6 THE THEORY OF 'CATALYSIS' OF BERZELIUS. [BOOK IL 



the actions of unformed, whilst the third has exclusively reference to 

 formed ferments. 



1. The contact or 'catalytic' theory of Berzelins. 



2. The modification of the catalytic theory formulated by Liebig. 



3. The physiological theory, which now holds undivided sway and 

 which owes its commanding position to the splendid researches of Pasteur. 

 This theory considers every ferment process to be the resultant of the 

 activities of a definite organism. 



The theory of There are certain chemical reactions which occur between 



' Catalysis ' of * wo bodies, in which the presence of a third exerts a 

 Berzelius. remarkable influence, without the third body appearing on 



superficial examination to be modified by the process which 

 it has helped to bring about. When, for instance, mixtures of hydrogen 

 and oxygen find themselves in the presence of finely divided platinum, the 

 two gases combine, under certain circumstances, with explosive violence. 

 Again, when platinum black is brought into contact with the vapour of 

 alcohol, the latter is oxidised and acetic acid is formed. To cite a third 

 case, when peroxide of hydrogen, H 2 2 , is treated with platinum black, 

 that very unstable compound breaks up into water and oxygen, it being 

 obvious that in this case two molecules, at least, of the peroxide must be 

 concerned, its results being the formation of two molecules of water and a 

 molecule of oxygen. As was discovered long ago, not only is this remark- 

 able reaction brought about by platinum and certain other inorganic 

 bodies, but also by certain organic substances. A shred of fibrin, for 

 instance, or a drop of blood, or of a solution of haemoglobin will suffice 

 to decompose a large quantity of a solution of hydrogen peroxide, which is 

 thrown into effervescence and rises in temperature. 



Berzelius was the first to bring together, and draw attention to, these 

 remarkable phenomena, which he distinguished as 'catalytic' and ex- 

 plained as due to the action of a hitherto unrecognised force, to which he 

 ascribed the term 'catalytic force 1 .' 



' It is then proved/ he remarked, ' that several simple and compound, 

 soluble and insoluble, bodies, are capable of exerting upon certain other 

 bodies an action which is very different from that of chemical affinity. 

 By this agency they are the means of producing in those bodies decomposi- 

 tion of their elements, and subsequent rearrangements of the same without 

 they themselves taking a part in them. 



* This new force, which has hitherto been unrecognised, is common to 

 organic and inorganic nature. I shall, therefore, call this force catalytic 

 force. I shall, similarly, call catalysis the decomposition of bodies through 

 the agency of this force. ' 



Amongst the most obvious examples of catalytic phenomena, Berzelius 

 classed the actions of ferments, both formed and unformed. In criticising 

 the theory of Berzelius we must appreciate that its essence consisted in 

 the hypothesis that the catalysing agent remained absolutely passive, 

 whilst no attempt was made to shew in what manner this remarkable 



1 Berzelius, ' Quelques idees sur une nouvelle force agissant dans les combinaisons 

 des corps organiques.' (Annales de Chimie et de Physique, Tome 61 (1838), pp. 146 

 151). 



