s observed to
be deficient, and sometimes too great. The former can scarcely be
considered as a morbid symptom, provided the digestion and health be
otherwise good. But when along with diminished thirst, the fauces and
tongue are dry, this deficiency may be regarded as a morbid and
dangerous symptom.

A more common morbid symptom, however, is too great thirst, which may
arise from a deficiency of fluids in the body, produced by violent
exercise, perspiration, too great a flow of urine, or too great an
evacuation of the intestines. A praeternatural thirst may likewise
arise from any acrid substance received into the stomach, which our
provident mother, nature, teaches us to correct by dilution; this is
the case with respect to salted meats, or those highly seasoned with
pepper. It may arise also from the stomach being overloaded with
unconcocted aliment, or from a suppressed or diminished secretion of
the salivary liquors in the mouth, which may arise from fever, spasm,
or affections of the mind; an increased thirst may likewise take
place, from a derivation or determination of the fluids to other
parts of the body; of this, dropsy affords an example. Indeed,
various causes may concur to increase the thirst; this is the case in
most fevers, where great thirst is occasioned by the dissipation of
the fluids of the body by heat, as well as by the diminished
secretion of the salivary humours which should moisten the mouth; to
which may be added, the heat and diminished concoctive powers of the
stomach.

From what has been said, we can easily understand, why praeternatural
thirst may sometimes be a necessary instinct of nature, at other
times, an unnecessary craving; why acids, acescent fruits, and weak
fermented liquors quench thirst more powerfully than pure water; and
lastly, why thirst, in some instances, may be relieved by emetics,
when it has resisted other remedies.

There is no organ of the body whose functions are so easily deranged
as those of the stomach; and these derangements prove a very fertile
source of disease; they ought, therefore, carefully to be guarded
against; and it is fortunate for us that we have this generally in
our power, if we would but avail ourselves of it: for most of the
derangements proceed from the improper use of food and drink, and a
neglect of exercise. Indeed, when we examine, we shall find but a
short list in the long catalogue of human diseases, which it is not
in our power to gu