Hippocrates frequently recommends gentle purgatives for the preservation of the health. Of this class, the herb mercury appears to have been his favourite. Galen has given two distinct treatises on purgatives, and the cases in which they are applicable. He dissuades those who are in good health from taking them, but says that they may often be used so as to prevent the recurrence of diseases. Hence, he says, that he had often prevented gout and rheumatism from relapsing, by the seasonable administration of purgatives. He forbids purgatives when the hypochondria are distended with flatulence. Aëtius gives a very lengthy account of the preparation of purgative medicines, which will be noticed more properly in the Seventh Book. He states that all medicines of a cutting or penetrative nature are diuretic. He mentions plantain, fennel, parsley, seseli, anise, valerian, bitter almonds, &c. (iii.) Celsus gives the following list of gentle diuretics: “Urinam movent quæcunque in horto nascentia boni odoris sunt, ut apium, ruta, anethum, ocimum, mentha, hyssopum, anisum, coriandrum, nasturtium, eruca, feniculum: præter hæc, asparagus, capparis, nepeta, thymum, saturcia, lapsana, pastinaca, magisque agrestis, radicula, siser, cepa; ex venatione, maximè lepus; vinum tenue, piper et rotundum et longum, sinapi, absinthium, nuclei pinei.” He also gives a long list of laxative articles, such as cabbage, mallows, sorrel, gourds, cherries, all ripe apples, green figs, cockles, oysters, muscles, milk, crude honey, and all fatty and salty substances. (ii, 29.) Horace makes mention of the laxative properties of oysters, cockles, dock, and white wine— “Si dura morabitur alvus Mitulus et viles pellent obstantia conchæ, Et lapathi brevis herba; sed albo non sine Coo.” (Sat. ii, 4.) Avicenna gives very minute directions respecting the use of purgatives. He very properly recommends us when a purgative medicine has been taken, and instead of operating, has occasioned heat, vertigo, and headach, to administer an injection. (i, 4.) Haly Abbas treats of these medicines in pretty much the same terms as our author. He remarks that obstruction of the bowels leads to colic, flatulence, difficult respiration, and vertigo. Retention of urine, he says, leads to ulcers in the bladder. He states that diuretics are useful in diseases of the joints and spine, dropsy, and various complaints, but are apt to render the body dry. (Pract. i, 12.) Diuretic medicines, he remarks in another place, are of a hot and sharp nature, so that they heat the kidneys, and thereby increase their attractive power. (ii, 27.) Alsaharavius cautions against the indiscriminate use of purgatives, which, he says, in a dry temperament disposes to phthisis, and to dropsy when the stomach is weak. When a purgative medicine has induced hypercatharsis, he prescribes astringent powders, containing sumach, pomegranate, and the like. (Theor. x. 1.)