PHYSIOLOGICAL CLASSES OF MEDICINES.

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beneficially employed in chronic catarrhs. Such are the balsams, theoleo-resins, the fetid gums, squills, &c. Many of the substances whichgive relief in chronic pulmonary complaints do not promote, but check,the secretion of bronchial mucus: as the sulphate of zinc,—towhich Begin ( Traiti de Therap. t. ii. p. 561) adds the balsams. Yetthese agents are usually classed with expectorants. Dr. Paris ( Phar -macologia) makes one class of expectorants to consist of “ medicineswhich diminish the inordinate flow of fluid into the lungs, and renderthe expectoration of the remainder more easy.”

Most of the substances usually denominated expectorants possess sti-mulant properties. Some of them become absorbed and act on the bron-chial membrane by local contact. They are principally employed inchronic catarrhs.

5. Emetics (emetica , from igto), I vomit,) are medicinal agents used forthe piu-pose of provoking vomiting. They are sometimes called vomits(vomitoria.)

Usually within twenty or thirty minutes after taking an emetic, a gene-ral feeling of uneasiness and of nausea comes on. The pulse becomessmall, feeble, and irregular ; the face and lips grow pale, a sensation ofrelaxation and coldness of the whole system is experienced, the salivaflows copiously from the mouth, the eyes lose their lustre, and the wholecountenance appears dejected. These symptoms, which constitute thefirst stage of vomiting, continue for a variable period, and are followed bythe ejection of the contents of the stomach. As soon as actual vomitingcommences, the general phenomena are altered: the pulse becomes fre-quent and full, the temperature of the body increases, and a sweat breaksout on the face and other parts of the body. Diuing the act of vomiting,in consequence of the pressure made on the abdominal aorta, and theinterruption to the circulation through the lungs, from the impededrespiration, the blood returns with difficulty from the head, the faceswells and becomes coloured, the conjunctiva is turgid and red, thejugular veins are gorged, and tears burst from the eyes. The violentstraining is often attended with pain in the head and eyes, and with theinvoluntary expulsion of the urine and fieces. The matters vomited varyaccording to circumstances; they may consist of the alimentary andother substances contained in the stomach previous to the exhibition ofthe emetic ; of the fluids collected by the action of the emetic; and,lastly, of the emetic itself. Sometimes striae of blood are observed, whichusually come from the pharynx. The number of vomitings, and the easewith which they are effected, are liable to considerable variation, arisingfrom the state of the digestive organs, the temperament of the patient, thestate of the cerebral functions, &c. When the vomiting has entirelyceased, the patient feels languid, oppressed, and drowsy, and the pulsebecomes weak and slow: the exhaustion is sometimes so great as to beattended with fatal consequences. A case of this kind is alluded to byDr. Paris ( Pharmacologia ) in which an emetic was imprudently given toa patient in the last stage of phthisis, with the intention of dislodging thepus with which the lungs were embarrassed: syncope was produced,from which the patient never recovered. Among other occasional illconsequences of vomiting may be mentioned comatose affections, uterineor pulmonary haemorrhages, hernia, abortion, suffocation, prolapsus of theuterus, rupture of the abdominal muscles, &c.