principle, such as
gluten, albumen, fibrin, &c.; and several of these combine to form a
complete organic substance. The chemical rank-and-file, so to speak,
form a battalion, and two or more battalions form the chemical army.
But it is a law in chemistry, that the more complex a substance
becomes, the less stable is its constitution, or the sooner is it
affected by disturbing influences. Hence organic substances are more
readily decomposed than inorganic. How striking, for instance, are the
changes easily wrought in a few grains of barley! They contain a kind
of starch or fecula; this starch, in the process of malting, becomes
converted into a kind of sugar; and from this malt-sugar or
transformed starch, may be obtained ale or beer, gin or whisky, and
vinegar, by various processes of fermenting and distilling. The
complex substance breaks up through very slight causes, and the simple
elements readjust themselves into new groupings. The same occurs in
animal as in vegetable substances, but still more rapidly, as the
former are more intricate in composition than the latter, and are held
together by a weaker tie.

What the 'vital principle' may be, neither chemists nor physiologists
can tell us with any great degree of clearness; but it is this vital
principle, whatever it may be, which prevents decay in a living
organic substance, however complex. When life departs, the onslaught
begins; the defender has been removed, and a number of assailants make
their appearance. _Air_, _heat_, and _moisture_ are the principal of
these; they attack the dead organism, and gradually convert it into
wholly different and inorganic compounds, such as water, carbonic
acid, ammonia, phosphuretted hydrogen, and many others. What, then,
would result if these disturbers could be warded off, one or all? It
is now pretty well ascertained, that if any one of the three--air,
heat, moisture--be absent, the decay is either greatly retarded or
indefinitely postponed; and we shall find that in all antiseptic or
preserving processes, the fundamental principle has simply such an
object in view.

Sometimes the operation of natural causes leads to the preservation of
dead animal substances for a great length of time, by excluding one
out of the above three disturbing influences. If heat be so deficient
that the animal juices become wholly frozen up, the substance is
almost proof against decay. Thus, about seventy years ago, a huge
animal was found imb