144 REPORT—1890. 
by some such relation asf s= 4m v*. Now, for the sake of temperature equilibrium, 
with molecules of somewhat similar structure, + m v? must be the same in all. It 
seems likely that, at least approximately, the kinetic energy of motion is proportional 
to the total energy, and that this is the same for each molecular group; if so, the 
kinetic energy must be approximately the same for different groups. Now, with very 
dilute solutions s must be nearly the same for different molecules, and if so we get 
that for temperature equilibrium f must be independent of the nature of the mole- 
cule. How this equalisation of f for different kinds of molecules comes about may 
be as follows. Molecules in a liquid move about among one another, but are well 
within the sphere of another’s attraction, as is evidenced by superficial tension and 
by the tension to which a liquid can be subject. A very small change in the distance 
apart of the molecules means, however, a very great change in the forces between 
them, as otherwise they would be extensible and compressible like gases. It seems 
likely, then, that when a salt dissolves in a liquid it requires for temperature equili-- 
brium that the distances of the molecules should change by the very small amount 
required in order that f may become the same for all substances. This very minute 
change in distance would not visibly affect s. 
The Committee request Mr. Shaw to continue his report on Electro- 
lysis, with the co-operation of Mr. Fitzpatrick ; and they ask for reappoint- 
ment, with a grant of 5/. to cover printing and postage expenses. 
Sixth Report of the Committee, consisting of Sir G. G. SToKEs 
(Chairman), Mr. G. J. Symons (Secretary), Professor ScHUSTER, 
Dr. G. Jonnstong Stoney, Sir H. E. Roscor, Captain ABNEY, 
and Mr. Wuterie, appointed for the purpose of considering the 
best methods of recording the direct Intensity of Solar Radia- 
tion. 
Ow1ne to the death of Professor Balfour Stewart and the numerous ayo- 
cations of Professor Schuster, the instrament constructed by this Com- 
mittee has not yet been tried. The Committee have now traced all parts 
of the apparatus and of the correspondence relating to it, and they are 
glad to state that Professor McLeod has agreed to join the Committee 
and to conduct a series of experiments with the apparatus. 
Report of the Committee, consisting of Dr. Joun KERR (Chairman), 
Sir WILLIAM THomson, Professor Ricker, and Mr. R. T. Guaze- 
BROOK (Secretary), appointed to co-operate with Dr. KERR in his 
researches on Electro-optics. 
Som progress in the experiments for the conduction of which the 
Committee were appointed has been made by Dr. Kerr, but the Com- 
mittee regret to have to report that they are still only in the preliminary 
stage. The first trials were made last winter at some length, but were 
without effect. The difficulty arose from some unexpected and serious 
defects in the new plate cell, which are now being remedied. 
The Committee hope that the apparatus may be in working order 
shortly, and look forward to being able to make a full report next year. 
They ask for reappointment. 
