Expectorants operate in different ways; for, if the humour secreted, be acrid and thin, and the pores of the glands be too much .constricted, these medicines generally relax, soften, and widen the passages -, diminish the acrimony of the animal fluids; and coagulate those parts which are too thin and watery : for which purpose, the li-quorice-root, honey, spermaceti, saffron, mallows, and oil of almonds, are very frequently used. But, if a considerable quantity of thick, viscid matter be lodged in the lungs, so as to obstruct breathing, it will be necessary to aid expectoration by means of such sub-stances as may dissolve the tough and glutinous humour. Tins ob-ject may be effected by taking de-coctions'of the Greater Celandine, Scabious, Elecampane, and other peroral herbs. - See also Cough, and Catarrh.
Great caution, however, is necessary in administering expectorants of whatever kind. Hence we cannot but censure the injudicious practice of those mothers and nurses, who often load the tender stomachs of infants with a variety of preparations, both of sweet and oily substances, with the view of relieving coughs ; but, as children have not sufficient strength to promote the evacuation of matter from the vessels of the breast, such potions, far from being of any real service, mast necessarily occasion no small injury. Indeed, this practice is the more dangerous, as the cough, and consequent stricture of the chest, may arise from a variety of causes, too numerous to be here recited.