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The Alcoholic Ferment of Yeast-yuice. Part IL—The Function 
of Phosphates in the Fermentation of Glucose by Yeast-jwmee. 
By ARTHUR HARDEN and WILLIAM JoHN YouNG (Biochemical Laboratory of 
the Lister Institute of Preventive Medicine). 
(Communicated by C. J. Martin, F.R.S. Received March 6,—Read 
April 2, 1908.) 
In a previous communication the authors have shown* that when a soluble 
phosphate is added to a fermenting mixture of glucose and yeast-juice the 
following phenomena are to be observed: (1) The rate of fermentation is at 
once greatly increased. (2) This acceleration lasts for a short time and the 
rate then falls off, and returns approximately to its original value. (3) During 
this period the extra amount of carbon dioxide evolved and alcohol produced 
are equivalent to the phosphate added. (4) The phosphate is converted into 
a form which is not precipitable by magnesia-mixture, and is then probably 
present as a salt of a hexosephosphoric acid. 
(1) Lffect of the Addition of Phosphate on the Total Fermentation. 
The addition of phosphate, however, does not simply produce this initial 
decomposition of an equivalent of glucose, but also, as a rule, a greater total 
fermentation, after allowance has been made for the amount decomposed 
during the initial period. 
This is clearly shown by the results embodied in the following table. 
In each experiment two or more portions of 25 cc. of yeast-juice were 
taken, a solution of glucose alone, or one of glucose and phosphate, added, and 
the total volume made to 50 ¢.c. The solution of phosphate employed had a 
concentration of about 0°3 molar, and the concentration of glucose was 
20 grammes per 100 c.c. in experiment 8, and 10 grammes per 100 c.c. in all 
the others. The fermentation was carried out at 25° in presence of toluene 
until the evolution of gas ceased. The numbers in the last column show the 
increase in the total fermentation produced during the period subsequent to 
the initial acceleration. 
It will be seen that the increase which occurs after the initial period varies 
from about 10 per cent. of the original fermentation to as much as 150 per 
cent. 
* “Roy. Soc. Proc.,’ B, vol. 77, 1906, p. 405. 
