| | | |
HO-C-H H-C-OH H-C-OH HO-C-H
| | | |
HO-C-H H-C-OH H-C-OH HO-C-H
| | | |
CHO CHO CHO CHO

2. Aldohexoses of the dulcitol series:

_d_-Galactose _l_-Galactose _d_-Talose _l_-Talose
CH_{2}OH CH_{2}OH CH_{2}OH CH_{2}OH
| | | |
H-C-OH HO-C-H H-C-OH HO-C-H
| | | |
HO-C-H H-C-OH HO-C-H H-C-OH
| | | |
HO-C-H H-C-OH HO-C-H H-C-OH
| | | |
H-C-OH HO-C-H HO-C-H H-C-OH
| | | |
CHO CHO CHO CHO

3. Ketohexoses:

_d_-Fructose _d_-Sorbose _d_-Tagatose
CH_{2}OH CH_{2}OH CH_{2}OH
| | |
H-C-OH HO-C-H H-C-OH
| | |
H-C-OH H-C-OH HO-C-H
| | |
HO-C-H HO-C-H HO-C-H
| | |
C=O C=O C=O
| | |
CH_{2}OH CH_{2}OH CH_{2}OH

Reference will be made in subsequent paragraphs to the probable chemical
constitution of the monosaccharides other than hexoses; but the above
discussion of the structure of the hexoses will serve as a sufficient
introduction to the study of the composition of the common carbohydrates.

CHARACTERISTIC REACTIONS OF HEXOSES

=Specific Rotatory Power.=--All soluble carbohydrates, since they contain
asymmetric carbon atoms, with the consequent larger groups on one side of
the molecule than the other, rotate the plane of polarized light when