458 BULLETIN OF THE BUSSEY INSTITUTION. 
Returning now to the soft, pasty mass which remained undis- 
solved when the mixture of strong acid and cotton was diluted 
with water, efforts were made to wash and collect this material in 
order that its weight might be subtracted from that of the cotton 
taken. To this end it was stirred up repeatedly with fresh por- 
tions of water and refiltered many times. Although it still 
retained an acid taste, the grayish mass was dried somewhat on 
a water-bath where it turned brown and eventually black. As 
soon as the pasty particles had begun to ball together on stirring 
a new attempt was made to wash the material, but it became 
pasty again on the addition of water. Finally, the matter was 
dried at 100° in a current of air and weighed. It amounted to 
27.82% of the original cotton dried at 100°. From the nature 
of the case, the subtraction of this highly impure material from 
the weight of the cotton can be regarded as affording only a 
rough approximation to the quantity of cotton that escaped solu- 
tion; but it is noteworthy that, afte: the subtraction of this 
insoluble matter, the percentage of dextrose yielded by the cotton 
cloth, minus the insoluble matter, amounted to no more than 
41.92% of the dry cotton. 
A quantity of the clear neutralized filtrate, resulting from the 
hydrolysis of the dissolved cotton, was evaporated to dryness on ~ 
a water-bath, and the residue was treated with several successive 
portions of cold, strong alcohol. Apparently, less than half of 
the residue dissolved; and, from evidence presented on previous 
pages, it is to be presumed that some part of this substance 
insoluble in alcohol must have been inorganic matter. After 
expelling the alcohol and dissolving in water, the matter insoluble 
in alcohol gave quasi(a) D= 55.°25, and Fehling’s liquor indi- 
cated enough dextrose to amount to 17.38% of the original cotton 
(dried at 100°), or to 24.07% of the cotton, after subtraction of 
that portion of the cotton which was left undissolved by the 
sulphuric acid. | 
Although the percentage of dextrose obtained in this particular 
instance is very much less than the quantity reported by Flechsig 
in the experiment made by him, of which the trial here reported 
is a repetition, it is noteworthy that the rotation observed 
(quasi (a) D = 54°.64) is decidedly nearer that of pure dextrose 
than had ordinarily been detected in any of the very large 
