Calcium and Hydrogen ion Concentration and the Interfacial Tension of Pyrethrum Extracts (With Four Text-figures.)

Abstract

1. The addition of a pyrethrum extract to a petroleum solvent, semirefined white spirit, considerably lowers its interfacial tension against water. The tension also depends upon the reaction of the aqueous phase, decreasing as the alkalinity increases.2. The addition of agral W.B. to a solution of pyrethrum extract further lowers the interfacial tension more especially against acid solutions, thereby decreasing the sensitivity of the tension value to thepH of the aqueous phase.3. The presence of calcium salts in the aqueous phase raises the interfacial tension of solutions of pyrethrum extract.4. Alkaline salts counteract the effect of calcium salts, and the resulting tension values can be correlated with the ratio of calcium to hydroxyl ion concentration.