AND STATICS UNDER T1IE INFLUENCE OF LIGHT. 
389 
of mass action. If after the values of K remain constant for a sufficient time, the 
light is removed for some hours, and the system again exposed to the light, we again 
find the same phenomenon ; the velocity constant K is not obtained at once but only 
after the reaction has gone on for some time. Further, it is found that in every 
case the same velocity constant is obtained after a time. It follows from this that 
the combining chlorine and carbon monoxide when exposed to light of a certain 
intensity and composition, always acquire after a certain time the same constant 
properties, the same chemical affinity to one another. The fact that the same 
constant was found in all curves of the same system, and that the investigation was 
carried on as far as 80'66 per cent, (in Tables I. and II.) and 39T6 per cent, (in 
Table III.) of the total amount of possible combination, shows that the above 
equation (3), p. 377, which is a true expression of the law of mass action, truly 
represents the fundamental law underlying chemical kinetics in light. At the same 
time the last two columns of the above tables illustrate beyond any doubt that it is 
no longer possible to assume that a law analogous to Faraday’s for electrolysis 
governs the phenomena of chemical kinetics in light. 
Instead of getting a constant in the last columns, the values of dx/dr -100 fall 
from 25'2 to 4T (in Table II.), and from 40 to 18'6 (in Table III.), and the values of 
~ : ^ ^ (in Table II.) fall from 50'9 to 9'9, and (in Table III.) from 205 
to 136. Special attention should be given to the curves (l), (2), (3), (4), and (5), 
of Table II. Here a large quantity of chlorine and a small quantity of carbon 
monoxide were employed ; in this way the variations in the quantity of carbon 
monoxide were increased, and in that of chlorine made small, i.e., it is the variation 
in the quantity of the carbon monoxide which absorbs but little light, and not in the 
quantity of the chlorine, which absorbs much, which in this case proves to be the 
main cause of the velocity of reaction decreasing so rapidly. It is thus evident that 
it is not the quantity of light absorbed by the molecules in the unit of time, but the 
quantity of the reacting substances present, which determines the velocity of the 
reaction, no matter what quantity of light the molecules absorb, provided that under 
the action of light the atoms and molecules acquire that quantity of energy which is 
characteristic of them after the period of “ induction ” has passed. In other words a 
system containing two molecules chlorine and one molecule carbon monoxide will 
combine at the same rate as a system containing one molecule chlorine and two 
molecules carbon monoxide, though the first system absorbs almost twice as much 
light as the second. 
The “ Induction ” and “ Deduction ” Periods of Energy of the System and the 
Chemical Periods of “ Induction ” and “ Deduction ” in Light. 
Having considered those parts of the curves where the velocity constant can be 
traced, we now consider the parts before the velocity constant is reached. We find 
