eats instantaneously when the heat was above 108, stopped
them as certainly when it was below that heat; and that flannels, wrung out
of warm water and wrapped round the legs and thighs, were then most
certainly productive of sweats.

5. The diaphoretics are all said to succeed much better, if given early in
the morning, about an hour before sun-rise, than at any other time; which
is owing to the great excitability of every part of the system after the
sensorial power has been accumulated during sleep. In those, who have
hectic fever, or the febricula, or nocturnal fever of debility, the morning
sweats are owing to the decline of the fever-fit, as explained in Sect.
XXXII. 9. In some of these patients the sweat does not occur till they
awake; because then the system is still more excitable than during sleep,
because the assistance of the voluntary power in respiration facilitates
the general circulation. See Class I. 2. 1. 3.

6. It must be observed, that the skin is very dry and hard to the touch,
where the absorbents, which open on its surface, do not act; as in some
dropsies, and other diseases attended with great thirst. This dryness, and
shrivelled appearance, and roughness, are owing to the mouths of the
absorbents being empty of their accustomed fluid, and is distinguishable
from the dryness of the skin above mentioned in the hot fits of fever, by
its not being attended with heat.

As the heat of the skin in the usual temperature of the air always evinces
an increased perspiration, whether visible or not, the heat being produced
along with the increase of secretion; it follows, that a defect of
perspiration can only exist, when the skin is cold.

7. Volatile alcali is a very powerful diaphoretic, and particularly if
exhibited in wine-whey; 20 drops of spirit of hartshorn every half hour in
half a pint of wine-whey, if the patient be kept in a moderately warm bed,
will in a few hours elicit most profuse sweats.

Neutral salts promote invisible perspiration, when the skin is not warmed
much externally, as is evinced from the great thirst, which succeeds a meal
of salt provisions, as of red herrings. When these are sufficiently diluted
with water, and the skin kept warm, copious sweats without inflaming the
habit, are the consequence. Half an ounce of vinegar saturated with
volatile alcali, taken every hour or two hours, well answers this purpose;
and is preferable perhaps in general to all others, where sweating