igos\ Wheeler— Problems in Cellulose Field. 109 



up, but that is rather a reserve material to be drawn upon in 

 case of cell starvation, that is, when all the cane sugar has 

 been translocated as dextrose and levulese. The problem can 

 not be regarded as settled and further work in this direction 

 is highly desirable. 



As already stated, the simple celluloses are represented by 

 the empirical formula (C 6 H io O s )n, the letter n standing for a 

 number which is wholly problematical, although Bumcke and 

 Wolffenstein have suggested 12. As for a constitutional for- 

 mula this has yet to be worked out. How much progress has 

 been made and what remains to be done? The great stability 

 of cellulose, made familiar by its almost universal use as a 

 filtering medium, has precluded in the minds of many of us a 

 realization of the chemical activity which it really possesses. 

 Its attraction for water is very strong, cotton cellulose retain- 

 ing from six to twelve per cent, in the air-dried condition, 

 and if this water is driven off, it will be reabsorbed on expos- 

 ure to the atmosphere. This hygroscopic property bears an 

 undetermined relation to the presence of hydroxyl groups 

 because it decreases as the number of hydroxyl groups is 

 diminished by substitution of acid radicals. Since the tetrace- 

 tate seems to be the highest normal acetate, it is probable 

 that there are four hydroxyl groups. The other oxygen atom 

 is combined with carbon to form a carbonyl group, although 

 this is not in the usual reactive condition. In the easily 

 derived hydro- and oxy-celluloses it appears at once in natural 

 character of a reducing agent. The large proportion of acetic 

 acid obtained when cellulose is fused with alkaline hydroxides 

 indicates the presence of CO-CH a groups. Its resistance to 

 the action of halog-ens and alkalies shows it to be a saturated 

 compound. Owing to the similarity of the empirical formula 

 of cellulose and starch and to their association in the pro- 

 cesses of nature, it has been customary to regard them as 

 very closely related in constitution. However, there is 

 undoubtedly a fundamental difference between them. Vignon 

 has subjected purified cotton and starch to hydrolysis with 



