322 



Messrs. A. Harden and W. J. Young. [Feb. 12, 



but exactly equivalent to the sugar according to the authors' equation (1) as 

 given above. 



Experiments 1 and 2. — Two quantities of 25 c.c. of yeast-juice were incubated at 25° 

 for 15 minutes. 



1. To one was added 4 c.c. of a 0"6 molar solution of dipotassium hydrogen phosphate, 

 saturated with carbon dioxide, and 1 c.c. of a solution containing 0'2 gramme of fructose 

 (pure from inulin). The volumes of gas evolved in successive periods of 5 minutes were 

 then read. As soon as a steady rate had been attained, a second addition of 4 c.c. of 

 potassium phosphate solution and 1 c.c. of fructose solution was made, and the volumes of 

 gas evolved observed as before. 



2. The second portion of yeast-juice was treated in the same way, except that 

 0'2 gramme of pure glucose was substituted for the fructose. 



The following are the actual readings : — 



Time 

 after addition. 



Fructose. 



Glucose. 



First addition. 



Second addition. 



First addition. 



Second addition. 





c.c. 



c.c. 



c.c. 



c.c. 



5 



20 -6 



20 -5 



() -9 





10 



9-2 



' 8-2 



9-7 



} 17-0 



15 



4 -2 



4-7 



12 -0 



12 -8 



20 



2-8 



3 -6 



() -2 



5 -4 



25 



2 -4 



2-6 



3 -0 



3 -3 



30 



1 -9 



2-6 



2 -3 



2 -6 



35 



2 -2 



2-1 



1 -8 



2 -2 



Total 



-13 -3 



44 -3 



41 -9 



43 -3 



Fermentation of juice 



15 -4 



15 -4 



15 -4 



15 -4 



at 2'2 CO. per 5 mins. 











Extra carbon dioxide ... 



27 -9 



28 -9 



2G -5 



27 -9 



The gas was measured moist at 17°. and 762-4 mm. 



The volume calculated at the same temperature and pressure — 



(a) From the ratio C,.,H,;05 : 200. = 53 92 



(b) „ ^C'nHipe : 2C0., = 26-9(). 



II. Fermentation in PrescHrc of SiikiII Amounts of Pliosphate. 



Nuiiicrous atteni])ts liav(! been iiiadd to procure conclusive experimental 

 evidence that alcoholic fermentation cannot talvc place in the absence of 

 ])hoHphat('s. Jlith(!rt(), however, it has not Immui found ])OHsilil(^ to free the 

 matci'ialis employed complctidy from ])hos])horus compounds which yield 

 ])li08phates by enzymic hydrolysiw during the ex])eriment, but it has been 

 found that when the phoHphatc contcmts are reduced to as low a limit as 

 ])OHsil)lr, I he amount of sugar I'ci nKmtcul l)ecomcs correspondingly small, and, 



