the hydrogen. Here the mystery ends; and
the contradictions are solved;—Oxygen and
hydrogen when combined, become water;
when separated the hydrogen gas burns with a
pale lambent flame. Many of Nature's most
delicate deceptions are accounted for by a
knowledge of these laws.

Your analytical chemist sadly annihilates,
with his scientific machinations, all poetry.
He bottles up at pleasure the Nine Muses,
and proves them—as the fisherman in the
Arabian Nights did the Afrite—to be all
smoke. Even the Will o' the Wisp cannot
flit across its own morass without being
pursued, overtaken, and burnt out by this
scientific detective policeman. He claps an
extinguisher upon Jack o' Lanthorn thus:—He
says that a certain combination of phosphorus
and hydrogen, which rises from watery
marshes, produces a gas called phosphuretted
hydrogen, which ignites spontaneously the
moment it bubbles up to the surface of the
water and meets with atmospheric air. Here
again, the Ithuriel wand of science dispels all
delusion, pointing out to us, that in such
places animal and vegetable substances are
undergoing constant decomposition; and as
phosphorus exists under a variety of forms
in these bodies, as phosphate of lime,
phosphate of soda, phosphate of magnesia, &c.,
and as furthermore the decomposition of
water itself is the initiatory process in these
changes, so we find that phosphorus and
hydrogen are supplied from these sources;
and we may therefore easily conceive the
consequent formation of phosphuretted
hydrogen. This gas rises in a thin stream from
its watery bed, and the moment it comes in
contact with the oxygen of the atmosphere,
it bursts into a flame so buoyant, that it
flickers with every breath of air, and realises
the description of Goëthe's Mephistopheles,
that the course of Jack-o'-lantern is generally
"zig-zag."

Who would suppose that absolute darkness
may be derived from two rays of light!
Yet such is the fact. If two rays proceed from
two luminous points very close to each other,
and are so directed as to cross at a given point
on a sheet of white paper in a dark room, their
united light will be twice as bright as either
ray singly would produce. But if the difference
in the distance of the two points be
diminished only one-half, the one light will
extinguish the other, and produce absolute
darkness. The same curious result may be
produced by viewing the flame of a candle
through two very fine slits near to each other
in a card. So, likewise, strange as it may
appear, if two musical strings be so made to
vibrate, in a certain succession of degrees, as
for the one to gain half a vibration on the
other, the two resulting sounds will
antagonise each other and produce an interval
of perfect silence. How are these mysteries
to be explained? The Delphic Oracle of
science must again be consulted, and among
the high priests who officiate at the shrine,
no one possesses more recondite knowledge, or
can recal it more instructively, than Sir David
Brewster. "The explanation which
philosophers have given," he observes, "of these
remarkable phenomena, is very satisfactory,
and may easily be understood. When a wave
is made on the surface of a still pool of water
by plunging a stone into it, the wave
advances along the surface, while the water
itself is never carried forward, but merely
rises into a height and falls into a hollow,
each portion of the surface experiencing an
elevation and a depression in its turn. If we
suppose two waves equal and similar, to be
produced by two separate stones, and if they
reach the same spot at the same time, that is,
if the two elevations should exactly coincide,
they would unite their effects, and produce a
wave twice the size of either; but if the one
wave should be put so far before the other,
that the hollow of the one coincided with the
elevation of the other, and the elevation of
the one with the hollow of the other, the
two waves would obliterate or destroy one
another; the elevation as it were of the one
filling up half the hollow of the other, and
the hollow of the one taking away half the
elevation of the other, so as to reduce the
surface to a level. These effects may be
exhibited by throwing two equal stones into a
pool of water; and also may be observed in
the Port of Batsha, where the two waves
arriving by channels of different lengths
actually obliterate each other. Now, as light
is supposed to be produced by waves or
undulations of an ethereal medium filling all
nature, and occupying the pores of the
transparent bodies; and as sound is produced by
undulations or waves in the air: so the
successive production of light and darkness by
two bright lights, and the production of
sound and silence by two loud sounds, may be
explained in the very same manner as we have
explained the increase and obliteration of
waves formed on the surface of water."

The apparent contradictions in chemistry
are, indeed, best exhibited in the lecture-
room, where they may be rendered visible
and tangible, and brought home to the
general comprehension. The Professor of
Analytical Chemistry, J. H. Pepper, who
demonstrates these things in the Royal
Polytechnic Institution, is an expert manipulator
in such mysteries; and, taking a leaf out of
his own magic-book, we shall conjure him up
before us, standing behind his own laboratory,
surrounded with all the implements of his
art. At our recent visit to this exhibition we
witnessed him perform, with much address,
the following experiments:—He placed before
us a pair of tall glass vessels, each filled,
apparently, with water;—he then took two
hen's eggs, one of these he dropped into one
of the glass vessels, and, as might have been
expected, it immediately sank to the bottom.
He then took the other egg, and dropped it