360 Mr. Whelpley on the Idea of an Atom. 



tain that the atmosphere absorbs a certain quantity of solar influ^ 

 ence, it may be assumed that gases have a feeble power of radia- 

 ting heat, absorption and radiation being equal. The two atoms 

 will consequently radiate a heat proportionate to their condensa- 

 tion. But this radiation seems to be only an effect happening in 

 the atom itself. For, because the normal size of the nucleus 

 pn^ represents a relation of the atom to itself which pervades all 

 space, if that relation be changed, the whole atom will share 

 in the change. If the central nucleus contracts by pulses^ or 

 minute vibrations, these must be radiated from it in the manner 

 of waves traversing space like the radiant pulses of light. But 

 why are not these waves the same with those pulses? Assum- 

 ing their identity, there would then he no place for an hypothesis 

 of a peculiar ether of light and heat ; since the atoms do of them- 

 selves constitute an ether ; for they pervade all space. 



Assuming that the temperature of an atom is an expression for 



C C 

 the diameter of its nucleus, if two atoms p ; — n p' ; — n'^ 



are in contact, but of different temperatures, their forces will 

 react in such a manner, that the difference shall be divided be- 

 tween them ; p'w' will contract, and j9 7i expand, the distance 

 between their centres remaining constant. And this will repre- 

 sent the restoration of the equilibrium of temperature by contact 

 of particles of the sam,e kind. 



But if the atoms are not of the same kind, (that is to say, if 

 the relation between the size of their nuclei and the normal 

 intensity of their polarities, (for that size,) be not the same,) the 

 equilibrium will be restored, and yet a difference of size or of 

 intensity may remain. And this difference will represent the 

 ratio of the specif c heats of the atoms. 



When two nuclei are brought into contact with each other 

 at different temperatures, one of them contracts as the other ex- 

 pands ; the cow^rac^w.^ nucleus will radiate "heat pulses," and 

 the expanding one " cold pulses ;" and the two kinds of radia- 

 tion, like opposing pulses of sound, will exactly cancel each 

 other; and no heat will become sensible. The outflowing or 

 " heat pulses," propagated through the whole of space with a 

 certain mensurable velocity, will cause expansions in other nuclei 

 through which they pass. 



