Some Experiments bearing on the Theory of Voltaic Action. 369 



Therefore the maximum mean efficiency was 0' 193 in the case of the 

 woman from seven experiments, and the minimum mean efficiency was 

 0*174 for E. E. from seventeen experiments; the general mean from 

 five different persons was 0*183. 



The general results obtained from this inquiry can be summarised as 

 follows : 



(1) There is no fixed relation per individual experiment between the 

 oxygen absorbed under excercise and the corresponding heat emitted, 

 although the mean for each person somewhat approximates a constant 

 figure which is 1 to 3*246. Considering that in the state of rest we 

 found the corresponding ratio to be 1 to 4-000, it may be concluded 

 that the oxygen is better utilised for the production of heat in a state 

 of rest than under exercise. 



(2) There is a marked excess of heat over normal given out under 

 exercise, this excess ( + theoretical heat) produced in doing a definite 

 amount of work (say 1000 kilogram-metres) varies for each of the five 

 persons under experiment. 



(3) The efficiency, or economic coefficient, for the five persons under 

 experiment varied from 0*193 to 0*174 with a mean of 0*183 ; or 18*3 

 per cent, of the excess heat produced + the theoretical heat corre- 

 sponding to the work done. This is a little less than a fifth. 



" Some Experiments bearing on the Theory of Voltaic Action." 

 By J. BROWN. Communicated by Professor EVERETT, F.RS. 

 Eeceived February 4, Eead February 23, 1899. 



In former papers on the " Theory of Voltaic Action,"* I have 

 adduced evidence in support of the view that the difference of electric 

 potential observed near the surface of two metals in contact is caused, 

 or at all events mainly influenced, by the chemical activity of films 



* 'Phil. Mag.,' vol. 6 (1878), p. 142; ibid., vol.7 (1879), p. 109; <Koy. Soc. 

 Proc.,' vol. 41 (1886), p. 294. 



