R. H. Chittenden—Dehydration of Glucose. 958 
phuric acid (the solution containing two per cent. H,SO,) the cupric 
_oxide-reducing power was increased to the equivalent of 0°134 gram 
of glucose, or nearly equal to the amount started with. 
It is to be noticed in the experiment just quoted, that the cupric 
oxide-reducing power, before and after treatment with sulphuric acid, 
stand to each other in the proportion of 58 : 100, or in about the rela- 
tion of maltose (61) to glucose (100). In some experiments, how- 
ever, the reducing power before boiling with dilute acid, was so low 
as to warrant the belief that dextrins were also formed. This result 
is a type of many similar ones obtained by Pavy with the stomach 
and intestines from various animals and in no instance, in the case 
of rabbits at least, so far as reported, were negative results obtained. 
The discovery of such a dehydrating ferment, hitherto unsus- 
pected, appeared to be a matter of so much importance that experi- 
ments have been tried in this laboratory from time to time during 
the past two years, with the view of confirming in part at least some 
of Dr. Pavy’s. results. To our ‘surprise, however, in no case, have 
we been able to obtain results corresponding to those of Pavy’s, 
although the animals experimented with (rabbits and cats) were 
taken in various stages of digestion. We therefore record here, 
some of the results simply in the hope that some light may be thrown 
upon the cause of this discrepancy ; or if, as may be, the ferment is 
not invariably present, some reason may be found for its constant 
absence in the tissues of the animals experimented with, and thus 
light be thrown upon the conditions which control its presence. 
The glucose used in the following experiments was a sample of 
crystallized anhydrous glucose presented to the laboratory by Dr. 
Arno Behr. The sugar was quite pure, as was ascertained by testing 
both its reducing power and specific rotary power, and more import- 
ant still, was not at all affected by boiling with dilute sulphuric acid. 
Thus 50 c¢.¢. of a one per cent. solution of the glucose, mixed with 
sufficient 10 per cent. sulphuric acid to have the mixture contain two 
per cent. of H,SO,, was boiled for one and one-half hours, the flask 
being connected with an inverted Liebig’s condenser to prevent con- 
centration. The solution was then neutralized, diluted to 100 «. ¢. 
and tested with Fehling’s solution according to the method of Allihn. 
25 c.c. yielded 0°2414 gram of metallic copper, corresponding to 
0°1246 gram of glucose, whereas the 25 ¢. c. of solution should have 
contained 0°1250 gram of sugar. Evidently then, the reducing 
power of the sugar is not affected by treatment with dilute acid. 
First experiment.—A rabbit in full digestion was killed, the stom- 
