W. A. Norton on Molecular and Cosmical Physics. 29 
the impinging atoms, or molecules, should give rise to a mutual 
repulsion, whatever might be the relative direction of the 
motions. In fact, in whatever mode of molecular motion heat 
may be supposed to CORE i ness be the only force of repul- 
sion, a certain amount of the living force of heat belonging 
to each of two impinging bodies would be expended in 
ishing the velocity of the one body and ae that of the 
other, and it would be impossible that they should become 
heated by the impact. Itis here assumed that the impact of 
two bodies must develop a force of mutual repulsion between 
the impinging molecules, which determines the equality of the 
action and reaction. This obvious fact seems now-a-days to be 
in a good degree ignored, and the exchange of momenta to be 
supposed to be brought about by some rey pees process, 
in which nA idea of force is shally lost si 
e must then conclude that there is a primary force of 
Sea repulsion, in addition to that of heat. We mi 
perhaps ascribe this force to the repulsion of the ethereal molec- 
ar atmospheres when brought into ae but to what can 
we ascribe the heat-repulsion? It has ome to be generally 
believed that it must consist in some HEB of motion of the 
atoms, or molecules of bodies, as a whole; either of vibration, 
revolution, or rotation. But it might be almost demonstrated, 
did space permit, that this cannot : the true nature or origin 
of heat. 1 will only allude here to one or two argum 
on rt of this statement, which may be briefly given. It is 
well known that whenever any body i is by collision eh another 
Y, orin any other way, p is given 
a Now me ~~ t that a force of pressure, or eto n, pro- 
a perm + compression, increasing W1 with its intensity, 
leads to the sisce inevitable inference that in sed act of com- 
1s ta and the condensation maintain ed. and that 
once must be proportionate to the degree of condensation, Dy 
to the amount of ews evolved. Can such a ce he oe 
— to the heat evolved, be connected by any admissibl 
rice ggamcasien with the a anemia Ligsgnets of "ibriton, revolt 
crease 0 
can | ascribed to an i motion “of ordinary atoms, or 
molecules, whether me are surrounded with ethereal atmos- 
