ck in which they are found. Did
you know that our wonderful mercury renders valuable aid in this? The
rock that contains the precious metal is crushed fine, sifted and
washed until as much as possible of the gold or silver is removed; then
it is placed in a vessel with the quicksilver, which seems immediately
to absorb it, thus separating it entirely from every particle of sand
or rock. If the metal to be cleansed is gold, you will see a pasty mass
or amalgam, as it is called, of a yellowish tinge. This is heated, and
the mercury flies away, leaving behind it the pure gold."

"How did people learn to do this?" asked Fred.

"They did not learn it all at once. It was only by years of patient
effort and frequent failure that they finally succeeded.

"You know there are many gold and silver mines in California,"
continued grandpa. "Near some of them large mines of quicksilver have
been discovered. You can imagine that this caused great rejoicing, for
all the quicksilver previously used was sent in ships to this part of
the world, which, of course, made it scarce and very expensive. Now, we
can send away quantities to other countries after supplying our own
wants.

"Notwithstanding that this strange metal renders such service to
mankind--for I could tell you of many other useful things it does--it
is a deadly poison. Its vapor is so dangerous that persons searching
for it often die from breathing the air where it is found. About
seventy years ago, the mines in Austria, took fire, and thirteen
hundred workmen were poisoned, and many of them died. The water that
was used to quench the fire being pumped into the river Idria, all the
fish died excepting the eels. Since that time, spiders and rats have
deserted the mines.

"Mercury is carried in sheepskin bags and cast-iron bottles. It is so
heavy that an ordinary cork would soon be forced out by it, therefore
an iron stopper must be screwed in.

"Once, some bags of mercury were stored in the hold of a foreign
vessel; unfortunately, a few of the bags were rotten and leaked. Every
person on board was poisoned, and every piece of metal connected with
the vessel received a silvery coating of mercury."

"It is dreadful! Fred, don't let us touch it," said Harry.

"Don't be frightened yet, Harry. Did you know that mercury is used as a
medicine? It is given in very small doses."

"I am sure I shall never take it," exclaimed Fred.

"Perhaps you may have done so already," repl