1 20 MR. E. SCHUNCK ON THE ACTION OF 



most remarkable; and its formation, though it has been 

 observed in other processes of fermentation, is still so uncom- 

 mon as to call for some further observation. 



I have discovered that on allowing grape sugar or sugar of 

 milk to ferment together with erythrozym and lime water in 

 the same way as cane sugar, succinic acid is also formed. 

 Indeed from sugar of milk I obtained in one experiment 

 more than three times as much of this acid as was ever 

 afforded under the most favourable circumstances by the 

 same quantity of cane sugar. From 1 lb. of cane sugar I 

 never obtained more than 3^ grs. of acid. In the experiment 

 just referred to I obtained from ^ lb. of sugar of milk nearly 

 6 grs. of acid. The quantities formed, even under apparently 

 the same circumstances, were, however, very variable. 

 Large quantities of cane sugar sometimes yielded only traces 

 of acid, while smaller quantities gave proportionally a large 

 amount. It is during the later stages of the fermentation, 

 I imagine, that the acid is chiefly formed. At least, I 

 have always found that its amount was greater after the 

 fermenting liquid had stood for several weeks or months 

 than during the first period of the fermentation, when the 

 disengagement of gas was most active. Whether the access 

 of atmospheric air is necessary for, or promotes the formation 

 of, the succinic acid, I am unable to say. I may mention, 

 that the phenomena attending the fermentation of grape 

 sugar and sugar of milk are apparently the same as when 

 cane sugar is employed. 



In order to be quite sure that the formation of the succinic 

 acid and the other products was due to the action of the 

 ferment on the sugar, and not to the decomposition of 

 the ferment itself, I have repeatedly allowed mixtures of 

 the ferment and lime water, without the addition of sugar, 

 to stand exposed to a warm temperature and under the 

 same conditions under which the fermentation was usually 

 conducted. In this case little or no gas was disengaged. 



