106 ANTI-CATALYSTS, ANTI-FERMENTS 



first shown by Graham, the oxidation or ignition of phosphorus is 

 also prevented by traces of organic substances such as turpentine, 

 alcohol, ether, and ethyl iodide. 



The number of such negative catalysts known to us is not so 

 large as that of those which increase the velocity, but this is 

 perhaps due to the fact that the interest and attention of the 

 chemist have been chiefly directed towards those substances which 

 cause or hasten reaction rather than to such as stop or retard it. 



We have already seen that the reactions caused by enzymes 

 do not proceed with a measurable velocity in the absence of the 

 enzymes, in fact, do not appear to occur at all, and hence there 

 is no necessity for the existence of negative enzymes in the body, 

 and none such have hitherto been described. 



It will be pointed out later that the existence of negative 

 catalysts, as has been urged by Ostwald, is a point of evidence 

 against the view that the mode of action of catalysts is in all cases 

 by the formation of intermediate compounds. 



ANTI-CATALYSTS, ANTI-FERMENTS, AND ANTI-ENZYMES 



Under the name of " Antikatalysatoren " or " Paralysatoren " 

 Bredig has designated those substances which by their presence 

 in small quantity retard or stop the action of a catalyst. Such 

 bodies differ from the " negative catalysts " mentioned above in 

 that they do not retard the reaction by directly acting upon the 

 substratum, but by acting upon a positive catalyst which is present 

 and preventing or retarding its action. Bredig places these sub- 

 stances in analogy with the antitoxins. Strictly speaking, all those 

 substances ought to be placed in this group, which have already 

 been described above as affecting enzyme action, such as acids 

 and alkalies, neutral salts, anaesthetics and antiseptics ; but it 

 is better to reserve the term, if it is to be used at all, for substances 

 which act after the fashion of catalysts of a second order, so to 

 speak, in quantities small compared to the amount of the primary 

 catalyst. 



An example of such an action is the " paralysis " of the action 

 of solutions of colloidal platinum upon hydrogen peroxide, by 

 the addition of traces of hydrocyanic acid. Thus, Bredig, Mliller 

 von Berneck, and Ikeda found that the addition of 0-000,000,001 



