46 SECTIONAL ADDRESSES. 



Synthetic Dextrins. 



[With Mr. J. W. H. Oldham, B.A.] 



With the courteous permission of Professor Pictet we have apphed 

 the methylatioii process to the synthetic dextrins recently prepared by 

 him.-* These compounds are formed by the polymerisation of 

 p-glucosan and, in properties and composition, they closely resemble 

 the natural dextrins. It is, however, abundantly evident that the 

 synthetic coanpounds differ structurally fi'om starch as, although 

 methylation was extremely tedious, complete alkylation was effected 

 with the production of trimethyl derivatives. Contraiy tO' expectation, 

 hydrolysis of these compounds did not lead to the formation of 2,'3,5- 

 trimetbyl glucose, although this sugar has already been obtained from 

 p.glucosan by similar treatment. On the other hand, large quantities 

 of 2,3,5,6-tetraJuethyl glucose were invariably for-med, together 

 with lower methylated glucoses in which the position of the alkyl 

 groups is unknown. It follows from these results that the synthetic 

 dextrins are complex polyglucose-glucosides, and it is interesting to note 

 that they thus conform to the structural type suggested for cellulose 

 by Hess. Although starch is convertible into glucosan and this, in 

 turn, into the synthetic dextrins, it is evident that profound structural 

 alterations must accompany each change. 



Inulin. 



[With Dr. Ettie S. Steele, Mr. G. McOwan, M.A., B.Sc, and Miss 



M. I. Shannox, B.Sc] 



The statement has been made that, of all the polysacchaiides, 

 inulin is the repi-esentative of which the structure has been most 

 definitely established. The opinion is gratifying, but not altogether 

 accurate. 



Inulin is derived from fructose, and, until recently, there was no 

 reaso'n to doubt that the parent hexose was the well-known laevo-rotatory 

 form of the ketose. This view is no longer tenable as, although inulin 

 itself yields the normal form of fructosei on hydrolysis, trimethyl inulin 

 is converted into a dextro-rotatory trimethyl fructose.^' In similar 

 manner, dimethyl inulin gives a dextro-rotatory dimethyl fructose. 

 Each of these alkylated ketoses was proved to be a derivative of the 

 ' Y-fi'Lictose,' which is a constituent of sucrose. 



This result places inulin in a position which is quite miique, and 

 the evidence is conclusive that thei polysaccharide is entirely composed 

 of y- fructose residues, each of which retains three hydroxyl gi'oups. 



The many problems involved in the constitution of inulin have been 

 discussed by us at some length in recent papers, and attention may 

 now be restricted tO' the additional evidence we have secured. One 

 important point left unsettled was whether the trimethyl y-fructose 

 obtained from trimethyl inulin is a single chemical substance or a 

 mixture ol iso«ierides. The question is fundamental, as only in the 

 event of the methylated fructose proving to be a single individual are 

 we justified in claiming that the hydroxyl gi-oups in inulin are 

 symmetiically disposed. The experimental difficulties in the way are 



