Note 465 — PHARMACOLOGIA. (continued 3)

Sulphate of Quina. As this preparation is considered the most active form of the salifiable principle of bark, I have subjoined the most approved formula for its preparation. Boil for half an hour two pounds of the appropriate bark in powder, in sixteen pints of distilled water, acidulated with two fluid-ounces of sulphuric acid; strain the decoction through a linen cloth, and submit the residue to a second ebullition in a similar quantity of acidulated water; mix the decoctions, and add by small portions at a time, powdered lime, constantly stirring it to facilitate its action on the acid decoction. (Half a pound is near the quantity requisite.) When the decoction has become slightly alkaline it assumes a dark brown colour, and deposits a reddish brown flocculent precipitate, which is to be separated by passing it through a linen cloth. The precipitate, is to be washed with a little cold distilled water and dried. When dry it is to be digested in rectified spirit, with a moderate heat for some hours; the liquid is then to be decanted, and fresh portions of spirit added till it no longer acquires a bitter taste. Unite the spirituous tinctures, and distil in a water-bath till three fourths of the spirit employed has distilled over. After this operation there remains in the vessel a brown viscid substance covered by a bitter, very alkaline and milky fluid. The two products are to be separated and treated as follows. To the alkaline liquid add a sufficient quantity of sulphuric acid to saturate it; reduce it by evaporation to half the quantity; add a small portion of charcoal, and after some minutes ebullition, filter it whilst hot, and crystals of Sulphate of Quina will form. The brown mass is to be boiled in a small quantity of water, slightly acidulated with sulphuric acid, which will convert a large portion of it into Sulphate of Quina. The crystals are to be dried by bibulous paper. Two pounds of bark will, it is said, yield 5 to 6 drachms of the sulphate; of which eight grains are considered equivalent to an ounce of bark. It has been prepared in this country by several manufacturing chemists, especially by Mr. Pope of Oxford Street, whose zeal and industry in Pharmaceutic experiments entitle him to great commendation. The superior price of the bark, however, from the duty in this country, as well as that of alcohol, must prevent us from entering into competition with the French in its manufacture, and it has accordingly been found more œconomical to import, than to prepare it.