Observations and photographs of black and grey soap films,” Proc. Collected Papers of Sir James Dewar, edited by L. Soap films as sound detectors: Stream lines and sound,” Proc. He may be one of the few scientists who took the close-up picture of the flow pattern of soap film at the end of 19th century. He has studied at his late research years on the dynamic properties of soap bubble film as a detector of sound. Professor James Dewar of Cambridge University is a British chemist and physicist renowned for his memorable accomplishments in cryogenic science and the invention of heat-insulating flask as well. The whole process occurs in the course of gravity-induced syneresis of aqueous soap film.
The phenomena were explained as the deposition of liquid crystalline phase in the isotropic gray film the nucleation of which is triggered by the stick-slip frictional sliding motion of black film at the border of gray film. The frequency of oscillational shear was found to be around 10 Hz for the shear velocity of 3 cm/s, which was approximated from the increased rate of black film area and the interval of beads in video images. The successive and periodical deposition of tiny white particles to form “threaded pearls” is explained as the result of repeated nucleation of liquid crystalline phase as triggered by the stick-slip frictional sliding of black film at the boundary of the isotropic gray film and the subsequent growth of particles by isothermal condensation. The flow pattern of “threaded white beads” was found to appear at the shear boundary of black and gray flowing films. The close-up pictures were taken by both still and video cameras at the magnification of around 10× with time for the draining flat bubble film prepared in vertically held rectangular frame made of a thin glass rod. The concentration of aqueous surfactant used is as high as 5% by weight. The flow patterns of “pearl string” in draining bubble film as first witnessed by Sir James Dewar some 100 years ago were successfully reproduced by using chemically stable aqueous alkylbenzenesulfonate instead of alkylcarboylate used by Dewar as a soap.
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