4 88 CHEMISTRY OF ALCOHOLIC FERMENTATION. 



hydroxyl groups and hydrogen atoms and at once parts with five 

 molecules of water, so that a temporary intermediate product, 6, 

 a dioxy-y-ketone acid, is formed. This latter combines with one 

 molecule of water (see Formula V.) and decomposes into two 

 molecules of lactic acid. That, from the theoretical point of view, 

 this acid may be regarded as the source of the carbon dioxide and 

 alcohol has already been mentioned on p. 487, vol. ii. 



FORMULA IV 



CHOH 

 CHOH 



CHJOH 



| : ..=, 



C IHOH 



I " 



CHOH 



0;H 



OH 



HJe 



OJH 

 OH 

 HiH 



COOH 

 CM OH 



CH 



I " + 

 CO 



CHOH 

 CH., 



H,0 



H,0 

 If/) 

 H.,0 



FORMULA V. 



COOH 

 CHOH 



CH 



CO 

 CHOH 



CH 2 

 b 



COOH 

 I 

 CHOPI 



CH 3 



COOH 

 CHOH 

 CH, 



The researches of GRtiss (I.) led him to conclude that the 

 reducing agent he discovered in yeast (see chap. Ixvi.) should 

 be regarded as hydrogenase. This would first split up the sugar 

 molecule into carbon dioxide and hydrogen, the latter then 

 causing a separation of alcohol and water from a second and 

 third molecule of sugar, as expressed in the following typical 

 equations : 



CH 2 OH + H 2 O 

 4(CHOH + H 2 0) 

 COH + H 2 



C0 2 + 

 4(C0 2 

 C0 2 + 



5H 



+ 4H) = 



2CH 2 OH + H 2 



2( 4 CHOH) + 8H 2 



2COH + *H 



C 2 H 5 OH + H 2 

 4C. 2 Hr,OH + 4H 

 C 2 H 5 OH + H 2 



