528 Materia Medica. — Super-to'rtras Potassce. part ir.

very bright yellow powder, and contains a minute portion ofsulphuric acid, from which it can be separated by washing itwith water. Sulphur volatilizes under 220° Fahr., at whichit fuses, and what is singular, by increasing the heat to 320°, itbecomes thick and viscid, and if then poured into water, itassumes a red colour and ductility like wax 1 : while its specificgravity is increased to 2 - S25. At 560°, it becomes an elasticfluid. When heated in the air it inflames at 300°, and burnswith a pale blue flame, emits pungent suffocating vapours, andbecomes acidified. It is insoluble in water ; but soluble in asmall degree in alcohol, ether, and oils ; and combines with thealkalies, and many of the earths, and metallic substances. Theexperiments of Davy led to the supposition that sulphur is atriple compound of oxygen, hydrogen, and a peculiar base -,but it is still an undecompounded substance.

Medical j'roperties and uses. — Sulphur is laxative, and astimulating diaphoretic. From the gentleness of its operationon the bowels, it is one of the best means for keeping themlax in hoemorrhoidal affections ; and the diaphoresis which it atthe same time excites has rendered it serviceable in chronicrheumatism and catarrh, and in atonic gout, rickets, asthma,and other pulmonary affections not attended with acute inflam-mation. It is supposed that it combines with hydrogen in thestomach. It manifestly transpires through die skin, perhaps,however, in the state of sulphuretted hydrogen, which may bethe cause that silver is blackened when kept in the pockets ofthose who take sulphur. It is specific in scabies and someother cutaneous affections, in which it is applied externally,and taken internally at the same time.

The dose may be from £j to ^iij, mixed into an electuarywith syrup or treacle, or in milk. To promote its purgativepower it may be combined with super-tartate of potass ; andin hemorrhoidal cases with magnesia.

Officinal preparations. Sulphur lotum, L. E. D. Sulphur prre-cipitatum, L. Ungucntum Svlphuris,'L.Yu,Y). Unguenti/m Sulphu-ric composititm, L.

SUPER-TARTRAS POTASSiE IMPURUS, Edin.Tartarum, Lond. Impure Super-tartrate of potass.

Syn. Tartre (F.), Roller \v e insteiii (G.), Tartaro bianco (I.), Tartaro (S.)-

This is a saline matter, which exists in the juice of the grape ;and is deposited on the sides of casks of wine, in the form of acrust, during the continuance of the slow fermentation whichgoes on in wine, till it attains the greatest perfection age canIt is well known by the name of tartar, and is named

give it.

1 In this state it is kneaded under the water, and used for receiving the impres-sions of seals and medals.

2 Phil. Trans. 1809.