



B.-CHEMISTRY. 



I ° 1 



— CH O CH • CHOH • CHOH • CH • CHOH • CH, 



CHOH 







I CHOH 



Lin 

 I 



CH CH, • CHOH • CH • CHOH • CHOH • CH 



(JH.OH ' I 



43 



XVII. 



O 



I 1 



CH CH • CHOH • CHOH • CH • CHOH • CH, 



I 

 CHOH 



I 

 CHOH O 



I 

 — CH 



I 

 CH CH • CHOH • CHOH • CH ■ CHOH • CH, 



CH.OH ^ 



XVIII. 



-CH 



-0 



HOH 







I CHOH 



Uh 



I 

 CH 0- 



CH., 



OH 



I « I 



CHj • CHOH • CH • CHOH • CHOH • CH 



O 



-CHj • CHOH • CH • CHOH • CHOH • CH 



I 0- -I 



XIX. 



(Letters in block type designate the potential reducing groups.) 



The inethylation process cannot discriminate between these possibiU- 

 ties, and with the data at our disposal it is inadvisable to make a definite 

 claim in favour of any one of them. Each formula postulates that 

 starch is derived entirely from the butylene-oxide form of glucose, and 

 this we have sliown to be the case. The formuhe arc all consistent with 

 the steric hindrance encountered in completing tlie methylation ol 

 starch, previous experience having shown that the alkylation of 

 position 5 is difficult when position 6 of the glucose chain is already 

 substituted. 



'I'hc fininiihc differ in one important I'cspect, as nialloso may l)e 

 obtained from foi'm XVI. in two ways, and in only one way from each 

 of XVIL, XVIII., XIX. Peiidino- the coni])]otion of furllier work on 

 this subject we prefer fornuda XVI., but ivcognisc tliat our results 

 apply only to a purified rice starch. 



