in alcohol, but soluble in alkaline solutions, and the oils; and when perfectly pure it is wholly volatilized by heat, and ought not to change the colour of litmus paper.

Effects and Uses.—In small and repeated doses sulphur is a gentle stimulant to the skin and mucous membranes, and in larger doses it acts as a mild purgative, without exciting the pulse or occasioning griping. It is probably absorbed by being converted in the small intestine, by the alkali of the bile, into a sulphide. After its continued use the intestinal gases give off sulphuretted hydrogen. It is employed in the cases to which laxatives are applicable, and also as an alterative diaphoretic in chronic cutaneous diseases, rheumatism and gout, and as an expectorant in pulmonary affections. It is considered a specially useful laxative in hæmorrhoids. To increase its cathartic effect it is often combined with cream of tartar or magnesia. Externally, it is a valuable remedy in various skin diseases, particularly scabies.

Administration.-Dose, 3j to 3iij or 3iv, in syrup, treacle or milk. Externally, it is applied in the form of vapour bath or ointment. Unguentum sulphuris consists of 30 parts of sulphur and 70 parts of benzoinated lard rubbed together until thoroughly mixed. Unguentum sulphuris alkalinum (alkaline sulphur ointment) consists of sulphur, 20 parts, potassium carbonate, 10 parts, water, 5 parts, and benzoinated lard, 65 parts, rubbed together until thoroughly mixed.

SULPHUR PRÆCIPITATUM (Precipitated Sulphur, or Lac Sulphuris) is prepared by boiling together sulphur, slaked lime and water, and afterwards precipitating the sulphur by hydrochloric acid. It is a finer and softer powder than sublimed sulphur, is of a paler yellow colour, with a grayish tint, and is not gritty between the teeth. When exposed to the air, however, it is liable to become contaminated with sulphuric acid, and, as found in commerce, it is often adulterated with calcium sulphate. Its effects, uses, and doses are the same as those of sublimed sulphur.

POTASSA SULPHURATA (Sulphurated Potassa), or Liver of Sulphur, is prepared by rubbing together one part of sublimed sulphur with two parts of potassium carbonate, afterwards

melting the mixture, and pouring it when cold into a bottle. Its composition is variable and uncertain, but it should contain about 50 per cent. of potassium sulphide. When freshly and carefully prepared it is of a liver colour, has an acrid, alkaline, disagreeable taste, and forms an orange-yellow solution with water. This preparation and the other sulphides probably act like sulphur. They are, perhaps, in part decomposed by the acids of the stomach, but any liberated sulphur must be again combined with the alkali of the bile. Taken in large quantities sulphurated potassa is considered to be a corrosive poison, capable of producing fatal gastro-enteric inflammation. The sulphides are considered to be expectorant, diaphoretic, and alterative. They have been especially recommended in the scrofulous abscesses of children-the calcium sulphide being preferred. Dose, for an adult, gr. ij-x, several times a day. They are used externally in scaly skin diseases in the form of ointment (3ss to 3j of lard) and of baths.

SALINE CATHARTICS.

MAGNESIA-MAGNESIA.

MAGNESIA PONDEROSA-HEAVY MAGNESIA.

Magnesia, sometimes called calcined magnesia, from the mode in which it is prepared, is procured by exposing magnesium carbonate to a red heat, till the carbonic acid is wholly expelled. It is a light, fine, white, colourless, odourless powder (MgO), of a feeble, earthy taste, very slightly soluble in water, and more soluble in cold than in hot water. Heavy magnesia is a white, fine, dense powder, chemically identical with magnesia and differing with it only in the degree of aggregation of their molecules. Henry's Magnesia, a patent English medicine, has the advantage over the ordinary magnesia of greater density and softness, and more ready miscibility with water, and corresponds to the officinal magnesia ponderosa. Magnesia prepared by Husband, and Ellis, of Philadelphia, is very similar in properties to Henry's.

Effects and Uses.-Magnesia is antacid and laxative. A

good deal of its cathartic effect is the result of its combination with the free acids of the stomach and intestines, in which soluble magnesian salts are formed. When taken in large quantities, and for too long a period, it sometimes accumulates in the bowels; and hence it is best to increase its solubility by giving it with lemonade. It is an excellent laxative where much acidity exists in the stomach, and is particularly useful in infantile cases. As an antacid it is employed in heartburn, sick headache and nephritic complaints. Dose, as a laxative, 3j; as an antacid, gr. xx, in water or milk. Of Henry's, half the quantity.

MAGNESII CARBONAS-MAGNESIUM CARBONATE.

Magnesium carbonate, sometimes called magnesia alba, is prepared by decomposing magnesium sulphate with an alkaline carbonate. As found in the shops it is a combination of magnesium carbonate and magnesium hydrate (4MgCo, Mg2HO,5H,O). It occurs in the form of light, white cubical cakes or powder; is inodorous, almost insipid, and nearly insoluble in water, but soluble in carbonic acid water.

