1. For description of some of the types of adsorption important in everyday life and in Nature, see e.g. C.H. Giles, Chem. and Ind., 724, 770 (1964).
2. J.W. McBain and C.W. Humphreys, J. Phys. Chem., 36, 300 (1932); J.W. McBain and R.C. Swain, Proc. Roy. Soc. Ser. A, 154, 608 (1936).
3. E.S. Snavely, G.M. Schmid and R.M. Hurd, Nature (London), 194 439 (1962).
4. W.C.M. Lewis, Phil. Mag., 15, 499 (1908); 17, 466 (1909); Z. Phys. Chem., 73, 129 (1910).
5. C.W. Gibby and C.C. Addison, J. Chem. Soc. London, 119, 1306, (1936).