i8 THE CHEMISTRY OF CATTLE FEEDING 

 C 6 H 12 6 + H 2 N.NHC 6 H 6 - C 6 H 12 O 5 (N.NHC 6 H 5 ) + H 2 O 



(Glucose.) (Phenylhydrazine.) (Glucose hydrazone.) 



By a secondary reaction with excess of the reagent they form 

 osazones, compounds which contain two hydrazine radicles. 



C 6 H 12 6 + 2 H 2 N.NHC 6 H 5 



(Glucose.) (Phenylhydrazine.) 



-> C 6 H 10 4 (N.NHC 6 H 5 ) 2 + 2 H 2 + H 2 



(Glucosazone.) 



As the same osazone 

 CH 2 (OH).(CH.OH) 8 .C{N 16 HCeH,).CH(N 2 HC $ H5) 



is produced from both glucose and fructose, it is evident that 

 the four carbon atoms which are not affected by the reagent 

 are united to the same groups of atoms and that these are 

 arranged in the same way in the two compounds. By the 

 action of strong hydrochloric acid the osazones are converted 

 into osones, and from these hexoses may be again regenerated 

 by reduction with hydrogen. 



C 6 H 10 4 (N 2 HC 6 H 5 ) 2 + 2H 2 



-> 2 N 2 H 3 C 6 H 5 + CH 2 (OH).(CH.OH) 3 .CO.CHO 



(Glucosone.) 



By this series of reactions, fructose may be obtained from 

 glucose. 



(3) Glucose is an aldehyde and fructose a ketone. 



By the action of oxidising agents which convert glucose 

 into acids containing six atoms of carbon, the carbon chain of 

 fructose is broken and the products contain less than six 

 atoms of carbon in the molecule. 



The difference in the constitution of the two compounds 

 may therefore be indicated as follows : 



CH 2 (OH).(CH.OH) 3 .CH(OH).CHO 



(Glucose.) 



CH 2 (OH).(CH.OH) 3 .CO,CH 2 (OH) 



(Fructose.) 



According to this view, the two substances are identical 

 as regards four of the carbon atoms and differ only in the 

 arrangement of the atoms attached to the other two. It must 

 be remembered, however, that three physical isomers the 

 dextro-rotatory, laevo-rotatory, and inactive forms of ^ each 



