Adeney — Aerobic Bacterial Fermentation. 



23 



The Fermentation of Rochelle Salt. 



Eochelle salt, as was shown in the earlier part of this communi- 

 cation, readily and quickly undergoes fermentative change when 

 mixed with urea. 



It also undergoes fermentation, though not so quickly, when 

 unassociated with any source of nitrogen, save that of the air. 



The experiments with this substance are recorded in Table VIII. 

 Different stages of fermentation from commencement to finish are 

 illustrated by them. 



On plotting the carbon dioxide formed with the oxygen absorbed, 

 the course of fermentation is seen to take place in two equal and 

 progressive stages, and the course of each is represented by a straight 

 line. 



During the first stage of oxidation, the Rochelle salt is converted 

 into potassium sodium malate, carbon dioxide, and water ; and the 

 malate is oxidised during the second stage to carbon dioxide and 

 water, according to the equations : — 



(1) 2C4H4KNa06 + 20^ = Q,li,l{.^^0, + 4CO2 + 2H2O + KNaO. 



(2) C,H4K]S"a05 + SO^ = 4CO2 + 2H,0 + KNaO. 



The volume of carbon dioxide formed, and of oxygen absorbed, by 

 the complete fermentation, may be taken, from experiments 48, 49, 

 and 50, to be 33-3 and 20 cc. per litre, respectively. These volumes 

 are in the proportion of 8 : 5, nearly ; that is, the proportions required 

 by the equation already given, p. 17, showing the complete oxidation 

 of the Eochelle salt into carbon dioxide, water, and sodium, and 

 potassium carbonate. 



The total volume of carbon dioxide formed in complete fermenta- 

 tion represents 74 -5 percent, of the carbon originally present in the 

 Rochelle salt. The other physiological processes not examined, 

 therefore, took up 25*5 per cent. 



[Table VIII. 



