258 Cellulose 



section of the molecule, which breaks down ultimately into maltose 

 when invertase is employed, or into dextrose when the hydrolysis is 

 completed by acids, the intermediate terms being the uncrystal- 

 lisable dextrines. Owing to the obviously simple relation of the pro- 

 ducts of resolution to the original molecule, we are justified in con- 

 cluding that starch represents an aggregate of considerable mole- 

 cular magnitude ; the ultimate constituent C 6 groups being linked 

 together by oxygen. The evidence, in fact, goes to show that starch 

 is of the same constitutional type as the bioses (e.g. cane sugar and 

 maltose) and trioses (e.g. melitriose). The combination of two 

 glucose residues, to form a biose, takes place in one of two ways 

 i.e. either one or both of the typical CO groups takes part in the 

 condensation ; in the former case (e.g. maltose) the free carbonyl 

 determines aldehydic properties, which disappear, in the latter case, 

 (e.g. cane sugar) with the suppression of the second CO group. 



In starch, the linking of the glucose residue is of the dicarbonyl 

 type, and it consequently fails to react with phenylhydrazine, 

 and does not reduce Fehling's solution. In the hydrolysis of 

 starch the carbonyl linkings are broken down successively, the 

 process being similar to that which takes place with the triose above 

 named, which is first resolved into melitriose and fructose, the 

 former then splitting into glucose and galactose. (See Scheibler 

 and Mittelmeier, Berl. Ber. 26, 2930.) 



Cellulose is identical with starch in empirical composition 

 (,C 6 H 10 O 5 ), and similar, in being an aggregate of hexose groups ; 

 but for resolution into the latter, cellulose requires the severe 

 treatment of solution in concentrated sulphuric acid. 



To give full value to these characteristic differences, we must 

 pronounce for a corresponding difference in molecular configu- 

 ration. 



The problem must next be considered from the point of view 

 of function of the reactive groups of cellulose. The student should 

 be reminded that carbon chemistry is very much a chemistry of 

 function. The idea of chemical function grew but slowly with the 

 study of the * inorganic ' elements, and indeed of the carbon 

 compounds also, so long as it was limited to individuals and 

 groups more or less isolated. It was a chemistry of jumps and 

 gaps. In modern 'organic' chemistry, on the other hand, the 

 carbon compounds are presented to us in extended series of 



