1910. | B. lactis aérogenes on Glucose and Mannitol. 273 
litre of medium treated. The flasks employed were of 1 litre capacity, and 
each was provided with a mercury trap which permitted the egress of the 
gases evolved. The fermentation was carried on under strictly anaérobic 
conditions, and the method of preparing the flasks was that employed by 
Harden.* While in the incubator they were agitated from time to time 
to distribute the chalk throughout the medium. The gas evolution was 
found to be vigorous during the first four days, but after two to four weeks 
ceased completely, and the quantity of unchanged sugar in the flask was 
very small indeed. 
At first every flask removed was tested by plating on agar, but the 
practice was frequently omitted and, instead, a culture on sloped agar in a 
test-tube made and examined. The quantities of the various substances 
found are stated in the previous paper. In order to isolate the crude 
butylene glycol, the contents of the flask were first filtered from excess of 
chalk and then evaporated at 55° under diminished pressure to dryness, and 
the dry residue, consisting of calcium salts and peptone, extracted with 
alcohol. The alcohol extracts yielded on fractionation a colourless liquid, 
boiling at 181° to 183° (corr.) at 760 mm. pressure. The yield was very 
small, only amounting to about 1 gramme’ per litre of medium containing 
20 grm. of glucose, but it was found possible to increase it by employing 
a medium containing 5 per cent. of glucose. In this way 8 grm. of the new 
substance containing 52°8 per cent, of carbon were obtained per litre of 
medium containing 50 erm. of sugar. This only accounts for about two- 
thirds of the missing carbon, and a rough estimate of the amount lost 
during the process of distillation and extraction was therefore made by 
dissolving 8 grm. of the material in 500 cc. of a medium containing 5 grm. 
of Witte peptone, 6 grm. of calcium lactate, and 6°5 germ. of alcohol, and 
then extracting it in the manner described above. Only 5:2 grm. were 
recovered, the loss per 500 c.c. being therefore about 2°8 grm., and the loss 
per litre about 56 grm. This brings the total amount produced from 
50 grm. of glucose to about 13°6 grm., slightly in excess of that required. 
In one case a yield of 10°75 grm. was obtained from 1 litre of medium 
containing 5 per cent. of glucose. Generally, only 7 to 8 grm. of the “ crude 
glycol” were obtained from each flask of 50 grm. of glucose, in spite of 
numerous attempts to improve the yield. 
I. THz NATURE OF THE “ CRUDE GLYCOL.” 
This substance boils at 181° to 183° (corr.) at ordinary pressure, and at 
12 mm. the boiling point is from 83° to 84°5 C.; it solidifies in the cold 
* ‘Jenner Inst. Trans., 1899, vol. 2, p. 126. 
