harmonious chain of life, are attached to this
grand human form; which rises as a central
pillar in the wide area of being. The
appreciation of the chemical changes which are
coincident with the life of man, yields a
knowledge of the system of laws which
govern the chemistry of the earth. The
analysis of the elements which build up the
human frame, not only brings into view the
close ties of relationship which bind humanity
to earth by similitude in composition, but it
throws a light upon the physical endowments
which we possess; upon the power which we
extend over the creatures of the earth; and
upon the privileges which we enjoy in their
use.

By examining the composition and form of
the teeth and digestive apparatus, the anatomist
has been able to declare, that the structure
of the human race bears the seal of
fitness for a combination of animal and
vegetable diet; testifying to the power which
has been given to us over the beast of
the field, as well as over the herb on which
it grazes. And, from the examination of
the chemical constitution of the body, it
might be predicated that, to man, has been
granted dominion over land and over sea; that
he is to find in each a feeding-ground; and
that the inhabitants of the one and the
products of the other are alike destined to be
supplementary to his wants and subservient
to his will. For if—after ascertaining that
salt, the mineral of the sea, lurks in the
recesses of the frame, and ranks among the
minerals which we eat—we extend further
the inquiry, potassium, the mineral of the
land, falls at once under our observation.

Potash presents itself in the human system
as frequently as sodium. Its presence in
large proportion in the globules of the blood
indicates a special importance; because, in all
probability, it is this portion of the blood
which is organised, and assumes the form of
muscle. Of course we ask here, too, those
questions—Why? and How? We have not
the same positive data of information as
to the uses of potash, which we had of the
utility of salt. Thus much may be said
about it:—

We eat large quantities of potash in all our
vegetable food; in bread, potatoes, carrots, and
especially in green vegetables. For, just
as sea-plants contain a great deal of salt, so
inland plants feed on potassium. And as
inland animals consume these plants, so their
flesh abounds in the same mineral. When
inland plants are burned, potassium is left
behind in the ash, in an oxidised form,
and is known as potash, or oxide of potassium.
In this form it has furnished many names of
drugs to the Pharmacopœia. A medical man
must blush for the reputation of his profession,
when he calls to mind the history of
potash as a pharmacopœial substance. Grave
and venerable physicians of a hundred years
since with ivory-handled sticks heavy square
wigs, and preternatural solemnity of
countenance, were caught in a terrible snare
when they handled this potash. They burnt
various inland plants, and carefully
collected the ash, storing it in mystic and
many-coloured bottles, calling it salt of
beanstalk, or salt of wormwood, or salt of willow,
according to the source from which it was
obtained. They were very careful to note
the season at which the wormwood was to
be collected, and the willow cut. They
enjoined an hour for the process of combustion
of the one, and a half-an-hour for the burning
of the other. The temperature was to be
raised in one case to one hundred and ninety
degrees, and in another to two hundred
degrees. And thus, since they believed each
to be a different salt, they found no difficulty
in differentiating their properties and
distinguishing their actions. The one cured
headaches, the other cured fevers, and a third
cured indigestion. They would no more have
thought of administering their so-called salt
of wormwood when the symptoms called for
salt of tartar, than a homœopathist would
think now of prescribing a thousandth part
of a grain of charcoal, when the urgency of the
case called for a thousandth of a grain of
plumbago. But—sad destruction to our
veneration for big wigs and ivory sticks, and
dogmatic experience—it was shown that
potash was simply potash; always the same,
and never anything else than oxide of potassium.

The uses of potash in the body have been
elucidated in investigating the causes of
scurvy. Until lately, this scourge carried off
from one-sixth to one-tenth of a ship's crew
on a long voyage. Scurvy results from
a continued diet of salt meat; not because
the salt is in excess, but because the potash
and other mineral constituents are in defect.
When meat is placed in brine, the salt
enters, driving out the potash and other
salts, usurping their place, and, like other
usurpers, doing a vast amount of mischief.
Lemon-juice and lime-juice were found to be
preventive of scurvy, and were powerfully
recommended. But Jack Tar has a fine
British element of practical obstinacy. Ship
captains disliked disturbing the vested
interests of scurvy. The British sailor would
cease to be a match for any dozen furrineers,
if he were to cease eating salt junk, straining
his water through his teeth, sleeping in close
hammocks, and braving scurvy and typhus
fever. But the law, after a time, enforces the
use of lime-juice; yet this was expensive, so
citric acid was substituted. Citric acid failed.
Then Dr. Garrod bethought him that lemon-juice
contains potash as well as citric acid;
and, since it was not the citric acid which was
doing good, probably it was the potash. Other
concurrent facts strengthened the belief.
Scurvy occurred in institutions with abundant
dietary and deficient only in potash.
Cocoa, and potatoes, and some other things