o-called "aromatic" or "medicated" baths, in which substances
are mixed to exert a special influence on the skin and peripheral nerves.
Of these the "pine-needle" bath has the greatest repute; it is made by
adding a decoction of the needles or young shoots of firs and pines. Fir
wood oil (a mixture of ethereal oils) or the tincture of an alcoholic
extract acts equally well. The volatile ethereal constituents are supposed
to penetrate the skin and to stimulate the cutaneous [v.03 p.0284]
circulation and peripheral nerves, being eliminated later by the ordinary
channels. Similar effects follow the addition to the bath of aromatic
herbs, such as camomile, thyme, &c. For a full-sized bath 1-1/2 to 2 lb of
herbs are tied in a muslin bag and infused in a gallon of boiling water;
the juices are then expressed and the infusion added to the bath.
Astringent baths are prepared in a similar way from decoctions of oak bark,
walnut leaves, &c. In many spas on the European continent baths are
prepared from peat or mud mixed with hot mineral water. Mineral peat
consists of decomposing vegetable soil that has been so long in the
neighbourhood of the medicinal spring that it has undergone peculiar and
variable chemical changes. This is mixed with the hot mineral water until
the bath has the desired consistency, the effect on the patient being in
almost direct proportion to the density. These baths vary greatly in
composition. Mud baths are chiefly prepared from muddy deposits found in
the neighbourhood of the springs, as at St Amand. They act like a large
poultice applied to the surface of the body, and in addition to the
influence of the temperature, they exert a considerable mechanical effect.
The pulse is accelerated some 6 to 12 beats a minute, the respiration
number rises, and the patient is thrown into a profuse perspiration. They
have very great value in gouty and rheumatic conditions and in some of the
special troubles of women.

There are certain conditions in which mineral water treatment is distinctly
contra-indicated. Advanced cardiac disease and cardiac cases with failure
of compensation must pre-eminently be treated at home, not at a spa.
Advanced arterio-sclerosis, any form of serious organic visceral disease,
advanced cirrhosis, pulmonary tuberculosis with a tendency to haemoptysis,
much elevation of temperature or emaciation, are all entirely unsuited for
this form of treatment. Serious organic nervous diseases, great ner