1902.] 



and Statics under the Action of Light. 



73 



according to the laws of action of mass, if the same chemical reaction would 

 go on in the dark as the outcome of those intrinsic properties of matin- only, 

 which we call chemical affinity or chemical potential. In the above equa- 

 tions K is the velocity constant, which gives the velocity of combina- 

 tion of Cl^ and CO, under given conditions of experiment, when A - x 

 for CI 2 is 1, and ~B-x for CO is 1. It should be remarked that K in 

 the above equations is the integral velocity-constant for acetylene 

 light, because the value of (K) is for each wave-length different. 

 Since, however, each wave-length has an equation of the same form 



~ - (K) (A - x) (B - x), the equation for light consisting of more than 



one wave-length remains the same, K or (K) is besides a function of 

 the intensity of light, of the temperature, of the chemical nature of 

 the reacting substances, and of the surrounding medium. 



The combination of CO and CI2 was allowed to go on so far as 

 80*66 per cent, of the total amount of possible combination in Table II 

 and 39*16 per cent, in Table III. On interruption of the light for 

 different periods and exposing the system again to the light, the induc- 

 tion periods changed according to circumstances, but always the same 

 velocity constant was observed. This shows that the above equation 

 must truly represent the fundamental law underlying velocity of 

 reaction in light. The results obtained further show that the velocity of com- 

 bination af CO and CI2 cannot possibly be regulated by a laid analogous to 

 that of Faraday, because this velocity is neither directly proportional to the 

 amount of light passing through the system nor to the light absorbed by the 

 same in the unit of time, the calculated values which ought to have 

 given a constant, falling for Table II from 25*2 to 4* 14, and from 

 40 to 18-6, and for Table III from 509 to 99, and from 187 to 136. 



The author further gives instances of chemical equilibria in homo- 

 geneous systems in light, in which one of the two opposite reactions 

 goes on only in light, and the other in light and in the dark, and 

 shows that since chemical equilibrium in a homogeneous system, as is estab- 

 lished, represents a reversible system, in which the two opposite reactions 

 become equal, and since the velocity of each reaction separately follows the law 

 of action of mass, the evidence is given by the above results that chemical 

 equilibrium in homogeneous systems must also and can only follow in light 

 the laws of action of mass, as they follow in the dark. 



Besides the above results, the author deals on the basis of the 

 experiments made with the phenomena of chemical induction (when the 

 system is exposed to light ; first observed by Bunsen and Koscoe) and 

 of chemical deduction (when the light is removed from the system), as 

 well as with the induction and deduction periods of energy ■ he also shows 

 the enormous influence of small traces of air and of water vapour upon 

 the velocity of the reaction (the first retards, the second accelerates 

 the same). 



