CHEMICAL REACTIVITY AND LIGHT ABSORPTION. PART IV.

Total absorption of light by a mixture of the reacting substances has been observed to be greater than the absorption of each substance taken separately in reactions studied in the present paper. The increase in light absorption in each case varies with the concentration of the reducing agent. The dark reaction velocity also decreases with the decrease of concentration of the reducing agent. The chemical reactivity and the increase in the light absorption by a mixture are almost equally affected by a change in concentration of the reducing agent. The increased Iight absorption appears to be due to the activation of molecules in the presence of the molecules of the sensitising agents. The activation of the molecules is associated with loosening of the binding forces and the consequent increased light absorption