PROCEEDINGS OF SECTION B. 123 



The tannin contained in the bark of this species belongs to quite a 

 different group to that occurring in the "ironbarks," as Eucalyptus 

 crebra and Eucalypt s sideroxylon, for instance ; and the peculiarities 

 shown by the barks of these latter species when used for tanning is 

 no criterion of what will be experienced with the barks of species allied 

 to the "mallet." It is to the presence of a large amount of kino in 

 "ironbark" barks that their apparent astring^ncy is due; but, although 

 so large a percentage of these barks is dissolved out with cold water, 

 yet this has very slow action on hide substance. This sluggishness 

 is due to the kinos of the " ironbarks " consisting very largely of a 

 glucoside ; and this, when hydrohzed, forms a substance of a very deep 

 red colour, which is more of a dye than a tannin, and when boiled with 

 mordanted cloth shows considerable permanency as a dye. The Idnos 

 or concentrated tannins of the "oaallet" bark ?.nd its related species 

 do not contain this glucoside, except occasionally in traces; and their 

 action on hide substance is very good and more in agreement with that 

 of other well-known tanning materials, consequently the barks of this 

 group of eucalypts can be utilized for tanning purposes, providing 

 of course, they contain sufficient tannin to make them profitable to 

 work. At present the greater portion of eucalyptus bark used for 

 tanning is derived from the " mallet." 



The last Annual Eeport of the Forest Department of Western 

 Australia shows that the value of " mallet " bark exported to countries 

 beyond the Commonwealth for the year ending 30th June, 1911, was 

 £73,247, to which must be added £10,675, the value of the bark shipped 

 to the Eastern States. For the twelve months ending 30th June, 

 1912, the value of this bark shipped to foreign countries had fallen 

 to £44,610, while the value of that sent to the Eastern States was 

 £13,902. These figures show a decrease in value over that of the 

 previous year of no less a sum than £25,410. This diminution is serious 

 when the question of permanency for the industry is considered, and it 

 appears that the naturally -growing trees of this species will not be 

 able to maintain the supply, or keep pace vdih the demands for 

 " mallet " bark. 



The large amount of tannin contained in " mallet " bark has estab- 

 lished a standard for eucalyptus barks to which it appears those of other 

 known species cannot reach. Although this may be true for bark 

 required to be used directly in the pits, yet there seems no reason why 

 tanning extracts should not be manufactured from the less rich barks 

 which contain a similar tannin. 



The feasibility of this may be shown from the results obtained 

 with " gimlet " bark (Eucalyptus salubris), another species of Western 

 Australia. The tannin in the bark of this species is for tanning purposes 

 of equal value with that of the " mallet," but the bark of the " gimlet " 

 only contains about 18 per cent, of tannin, scarcely half that in " mallet " 



