GENERAL CHEMISTRY OF LIFE PHENOMENA 27 



which indicate that H 2 O 2 is capable of adding itself to a large number 

 of compounds and forming bodies like the following: B a O 2 H 2 O 2 or 

 K 2 O 2 2 H 2 O 2 . Jones and Carroll found that certain acids and salts 

 show in water with solutions of H 2 O 2 an abnormal depression of their 

 freezing point. They conclude that in this case a combination between 

 the molecules of the salts and the H 2 O 2 is formed. From this and similar 

 observations Kastle and Loevenhart draw the conclusion that those 

 substances which like platinum accelerate the decomposition of H 2 O 2 , 

 first combine with H 2 O 2 , and that this combination is unstable and rapidly 

 falls apart into molecular oxygen, water, and the catalyzer, i.e. platinum. 

 If this occurs in the presence of reducing bodies which do not act directly 

 on H 2 O 2 , they may be oxidized in this process. The platinum may 

 afterwards combine again with another molecule of H 2 O 2 , and the 

 process be repeated. 



These views find a nice confirmation through the investigation of 

 the action of certain poisons like HCN on the decomposition of H 2 O 2 

 by platinum or catalase. It is well known that HCN kills warm-blooded 

 animals rather rapidly under the symptoms of lack of oxygen. Schoen- 

 bein had already shown that prussic acid inhibits the decomposition of 

 H 2 O 2 through animal tissues (or the catalase contained in them). Gep- 

 pert showed that HCN prevents them from consuming the free oxygen, 

 hence the animals die under symptoms of asphyxiation. HCN prevents 

 also the decomposition of H 2 O 2 through platinum. Bredig has con- 

 tinued the experiments of Schoenbein. As the velocity of the catalytic 

 action of platinum must be in proportion to the surface of the metal, 

 Bredig, in order to get a maximal surface, made colloidal solutions of 

 platinum and other metals. He showed that extremely small doses 

 of HCN are sufficient to prevent the catalytic action of colloidal platinum 

 upon H 2 O 2 . Kastle and Loevenhart made it probable that this "toxic" 

 effect of HCN upon the catalytic action of platinum upon H 2 O 2 is deter- 

 mined by the fact that platinum forms an insoluble combination with 

 HCN. The formation of a film of this insoluble compound on the 

 surface of the platinum prevents the latter from forming the unstable 

 combination with H 2 O 2 which must precede the decomposition of the 

 latter. The reason why so little of the poison is required for this effect 

 is due to the fact that the film which is formed on the surface of the 

 metal may be infinitely thin. Kastle and Loevenhart were able to 

 put their hypothesis to a test. Silver and thallium act much like plati- 

 num upon the hydrogenperoxide, inasmuch as both accelerate its decom- 

 position. While silver forms a combination with HCN which is insoluble 

 in water, thallium forms a soluble combination. Kastle and Loeven- 

 hart showed that while hydrocyanic acid inhibits the decomposition 



