1889.] On a pure Fermentation of Mannite and Glycerin. 355 



Alcohol. — Repeated distillation yielded 63*4775 grams of liquid, of 

 specific gravity 0*9803, corresponding to 8*20 grams of absolute 

 alcohol ; after further rectification the weight of liquid was reduced to 

 54*0 grams, of specific gravity 0*9776, corresponding to 8*14 grams 

 absolute alcohol. By dehydrating this with fused potassium car- 

 bonate, 7*518 grams of alcohol, boiling at 79° C, were obtained. 



Volatile Acids. — Proceeding as before, the following amount of 

 barium salt was obtained : — 



Total barium salt = 8*239 grams, giving 91*08 per cent. BaSO^. 

 Pure Ba-acetate gives 91*37 per cent. BaS0 4 . 



Thus the whole of the salt was practically pure barium acetate, 

 although a trace of formic acid was discoverable qualitatively. 



The total quantity of acetic acid, as calculated from the barium 

 salt, amounted to 3*877 grams. 



Fixed Acids. — Using the same method of separation as described in 

 the first fermentation of glycerol, 0*063 gram of succinic acid was 

 found, whilst 24*19 grams of unaltered glycerol were recovered. This 

 glycerol on incineration yielded only 0*96 per cent, of ash. 



The results obtained in this fermentation, therefore, fully substan- 

 tiate those of the first. The glycerol was only very partially 

 decomposed, the principal products being again alcohol and acetic 

 acid, with traces of formic and succinic acids. 



In the fermentation of the glycerol, as in that of the mannitol, it 

 would appear that the formic acid is produced at the expense of the 

 acetic acid, for in this second fermentation of glycerol, in which only 

 traces of formic acid were discovered, the proportion of acetic acid 

 was considerably greater than in the first fermentation, in which a 

 notable quantity of formic acid was found. 



The results obtained in the several fermentations may be tabulated 

 as follows : — 



Mannitol Fermentations. 



Alcohol. Acetic acid. Formic acid. Succinic acid. 



I.. 11*415 grams 7*008 grams .. 0*0215 gram 



II.. 9*3 „ [5*7141*] „ .. 0*034 „ 



III.. .. 3*475 „ 1*104 grams 0*027 „ 



Glycerol Fermentations. 



Alcohol. Acetic acid. Formic acid. Succinic acid. 



I.. [4*90] grams [2*75] grams [0*32 gram] 0*079 gram 



II.. 8*17 „ 3*877 „ trace 0*063 



■)■> 



* Total volatile acid calculated as acetic acid. 



