(b) By inhalation of substances requiring heat for volatilization, e.g. mercury and sulphur. The patient, enveloped in a sheet, sits on a chair, while the substance, placed in a vessel on the floor inside the enveloping sheet near the patient, is heated by a spirit lamp or similar method. Mercury is used for chronic and syphilitic laryngitis and pharyngitis; sulphur for scabies and other skin diseases.
(c) By inhalation of steam or warm-water vapour with a drug added. Apparatus of various kinds is used, the simplest of which is a wide-mouthed jug filled with boiling water to which the drug has been added. The patient takes a deep breath, drawing the vapour into his mouth up a napkin arranged in the form of a tube. More complicated forms of apparatus are steam-sprays and nebulizers for laryngeal and bronchial troubles.
(d) Cold medicated sprays and inhalations. Throat- and nose-sprays are much used, also sprays for the administration of local anæsthetics (ethyl chloride). Respirators are made of wire gauze with cotton wool or a sponge; the substance is poured on and inhaled by the patient.
For (c) and (d) the following drugs are used: carbolic acid, creosote, terebine, thymol, eucalyptol, zinc sulphate, in phthisis and bronchial affections; and eusol, izal, lysol, &c., for disinfection and fumigation.
2. Changes produced by variation in barometric pressure considered in treatment of disease:
Normal barometric pressure at sea-level, 29-30 inches; at Davos (5200 feet), 25 inches; at summit of Pike's Peak, Colorado (14,000 feet), 17½ inches; in balloon ascent (Glaisher and Coxwell) of 29,000 feet, 9¾ inches.
The effects of high pressure are seen in divers, caisson workers, miners. The effects of low pressure are seen in balloonists, airmen. The effect of sudden return to normal from high pressure is seen in cases of caisson disease (q.v.). The effects of low pressure were first applied to the human body in 1835 by V.T. Junot. He contrived a hollow copper ball, 4 yards in diameter, capable of containing a man, and by pumping out air gradually, produced the effects of low pressure. This principle was then applied by him locally by cupping-glasses similar in shape to the upper part of a wineglass. There are two types of cupping:
(a) In wet cupping an incision is made in the skin of the part to be treated. The air inside the glass is exhausted by introducing a lighted match, then the open end of the glass is immediately applied to the surface of the skin.
(b) In dry cupping the treatment is similarly carried out, but no incision is made.
The low pressure (partial vacuum) draws blood to the part. Cupping is used in congestion of internal organs, e.g. lungs, kidneys.