AND STATICS UNDER THE INFLUENCE OF LIGHT. 
391 
tion ” and “induction.” On exposing the system for the first time to light, the 
energy of the light is absorbed by the system for a considerable time before the 
atoms and molecules acquire the state of energy when the reaction becomes apparent, 
i.e. , the energy of the system first continuously increases and changes though no 
chemical effect can be perceived in the system. When the chemical reaction 
becomes evident the chemical “ induction period” then continues till the new constant 
state of energy characterised by K is reached. On removing the light, the chemical 
“deduction period” continues only a short time, when the reaction ceases to take 
place, but it takes a long time for the atoms and molecules to lose those properties 
which they acquired in the light before chemical reaction started, and this gradual 
diminution of the energy of the system is again not to be discovered from the 
chemical reactions of the systems. The chemical “ deduction period,” however, lasts 
much less time than the chemical “induction period.” It is evident that the curves 
of the “ induction ” and “ deduction periods ” given above only rejmesent the amount 
of chemical transformation, i.e., are curves of chemical “ induction ” and “ deduction,” 
and are not the curves which represent the gradual increase and decrease, the 
“induction” and “deduction” periods, of the whole energy of the system, when it is 
exposed to light or when light is removed from the same. There are other methods 
by which the variation of energy during the “ induction ” and “ deduction ” periods 
may be determined. The author is now engaged in the elucidation of the laws 
concerning the induction and deduction periods of energy which up to the present 
have only the character of qualitative observations.* 
The InjliLence of Small Traces of Air and Water upon the Mixture of Pure 
Chlorine and Carhon Monoxide (and other Gaseous Systems ). 
The admixture of small traces of air with the reacting gases jnoduces a most 
remarkable retarding effect upon the velocity of the reaction. Bunsen and Boscoe 
found that this held for a mixture of chlorine and hydrogen, so that it appears to 
be a general rule for all gaseous systems. 
Two “ quartz vessels ” were placed one behind the other, both vessels were 
evacuated and treated in exactly the same way, and finally filled with carbon 
monoxide from the same sample at the same time. Chlorine from the same sample 
was driven by means of the same concentrated sulphuric acid (which, for reasons 
mentioned before, it was impossible to keep for any length of time quite free from 
* As to the chemical induction and deduction periods it is evident that, since velocity of reaction 
follows the law of action of mass, when the molecules taking part in the reaction have attained, under 
the influence of light, a constant value of their chemical potentials, the same law of mass action must also 
he the governing principle for the velocity of reaction at any given moment of the chemical induction and 
deduction periods, only the velocity constant, K in equation (3), will vary in time as the chemical 
potentials of the reacting substances change. 
