145 



Extract. 



Phenol. 



Time. 



Color. 



The discoloration became apparent in the solutions vrith pyrocatechin 

 in about 15 minutes, while the same extent of discoloration was not ap- 

 parent in the solutions with hydroquinon for an hour. The table gives the 

 results at the end of twelve hours, but the solutions were kept for a week. 

 The longer they stood, the darker they became, the hydroquinon being of 

 a wine red color, while the pyrocatechin solutions were of a brown color. 

 At the end ot four days, the six days extract with pyrocatechin was al- 

 most black. The experiments were carried on at room temperature. The 

 solutions remained clear, no pi-ecipitates forming. 



Temperature Tests. 



To determine the temperature at which the enzyme was destroyed, 

 the three extracts were heated to 60 degrees C. The tubes containing the 

 extracts were placed in the steam sterilizer, a corresponding amount of 

 water being placed in another tube in which was placed a thermometer. 

 The extracts were kept in the sterilizer for one minute after the ther- 

 mometer registered 60 degrees C. 



Another set was tested but the temperature raised to 100 degrees C. 

 Pyrocatechin was used Avith the enzyme, as, in the other tests, it gave a 

 more rapid response than the hydroquinon. 



60 Degrees C. — A slight darkening was apparent in twenty minutes. 

 The longer they were kept, the darker they became, until at the end of 

 four days they had a rich, deep bi'own color. They also showed the varia- 



10— A. OF Science. 



