386 DR. MEYER WILDERMAN ON THE CHEMICAL STATICS AND DYNAMICS OF 
failure is not far to seek ; in all the above researches the reactions used are either of 
a compound character (Cl 2 and H 2 ) or they do not admit a quantitative investigation 
(Anthracen and Dianthracen); the authors possessed no constant source of light 
and no photometer for measuring its intensity, take no account of the induction 
(except Bevan) and deduction periods, nor of the very great number of sources of 
error one meets in this regiou. 
(b) Experimental Proof that Chemical Equilibrium in Heterogeneous Systems, when 
Shifted by Light at a Constant Temperature to a Neiv Point, follows, after the 
Induction Period has passed, the same Laws as in the Dark. 
Since the E.M.F. of the reversible heterogeneous system forming the galvanic 
cell gives, after the induction period has passed, the maximum work performed 
in it under the action of light, and since the equations giving the maximum work 
under the action of light contain also the constant of chemical equilibrium of the 
heterogeneous system, as in ordinary galvanic cells, an experimental proof is thus 
given that chemical equilibrium in heterogeneous systems follows, under the action 
of light (after the induction period has passed) the same laws as in the dark. In 
the ‘ Zeit-schr. physik. Chemie’ (vol. 30, pp. 371-382, 1899) I showed that the 
laws of Guldberg and Waage and others, for equilibrium of ordinary hetero¬ 
geneous systems, must be conceived as the result of a combination of static 
equilibria between the different parts of the heterogeneous system and of dynamic 
equilibria in the homogeneous parts, and that it is the form of the last which 
determines at the same time the form of Guldberg-Waage’s laws. The present 
research, dealing with heterogeneous systems, gives us for this reason at the same 
time also experimental proof that equilibrium in homogeneous systems, and with it 
velocity of reaction, follows in light, after the induction period, the laws of mass 
action. 
(c) The Maximum Work (Constant of Equilibrium) and the Laiv of Intensity 
of Light. 
We have found that the E.M.F. or maximum work done under the action of light 
in the reversible heterogeneous systems forming the galvanic cells is, after the 
induction has passed, directly proportional to the intensity of light. 
This must therefore hold good, after the induction period, also for the maximum 
work done under the action of light in homogeneous system, i.e., 
RTlog.g!!l^-; = RTlog,|i = ETlog.K = CI 1 . 
Kh 
( a )> 
where C 2 . . . C 3 , C 4 . . . are the concentrations of the substances taking part in 
the opposite reactions, K 1} K 2 the velocity constants of the two opposite reactions, 
