4 Scientific Proceedings, Royal Dublin Society. 



It is of interest to compare the activity of the fluid extracted by means of 

 the liquid air in tlie manner described with that extracted from yeast-cells 

 by other methods. 



In 1912 Lebedeif (4) described a method of extracting zymase from yeast 

 by simple maceration. His method consists essentially in drying the yeast 

 at 30°, and in macerating it for two hours at 35°C. with three times its weight 

 of water, or for a longer period at a lower temperature. To compare the two 

 methods the following experiment was made : — the beer was pressed off some 

 " liquid yeast " and two samples of the solid yeast [A and B each about 100 g.) 

 were made. A was dried at 30°C. for twenty-four hours, and weighed 25 g. 

 The temperature was kept for three days at 35°C., and the yeast lost 0'4 g. 

 To the dried solid 75 c.c. of water and a little toluene were added, and 

 it was left to macerate for two hours at 35°C. It was then centrifuged 

 and yielded 41 c.c. of liquid. 30 c.c. of this was put in the conical flask 

 with 12 g. sugar and a little toluene. The production of CO^ is given 

 below : — 



In column B are given the volumes of COo produced by 30 c.o. of yeast- 

 sap extracted by means of liquid air under similar conditions. 



The 100 g. of the solid yeast in this case yielded a little over 32 c.c. sap. 

 Calculation from the foregoing data shows that each gramme of fresh yeast 

 afforded a total fermentation-volume of 0'35 c.c. CO2 by Lebedeff's method, 

 and 0-37 c.c. by liquid-air extraction. 



From this comparison it appears that the fluid extracted from the sample 

 of yeast by means of liquid air is quite as active as that obtained by the 

 maceration method. 



This experience was confirmed by another experiment where the mace- 

 ration was effected at 20°-25°C. and a larger volume of water added, viz. : — 

 to 21 g. of dried yeast 100 c.c. of water was added and maceration proceeded for 

 twenty-one hours. As before, 30 c.c. of the fluid with 12 g. of sugar and a 



