294 Prof. A. J. Ewart. Comparative Study of Oxidation by 





<D C 



a 





"o 



1 



S3 



'o 



'3 







atalas 

 actio 



3 



o 





yrogal 



ydro- 

 qumo 



allic a 



allota) 

 acid. 



prosin, 







o 



i — . 

 P 



Pm 



K 



$ 



as 





Acid potassium phos- 



















phate 



















Do. + H 2 C- 2 



+ 





+ 













Neutral potassium phos- 









? 











phate 



















Do. + H. 2 2 







+ 



+ 



+ 









Potassium ferrocyanide 















? 





and acid phosphate 



















Do. + H 2 0, 



+ 



+ + + 



+ + 



+ 





+ 



+ 



* 



Potassium ferrocyanide 





+ 



+ + 



+ 











and neutral phosphate 



















TV> J. TT n 



+ 



+ + 



+ + + 



+ + 



+ + 



+ + 



+ + 



+ 



Potassium ferricyanide 





+ + 



+ 



+ 





+ + 



+ + 





and acid phosphate 



















Do. + H 2 2 



Potassium ferricyanide 





+ + + 



+ + + 



+ 



+ 



+ 



+ + 







+ + + 



+ + + 



+ + 



+ 



+ + + 



+ + + 





and neutral phosphate 



















Do. + H 2 2 



+ 



+ + + 



+ + + 



+ + + 



+ + + 



+ + + 



+ + + 



+ 





















Yellowish colour due to formation of ferricyanide. 



To some extent acid potassium phosphate and peroxide of hydrogen are 

 antagonistic in their action on potassium ferricyanide, and hence the oxidation 

 produced when both are added may be no greater or even less than when 

 either is added singly. 



In the case of tannic acid, the addition of sodium or potassium phosphate 

 seems not so much to accelerate the action of the oxidase as to render the 

 tannic acid more liable to oxidation. The chlorides and bromides of sodium 

 and potassium act as strong sensitisers to certain metallic oxidases but not to 

 others, and even with the former the sensitising action is not the same to all 

 oxidants. By themselves these salts exhibit no oxidase properties with any 

 •of the oxidants mentioned. 



A detailed comparison is given beneath of the influence of potassium 

 chloride upon the oxidase action of relatively inert oxidase salts such as 





italase 



action. 



.laiacum. 



■sol 



tartrate. 



'rogallol. 



fdro- 

 quinone. 



illic acid. 



tnnic acid. 



'rosin. 











P 





W 



a 



W 





Copper sulphate and sodium chloride 



+ 



+ 



+ + + 





-t- 





+ 



+ 





Ferrous sulphate and potassium chloride 



+ 



+ 



+ * 





+ 





t 







Chromium chloride and sodium chloride 







+ 





+ 











* Fading again on long standing. 



f A pale violet colour darkening from the surface possibly owing to oxidation to ferric salts. 



