604 THE GUM FBRMKNTATION OF SUGAR CANE JUICE, 



water. The inlet tube of the culture flask was fastened with a 

 clip, and to the outlet tube of the third baryta flask a tube con- 

 taining soda lime was attached to prevent the inward passage of 

 atmospheric carbon dioxide. A current of air was sucked 

 through the apparatus daily after attaching a soda lime tube to 

 the inlet tube of the culture flask. The evolved gas was thus 

 daily removed from the culture. On the fifth day the baryta 

 solutions were added together and rapidly filtered, the barium 

 carbonate was washed and then suspended in water. After 

 adding phenolphthalein, 20 c.c. of standard acid were run in, 

 and the solution boiled to expel the displaced carbon dioxide. 

 The excess of acid was then determined, and by difference the 

 carbon dioxide equivalent obtained. 



11-6 c.c. ^/o acid used to decompose the barium carbonate 

 = 0-1276 grm. COo from 10 grms. sugar 

 = 1-28 grms. COo from 100 grms. sugar. 

 From the determination it is seen that a considerable quantity 

 of carbon dioxide is formed during the fermentation. 



The Production of Acid. 



When the cultures were tested with litmus they were found 

 to be distinctly acid, and when small cultures (10 c.c.) were 

 titrated, quantities of ^'/s alkali varying from 0-3 to 0*6 c.c. were 

 required to neutralise the acidity to phenolphthalein. It was 

 also noted that old cultures contained less acid than compara- 

 tively young ones, a circumstance which pointed to the volatili- 

 sation of a Aolatile acid. Jn connection with this it may be 

 mentioned that the cultures, and also the air of the incubator 

 containing the cultures, had a faint not unpleasant cheesy smell. 



During the cultivation at 22° of a two-litre culture, 10 c.c. 

 portions were abstracted and tested. By the second day the 

 acidity was equal to 0-4 c.c. ^/^ alkali, and it slowly rose to 4 5 

 c.c. on the tenth day. This is equivalent to from 0-07 to 08 % 

 lactic acid. 



A number of 50 c.c. portions of saccharose media were infected 

 with several races of the bacillus, and tested after incubation for 

 a week at 37°, with the following results. 



