ELECTRICAL AND OTHER FACTORS 239 



similar to anaesthesia, the bioelectric P.D. is incrcasecl.' 

 The local negativity produced by anaesthetics under 

 certain conditions, as in Allcock's experiments,^ is 

 probably to be referred to the permeability-increasing 

 effect of the compounds in higher concentrations. 



The connection between adsorption and contact 

 catalytic action has been usually regarded as a special 

 case of the mass-action law. Since any increase in the 

 concentration of a reacting substance involves a propor- 

 tional increase in reaction-velocity, and since the concen- 

 tration of many dissolved substances is increased in the 

 layer of solution adjoining an interface, it follows that 

 in any such case there must be increased reaction- 

 velocity in that region. Hence if the adsorbing 

 surface is sufficient in area, as with fine subdivision, a 

 large proportion of the reacting material may be present 

 in the surface layer at any time, and a considerable 

 increase in reaction- velocity may result. Direct parallels 

 between adsorption and catalysis have in fact been 

 observed in certain cases.^ 



It is, however, questionable if this influence is in 

 itself sufficient to account for the effects observed; in 

 many cases the surface appears to exercise some specific 

 chemical influence; and certain contact catalyzers, 

 especially platinum, have an accelerative action which is 

 far greater than can be accounted for on the ground of 

 their adsorptive capacity alone.'* 



^Cf. Briinings, Arch. ges. Physiol, XCVIII (1903), 241. M:ic- 

 donald's work also shows an increase of the demarcation potential with 

 decrease in the external electrolyte content. Cf. p. 304. 



2 Allcock, Proceedings of the Royal Society, B, LXXVII (1906), p. 267. 



3 Cf. Hober's Physik. Chcmic d. Zclle (1914), P- 705- 



4 Cf. Bancroft's Applied Colloid Chemistry, p. 40. 



