but if the temperature be not attended to, or
the solution be improperly disturbed, they
increase chiefly in numbers, and the larger
crystals are apt to be disfigured by adhering
small ones. The beautiful crystalline masses ,
that are now so common as ornaments in a
druggist's window, and that were so
conspicuous at the Industrial Exhibition of
eighteen hundred and fifty-one, cannot be
produced without the greatest care and
attention, each crystal being separated from
the mother liquor when it has attained a
sufficient size, and being placed alone in a
shallow pan, perfectly glazed, at a temperature
carefully regulated, and under a solution
of a specified strength. It is then turned
over from day to day, as otherwise the facet
in contact with the pan would be prevented
from increasing, and a deformed crystal would
result. It is also carefully supplied with
fresh solution from time to time: because, if
that around it were exhausted, its most
prominent angles would be re-dissolved. By
neglecting these precautions, deformed or
monstrous crystals are obtained, and are
exhibited, perhaps, as often as the perfect, ones.
Crystalline masses of the blue sulphate of
copper, the red chromate of potash, of alum,
and some other salts, may be produced of
almost any magnitude that is desired.

The simple forms of crystals are not
numerous, and are all traceable to a cube,
from which certain portions have been cut
off. If I had any way of describing them in
English, without long words and prolixity, I
would endeavour to avail myself of it. But
an octohedron with triangular bases is the
mildest known example of scientific crystalline
nomenclature, and the terms at the other
end of the scale, like the technicalities of
most secondary sciences, are cacophonous and
sesquipedalian beyond compare,—harder to
prouounce than the song of Hiawatha, more
difficult to remember than the names in the
roll-call of old Fritz's Polish regiment. The
secondary or compound forms are almost
infinite; but the crystals presenting them may
generally be cut, by cleavage, to some simple
shape. It is this property which enables
lapidaries to cut gems in certain directions; the
translucent precious stones being all natural
crystals, and having each its primary or
natural shape. It may safely be presumed
that they were produced by fusion or solution
at a temperature and under conditions which
it would be impossible even to conjecture.

The larger crystals, which are sought for
in the arts, have no advantage over the small
in point of beauty, except such as is due to
their being more readily examined and
appreciated. Snow seen through a microscope
exhibits the most beautiful, and infinitely varied
crystalline phenomena, of any known
substance. A. volume of plates would fail to
exhaust all the shapes and positions in which
the delicate needles of ice cohere—forming
wreaths, and wheels, and arrows, and stars,
and resemblances to almost every object in
art or nature. In like manner, the minute
crystals or raphides that are found in certain
plants, and especially in rhubarb, are well
worthy of microscopic examination,

The manner in which crystals fasten upon
any nucleus that occupies a prominent position
in the liquid affording them is a fact applied
to many useful purposes in the arts. Not
only does it facilitate all kinds of ornamental
crystallisation, from the alum-basket upwards,
but it enables the chemist to draw together,
and collect readily, the smallest quantities
that can be thrown down from solution,
Where only two or three very minute crystals
can be deposited, it is usual to place a morsel
of thread, or other fitting nucleus, into the
liquor; and upon this nucleus, if anywhere,
the crystals will be found. In larger
undertakings,a nucleus is often supplied to act as
a skeleton, and to determine the general shape
of the mass that is to be produced.

Native crystals, many of which it is beyond
the power of art to imitate, have been formed
in various ways, both by solution and by fusion.
The diamond is, perhaps, the most remarkable
of them; and, as now discovered, usually
appears to have been subjected to attrition
under water, by which its shape has been
modified and its lustre obscured, so that cutting
and polishing are required for the development
of its beauties. It is universally known
to consist of pure carbon (the same substance
with which we are familiar as charcoal and as
plumbago), but which cannot be either fused
or dissolved, and consequently cannot be
crystallised by any means at present known,
Such means have been eagerly sought for,
however, since the composition of the diamond
has been discovered; and there seems no
reason why they should not one day be
found. The crystallisation of boron—a
substance having some analogies to charcoal, and
heretofore only obtained in powder—has
lately been announced, and the crystals
formed, although too small to have any great
value, are said to resemble the diamond in
lustre and refractive power. If this be so,
there can be little doubt that they will be
used, as the art of forming them is perfected,
for ornamental purposes; and it is
possible that the crystallisation of boron may
lead on to that of carbon itself. It is curious
to reflect how the speculations and
experiments of the alchemists would have been
affected if they had possessed our knowledge
of the composition of the diamond, and how
they would have abandoned their endeavours
at the transmutation of metals, to search for
a road to wealth more rapid and seemingly
more easy of attainment. The alkahest, or
universal solvent, which was the object of
enthusiastic quest among the less mercenary
or more scientific of the alchemists, would
have supplied the means, if discovered, of
converting the most universal and valueless
of substances into the most precious of gems;