252 



ON SOME N.S.W. TAN-SUBSTANCES. 



and will be more thoroughly studied as Eucalyptus leaves 

 increasingly enter into commerce. Where a leaf under examination 

 presents a difference from the published description, that difference 

 lias been pointed out. 



10. According to Watts' Diet: Chevreul discovered a yellow 

 colouring matter in Sumach, which separates from a concentrated 

 decoction on cooling, in small crystalline grains. I have been 

 unsuccessful, up to the present, in tracing the original memoir, 

 but the yellow colouring matter before you, has been deposited 

 from Eucalyptus leaves in a similar manner to that of the yellow 

 pigment of Chevreul obtained from Sumach. Of those species, I 

 have up to the present examined, E. macula fa contains a small 

 quantity, but E. rhacrorrhyncha contains it in abundance. In 

 boiling the leaves with a limited quantity of water, the greater- 

 part of the tannic acid is dissolved out, and but little colouring 

 matter. Prolonged boiling with a second water extracts the 

 colouring matter freely. This is but a preliminary note, for the 

 Substance is of such great interest, and, probably, of commercial 

 importance, that I am subjecting it to careful examination from 

 the point of view both of the chemist and colourist. 



Tannic Acid in Leaves — Preliminary notes. 



1. Allusions to the tannin of leaves (with the exceedingly 

 important exception of Sumach) in text-books and the proceedings 

 of societies, are of the rarest occurrence. I have therefore 

 considered it convenient to present a few notes which I have 

 come across, on the leaves of such plants as have been examined 

 for tannic acid. It will be interesting to compare these results 

 with those of the few New South Wales species referred torn the 

 present paper. Leaves as a rule are solely valued as a manure, 

 and hence the frequent determinations of the ash of them, e.[/., 

 Gueymard (Comptes Rendus, lix., 9-89). 



2. Tannin (Tannic acid) is found more constantly in cells 

 presenting a low degree of vital activity, as those of the wood and 

 bark ; and that of early decaying excrescences, as galls : but still 

 it is found in many leaves, as those of the tea-plant, and of the 

 Ericacece ; but here, perhaps, it only occurs in the bundles of 

 vessels, or less actively vital cells of the leaf. (Princip. of 

 Scientific Botany, Schleiden, 1849). 



(A.) Tannic Acid in Leaves not Australian. 



1 . Although I cannot find it specifically stated that the leaves 

 of any Indian Acacia are used in tanning, yet the astringent 

 properties of the leaves of some species cause them to be used in 

 medicine. The leaves of A. arabica, for instance, are used in 

 India as an astringent and stimulant application to ulcers attended 



