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



capable of oxidation with the same relatively greater intensity than does 

 a feeble oxidase, or whether a strong oxidase to one substance may be 

 a feeble oxidase to another as in the case of the organic oxidases. Other 

 points needing elucidation are as to whether oxidase action is solely due to 

 the metallic base, and what influence a metal such as iron will have when 

 present as an acid. Also as to whether peroxide of hydrogen only 

 accelerates oxidase action when the oxidase salt decomposes it. In the 

 following table the results of a series of tests are given using guaiacum, ursol 

 tartrate,* hydroquinone, pyrogallic acid, gallic acid, tannic acid, and tyrosin 

 as oxidant substances. In order to render possible a comparison of the 

 relative activities in each case, the oxidase was present in one-tenth the 

 molecular concentration of the oxidant, except in the case of the guaiacum, 

 where the alcoholic solution is best allowed to float as a thin layer on the 

 oxidase solution. 



The exposure to air was continued for one day, and if the colour was still 

 the same as the test solution the result is given as nil. A rapid reaction is 

 indicated by three positive signs (+ + +), slower ones taking one or more 

 hours to become distinctly perceptible by two signs (+ +), a very slow one 

 taking the full 24 hours by one (+ ). In the case of guaiacum, owing to the 

 mode of application of the test, the time factor does not enter to the same 

 extent, but a difference in the strength of the oxidase is indicated by the 

 depth of the blue coloration (strong = + + +■, weaker blue = + + , feeble 

 blue = + ). 





lase 

 tion. 



S 



o 

 03 



1 



■trate. 



gallol. 



•auom 



-OJ 



c acid. 



)tannic 

 d. 



d 



'oo 





C3 O 



'3 





o 







^ o 



"3 « 



Tyro 





M 







K 





O 



Cupric chloride 





+ + 





+ 





+ 







Do. + H 2 2 ... 



+ + 



+ + + 



+ + + 



+ + + 



+ + + 



+ + + 



+ 





Cupric sulphate ... 















+ 





Do. +H,0 2 ... 





+ + 



+ 



+ + + 



+ + + 



+ + + 



+ 





Copper oxychloride 









+ 











Do. +H 2 2 ... 





+ 



+ 



+ + 



+ + 



+ + + 



+ 



+ 



Copper acetate and 





+ 





+ 



+ 









subaeetate 



















Do. + H 2 2 ... 



+ * 



+ + + 



+ 



+ + 



+ + . 



. + + 



+ 



+ 



Ferric chloride 





+ + + 



+ + + 



+ + 











Do. +H 2 Cy ... 



+ + + 



+ + + 



+ + + 



+ + + 



+ + +f 



+ +'?;, 



+ ? 



+ 



Ferrous sulphate ... 



















Do. +H 2 2 ... 



+ + +t 



+ + 



+ + 



+ + 





+ +? 



+ ? 



+ 



* Cu 3 2 Cl 2 ,4H 2 0. 



f Flat black shining needles separate out on standing in the cold, but no distinct oxidase action 

 is shown. 



X Liquid yellow, then slowly brown precipitate. 



Paraphenylenediamine tartrate. 



