FOHMATION OF VEGETABLE PRODUCTS. 79 



It seems probable, however, that the process by which such bodies 

 are constructed does not consist in the simultaneous deoxidation 

 of several atoms of carbonic acid into one complex molecule, as 

 illustrated by the equation used in my last lecture to explain the 

 production of mannite, 



Garb-anhydride Water Oxygen Mannite 



6 CO Z + 7 H a O - 130 = C 6 H I4 6 ; 



but that a series of more and more complex, less and less oxidised, 

 intermediate bodies are successively produced, by the. fixation of 

 deoxidised carbonic acid upon the previously formed compounds. 

 For example, we may conceive mannite to be built up somewhat 

 in this manner. By a simultaneous dehydration and deoxidation 

 of two molecules of carbonic acid, we should first obtain oxalic 

 acid, thus : 



z Carbonic acid i Oxalic acid 



Then by a further deoxidation of oxalic and carbonic acids, we 

 might obtain tartaric acid, thus : 



i Oxalic acid C, H, 4 



a Carbonic acid C a H 4 6 



C 4 H 6 10 

 4 Oxygen 4 



Tartaric acid C 4 H 6 6 



Lastly, by a joint deoxidation of tartaric acid, carbonic acid, and 

 water, we might obtain mannite, thus : 



1 Tartaric acid C 4 H 6 Q 6 



2 Carbonic acid C a H 4 6 

 a Water H 4 O z 



8 Oxygen 



Mannite C 6 H I4 6 



