atmospheres.

The curious properties of fluid carbonic acid are now generally
known. When a small quantity is permitted to escape into the
atmosphere, it assumes its gaseous state with extraordinary
rapidity, and deprives the remaining fluid of caloric so rapidly
that it congeals into a white crystalline mass like snow: at first,
indeed, it was thought to be really snow, but upon examination it
proved to be pure frozen carbonic acid. This solid, contrary to
expectation, exercises only a feeble pressure upon the surrounding
medium. The fluid acid inclosed in a glass tube rushes at once, when
opened, into a gaseous state, with an explosion which shatters the
tube into fragments; but solid carbonic acid can be handled without
producing any other effect than a feeling of intense cold. The
particles of the carbonic acid being so closely approximated in the
solid, the whole force of cohesive attraction (which in the fluid is
weak) becomes exerted, and opposes its tendency to assume its
gaseous state; but as it receives heat from surrounding bodies, it
passes into gas gradually and without violence. The transition of
solid carbonic acid into gas deprives all around it of caloric so
rapidly and to so great an extent, that a degree of cold is produced
immeasurably great, the greatest indeed known. Ten, twenty, or more
pounds weight of mercury, brought into contact with a mixture of
ether and solid carbonic acid, becomes in a few moments firm and
malleable. This, however, cannot be accomplished without
considerable danger. A melancholy accident occurred at Paris, which
will probably prevent for the future the formation of solid carbonic
acid in these large quantities, and deprive the next generation of
the gratification of witnessing these curious experiments. Just
before the commencement of the lecture in the Laboratory of the