17,4 Carsten: Utilization of Waste Molasses 405 
10. THE MANUFACTURE OF GLYCERIN BY FERMENTATION 7 
In Germany large quantities of glycerin were obtained through 
the fermentation of sugar. In that country sufficient sodium 
sulphite was added to the fermenting liquid to produce the degree 
of alkalinity that would cause the yeast cells to perform their 
work as well as to propagate. 
The test was made as follows: One kilogram of sugar and 
400 grams of sulphite were dissolved in 10 liters of water. To 
the feed yeast there were added ammonium sulphate, sodium 
phosphate, and a little potassium salt. After some hours car- 
bon dioxide was given off, and after about two days all the 
sugar was fermented. 
The liquid filtered from the yeast cells contained water, alco- 
hol, aldehyde, glycerin, and salts. Salts were precipitated and 
a good grade of glycerin was obtained by distillation. The sole 
difficulty was that the decomposition of glycerin caused the for- 
mation of trimethylglycol. After much experimentation this 
difficulty was overcome, and the process is now practicable. 
It is a peculiar fact that, with a higher percentage of sulphite, 
the quantity of glycerin and aldehyde increases, while that of 
alcohol and carbon dioxide becomes less. This seems to involve 
a double reaction. It has been noticed that a large quantity 
of a neutral salt, even if reacting alkaline, increases the glycerin 
fermentation. Apparently a specific reaction must be ascribed 
to the sulphite. 
In the United States the fermentation process has been made 
practicable by John R. Eoff. 8 The greatest quantities of gly- 
cerin were obtained from sugar solutions containing 5 per cent 
sodium carbonate, which is not all added at once. He found 
that a less quantity decreased production, and a larger stopped 
fermentation. Sodium hydroxide, potassium hydroxide, or borax 
can be used, but sodium carbonate is cheapest. The sodium 
carbonate was added when fermentation had well started, and as 
much as possible while fermentation was in progress ; the earlier 
it was added the greater the glycerin product. To maintain yeast 
growth, ammonium chloride was added. 
The best temperature is between 30° and 32° C.; a higher 
temperature caused decomposition of alcohol and glycerin, while 
a lower temperature decreased production. 
7 Deutsche Zuckerindustrie, May 16, 1919; see also Journ. Soc. Chem. 
Ind. 38 (1919) 175R-177R. 
8 Journ. Soc. Chem. Ind. 38 (1919) 176R. 
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