Edhl.

"Take of senna leaves, six drachms; ginger root, bruised, a scruple; boiling water, nine ounces. Macerate for an hour in a lightly-covered vessel, and strain."

Syn. Infusion de Sene (F.), Senna aufguss (G.), Infuso di Senna (I.).

This infusion should be clear; have a deep red-brown colour, and a slightly bitter, mawkish taste, which is scarcely corrected by the aromatic. In warm weather it spoils in forty-eight hours; and by simple exposure to the air attracts oxygen, which occasions a yellowish precipitate of oxidized extractive, which is not purgative, but gripes violently. On this account it should be preserved in a well-closed vessel, or made only when it is wanted. Dr. Paris (Pharmacologia) observes, that the nauseous taste of this infusion is completely covered by the addition of Bohea tea. Decoction of guaiac is said to increase its powers, and to render it milder. Camphor mixture augments its activity. It is precipitated by the strong acids, the alkaline carbonates, lime-water, solutions of nitrate of silver, bichloride of mercury, acetate and diacetate of lead, tartar emetic, and infusion of yellow cinchona bark, which are consequently incompatible in formulae with these infusions.

Medical properties and uses. - This infusion contains all the purgative principles of the plant, whilst the aromatics correct its griping properties: but there is a waste of senna in the London formula. It would be better to pulverize the leaves, and macerate the powder in water at 160°: all the active matter is dissolved, and little of the griping part of the leaf. It is given generally combined with neutral salts and manna. The dose of the simple infusion may be from f ij. to f iv.; but with the addition of 3 j. of the tartrate of potassa, or 3 iij. of the sulphate of magnesia, which are the usual adjuncts, f ij. are sufficient.