Its effects and uses are nearly the same as those of calcined magnesia; but from its effervescence with the acids of the stomach, it is apt to create flatulence, though sometimes, on this account, more acceptable to delicate stomachs. Dose, as a laxative, 3j-ij; as an antacid, gr. x.

MAGNESII SULPHAS-MAGNESIUM SULPHATE.

This salt (MgSO,.7H2O), commonly called Epsom Salt, from its having been first procured from the Epsom mineral water in England, occurs in native crystals, and is a constituent of seawater and many saline springs. It is obtained in England from dolomite, or magnesian limestone; and also from bittern, or the residual liquor of sea-water, from which common salt has been separated. In this country it is extensively manufactured at Baltimore and Philadelphia, by the action of sulphuric acid on magnesite, the silicious magnesium hydrate. It is usually met with in small acicular crystals, which are colourless, trans

SOLUTION OF MAGNESIUM CITRATE.

287

parent and odourless, but have an extremely bitter taste. They effloresce on exposure to the air, are very soluble in water, and insoluble in alcohol.

Effects and Uses.-Epsom salt is a mild, safe, refrigerant purgative, which, from its cheapness, is by far the most commonly employed of all cathartics. It produces free, watery purgation, with very little irritation of the intestines, stimulating the intestinal glands, but not affecting the liver. Recently it has been found that hypodermic injections of small amounts of magnesium sulphate in solution will produce several watery stools. In the treatment of lead colic and the cachexia resulting from chronic lead poisoning, this salt, combined with diluted sulphuric acid, is of the greatest service. It is also used in combination with opium in acute dysentery, but is inferior to Rochelle salts in the treatment of this complaint. It is sometimes combined with senna, sometimes with bitter infusions, and is most agreeably administered in solution in carbonic acid water. Dose, 3j.

LIQUOR MAGNESII CITRATIS-SOLUTION OF MAGNESIUM

CITRATE.

Under this name magnesium citrate is employed in solution, with slight excess of acid, and in the effervescing state. It is prepared according to the following formula: citric acid gr. 400 are dissolved in water gr. 2000, and in this solution magnesium carbonate gr. 200 are stirred until dissolved: this solution is filtered into a strong twelve-ounce bottle, containing syrup of citric acid gr. 1200; to this is added water previously boiled and filtered enough to nearly fill the bottle; potassium bicarbonate gr. xxx, are then dropped in and the bottle is immediately closed with a cork, and secured with twine; the mixture must be occasionally shaken to insure the solution of the bicarbonate. The effervescing solution has a pleasant acid taste, without anything disagreeable. It is a very grateful cathartic, and is much employed as a substitute for Epsom salt, but is more apt to produce slight griping. Dose, from a half to a whole bottle.

MAGNESII CITRAS GRANULATUS (Granulated Magnesium Citrate) is a white, coarsely-granular salt, deliquescent on exposure to air, odourless, having a mildly acidulous, refreshing taste, and an acrid reaction. Soluble with copious effervescence in two parts of water; almost insoluble in alcohol. It should be kept in closely stoppered bottles. Its effects are similar to those of the solution, and it is used for the same purpose. It has the advantage of portability. Dose, 5j-iv dissolved in water and taken while effervescing.

SODII SULPHAS-SODIUM SULPHATE.

Sodium sulphate, commonly called Glauber's Salt (Na2SO IOH,O), is a constituent of many mineral springs, and is prepared in various chemical processes. It occurs as a residuum in the manufacture of hydrochloric acid, made by adding sulphuric acid to sodium chloride, and it is obtained from seawater in the winter season. It is found in colourless, six-sided, very efflorescent crystals, which are inodorous, but have a cooling, saline, very bitter taste. It is soluble in water-more readily in hot than in cold water--and is insoluble in alcohol.

Its effects and uses are very similar to those of Epsom salt, but it is more bitter and nauseous, and is now little used. It is a mild hepatic stimulant, according to the experiments of Rutherford on dogs. The effects of the sodium salts have already been considered (vide page 215). It has an antiplastic action on the blood, due to the sodium which it contains. Dose, 3j; in an effloresced state, 3ss.

MANGANI SULPHAS-MANGANESE SULPHATE.

This salt (MnSO1.4H2O) is made by heating the native black oxide with concentrated sulphuric acid. It occurs in rhombic, prismatic crystals, of a pale-rose or pink colour, transparent, and of an astringent, bitterish taste. It is very soluble in water, insoluble in alcohol.

In its effects it is said to resemble Glauber's Salt, acting also as a cholagogue. Dose, as a purgative, 3j-ij. As a tonic (vide p. 139) it has been given in doses of gr. v-xx.