460 FOREST CULTURE AND 
pounds of Black Wattle-bark gives 1 pound of leather, 
whereas, 5 poundsof English Oak-bark are requisite for 
thesame results, but the tannin principle of both is not 
absolutely identical. The bark of the variety passing 
generally as the Silver Wattle (Acacia dealbata, Link), 
is generally of less value, often even fetching only 
half the price of that of the Black Wattle. The tan- 
nin of these Acacie yields a gray precipitate, with the 
oxidesalts of iron, anda violet color with sub-oxides ; 
it is completely thrown down 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 mimo- 
sa tannin, produces a ruby-red liquid, fit for dye pur- 
poses, and this solution gives, with the salts of sub- 
oxide of iron, black pigments, and with the salts of 
the full oxide of iron, red-brown dyes. 
Acacia saligna, Wendland.—South-west Australia, 
‘where it is the principal tree chosen for tanner’s bark. 
It is a widely-spreading, small tree, fit for avenues. 
The bark contains nearly 30 per cent. of mimosa-tan- 
nin. 
Achillea moschata, Wulfen. —Alps of Europe. The 
Genipi or Iva of the alpine inhabitants. This peren- 
nial herb ought to be transferred to our snowy moun- 
tains. With the allied A. nana, L., and A. atrata, 
L., it enters as a component into the aromatic medic- 
inal Swiss tea. Many species of this genus, includ- 
ding the Yarrow, are wholesome to sheep. A. fra- 
grintissima, Reichenbach, is a shrubby species from 
the deserts of Egypt, valuable for its medicinal flow- 
ers, 
