CH. XVl] GLYCASE. 291 



The solution does not invert cane-sugar. 



(2) Mash up some yeast thoroughly with a little 

 water and ether, (to kill the yeast cells) filter as in 

 (1). The solution contains invertase and will invert 

 cane-sugar rapidly. 



Use a 2 p.c. solution of cane-sugar for these experi- 

 ments and treat it for one hour at 20° — 30°. 



Test for glucoses (products of inversion) with alkaline 

 copper or mercury solutions, etc. as described on p. 264. 



Hydrolysis of Maltose by G-lycase. 



Act on 200 c.c. of starch solution with diastase dissolved 

 in water, or fresh malt extract as in experiments on p. 287, 

 till the mixture no longer gives any reaction with iodine. 



The solution boiled and filtered till quite clear, contains 

 dextrins and maltose but no glucose : test a portion of the 

 solution by phenyl-hydrazin, and also by acetic acid cupric 

 acetate, to shew that it contains no glucose. The boiling 

 prevents any further action of the diastase or of enzymes 

 in the malt extract. 



To the remainder of the solution add 10 grs. of coarsely 

 ground maize and keep the mixture at 40° — 50° C. on the 

 water bath for 5 or 6 hours. Boil and filter till quite clear : 

 the solution contains much glucose, as is easily shewn by 

 the tests mentioned above. A control experiment should 

 be conducted at the same time to shew that the glucose 

 was produced by the hydrolysis of maltose and not from 

 the maize itself 



For this purpose another 10 grs. of coarsely ground 

 maize is digested under similar conditions with about 



19—2 



