Purgatives are active cathartics, and are divided into several classes, according to the nature of their action, such as: Laxatives, which incite intestinal movements without much increase of the intestinal secretions. Included in this class are manna, sulphur, magnesia, castor oil, etc. Saline Purgatives, which produce increased secretion, and at the same time hasten the peristaltic action, the stools being loose and watery. Included in this class are sulphate of magnesia, phosphate of soda, tartrate of potassium and sodium, Seidlitz powder, bitartrate of potassium, etc. Mercurial Purgatives, principally calomel and blue mass, which are supposed to produce cholagogue effects, and also an influence peculiar to themselves. Tonic-astringent and resin-bearing purgatives, which have an influence over the liver and the glandular appendages, and promote the tonicity of the muscular layer of the intestines. Included in this class are senna, rhubarb, aloes, jalap, scammony, colocynth, podophyllum, etc. Hydragogue purgatives, which are very energetic in their action, increase the glandular secretions and cause an abundant outward diffusion to such a degree as to produce very watery stools; and also excite rapid and severe peristaltic movements. Included in this class are gambogia, croton-oil, elaterium, etc. (See Cathartics.)


Refrigerants are medicinal agents which are capable of diminishing heat and allaying thirst. . They are also called Febrifuges. Included in this class are nitrate of potassa, chlorate of potassa, solution of acetate of ammonia, acetic acid, citric acid, hydrochloric acid, nitric acid, tartaric acid, spirits nitrous ether, etc., etc.


Resolvents belong to the class of Alteratives and Emollients, being medicinal agents capable of reducing inflammation and dispersing morbid swellings. (See Alteratives and Emollients.)


Restoratives belong to the class of Stimulants and Tonics. (See Stimulants and Tonics.)


Sialagogues are medicinal substances capable of increasing the salivary secretion by a stimulant or irritant effect. By the excitant properties of these agents the lining membrane of the mouth is irritated, the effect extending along the ducts to the salivary glands, so that not only is the quantity of fluid exhaled from the mucous membrane increased, but salivation results. In this way depletion follows their employment, and more or less revulsive effect ensues, which may prove beneficial to distant parts affected by disease. Sialagogues may also prove useful in cases of paralysis of the tongue, etc., by their directly excitant properties; also in local palsy of the tongue. They are occasionally employed as masticatories in odontalgia, and in such affections of the head as may indicate the use of substances which excite irritation in and increased discharge from the lining membrane of the nasal cavities. Included in this class are pyrethrum, horse radish, calamus, ginger, tobacco, calomel, corrosive sublimate, blue mass, iodide of mercury, etc.