OUR LOCAL FLORA : ITS ECONOMIC ASPECT. 
145 
containing a considerable quantity of tannic acid, is sometimes 
used for tanning leather. It is this tannic acid probably that 
causes the yellow flowers of broom to turn black when dried, and 
to differ in this respect from other yellow flowers, whose colour can 
generally be particularly well preserved. Branches of the larger 
shrubs were formerly much used for brooms or besoms. 
Agrimonia eupatoria, common Agrimony, is very common ; and 
much gathered, Mr. Briggs says, by poor persons for medicinal 
purposes. The expressed juice of the common agrimony before it 
has flowered dyes woollen goods a nankeen colour ; but if the plant 
is gathered after the flowers are over, the colour is much darker. 
It contains tanning properties, and has been used in the process of 
tanning leather. The tannic acid in all genuine beer arises from 
hops, referred to presently. 
Potentilla tormentilla, common Tormentil, common on the moors 
and dry banks ; and Potentilla reptans, creeping Tormentil, very 
common on banks, occurring on the Hoe, have roots which contain 
as much as 17 per cent, of tannic acid. It is said that 7 lbs. of 
the best oak-bark for tanning purposes are equal only to 1 lb. of 
tormentil roots, which are superior in this respect to everything 
but galls ; valonia, obtained from two different species of oak 
found in Asia Minor ; and catechu, from Acacia catechu, in India. 
Leather is tanned by the tormentil roots in the Hebrides and Orkney 
Islands, and in Lapland skins dyed of a red colour. It is said that 
because sheep are never attacked with the rot where the tormentil 
grows it should be planted in damp pastures where the disease is 
prevalent among flocks. It is one thing to suggest, another to 
carry out. The very fact that the tormentil's habitat is commons, 
moors, and undisturbed soil, exposed to the greatest amount of air 
and sunshine, where also sheep flourish best, seems to prove that 
where sheep do badly the tormentil would do badly also. 
Thus much as to plants with tanning properties. Kecalling 
your attention to the trees, we have Castanea vulgaris, sweet or 
Spanish Chestnut, rather rare, and with no claim to be considered 
native, except possibly so in the South or West of England. 
Mr. Briggs indeed marks it as an alien, but says it is naturalized 
in Cotehele Wood, where the chestnut trees are justly celebrated 
for their size and age. The great chestnut at Tortworth, 
Gloucestershire, measures 52 feet in circumference, and is still 
flourishing in its green old age. . As it was referred to in the 
VOL. IX. L 
