18 



TABLE VI. 



Showing the percentage of Tannic and Gallic acids in the barks 

 of some species of Eucalypts. 



III. GUM-RESINS OF THE EUCALYPTS. 



These are produced in greater or lesser quantities by all the 

 species of this genus ; from this circumstance the Eucalypts are 

 almost universally called by the Colonists " Gum trees.' 1 



These substances occur within the trunks of trees of all sizes, 

 in flattened cavities in the otherwise solid wood, which often lie 

 parallel to the rings of growth. In such places the deposition of 

 the gum-resin, which is at first a viscid liquid, becomes gradu- 

 ally inspissated, and subsequently hard and brittle. The liquid 

 gum-resin may be obtained by making incisions in the stems of 

 growing trees ; they are very viscid treacle-like fluids, not differ- 

 ing in chemical composition from those which have undergone 

 indurations, save that they contain more water ; the indurated 

 looses from 15 to 20, and the liquid gum-resin about 65 percent, 

 at a temperature of 212 F. When thus dried they are exceed- 

 ingly friable and easily pulverised. 



In their general characteristics, these gum-resins resemble 

 each other very closely. In the solid form they present the ap- 

 pearance of small angular masses, not unfrequently intermixed 

 with particles of wood. The prevailing color is dark red-brown, 

 in some cases dull with olive and yellowish tints, in others bright 

 ruby colored and transparent ; black and opaque pieces are also 

 very commonly interspersed through each of the varieties de- 

 scribed. In the mouth they are tough, adhere to the teeth, and 

 color the saliva red ; their taste is intensely astringent, with a 

 slight bitter flavor ; in this respect, however, there is some dis- 

 similarity. 



The gum-resin from Eucalyptus resinifera is that which is 

 known under the name of Botany Bay Kino-; it is for all medi- 



