Also Kiliani found that the lactone derived from the cyanhydrin of natural arabinose (laevo) was identical with the previous lactone except that its rotation was equal and opposite.
2
Arabinose being convertible into /-glucose and xylose into l-gulose, the alternative formulae to be considered are CH 2 (OH) - - - +COH CH 2 (OH) + + - COH.
3
As a matter of fact, only arabinose gives an active product on oxidation; it is therefore to be supposed that arabinose is the - - - compound, and consequently CH 2 (OH) - - - + COH = /-glucose CH 2 (OH) + - - - COH = l-gulose.
4
To settle this point it is necessary to consider the configuration of the isomeric pentoses - arabinose and xylosefrom which they may be prepared.