1910. | B. lactis aérogenes on Glucose and Mannitol. 277 
(3) The crude glycol does not reduce Fehling’s solution either in the 
cold or on heating, though it contains a constituent which reduces ammoniacal 
silver nitrate* in the cold. This may be removed without any apparent 
accompanying change to the “crude glycol” by boiling for eight hours 
with 30-per-cent. caustic soda solution. When the “crude glycol” was 
boiled at atmospheric pressure for seven hours in contact with air the 
liquid assumed a brownish tint, which did not increase with time, and 
{«]p fell from + 0°723 to + 0590. On boiling with animal charcoal in 
aqueous solution and recovering the glycol, the [a]p was found to be 0°749. 
No reaction product could be obtained by heating an aqueous solution of 
“crude glycol” and phenylhydrazine acetate to 100° for one hour. 
A mixture of 10 grm. glycol, 32 grm. water, and 8 grm. concentrated 
sulphuric acid boiled up for 10 hours apparently underwent no change, 
the material being recovered unaltered. 
The above experiments, beyond showing the general chemical stability 
of the constituents of the “crude glycol,” indicated that it was not a pure 
chemical substance, but did not provide any information as to the other 
substances accompanying the 2: 3-butanediol therein. 
Treatment of “Crude Glycol” with Phenylisocyanate, and Fractionation of the 
Resulting Phenylurethanes. 
20°4 grm. of “crude glycol,” 64 ¢.c. phenylisocyanate, 250 cc. of pure dry 
ether were boiled on a water-bath for 12 hours till “bumping,” due to 
deposition of crystals commenced. The mixture was then allowed to cool. 
The supernatant fluid was poured off, and, together with the dry ethereal 
washings of the crystals, boiled up again for an additional seven hours. This 
liquid was concentrated, and, on cooling, the mother liquors containing the 
excess of phenylisocyanate were removed, and the isocyanate decomposed by 
alcohol. In some later preparations the excess of phenylisocyanate, together 
with the most soluble phenylurethanes, was carried on to the next batch. 
Precautions were taken to prevent access of water during the performance of 
the above operations. The fractionation of the reaction-products was com- 
menced by recrystallisation from alcohol. Four substances were obtained 
pure in this way. The mother liquors containing substances more soluble in 
alcohol were dissolved in benzene, and precipitated fractionally by adding 
light petroleum. 
Altogether, about 105 grm. of “crude glycol” were treated with phenyl- 
isocyanate, corresponding to about 383 grm. of mixed phenylurethanes. 
From alcohol there were obtained :— 
* Tollens, ‘ Ber.,’ vol. 15, p. 1635. 
