, and always drop to the bottom of the vessel, immediately as
the water is voided.

Though the proximate cause of the formation of the calculous concretions of
the kidneys, and of chalk-stones in the gout, and of the insoluble
concretions of coagulable lymph, which are found on membranes, which have
been inflamed in peripneumony, or rheumatism, consists in the too great
action of the absorbent vessels of those parts; yet the remote cause in
these cases is probably owing to the inflammation of the membranes; which
at that time are believed to secrete a material more liable to coagulate or
concrete, than they would otherwise produce by increased action alone
without the production of new vessels, which constitutes inflammation. As
defined in Class II. 1. 2.

The fluids secreted from the mucous membranes of animals are of various
kinds and consistencies. Hair, silk, scales, horns, fingernails, are owing
to natural processes. Gall-stones, stones found in the intestines of
horses, scurf of the skin in leprosy, stones of the kidnies and bladder,
the callus from the inflamed periosteum, which unites broken bones, the
calcareous cement, which repairs the injured shells of snails, the
calcareous crust on the eggs of birds, the annually renewed shells of
crabs, are all instances of productions from mucous membranes, afterwards
indurated by absorption of their thinner parts.

All these concretions contain phosphoric acid, mucus, and calcareous earth
in different proportions; and are probably so far analogous in respect to
their component parts as well as their mode of formation. Some calcareous
earth has been discovered after putrefaction in the coagulable lymph of
animals. Fordyce's Elements of Practice. A little calcareous earth was
detected by Scheel or Bergman in the calculus of the bladder with much
phosphoric acid, and a great quantity of phosphoric acid is shewn to exist
in oyster-shells by their becoming luminous on exposing them a while to the
sun's light after calcination; as in the experiments of Wilson. Botanic
Garden, P. 1. Canto 1. l. 182, note. The exchange of which phosphoric acid
for carbonic acid, or fixed air, converts shells into limestone, producing
mountains of marble, or calcareous strata.

Now as the hard lumps of calcareous matter, termed crabs' eyes, which are
found in the stomachs of those animals previous to the annual renewal of
their shells, are redissolved, probably by their gastric acid, and again