1911.] ~§ - Lhe Alcoholic Ferment of Yeast-juice, 453 
Lxpervment 2.—(1) 20 cc. yeast-juice+5 c.c. of 03 molar phosphate ; 
(2) 20 cc. yeast-juice+5 cc. of 03 molar arsenate; (3) 20 cc. yeast- 
juice + 0°75 c.c. of 0°3 molar arsenate. : 
Excess of sugar was present in each case, and the solutions of phosphate 
and arsenate were each equivalent to 36 .c. of carbon dioxide for 5 c.c. of 
the solution. The normal rate of fermentation of the juice was 1°8 c.c. per 
five minutes. 
1 2. 3 
Time. 
Rate Rate Rate 
tout per 5 minutes. oe per 5 minutes. BOs |e per 5 minutes. 
5 7-1 71 11 *4 11 °4 PAL ef 21 ‘7 
10 19 °8 Didi 26 °5 15:1 46 24 °3 
15 36 “1 16 °3 43 16 °5 71 25 
20 43 °8 pha | 59 16 95 °3 24. °3 
25 45 °7 1°9 75 16 °3 119 °8 24,°5 
30 47 °5 1°8 
Calculating the extra amount of carbon dioxide evolved in each case 
beyond that due to the normal rate of the juice, it is found that, in 
presence of phosphate, this amounts to 36°7 cc., and that the rate has 
fallen to that of the original juice. In presence of arsenate, although the 
extra amount of carbon dioxide is 66:3 cc, the rate has remained 
unaltered at the high value of 16. The disparity between this extra 
amount of carbon dioxide and the equivalent of the arsenate added is 
still more strikingly illustrated when only a small amount of arsenate is 
added. This is shown in No. (3) above, to which only 0°75 cc. of 
arsenate, equivalent to 5:4 c.c. of carbon dioxide, was added. In spite of 
this the extra amount of carbon dioxide evolved in 25 minutes was 
120°8 c.c., and the rate at the end of that time was still 245 cc. per 
5 minutes. , 
In order to show that the whole of the arsenate is still present in its 
original state after the evolution of an equivalent amount of carbon 
dioxide, the following experiment was made :— 
Experiment 3.—Four quantities of 25 c.c. of yeast-juice + 2°5 grm. of 
glucose were incubated until a steady rate had been attained. 
To these were added :— 
(1) 5 ce. water. 
(2) 5 cc. of sodium arsenate solution, yielding 0:2211 grm. of Mg2AseO;, 
and equivalent to 35 c.c. of carbon dioxide. 
