330 REPORT—1890. 
would rather look for an explanation of both in the direction I have 
already pointed towards as to the dependence of the forces between 
molecules upon their distance apart and on the way these and their 
internal energy are all bound together by the conditions of temperature 
equilibrium. The question is evidently in the highest degree compli- 
cated, and for a complete discussion must introduce the theory as to the 
nature of temperature equilibrium, and in the meanwhile it is misleading 
to pretend that a matter is simple which is in reality most obscure by 
speaking of acknowledged analogies as if they really explained anything. 
It may be of interest to remark in connection with the question of the 
chinks within which molecules move that a very rough estimate can be 
made as to their size by considering the crude hypothesis that each ion 
is moved by the electric force near it acting on its ionic charge, and by 
calculating how long it would be in getting up its ionic velocity. Assum- 
ing that the ion moves like a body in a viscous liquid, the time it takes 
to get up its velocity must be a very small part of the time during which 
a current acts on it, and for which it obeys Ohm’s law, because, for this 
to hold, the velocity must be independent of the time during which the 
current is acting. By some rough estimates as to the quantities involved 
it appears that the time during which an atom is acquiring its ionic 
velocity is somewhere about 10°!° of a second, and that the space it 
would acquire it in is about 10° of a centimetre. This seems as if the 
intermolecular bombardment distances were probably very small, and it 
shows that we can hardly expect Ohm’s law to fail for electrolytes due. 
to this cause until the rate of alternation of our current is comparable | 
with that of light. Of course the actual jostling of an atom through the 
molecules can hardly be fairly represented by such a crude hypothesis as 
that it is like a body moving in a viscous fluid ; yet such a calculation as 
the above may be of use in showing the sort of quantities we may have 
to deal with. 
Professor Ontver Lopce said he had not been closely attending to 
these subjects during the past year or two, and accordingly only made 
a very few remarks, mainly with reference to the views he formerly 
expressed. 
He had always endeavoured to moderate between the extreme disso- 
ciation views on the one hand, and those which require the molecule to 
be electrolytically torn asunder on the other. One reconciling fact is the 
chemically proved fact of double decomposition whenever two substances 
are mixed; this seemed to him to establish clearly that molecules are 
accustomed to interchange their atoms. Now, during the moment of 
interchange there is an instant of freedom, an instant of potential dissocia- 
tion, and it is upon this that he had looked as the opportunity demanded 
by electric force to cause a slight diversion, sufficient in the long run to 
result in opposite atomic processions. 
But, as Fitzgerald has somewhere pointed out, an infinitesimal moment 
of time is not sufficient to permit any finite effect, unless the forces acting 
are enormous, which in the middle of the liquid they certainly are not. 
This is therefore a difficulty, for if the atoms are solitary for any reason- 
able time, that amounts at once to actual dissociation, as postulated by 
Clausius. One may have to fali back, therefore, on the outlying atom 
stragglers from gross complex molecules as giving the necessary pseudo- 
freedom or potential dissociation which is all that Ohm’s law and electro- 
