HHAKHOSE, 



It was stated above that rjcmid obtained a sugar solution 



by the decomposition of a fisetin-gluooside from Rhus cotlnus, 



and Parkin obtained the same from a glucoside in Rhus rhodan- 



thema. These investigators thought that the sugar was iso- 



dulcite or rharcnose but they did not isolate It on account 



of the small quantities of material at their disposal. More- 



over, the sugar is very hard to crystallize in the presence of 



other soluble substances and ir not found in large quantity 



1 ^ 



in plants. Maquenne could obtain only 15«»20 gm. of rham- 



nose by working up 1kg. of the berries of Rhamnus infect orius. 



As-uming that the free fisetin found in poison ivy leaves 



had its origin in the decomposition of a fisetin-glucoflide 



by natural processes, it was reasonable to suppose that the 



sugar would also be found in the free state although according 



Z 

 to Roscoe and Scharlemmer : "Isodulcite does not occur in the 



free state in nature, but ir; found as a peculiar ethereal 



salt belonging to the class of glucosides. On boiling with 



dilute sulphuric acid, this splits up into isodulcite and 



other bodies " The more recent works on the sugars 



3 

 and on plant chemistry mention the occurrence of rhamnose only 



1, Ann. de Chtm. et de Phys. . 6th Series, ZIII, 76 (1891). 



2, Treatise on Chem. Vol III, Pt. Ill, 492. 



3, les Sucres; Chem. der Zuck. ; Biochem. der Pflan, 



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