1833.] Attraction and Repulsion. 461 
That the particles of solids are in a constant state of vibratory mo- 
tion is incompatible with their mutual attractions, and their gravity. 
If temperature depended on vibration of atoms, bodies would soon have 
no temperature, (i. e. fall to natural zero,) for their particles would soon 
cease to vibrate. 
This theory cannot explain temperature ; for bodies would lose their 
temperature if temperature be vibration. Nor capacity, if capacity be lati- 
tude of motion. Nor could radiation take place, if radiated heat be vibra- 
tions communicated through the air, for according to this theory, the par- 
ticles of elastic fluids move with the greatest quickness. Thus, suppose 
the particles of any body A, are vibrating at any given rate 10, and 
those of another distant body B, at any less rate 8, as the air between 
them is vibrating with the greatest quickness, let its rate be 20. If 
the air vibrating at the rate 20 does not increase the rate of vibration 
in A and B, how can it transmit from A to B the small difference of 
their vibration ?>—or how can it receive vibrations from A, which vi- 
brates at a less rate than itself. And moreover, as matter of some kind 
must be present to transmit vibrations, radiation could not take place 
through a vacuum, as it is known to do, unless the ‘‘ subtle medium” 
of NewTon* be supposed to exist, which is not a part of this hypothesis, 
and which, as will hereafter be shewn, is very nearly allied to the *‘ mat- 
ter of heat’’ of Lavoisi=Er. 
That the repulsive force opposing attraction cannot be explained by 
vibratory motions, supposed to exist in the atoms themselves of bodies, 
has been, I trust, proved by numerous unanswerable objections. 
2. That heat is a subtle, elastic fluid, pervading all bodies. 
The doctrine of the materiality of heat has been adopted by the 
greater part of modern philosophers; and the cause of its entering 
bodies, and separating their particles, has been explained in three ways: 
First.—Borruaave, with some other philosophers, attempted to ex- 
plain the distribution of heat, solely by supposing that its particles are 
mutually repellent. Hence its perfect elasticity, which it was supposed 
would expand it equally through space, so that, in equal volumes of 
space, there would be equal quantities of heat, whether occupied by 
other matter or not. And hence he concluded that equal volumes of 
matter always would contain equal quantities of heat. 
That this is not the case, is proved by experiment, for equal volumes 
of matter, it is well known, contain very different quantities of heat, 
Moreover, the argument itself is not sound ; for very dense bodies, be- 
tween the atoms of which a powerful attraction subsists, would never 
* Treatise on Optics, Query 18, 
