548 BACTERIAL ORIGIN OF GUMS OF ARABIN GROUP, 



apparently contained in comparatively large masses of slime. 

 These masses were also noted when glycerine had been added to 

 the nutrient agar. They lay loosely upon the agar and could 

 be scraped together into a gelatinous heap." 



Since the gum can be formed from glycerine, this substance 

 should be much better than saccharose when the gum is required 

 in quantity, for the residual glycerine could be more easily 

 removed. Furthermore, a whiter gum could be obtained; the 

 saccharose solutions during sterilisation, etc., become brownish 

 in colour, and as this colour is con\e3^ed to the purified gum, its 

 solutions are not colourless. 



The other hi/products of the fermentation of saccharose. — A 

 saccharose-peptone-medium contained in a small flask was 

 infected with the organism and connected with another flask 

 containing baryta water. The air inlet was sealed with a screw- 

 clip and the air outlet was connected with a tube of soda-lime. 

 No aerial carbon dioxide could therefore gain access to the 

 apparatus. At the end of five days the air from the culture 

 flask was drawn through the baryta water, when a copious 

 formation of barium carbonate occurred. Carbon dioxide is thus 

 a byproduct in the fermentation of saccharose. 



The supernatant liquid from a 20 days' culture containing 

 chalk and saccharose was treated with barium hydroxide and 

 boiled under an inverted condenser in order to saponify alcoholic 

 esters. The liquid, after cooling, was filtered and distilled in a 

 partial vacuum until about one- third had passed over. The 

 residual fluid was evaporated down and reserved for the extrac- 

 tion of the acids. The distillate was distilled and the process 

 repeated until about 10 c.c. of fluid had been obtained. As this 

 contained ammonia it was made acid to litmus with phosphoric 

 acid and distilled at atmospheric pressure. The first 2 c.c. of 

 distillate were absorbed with anhydrous sodium carbonate and 

 distilled. The first drops that passed over were collected and 

 the boiling point determined by Siwoloboff's method. The fluid 

 boiled at TS'-^ and burned with a blue flame. It also gave the 

 iodoform reaction, and undoubtedly was ethyl alcohol. 



