chinery, and amongst other things it will be applied
to impel the carriages of railroads, and this at so small a cost,
that expense will no longer be matter of consideration. England is
to lose her superiority as a manufacturing country, inasmuch as her
vast store of coals will no longer avail her as an economical source
of motive power. "We," say the German cultivators of this science,
"have cheap zinc, and, how small a quantity of this metal is
required to turn a lathe, and consequently to give motion to any
kind of machinery!"

Such expectations may be very attractive, and yet they are
altogether illusory! they will not bear the test of a few simple
calculations; and these our friends have not troubled themselves to
institute.

With a simple flame of spirits of wine, under a proper vessel
containing boiling water, a small carriage of 200 to 300 pounds
weight can be put into motion, or a weight of 80 to 100 pounds may
be raised to a height of 20 feet. The same effects may be produced
by dissolving zinc in dilute sulphuric acid in a certain apparatus.
This is certainly an astonishing and highly interesting discovery;
but the question to be determined is, which of the two processes is
the least expensive?

In order to answer this question, and to judge correctly of the
hopes entertained from this discovery, let me remind you of what
chemists denominate "equivalents." These are certain unalterable
ratios of effects which are proportionate to each other, and may
therefore be expressed in numbers. Thus, if we require 8 pounds of
oxygen to produce a certain effect, and we wish to employ chlorine
for the same effect, we must employ neither more nor less than 35
1/2 pounds weight. In the same manner, 6 pounds weight of coal are
equivalent to 32 pounds weight of zinc. The numbers representing
chemical equivalents express very general ratios of effects,
comprehending for all bodies all the actions they are capable of
producing.

If zinc be combined in a certain manner with another metal, and
submitted to the action of dilute sulphuric acid, it is dissolved in
the form of an oxide; it is in fact burned at the expense of the
oxygen contained in the fluid. A consequence of this action is the
production of an electric current, which, if conducted through a
wire, renders it magnetic. In thus effecting the solution of a pound
weight, for example, of zinc, we obtain a definite amount of force
adequate to raise a given weight on