Thus, for the perchlorates the self-ionization equilibrium might be represented as CIO4-C103+ + O2-(32) and Cl2 evolution would then ensue by the reaction C103+ + CIO4--> [CIA] -> Cl, + 7*0, (33) Such a mechanism would also be consistent with the oxide-donating or basic properties of perchlorates, so that an 02_ ion acceptor or acid would move reaction 32 to the right and thus increase the rate and extent of reaction 33. A number of investigators have noted that catalysts for MC10, and MCIO4 decompositions can generally be divided into two categories: oxide catalysts (e.g., Fe203, Mn02, Bi203, CuO, Sn02, etc.) which yield substantially Cl2-free 02 and oxide catalysts (e.g., PA, B203, W03, Mo03, V205, etc.) which cause much Cl2 production. It now seems clear that the first group of materials represents true catalytic agents while the second group of substances are polymeric acids, capable of 02~ion capture and thus enter into specific, irreversible chemical reactions with the Cl-containing oxy anions.Acknowledgment. The aid and encouragement given by B. Schrier during the performance of this work are greatly appreciated.Remarks on Refractive Index Mixture Rules

has shown that commercial azobenzene mainly consisting of the trans isomer can be converted partly into the cis isomer, when exposed to daylight in dilute solution. He

No abstract

It had previously been found in this laboratory that flexible polymer molecules adsorbed at colloidal particles most likely extend with many segments into the interior of the surrounding medium. This led one to expect a possible “steric protection” of colloidal particles by adsorption of flexible polymers of sufficiently high molecular weight since the merely slight interpenetration of polymer chains protruding from two colliding particles should keep them at distances too large to give a van der Waals interaction energy sufficient for coherence. This new type of stabilization was now proved using gold hydrosols as test systems and polyethylene glycols as adsorptives. The stabilization was found to increase with polymer concentration and, particularly, with the molecular weight of the polymer. In analogy with the previous finding, that the adsorption equilibrium is being approached very slowly if the molecular weight of the polymer exceeds several thousand, it was found that the degree of stabilization achieved by addition of polymer to the gold sols increases with the time elapsed before the subsequent addition of coagulating electrolyte. This increase is particularly strong during the first hour following addition of the polymer. The potential significance of the results for stabilization of organosols is discussed.