YEASTS. 



43 



sixteenth of a cake of compressed yeast. Put each 

 portion into a clear glass bottle or tumbler and place 

 all three in a warm place, about 75 or 80 F., for an 

 hour or two. Watch carefully for the first sign of 

 bubbles which show that gas is forming. Note in 

 which glass the larger amount of gas is found. 



OC 



FIG. 26. YEAST GENERATING CARBON DIOXIDE. 



(a) Tube filled with molasses and water. 



(b) Carbon dioxide collecting In top of tube. 



Fill a test tube or thin, clear glass vial with a 

 mixture of molasses and tepid water. Add a little 

 yeast and invert the vial in a dish which also con- 

 tains molasses and water. Fasten the vial so that it 

 will remain standing, closed, in the dish for a day or 

 more. Fig. 26, a and b. 



