ALCOHOLIC FERMENTATION 383 



QUANTITATIVE DETERMINATION OF THE ACTIVITY OF 

 ZYMASE. 



The amount of carbon dioxide evolved, either by volume 

 or by weight, may be taken as a measure of the enzymic 

 activity. 



For the estimation of the volume and the rate of evolution 

 of gas given off during the fermentation of sugar by yeast- 

 juice, Harden, Thompson and Young* give the following 

 method (Fig. 5) which yields satisfactory results, provided 



FIG. 5. 



that not more than 30 c.c. and not less than -5 c.c. of gas 

 is evolved in five minutes. 



The fermenting mixture is placed in the flask F, of 100 to 

 200 c.c. capacity, which is kept at a constant temperature by 

 means of a thermostat, T. The flask is fitted with a three- 

 way tap, which is connected by means of rubber and glass 

 tubing to a Schiff nitrometer, N, of 100 c.c. capacity and 

 graduated to P 2 c.c. The nitrometer is connected with a 

 reservoir, R, which is fitted with a bung, through which passes 



Harden, Thompson and Young : "Biochem. Journ.," 1911, 5, 230. 



