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



bubbles, and still less influence was exercised upon the decomposition 

 produced by potassium permanganate and black oxide of manganese, 

 although in the latter case some remarkable surface tension effects were 

 exercised. 



Hydrogen peroxide is readily soluble in ether, which will in fact remove it 

 from a watery solution. It is only sparingly soluble in, chloroform, for, 

 although the chloroform solution will not give any blue with chromic acid, it 

 gives a feeble reaction with a watery solution of starch and potassium 

 iodide or with ferrous sulphate. Chloroform prevents the ether-chromic 

 acid reaction for hydrogen peroxide being given but not by destroying the 

 hydrogen peroxide. In fact the hydrogen peroxide can be shaken with 

 chloroform and the latter then boiled off without the former being destroyed. 

 The retarding action on peroxide decomposition produced by ether might 

 depend upon whether the " katalase " salt dissolves in it as well as in water, 

 since otherwise the hydrogen peroxide might be removed from katalase 

 action except at the contact surface. In the case of chloroform any bubbles 

 produced form mainly below the surface tension film, although both hydrogen 

 peroxide and the katalase salt may be present in abundance in the licpiid 

 above. The chloroform apparently acts as an " anaesthetic " to " katalase " 

 chemical action. 



The Oxidases of the Lemon and Orange. 



According to Moore and Whitley there are no " peroxidases " in the pulp 

 or rind of these fruits. This is hardly the case, as no allowance was made 

 for the effect of the acid in the pulp or of the oils in the skin. Quarters of 

 the pulp were squeezed dry in a press between blotting paper, and collected 

 until a sufficiency of clean material free from acid was obtained. This gave 

 no reaction with guaiacum alone and none with ursol tartrate except that the 

 fragments of the tracheae coloured brownish-red. On adding a drop of 

 peroxide of hydrogen a pale but distinct blue was given with guaiacum and 

 a slow change to violet with ursol tartrate. The pounded pulp does not 

 decompose hydrogen peroxide appreciably. On dissecting out the vascular 

 bundles and applying ursol tartrate and peroxide of hydrogen, all the veins 

 right down to the stalks of the endocarpal hairs turned green, then brown, 

 then violet, but no other parts. They also showed a feeble power of decom- 

 posing H 2 2 . After soaking in orange or lemon juice for some hours or after 

 boiling no oxidase reaction was given but the walls of the tracheae gave 

 .a bright red lignin reaction, making the bundles look like blood-vessels 

 injected with carmine. 



