66 . HENRY G. SMITH. 



direct action of the acids upon the alcohols, and is assisted 

 by a special dehydrating agent, as suggested by the above 

 authors, the question arises as to what this special agent 

 is that brings about the formation of this ester in the oil 

 of E. Macarthuri alone of all the Eucalypts. It may be 

 suggested that the reason is because geraniol is the most 

 abundant alcohol in this species of Eucalyptus. The com- 

 parative absence of this terpene alcohol in the other 

 members of this genus is thus difficult to understand, and 

 the whole problem respecting the four esters now known 

 to exist in Eucalyptus oils thus becomes one of exceeding 

 interest, and worthy of special scientific study. 



(2) Myrticolorin. 

 In a paper 1 on the chemistry of the dye-material Myrti- 

 colorin, discovered by myself in the leaves of Eucalyptus 

 species, particularly in those of the "Red Stringybark " 

 Eucalyptus macrorhynclia, it was shown that its formula 

 was 27 H 2 80i 6 , that it was a quercetin glucoside, and that 

 on hydrolysis it formed quercetin and a glucose. 



There were at that time two other quercetin glucosides 

 closely resembling myrticolorin ; one, Osyritrin, discovered 

 by Mr. A. G. Perkin, and obtained from the Cape Sumach 

 Colpoon compressum; the other known as Violaquercitrin, 

 described by Mandelin 3 and obtained from the flowers of 

 Viola tricolor variensis. These three glucosides were 

 supposed to differ from each other by one molecule of water 

 of hydrolysis only. 



Further researches on these three glucosides have 

 recently been undertaken by Mr. Perkin, and in a note on 

 Violaquercitrin he shows that the formula for this sub- 

 stance was incorrectly stated by Mandelin, and that its 

 formula is 2 7H 28 Oi 6 . It is thus identical with Myrticolorin. 



1 Trans. Chem. Soc, 1893, p. 697. 2 Loc. cit., 1897, p. 1132. 



* Jahresber., 1883, p. 1369. * Proc. Chem. Soc, xvn., p. 88. 



