SUGARS 121 



acid, and the acid into aldehyde. These two isomers, 

 glucose and mannose, are converted by oxydation into 

 saccharic and mannosaccharic acids, with the formula 

 COOH(CHOH) 4 COOH, which are active, a fact only 

 compatible with type 2, 7 which leads to the bodies 



of which the latter is symmetrical, and belongs to the class 

 of inactive undecomposable modifications. 



Whilst therefore the configuration may, reasoning from 

 the necessary symmetry of the inactive undecomposable 

 type, be traced out into detail, it remains undecided which 

 of the two enantiomorphic forms 2 and 7 is to be identified 

 with a given arabinose. 



No. 2 No. 7 



CH 2 OH CH 2 OH 



HCOH HOCH 



HCOH HOCH 



HOCH HCOH 



COH COH 



3. Double Linkage and Ring Formation. 



Carbon double linkage may be represented graphically 

 by a pair of tetrahedra, as in Fig. 34, which are so connected 

 as to use up two bonds on each side. The other four then 



