25 



The improvement of the strength of wattle bark during a year's storage seems to arise 

 from the augmentation of catechu-rtannic acid through conversion or oxydation of catechuic 

 acid, the latter possessing no tannic properties. Bark, exposed to weather and particularly 

 also moisture, deteriorates in strength by a change of some of the tannic acid into pyro- 

 catechin or oxyphenic acid and into phlobaphen. 



NATIVE TREES, BEYOND BLACK AND GOLDEN WATTLES, AVAILABLE 



FOR TANNERIES. 



Acacia melanoxylon ; the blackwood tree. The bark of this highly valuable timber tree 

 has generally gone to waste, after from the logs the splendid wood was obtained. The bark 

 is however very rich in tannic acid, and ought not to be left unutilized, although no 

 blackwood trees should be sacrificed for the sake of their bark alone. 



Acacia penninervis ; similar to the golden wattle. It occurs in Victoria on the Ovens 

 and Snowy River and their upper tributaries, ascending to subalpine elevations, taking 

 there the place of A. pycnantha. Aii only experiment with the bark gave 18 per cent, of 

 catechu-tannic acid. 



Eucalyptus leucoxylon ; the Victorian ironbark tree. The bark contains in a fresh state 

 as much as 22 per cent, of kino-tannic acid ; it is, however, available for inferior leather 

 only, as the extractive substance of this bark imparts a dark coloration, and seems also to 

 impair the tanning process. As an admixture to wattle bark, that of Eucalyptus leucoxylon 

 may attain yet great importance, this bark moreover being so heavy and obtainable from 

 gigantic trees. From stringybark, that of E. obliqua, as much as 13| per cent, of kino- 

 tannin can be obtained. 



Eugenia Smithii ; a large and very umbrageous myrtle tree, of the lower Snowy River, 

 and thence extending along the lowland streams eastward. As much as 17 per cent, of 

 tannin has been obtained from its bark in the laboratory of the writer. 



BanJcsia marginata ; the common honeysuckle tree. It is contended, that the bark of 

 this tree and other Banksias can be utilized for tanneries only in a fresh state. It is 

 moreover shown to be of much less tan-strength than our acacia bark. The bark of B. 

 serrata of South Gippsland has proved to yield nearly 11 per cent, of tannin. Banksias 

 cannot be reared with the same ease as wattles. 



