CATALYSIS AND BIOCHEMICAL PROCESSES 233 



by the salts present and the uniform and gradual building 

 up of regular structure would be impossible. 



All of the above-described effects depend on the 

 formation of interfacial films which alter the physical 

 properties of the surfaces. Apparently also the chemical 

 or adsorptive and hence catalytic properties of the 

 surfaces are secondarily altered by the deposition of 

 such foreign materials; and the foregoing evidence indi- 

 cates that the an ti catalytic action of surface-active 

 compounds depends on a surface-concentration of this 

 kind. 



Anticatalytic action is, however, also well known in 

 homogeneous solutions and even in gases, so that this 

 form of explanation does not always apply. Numerous 

 instances of anticatalysis in homogeneous solutions are 

 cited by Traube in his Theorie der Narkose;^ Bigelow's 

 observations^ on the oxidation of Na2S03 by oxygen 

 furnish many striking illustrations; he found that this 

 reaction was depressed by a large number of organic 

 substances; for example, a trace of mannite (about 

 .0014 per cent) decreased the reaction velocity by 50 

 per cent; benzyl alcohol and aldehyde, isobutyl alcohol 

 and ethyl alcohol were even more effective in checking 

 the reaction. It is interesting to note that the alcohols 

 showed increasing effectiveness with increasing molecular 

 weight, and that the effect decreased with the number of 

 hydroxyls in the compound (e.g., monohydroxylic alco- 

 hols > dihydroxyhc > trihydroxyHc, etc). Aromatic 

 compounds were more effective than chain compounds.^ 



^ Arch. ges. Physiol., CLIII (1913), 279. 



^Bigelow, Z. physik. Chem., XXVI (1898), 423, and XXVII, 585. 

 3 Many other similar cases are cited in Traube's paper (the work of 

 Veley, Titoff, Young, and others). 



