AND STATICS UNDER THE INFLUENCE OF LIGHT. 
377 
The differential equation giving the law of velocity of reaction is thus 
f = K (A - z) (B - *).(3), 
%. e. , the velocity of combination of chlorine and carbon monoxide in light, or the 
velocity of the formation of carbonyl chloride, is at the time r directly proportional to 
the product of the reacting masses at the time r. Since the chemical equation for 
the reaction is Cl 2 + CO = CO Cl 2 , this equation, in light has the form which it ought 
to have according to the law of mass action in homogeneous systems, if the chemical 
reaction were to go on in the dark as the outcome of those intrinsic properties of 
matter only, which we call chemical affinity or chemical potential. In the above 
equations K is the velocity constant, which gives the velocity of combination of chlorine 
and carbon monoxide under given conditions of experiment, when A — x for chlorine 
is 1 and B — x for carbon monoxide is 1. K in the above equations is evidently also 
an integral velocity constant for all wave lengths of the acetylene light, the value of 
(K) being different for each wave length. Since, however, each wave length has an 
Jx 
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, and of the surrounding medium. 
In the following tables (II., III., IV. and V.): 
No. is the number of the observation. 
tt' — n" = dx is the amount of carbonyl chloride formed, or of chlorine or of carbon 
monoxide which has disappeared during the times r 2 — r 1 . 
A — x is the quantity of chlorine present in the system at the time r. 
B — x is the quantity of carbon monoxide present in the system at the time r. 
r 2 — is the time between two successive observations. 
Equation (2) should be true if the law of mass action holds good. 
— gives the rate of formation of carbonyl chloride at the successive times ; this 
ought to be constant, if the rate of formation of carbonyl chloride in a unit 
of time were independent of the reacting masses and were directly proportional 
to the intensity of the light introduced only. 
St 
i ; ( A — x ) gives the rate of formation of carbonyl chloride at the time r, divided 
by the quantity of chlorine present in the system at the time r. This ought 
to be constant if the rate of formation of carbonyl chloride at a given intensity 
of light were directly proportional to the amount of light absorbed by the 
system (i.e., by chlorine) in the unit of time during the reaction. 
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VOL. CXCIX.-A, 
