No abstract

The effect of salts and gelatin on the surface tension of solutions of Manoxol OT has been studied in the period from 0.2 to 100 sec after formation of the surface by a bubble-pressure method. The effect of salts can be explained on the assumption that adsorption at the surface is controlled by diffusion up to the point where an electrostatic energy barrier begins to be formed by the adsorbed molecules. This point occurs at increasingly low surface tensions as the total electrolyte concentration increases.Gelatin exhibited only the typical effects of a monovalent electrolyte when added to Manoxol solutions. There was no evidence that it affected the diffusion rate, nor the critical micelle concentration of the wetting agent when an excess of electrolyte was present, as would be expected if a complex were formed.

No abstract

The effect of layer thickness on the elastic response of thin layers loaded with a relatively large ball indentor was determined with a Wallace Indentation Tester. Thin coatings of gelatin gel on a rigid support were used and the identation results compared with absolute determinations of rigidity modulus. The empirical equation obtained relates rigidity modulus to the load, indentation, layer thickness and ball radius. The constant in the equation obtained for gelatin gels of rigidity modulus up to 1·5×105 dyn cm−2 was found to apply also to rubber of rigidity modulus 107 dyn cm−2.

No abstract