38 



SECTIONAL ADDRESSES. 



In terms of the above structure, 100 parts of cellulose should give 

 I1O5.5 parts of ct'Uobiose, and here the difficulty is encountered that the 

 yields of this disaccharide are extremely variable, and rarely exceed 

 35 per cent. The highest claimed is of the order 50-60 per cent., and 

 in the meantime it is prudent to select a formula for cellulose which 

 will give a result only slightly higher than this figure. We therefore 

 propose the symmetrical tri-l,5-anhydro-glucose (VIII.) for the unit 

 of cellulose, on the ground that this structure would give a 70 per cent, 

 yield of cellobiose as the tlieoretical maximum. 



CH.,OHj O 



-CH — O — CH ■ CH • CHOH • CHOH • CH 



O 



CHOH 



I 

 CHOH 



I 

 — CH 



I 

 CH 0- 



CHoOH 



O 



-CH • CHOH • CHOH • CH • CH • CH.,OH 

 I I 



vm. 



There is, however, an alternative method of coupling the glucose 

 residues, and this gives the structure shown in Formula IX. 



O 







-CH — O — CH • CHOH • CHOH • CH • H ■ CH-^OH 



CHOH 



I 

 CHOH 



-cSh 

 ch — — ch ■ choh • choh ■ ch • ch • chjoh 



I 

 CH2OH 



IX. 



-0 



Taking into account the fact that it can yield only one disaccharide, we 

 prefer Formula VIII. to the above structure. The essential properties 

 of cellulose, so far as they are displayed in chemical reactions, are 

 accounted for by both formulae. Further, the structures are not incon- 

 sistent with the production of bromomethyl furfuraldehyde ^ from cellu- 

 lose, and indicate that the normal yield of this derivative involves the 

 reaction of one-third of the total unit. 



The various formulae which, in tlie past, have been proposed for 

 cellulose have been summarised by Hibbert.'" With the exception of 

 a structure suggested by this author, and in supporting which he pre- 

 maturely assumed that only one form of trimethyl glucose could be 

 obtained from cellulose, the structures he tabulates do not in any case 

 agree with the evidence we now produce. Typical examples are 

 quoted : — 



