324 PLANT AND ORGANIC CHEMISTRY 



spectively gluconic and galactonic acids. By complete oxida- 

 tion they both give saccharic acid. 1 



Conversely to the aldehyde sugars, fruit sugar is slowly 

 attacked by bromine water. By the action of a more powerful 

 oxidizing reagent it is decomposed into products containing 

 fewer carbon atoms. 



The aldehyde and ketone character of these compounds 

 is shown by the readiness with which the sugars form hy- 

 drazone and osazone compounds. This reaction with phe- 

 nylhydrazine is characteristic of all compounds containing 

 aldehyde and ketone groups. 2 



The sugar varieties which to-day go to make up a magnifi- 

 cent display of synthetic skill include many isomers, depend- 

 ing upon the different arrangement of the atoms in space. In 

 order to have a clear view over this field, it is important to as- 

 certain the spacial relations or configuration of each member 

 of the sugar groups. 3 



The latest publications by Emil Fischer on the stereomers 

 of the sugar groups show an admirable agreement between 

 the conflicting facts pertaining to the sugars which have poured 

 in from isolated researches during past years, when these are 

 considered in the light of Le Bel and Van't Hoff's theory. The 

 names of these investigators are especially identified with 

 stereo-chemistry, although others have followed in the same 

 lines. 



Among the writings of the past, the geometrical forms of 

 matter were suggested by the Greeks, and later by Sweden- 

 borg as a possibility; but it was Pasteur, in 1860, who gave 

 the underlying idea of grouping of atoms in space. 



1 When a solution of the alcohol mannite is heated for some hours to 42 C. 

 with nitric acid, it is oxidized to mannose; if the reaction is continued with 

 increased heat, the oxidation is carried on to the acid formation. 



2 CH 2 OH(CHOH) 4 CHO + C C H 5 HN 2 H 2 = CH 2 OH(CHOH) 4 CH 



N 2 HC 6 H 6 +H 2 



CH 2 OH(CHOH) 3 CO . CH 2 OH+C C H 5 HN 2 H 2 =CH 2 OH(CHOH) 3 C.CH 2 OH 

 + H 2 | 



N 2 HC 6 H 5 



3 The configuration of a compound is the relative position of its atoms in 

 space. The portion of chemistry treating on this subject is called stereo- 

 chemistry. 



