450 A NOTE ON ADSORPTION [ch. 



vast aggregate of interfacial contact. It gives us a new conception, 

 as Wolfgang Ostwald was the first to shew, of the relation of oxygen 

 to the red corpuscles of the blood*. But many more and still more 

 comphcated "film-reactions" are started or intensified by the oriented 

 molecules of the monolayer. The catalytic action of living ferments 

 (a subject vast indeed) is largely .a question of modified adsorption, 

 or of surface-action. The range of bodies so adsorbed is extremply 

 hmited; the specific reactions, which depend on the bacterium 

 engaged, are fewer still ; and sometimes a whole class of substances 

 may be adsorbed, and only one of them thrown specifically into 

 action!. The physiological, and sometimes lethal, actions of 

 various substances are examples of similar effects. The chemistry 

 of the surface-layer in this cell or that may be elucidated by its 

 reactions to various "penetrants," and depends somehow on the 

 molecular orientation of the surfaces, and on the potentials associated 

 with the characteristic electric fields which we may suppose to 

 correspond to the particular molecular arrangements J. 



It is the dynamic aspect of the case, the ingresses, egresses and 

 metabolic changes associated with the boundary-layer, which interest 

 the physiologist. He finds the monolayer acting in ways not known 

 in a homogeneous hquid — and adsorption is one of these ways. We 

 keep as much as may be to the morphological side of the case rather 

 than to the physiological, to the static side rather than to the 

 dynamic, to the equilibrium attained rather than to the energies to 

 which it is due. We continue to speak of surface, and of surface- 



* Ueber die Natur der Bindung der Gase im Blut und in seinen Bestandteilen, 

 Kolloid Ztschr. ii, pp. 264-272, 1908; cf. Loewy. Dissociationsspannung des 

 Oxyhaemoglobin im Blut, Arch. f. Anat. u. Physiol. 1904, p. 231. Arrhenius 

 remarked long ago that the forces which produce adsorption are of the same order, 

 and of the same nature, as those which cause the mutual attractions of the molecules 

 of a gas. Hence the order is constant in which various gases are adsorbed by 

 different adsorbents. The question of the inner mechanism of the forces which 

 result in surface-tension, adsorption and allied phenomena, and their relation 

 to electric charge on particles or ions, belongs to the highest parts of physical 

 chemistry. Besides countless recent papers, M. v. Smoluchowski's Versuch einer 

 mathematischen Theorie der Koagulationskritik, Z.f. physik. Chemie, xcii, pp. 129- 

 168, 1918, is still interesting. 



t Cf. N. K. Adams, Physics and Chemistry of Surfaces, 1930. Also {int. al.) 

 J. H. Quastel, Mechanism of bacterial action. Trans. Faraday Soc. xxvi, pp. 831- 

 861, 19.30. 



+ This is Loeb's so-called "membrane-effect," cf. Journ. Biol. Chemistry, xxxii, 

 p. 147, 1917; and J. Gray, Journ. Physiol. Liv, pp. 68-78, 1920. 



