AND CHLORINE UNDER THE INFLUENCE OF LIGHT. 
101 ) 
(3.) Radium Rays. —The rays from a specimen of radium were found to produce 
no effect after two hours. 
(4.) Hydrogen Peroxide. —Hydrogen peroxide was introduced into the insolation 
bull), and the effect was, as in the case of other impurities, to diminish the rate of 
action. 
HI. Theory of the Action. 
At present there is nothing that can he called a satisfactory theory of chemical 
action. In nearly all cases the process of an action is very much more complicated 
than is expressed by ordinary chemical equations. These represent only the initial 
and final stages which are observed. For example, in actions between electrolytes in 
solution the individuals taking part in the change are ions and not the salts them¬ 
selves ; and in gaseous systems there appears to be, in very many cases, the necessity 
for some catalyser to be present for any action to occur. The law of mass action has 
jDi'oved very fruitful as the foundation of chemical kinetics, but the most successful 
applications of this law have been in cases of actions between molecides in solution, 
and when gaseous actions have been used as subjects of investigation for the 
application of this law, the results have only in a few cases'^ been in agreement 
with what the law would lead us to expect. Even in these instances the initial 
stages of the actions have not been studied, so that the agreement with the expected 
results is only for the case when the action has pi'ogressed for some time. The 
hydrogen and chlorine action is the one to which most attention has been paid in the 
initial stages, and the initial phenomena do not at all agree with those to he expected 
from equations derived on the ordinary chemical kinetic theory. 
The case of solutions is different from that of gases, as the action is between ions, 
and the mass law applies at once, for the final products result from direct combination 
of ions. In gaseous systems, however, we have at the beginning of the action 
stable gaseous molecules, and the production of the final compounds requires a 
decomposition, so that the atoms which originally were united become separated and 
attached to different atoms. An action of this kind therefore involves at least two 
steps—a decomposition and a composition. In most gaseous actions, in addition to 
the gases themselves necessary for the formation of the final products, some catalyser 
is also necessary for the action to proceed with a finite velocity. 
The case of a gaseous action is thus still further complicated. In addition to the 
change from the one form of stable molecule to another, there is the part played by 
the catalyser to consider. Water vapour is the most commonly-occurring catalyser 
of this kind, and the natural assumption to explain its action is that intermediate 
compounds with the molecules of the re-acting gases are formed. We are thus led to 
* For example, “ The Decomposition of AsHs and PH3,” Koou, ‘ Zeit. Pliys. Chemie,’ vol. 12, p, 155; 
“The Formation of HoS and HoSe, and the Formation of HI,” BoDENSTEiN, ‘Zeit. Phys. Chem.,’ vol. 29. 
