W. A. Norton—Force of Effective Molecular Action. 445 
At the point of incipient condensation of carbon-dioxide, 
ine below the ‘critical temperature” (81° C.), for which 
=73r I find g=27114. With this value of g, and k=4°7 I 
Shiain P,=72'2 atmospheres. Dr. Andrews found the elastic 
pressure at the critical point to be 75 atmospheres. The small 
discrepancy results from the fact that the precise critical curve 
is slightly below that for k=4°7, and the corresponding molec- 
ular repulsion is greater in the ratio of 51, or 52, to » Mak- 
ing me Mpubige. we have or P, 75 or 76 atmosphere 
o examples must suffice for the present as "ede: 
tions of i applicability of ie formula, and verifications of its 
accuracy. 
From the point of view I have taken, chemical combinations 
consist, essentially, in changes effected in the condition of the 
molec ules of the constituents, by which they are brought into 
approximate correspondence, and take up the relative positions 
suited to that uniform condition, just as a mass of similar mole- 
cules in that date would do. The change of state consists 
results a change in the value of the ratio &, ane in the corres- 
ponding curve of effective action. The determining cause of 
this change is the difference in the mechanical condition of the 
dissimilar molecul ore or less enhanc the unequal 
either an expansion of the one molecular envelope and collapse 
of the other, or a collapse of ize incited by a flow of electric 
ether from the source of heat or electricity. The union of 
ate 
bustion, we must suppose there is a flow of electric ether fos 
the solid to the oxygen molecule, and the former molecule 
expands somewhat while the meg contracts to the dimensions 
answering to the solid conditio 
eat, in its association with anes consists of the energy 
of recurring pulses and vibrations in the molecular envelopes, 
and has two modes of motion or two dynamical aspects, radial 
and tangential. The energy connected with the former, is the 
origin of its expansive force. The propagation of the jaiten in 
ethereal waves of transverse vibration, constitutes the ra 
heat emitted by bodies. 
Heat energy may be expended not only in the expansion of 
bodies, but also in augmenting the potential energy of the 
individual molecules by enlarging their envelopes. In this 
way a certain amount of heat becomes latent in the process of 
liquefaction. A portion of the heat of vaporization is expende 
