great abundance to the wound. Gallic acid is one of the ingredients used
in dyeing stuffs and cloths, and therefore the supply yielded by the
nut-gall is highly welcome. The nut-galls are carefully collected from
the small oak on which they are found, the Pyreneean oak. It is easily
known by the dense covering of down on the young leaves, that appear
some weeks later than the leaves of the common oak. The galls are
pounded and boiled, and into the infusion thus made the stuffs about to
be dyed are dipped,'"

"I should think," said Clara, "that people would plant oak trees
everywhere, when they are so useful. Is anything done with the bark?"

"Yes," said her governess; "the bark, which is very rough, is valuable
for tanning leather and for medicine. The element which has the effect
of turning raw hide or skin into leather is called _tannin_; it is also
found in the bark of some other trees and in tropical plants."

"Didn't people use to worship oak trees," asked Malcolm--"people who
lived ever so long ago?"

"You are thinking of the Druids, who lived in old times in Britain and
Gaul," replied Miss Harson, "and whose strange heathen rites were
practiced in oak-groves; and they really did consider the tree sacred.
These Druids have left their traces in some parts of England and France
in rows of huge stones set upright; and wherever an immense stone was
found lying on two others, in the shape of a table, there had been a
Druid altar, where the priest offered sacrifices, often of human beings.
So horrible may be a so-called religion that men themselves devise,
and that has not come from the true God.