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THE ACID FERMENTATION OF RAW SUGAR 

 CRYSTALS. 



By R. Greig Smith, M.Sc, Macleay Bacteriologist 

 TO THE Society. 



During the storage of raw sugar crystals in bags, an acid 

 fermentation occasionally sets in. The sugar becomes decidedly 

 warm to the hand, and a strongly acid odour, suggestive of a 

 mixture of acetic and butyric acids, is evolved. 



Two samples of sugar undergoing this fermentation were 

 investigated for microscopic fungi after the manner already 

 described in the preceding paper. The first sample, which had an 

 acidity to phenolphthalein equivalent to 36 % lactic acid, con- 

 tained both kinds of Bac. levaniformayi^, the gum bacillus, and 

 no other bacteria, yeasts or moulds. The second sample had an 

 acidity equivalent to 0*3 1 % lactic acid, and contained the derived 

 type of Bac. levani/ormavs in pure culture. 



From the presence of this bacillus in the sugar, it cannot be 

 doubted that it is alone responsible for the acid fermentation. 

 It has been already shown that the acids secreted during the 

 growth of the organism consist of capric, carbonic, lactic, butyric, 

 acetic and formic. The odour of the sugar is suggestive . of 

 butyric and acetic acids, but formic acid might easily be contained 

 among the volatile acids. The latter is readily detectable by 

 mercuric chloride, and in order to test if it were present, about 

 25 grms. of sugar were acidified with dilute sulphuric acid and 

 distilled. On heating the distillate with mercuric chloride, a 

 white precipitate of calomel was obtained. This test is sufficient 

 to indicate formic acid, and the presence of this acid, which is 

 one of the byproducts of the gum bacillus, confirms the fact 

 that this organism is the cause of the acid fermentation. 



