ble upon the sugar-makers. It is nothing
less than flint, which the roots of the maple absorbed, while it was
dissolved in water in the soil. The sap, still holding the flint in
solution, flows out, clear as water, when the tree is tapped; but when
it is concentrated by boiling, the silicious mineral is deposited in
little crystals, so that the bottom of the pan appears to be covered
with sand. We could not select a more interesting example of the very
wide diffusion of some compound substances than this one of silicic
acid. It is found in the mineral and vegetable kingdoms. Being a
mineral, it cannot be appropriated to animal uses, without being
decomposed and transformed into an organic condition; but in the
numerous species of plants whose stalks require stiffening against
the winds,--in the grasses and canes, including all our grains, the
sugar-cane, and the bamboo,--a silicate (an actual flint) is taken up by
the roots and stored away in the stalks as a stiffener. The rough, sharp
edge of a blade of grass sometimes makes an ugly cut on one's finger by
means of the flint it contains. Silex is the chief ingredient in quartz
rock, which is so widely diffused over the earth, and enters into the
composition of most of the precious stones. The ruby, the emerald, the
topaz, the amethyst, chalcedony, carnelian, jasper, agate, and garnet,
and all the beautiful varieties of rock crystal, are mostly or entirely
silex. Glass is a compound of silex and pearlash. One who is curious in
such things may make glass out of a straw, by burning it and heating the
ashes with a blowpipe. A little globule of pure glass will form as the
ashes are consumed. The following curious instance, quoted by that
interesting physiologist, Dr. Carpenter, shows the same effect upon a
large scale. A melted mass of glassy substance was found on a meadow
between Mannheim and Heidelberg, in Germany, after a thunder-storm. It
was, at first, supposed to be a meteor; but, when chemically examined,
it proved to consist of silex, combined with potash,--in the form
in which it exists in grasses; and, upon further inquiry, it was
ascertained that a stack of hay had stood upon the spot, of which
nothing remained but the ashes, the whole having been ignited by the
lightning.

There is nothing in Nature more striking to the novice than the first
suggestions of the various, and apparently contradictory, at least
unexpected, positions in which the same mineral is foun