Naturalisation in Extra-Tropical Countries. 9 



Acacia mollissima, Willdenow.* 



The Black Wattle of South-Eastern Australia and Tasmania. It 

 seems best to re-adopt the systematic names, by which our three 

 principal feather-leaved wattles were distinguished during the first 

 half of the century. The systematic affinity of A. mollissima is 

 nearer to A. dealbata than to A. decurrens, the differences having 

 already been set forth under those two species. It is generally a 

 middle-sized tree, its wood being used for staves, occasionally also for 

 pick-handles and similar purposes, but principally serving as an 

 excellent fuel. A chief use of the tree would also be to afford the 

 first shelter in treeless localities for raising forests in regions where 

 no severe frosts occur. It also exudes a useful gum. By far its 

 greatest importance however rests upon its bark, so highly valuable 

 for tanning ; indeed it seems destined to stand ahead of all the other 

 tan-trees of the world through the facility of its culture in suitable 

 localities and the strength of its product. Mr. James Dickinson states 

 that he has seen 10 cwt. of fresh bark obtained from a single tree of 

 gigantic dimensions at Southport. A quarter of a ton of bark was 

 got from one tree at Tambo, without stripping all the branches. The 

 height of this tree was 60 feet, and the stem 2 feet in diameter. 

 The English price of the bark ranges generally from 7 to 12. In 

 Melbourne it averages about 5 to 10 per ton. It varies, so far 

 as experiments made in my laboratory have shown, in its contents 

 of tannic principle from 30 to 40 per cent, in bark completely dried, 

 but this is not all pure tannic acid. In the mercantile bark the 

 percentage is somewhat less, according to the state of its dryness, 

 it retaining abont 10 per cent, moisture. 1^ Ibs. of Black Wattle- 

 bark give 1 Ib. of leather, whereas 5 Ibs. of English Oak-bark are 

 requisite for the same results ; but the tannic principle of both is 

 not absolutely identical. Melbourne tanners consider a ton of 

 Black Wattle-bark sufficient to tan 25 to 30 hides ; it is best 

 adapted for sole-leather and other so-called heavy goods. The 

 leather is fully as durable as that tanned with oak -bark, and nearly 

 as good in colour. Bark, carefully stored for a season, improves in 

 tanning power considerably. From experiments made under the 

 author's direction it appears, that no appreciable difference exists 

 in the percentage of tannin in Wattle-bark, whether obtained in 

 the dry or in the wet season. The tannin of this Acacia yields a 

 grey precipitate with ferric and a violet colour with ferrous salts ; 

 it is completely precipitated from a strong aqueous solution by 

 means of concentrated sulphuric acid. The bark improves by age 

 and desiccation, and yields about 40 per cent, of catechu, rather 

 more than half of which is tannic acid. Bichromate of potash 

 added in a minute quantity to the boiling solution of mimosa- 

 tannin, produces a ruby-red liquid, fit for dye-purposes ; and this 

 solution gives with the salt of sub-oxide of iron black pigments, 

 and with the salts of the full oxide of iron red-brown dyes [F. v. M. 

 and Eummell. As far back as 1823 a fluid extract of Wattle-bark 

 was shipped to London, fetching then an extraordinary price, 



