2. Of Expectorants.
The direct effects of the medicines which are employed under this name are as follow : they stimulate the lungs them selves; they augment the secretion tak ing place by the mucous glands of the lungs; they increase the excretion of mucus from the lungs. The changes in duced in the system, from the primary effects of expectorants, are, an alteration in the state of the mucus excreted to a more thin and fluid consistence ; an in crease of the sensibility of the lungs ; free circulation through the blood-vessels of the secreting 5lands ; and the evacuation of those cavities in the lungs in which mucus is deposited.
Expectorants may be divided into the nauseating, as squills, gum-ammoniac, and garlic ; the antispasmodic, as blis ters, feet, and vapour-baths ; and irrita tive, as acid vapours, and the common smoking of tobacco. The indications these medicines are capable of fulfilling may be traced as follows : 1. From their affecting the secretion of mucus ; whence they may be used, to promote the secre tion of mucus by the lungs, when mor bidly diminished there ; to render the mucus of the lungs thinner, when mor bidly thick and viscid. 2. From their af fecting the excretion of mucus ; whence they may be employed, to evacuate mor bid accumulations of mucus in the lungs ; to supply irritation to the lungs when morbidly deficient. 3. From their af fecting the state of the lungs themselves; whence they may be employed as local stimulants. The cautions to be observed in the employment of expectorants, as derived from their nature, chiefly respect their operations as exciting nausea; their power of stimulating the system in gene ral from acting on the and their influence as irritating the lungs them selves. The conditions of the system which chiefly require attention in their employment are, the degree of irritabili ty with which the lungs are endowed; and the youth of the patient. The circum stances chiefly to be attended to in the regimen necessary for this class, are, the state of the stomach; the employment of diet fitted to conspire with the effect of the medicine ; the free use of exercise; and the state of the atmosphere in which the patient breathes.
The different individuals belonging to the class of expectorants, are chiefly con tra-indicated by the presence of the fol lowing morbid states ; a high degree of increased sensibility in the lungs ; and an uncommonly quick excretion of mucus from the lungs.
3. Of Diaphoretics.
These are medicines, which, taken in- ternally, increase the discharge by the` skin, without exciting this effect in con- , sequence of violent agitation or acute pain. The following are their direct results : they accelerate the motion of the blood ; produce free circulation through the vessels on the surface ; and excite a discharge of sweat. The changes induced in the system, from the more immediate effects of diaphoretics, are, a change in the balance of the circulation ; a diminution of the quantity of circulating fluids ; and a diminution more particular ly of the serosity.
Diaphoretics may be regarded as pun gent, of which we have instances in spirit of hartshorn, oil of lavender, or amber stimulant, as various preparations of anti mony and quicksilver, guiacum, contra yerva, and snake-root; antispasmodic, as musk, opium, and camphor; and diluent, as water and whey. Their use and indi cation may be collected, 1. From their changing the mode of circulation; whence. they may be employed, to obviate morbid determination taking place to the inter nal viscera ; to remove various causes ob structing or impeding the natural state of circulation on the surface ; to restore the natural discharge from the body, which should take place by the surface, in those cases where it is morbidly diminished. 2. From their producing evacuation; whence they may he employed, to diminish the quantity of circulating fluids, where it is greater than the state of the system at the time can admit of; to restore dimi nished lymphatic absorption, and to dis charge morbid accumulations of serum. These indications may be illustrated and confirmed, from practical observations concerning the effects of diaphoretic me dicines in fever, dysentery, rheumatism, dropsy, and herpes.