98 ACTION OF LIGHT RAYS 



of such a system are treated of in this section, and tire effects of 

 general or local concentration are considered. The equilibrium 

 point in reversible reactions is shown to be dependent on concen- 

 tration. 



In the concluding section a general reversible reaction is de- 

 Ascribed as a result of which formaldehyde arises in all intense 

 reactions of light upon substances of biochemical origin. This 

 reaction in presence of excess of light is an interesting reversal of 

 the process by which all organic matter has been built up from 

 inorganic sources. 



The bearing of this process upon the germicidal action of sun- 

 light, and the destruction of living organisms by ultra-violet light, 

 is discussed, and it is pointed out that the simple organic products 

 so formed are incompatible with the life processes of living organ- 

 isms, and so lead to their destruction. 



