A study of the electrical conductivity of foam

The relationship between the volumetric fraction of liquid in a foam and the ratio of the conductivity of the foam to that of the liquid was studied experimentally. The method employed a precise yet convenient, novel, sampling technique which involved snatching a removable test section away from a vertical column of slowly ascending, ordinary, polydisperse foam. Results confirmed and extended the classical experiments of Clark, and showed the existence of an essentially unique relationship. In addition, this experimentally determined relationship was approximated with theory by extending the approach of Meredith and Tobias. Finally, extrapolation of the experimental results was shown to confirm the limiting value of 3.0 derived by Lemlich for the ratio of the said volumetric fraction to the said conductivity ratio as the volumetric fraction approaches zero.