shades of violet and purple, according to the proportions of the materials. By using solution of tin as the mordant, various shades of red, lilac, and violet, may be obtained. The addition of a little Brazil wood is commonly made to brighten the red. With a mordant of sulphate or acetate of iron it dyes black; and with the addition of a little sulphate of copper greys of various shades. It is, however, chiefly employed, in conjunction with gall-nuts, for blacks, to which it imparts a lustre and velvety appearance. Silk is usually turned through the cold decoction, but for wool the decoction is used either hot or boiling. Logwood is one of the cheapest and most easily managed of the dye stuffs. It is also used to make ink. See Hematoxylin, Ink, &c.
LO′HOCH. See Linctus.
LOR′ICA. A species of lute applied as a coating to chemical vessels before exposing them to the fire. Its application is called LORICATION. See Lute.
LO′TION. Syn. Lotio, L. An external application, or wash, consisting of water holding in solution medicinal substances. Lotions may be prepared of any soluble medicaments that are capable of exerting their action by contact with the skin. Writers on pharmacology have arranged them in classes, as sedative, anodyne, stimulant, &c., according to their effects. Sedative and refrigerant lotions are commonly employed to allay inflammation;—anodyne and narcotic lotions, to relieve pain;—stimulant lotions, to induce the maturation of tumours, &c.;—detergent lotions, to clean foul ulcers;—repellent and resolvent lotions, to discuss tumours, remove eruptions, &c.;—counter-irritant lotions, to excite a secondary morbid action, with the intention of relieving one already existing. Lotions are usually applied by wetting a piece of linen with them and keeping it on the part affected; or, in slight cases, by moistening the part with the fingers previously dipped into them. Lotions are more agreeable if made with rose water, but are not thereby rendered more efficacious. In all cases, distilled water, or filtered soft water, is alone admissible as the solvent.
As lotions are, in general, mere extemporaneous or magistral preparations, it will, of course, be only necessary here to give the formulæ for a few of those which are the most useful or the most frequently employed. These will serve as examples from which others may be prepared. As a general rule, the medium dose of any substance dissolved in a fluid ounce of distilled water, forms a lotion of the proper strength, under all ordinary circumstances; or, what is the same thing, the medium dose in grains, taken in scruples, is sufficient for a pint of such a lotion. Thus, the dose of sulphate of zinc is 1 to 3 gr., therefore— (1 + 3)/2 = 2 gr., which is the proportion
of sulphate of zinc to be taken for 1 fl. oz. of water, or 40 gr. for 1 pint. Again, the dose of bichloride of mercury is 1⁄8 to 3⁄4 gr.; therefore— (1⁄8+3⁄4)/2 = 7⁄16 gr.; or nearly 1⁄2 gr. per fl. oz., and 81⁄2 gr. per pint. In this method extreme or unusual doses, as, for instance, those of sulphate of zinc, as an emetic, in poisoning, &c., are not taken into the calculation. In all cases in which lotions are intended for extremely susceptible parts, it is proper to dilute them with an equal bulk of water. When intended for eye-waters (COLLYRIA), they should be diluted with at least 3 to 4 times their bulk of water. See Embrocation, Liniment, &c.
Lotion of Ac′etate of Ammo′′nia. Syn. Lotio ammoniæ acetatis, L. Prep. 1. Solution of acetate of ammonia, 1 part; water, 2 parts.
2. (Hosp. F.) Solution of acetate of ammonia, rectified spirit, and water, equal parts. Discutient and refrigerant. In ordinary inflammations.
Lotion of Ac′etate of Lead. Syn. Lotio plumbi acetatis, L. Prep. 1. (Collier.) Acetate of lead, 1 dr.; distilled water, 8 fl. oz. Sometimes a little vinegar is added. In excoriations, burns, sprains, contusions, &c. See Solution of Diacetate of Lead.
2. Acetate of lead, 2 gr.; distilled water, 1 oz. (Ophthalmic Hospital.)