will be the result, possessing, with great body,
the property of not blackening by exposure
to sulphuretted hydrogen gas, protected as it
appears to be by the zinc-salt in the
compound. In like manner, the addition of
chromate of potash, instead of the prussiate,
to the residuum of the iron battery yields a
brown pigment of considerable depth.

In stating that the market value of these
new colours far exceeds the whole cost of the
original elements of the electro-chromatic
battery, we do so from no desire to take a
mere commercial view of the process: such
would be altogether beside our purpose; but
we mention the fact with a view to show
that is of great importance to society—that
by covering the cost of all the materials
employed in these batteries by the conversion
of their hitherto waste products into electro-
colours, the electricity developed during the
process becomes a costless article—we have
it gratis. Here, then, the great obstacle to
the electric light is fairly overcome. That
which before had been too costly in spite of
its utility, for general purposes, becomes at
once a cheap commodity.

During a fog, the ordinary red and green
lights on railways are all but obscured, or if
seen appear as of one colour, and trains are
left to the chance of fog-signals. Through
the heaviest fog that ever swallowed the
metropolis in its murky jaws, the electric
light shines in all its wonted mid-day
brilliancy, heedless of heavy atmosphere. Along
our dangerous coasts, during winter months,
how many ships are lost, how many lives
are sacrificed, how many valuable cargoes
destroyed from the want of a light sufficiently
powerful to burst through the thick midnight
haze of storm, and warn the voyager of the
hidden danger ere it be too late. Surely in
these cases interest and humanity would
prompt the availing of this new, and now cheap
and simple light. It is worth while, too, to
dwell upon the great simplicity of the electric
lamp, which may be turned on and attended
to by the most ordinary person; and insomuch
as the electric light signals proposed to be
employed, do not depend on colour, but on
shape for their signification, there can be no
confusion during the most foggy weather. A
simple straight line of electric light denotes
that all is right; a semicircle of brilliant
rays to the left or right of the signal-post
indicates the side on which danger presents
itself, whilst an entire circle of light warns an
approaching train to stop altogether.

Amongst those purposes to which cheap
electricity may be applied, is that of conveying
semaphoric messages by night across the
ocean, and thus avoiding the great cost of
telegraph cables. Electric light is readily
distinguishable for a distance of forty miles;
and it is stated that, by a series of signal
stations, many seas might be traversed by
messages; from one to the other, where islands or
rocks offer connecting links.

As a cheap product for all purposes of
electrotyping, it cannot but prove more
acceptable, and not less so in one or two other
branches of manufacture, which it may be
interesting to mention. It was ascertained
some time since, that if the poles of a powerful
battery be applied to a mass of coal
undergoing the process of coking in an ordinary
coke oven, in proportion as the coal loses its
bituminous character, and assumes the
properties of coke, there is a greater facility
afforded to the current of electricity for its
passage, accompanied by a more rapid
disengagement of the sulphur of the coal, and
a greater and more effectual separation of
the earthy and metallic impurities. Besides
this, the coke thus produced, and, as it were
electrolysed, is much more compact, and
consumes more equally than the material
employed by the ordinary method. The
importance of obtaining a coke free from
sulphur for metallic manufactures, and
smelting processes is undeniable; equally
desirable is it to obtain a large amount of
carbon compressed within a small space for
sea-going steamers. All these advantages
have hitherto been forbidden by the costly
nature of intense electricity; now that coke
manufacturers can obtain their power at a
trifling cost, the whole feature of their
process will be changed.

Again, our supplies of sulphur are derived
from Sicily, the government of which has
recently forbidden the export of the article,
which is consequently at an exorbitant price.
We have no sulphur deposits in this country;
but there exist large quantities of
sulphur in close combination with iron, under
the form of iron pyrites, in many parts
of England. It has been found
practicable to decompose this article, and obtain
its sulphur and iron separate by smelting it
with the aid of intense electiicity; here
again, the cost of the electric agent was the
barrier, and here also cheap electricity comes
to the rescue, and will shortly place this
country independent of Sicily.

To the wholesale assayer of metals a cheap
supply of intense electricity will be an
inestimable boon; for it creates not only an
enormous saving of fuel, but the six operations
at present involved in the ordinary
process, may be reduced to one.

Cheap electricity will enable railway
companies to electrolyse the tires of their engine
and carriage wheels with a coating of steel,
and thus avoid the great and incessant wear
of the biting surface of the wheels, which,
especially with their engines, require constant
repair.

The quantity of bleaching material
employed in this country is something enormous,
and would doubtless sound incredible in the
ears of the reader. An economical bleaching
agent may be obtained by the decomposition
of common salt in a state of solution, by
means of electricity.