216 SCIENCE PROGRESS 



berg (Berichte, 1919, 52, [b], 177) ; on hydrolysis, by means of 

 tannase, of a dilute aqueous solution covered with toluol, this 

 author obtained gallic acid and a sugar (calculated as a hexose) 

 in quantities corresponding with the formula of a digalloyl 

 hexose. 



The shortage of fats in Germany during the war necessi- 

 tated the production of glycerol from other sources, and 

 during the summer of 191 7 the Germans were producing 

 glycerol in large quantities by fermentation. At the instiga- 

 tion of the American Government, experiments were under- 

 taken with a view to discovering some similar method for use 

 by the Allies, and in three months' time, Messrs. Eoff, Linder 

 and Beyer announced the production of glycerol in 20-25 per 

 cent, yield by the addition of 5 per cent, of sodium carbonate 

 (in solid form) to a 17-20 per cent, solution of sugar set 

 in active fermentation by Saccharomyces ellipsoideus. On 

 adding the sodium carbonate, a copious precipitate is formed 

 and the evolution of gas ceases, while the yeast becomes 

 dormant. After a while the precipitate disappears and the 

 fermentation starts again. The formation of the precipitate 

 and the dormant period are essential to the success of the 

 whole process ; it has also been observed that the addition of 

 ammonium chloride to the fermenting liquid increases the yield 

 of glycerol ; the most favourable fermentation temperature is 

 from 30-3 2 C. Trial runs on a commercial scale were carried 

 out on molasses, but experiments have also been made with 

 cane-sugar and starch glucose ; in these cases, however, yeast 

 food had to be added in such quantities as to increase the 

 difficulty of purifying the glycerol. A fuller account of this 

 work may be found in an article by Ling entitled " Production 

 of Glycerin from Molasses" {Jour. Soc. Chem. Ind., 191 9, 38, 

 175R.). More recently Schweizer {Helv. Chim. Acta, 1919, 2, 

 167) has published the results of his experiments on the produc- 

 tion of glycerol by fermentation. Starting from the assumption 

 that fermentation glycerol was produced by the reduction of 

 glyceric aldehyde or dihydroxyacetone, he has tried the effect 

 of adding various reducing agents to the fermenting liquid ; acid 

 reducing agents were found to be deleterious for the yeast, but 

 eventually sodium sulphite was found to produce an increased 

 yield of glycerol ; by the addition of 7-8 per cent, of this salt 

 to a 10 per cent, solution of fermenting sugar he was able to 



