It is not, however, in febrile affections alone that this class of remedies proves highly beneficial; the very intimate sympathetic connection which subsists between the functions of the lungs and skins, renders the use of such medicines particularly advantageous in the cure of the diseases incident to the former of these organs; a fact upon which we shall hereafter offer some remarks under the history of Expectorants.
So again, in the treatment of bowel affections, in consequence of the intimate relation which exists between the cutaneous capillaries and those of the internal organs, gentle diaphoretics offer a valuable resource in their cure. How frequently do Diarrhæa, Enteritis, &c. ensue from the sudden suppression of perspiration by cold?
From the influence which these medicines exert upon the extreme vessels of the skin, they are also highly serviceable in various obstinate cutaneous affections, as Herpes, Lepra, &c.
As evacuating the serous part of the blood must necessarily have an indirect effect in promoting absorption, Sudorifics have been occasionally exhibited in Dropsy, especially in that form of the disease called Anasarca. It has been already observed that cases too frequently occur in which the discharge of urine cannot be increased by art; upon such occasions practitioners have sometimes had recourse to a trial of Sudorifics,[[165]] but from the great difficulty which generally exists in exciting sweating in such affections, the indication has rarely been fulfilled. Where however a sudorific does succeed, it is less liable to debilitate than the other alternative of a drastic purgative.
There is still another point of view in which the therapeutic importance of Diaphoretics may be considered. It is generally acknowledged that by cutaneous transpiration a portion of excrementitious matter is ejected from the system; hence by the failure or imperfect performance of this function, a deleterious fluid is retained which may give origin to disease; to such a cause may perhaps be attributed the generation of Calculi, and other diseases of the urinary system, as we shall have occasion to notice under the head of Lithonthryptics.
The increased efficacy which these medicines derive from combination with each other, will form a subject of interesting enquiry in the succeeding essay.
EXPECTORANTS.
Medicines which are supposed to be capable of facilitating the excretion of mucus from the breast, ex pectore, that is, from the trachea, and cells and passages of the lungs.
If the term Expectorant be intended to express a medicinal substance which has the power of promoting the expulsion of fluid from the lungs, by some specific action on the parts concerned, we can have no hesitation in at once rejecting the word, and denying the existence of such remedies: if, however the term be received, conventionally, as comprehending all those substances which are capable, according to the state of the system in each particular case, of producing expectoration, it will be extremely proper to recognise, and practically useful to retain, such a class of medicinal agents. In order that their modus operandi may be correctly understood, the following classification is submitted to the reader.