r Pepper, be also used.

CAUSTICS.

_Caustics_ are substances which have the power of destroying or
disorganizing animal structures. By their action they destroy the tissue
to which they are applied, and form a crust, which is thrown off by a
separation from the parts beneath. Their caustic property may be
destroyed by dilution with other substances, to such an extent that they
will only irritate or stimulate, and not destroy. Much care is necessary
in their employment, and it is not expected that the unprofessional
reader will have much to do with them; hence, we have deemed it best not
to give a list of these agents.

COUNTER-IRRITANTS.

_Counter-irritants_ are substances which produce irritation of the part
to which they are applied, varying in degree from a slight redness to a
blister or pustule. They are applied to the surface with a view of
producing an irritation to relieve irritation or inflammation in some
other or deeper seated part. They are a class of agents which we very
seldom employ, and, hence, we shall notice only a couple of the most
simple.

MUSTARD (_Sinapis_). The flour of mustard, which is best adapted for
domestic use, is employed in the form of a paste spread on cloth. It
takes effect in a few moments; the length of time it remains in contact
with the skin and the strength of the mustard determine the effect
produced.

HORSE-RADISH (_Cochlearia Armoracia_). The leaves are the parts used.
Let them wilt and bind them on the part affected. They act nearly as
energetically as mustard.

DIAPHORETICS.

_Diaphoretics_ are medicines which increase perspiration. Those which
occasion profuse sweating are termed _Sudorifics_. The two terms
indicate different degrees of the same operation. They constitute an
important element in domestic practice, on account of the salutary
effects which generally follow their action. Their operation is favored
by warmth externally, and warm drinks, when they are not given in hot
infusion.

[Illustration: Fig. 127.
Pleurisy-root. ]

PLEURISY-ROOT (_Asclepias Tuberosa_), is also known as White-root, and
Butterfly-weed. It is a valuable remedy, well adapted to break up
inflammations and disease of the chest. _Dose_--Of infusion, one to two
ounces; of fluid extract, one-fourth to one-half teaspoonful; of the
concentrated principle, Asclepin, one to three grains.

SAFFRON (_Crocus Sativus_). Golden Saffron. _Dose_--Of infusion (one
drachm to a pint o