This section is from the book "Materia Medica And Therapeutics Inorganic Substances", by Charles D. F. Phillips. Also available from Amazon: Materia medica and therapeutics.
Tartar emetic seems to me to exert almost a specific effect on inflamed bronchial membrane. In the case of old people it is useful especially when the cough is convulsive in character, most troublesome at night, and attended with loud wheezing respiration, paroxysmal dyspnoea, and profuse secretion of mucus which is, with difficulty, expectorated. When inflammation affects the smaller tubes of young adults, an emetic dose may be found sometimes desirable, but as a rule, 1/16 to1/8 gr. every two to three hours will suffice to render free and less tenacious the bronchial secretion, to lower the blood-tension, diminish pyrexia, and relieve local congestion and oppression. The action of the skin and of the kidneys is increased usually in inverse ratio - if one is more, the other is less marked. If cough be very severe, a little morphia or belladonna may be combined with the antimony, while in later stages, if more stimulus to expectoration is needed, squill is a useful adjunct.
In the capillary bronchitis of children, tartar emetic often proves valuable. 1 have treated with it nine cases during the last season; all were under two and a half years old, and suffered with distressing paroxysmal cough, which caused much exhaustion; the respiration was much quickened, the pulse 130 to 140, small and feeble, the temperature 101° to 103° F.; there were the ordinary physical signs in the lungs, the face was dusky and oedematous, the skin covered with a clammy moisture; restlessness was extreme, and cerebral symptoms, such as sopor, delirium, and even (in some) coma, were present; these patients were ordered small but frequent doses, 1/64 gr. every half-hour for four doses, afterward every one to three hours, according to the amount of cough or oppression: of the nine cases, four vomited within two hours of the first dose, and all showed signs of exhaustion under the medicine, but all of them made good recoveries.