slow moving stone and by a 
rifle bullet. 
The effect of a rapid blow on water in an open vessel is 
another illustration. A ‘“‘ Prince Rupert’s drop,” broken 
under the surface of water in an open phial, will breaka 
phial that is unharmed if water is absent. 
A faét connected with the spheroidal state of liquids\is 
also significant. A quantity of water on a red-hot solid in 
the well-known spheroidal state is exploded if struck a 
smart blow, or if the water be dropped upon the heated 
surface from a sufficient height an explosion ensues. 
Recently, at an alkali works in Newcastle, serious damage 
followed from this cause—the instrument being a falling hot 
**black-ash ball.’”* | A still more serious case is on record of 
a copper foundry being destroyed from a workman spitting 
into a large quantity of melted copper. 
One remarkable characteristic of molecules has been 
pointed out by Sir John Herschel, who says, in effect, that 
the exact equality of each molecule to all others of the same 
kind gives it the essential character of a manufactured 
article, and precludes the idea of its being eternal and self- 
existent, and this thought well deserves careful examination. 
