208 Dr. G". Senter. [June 2, 



Quite an appreciable acceleration is caused by sodium acetate, and its 

 amount seems, curiously enough, to be almost independent of the salt 

 concentration. It has been found that neither sodium acetate nor 

 sodium sulphate appreciably catalyse hydrogen peroxide in the con- 

 centrations employed. 



Effect of Alkali Salts with Oxidising Properties. 



In my former paper,* experiments with KClOs and KNOs are 

 described, and it was shown that these salts at 0, even in 1/80,000 molar 

 solution, exert a powerful depressing effect on the action, the constants 

 at the same time decreasing as if the enzyme were being gradually 

 oxidised. There seems, however, to be a depressing effect independent 

 of the oxidation since, with the weaker solutions, there is a considerable 

 decrease in the velocity, though the constants do not appreciably 

 decrease during the action. This is also evident from the experiment 

 with nitric acid quoted on p. 204. 



Experiments have now been carried out with potassium perchlorate 

 and potassium persulphate, an experiment with KClOs being made at 

 the same time for the sake of comparison. 



Table VII. 



Salt used. * Constants. Salt used. Constants. 



KC10 4 , w/50,000 0-0039 KSO 4 , w/200 '0076 



w/100,000 -0070 m/400 '0137 



m/250,000 -0133 Control experiment '0300 



KC10 3 , w/1, 000,000. . -00540 -0024 



It is interesting to note that the constants do not decrease during 

 the action with potassium perchlorate and potassium persulphate, so 

 that the enzyme is not being appreciably oxidised ; there is, on the 

 other hand, a marked decrease with potassium chlorate, from 0-0054 

 0-0024 in the course of 3 hours. 



The results with potassium chlorate are interesting since this salt is 

 a blood-poison, owing to its power of converting hemoglobin into 

 methsemoglobin. According to preliminary experiments by Professors 

 Robert and Schar,f potassium chlorate does not greatly retard the 

 catalysis of hydrogen peroxide by blood; that this view is erroneous is 

 evident from the results here given. 



Potassium chlorate is not very poisonous towards the lower 

 organisms. } 



* Senter, loc. cit., p. 304. 



t Quoted by Bredig, loc. cit. t pp. 81 and 85 



J Loew, ' Die Giftwirkungen,' p. 17. 



