Grieves, R. B., Ugonnaya Ogbu, I.,
Bhattacharyya, D., and Conger, W. L.
Foam fractionation rates.
Separation Science, Vol. 5, No. 5, pp. 583-601, 1970.
Mentions producing the bubbles by precipitation of dissolved air. The
mention is brief, and without a reference.
Selected References
Lemlich, R.
Ind. Eng. Chem.
Vol. 60, No. 10, p. 16, 1968.