Trochisci.—Troches.
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Troches, or lozenges, are medicinal substances in powder, which are formed into solid cakes, by the aid of sugar and gum. These cakes are circular, flat, a line or so in thickness, and about ½ inch in diameter. They are usually intended for gradual solution while retained in the mouth, and form a very pleasant mode of exhibiting many useful remedies. Gum Arabic and tragacanth are both employed, but the latter is preferred on account of the greater cohesiveness of its gum. In preparing troches, the best tragacanth should be selected, and placed in sufficient cold water to form a mucilage of the consistence of paste; this must be strained previous to using it. The medicinal powders having been well incorporated with the sugar, are by means of a sufficient quantity of the mucilage of tragacanth, worked into a soft dough, upon a plate of marble or porcelain. After all have been duly incorporated, the thick paste or dough is rolled out on the marble plate, its adhesion to the roller being prevented by sprinkling over it, from time to time, some powdered starch, or a powder of starch and sugar. Uniformity of thickness is effected by the use of a frame of wood or iron, which is placed upon the marble plate, and upon which the extremities of the roller move during the process of rolling. The rolled-out or extended layer of dough is now sprinkled with some of the powdered starch, and the troches are cut of the required shape and size by means of a tin-plate punch. The troches are then placed on a sieve, and dried in a drying-room or closet, after which the superfluous powder is removed by means of the sieve, and the troches placed in well-covered bottles (Mohr and Redwood).
"Lozenges are frequently composed of extract of liquorice and gum Arabic with sugar, which renders them quite tough, so as to become unmanageable by long standing. In such cases, the best mode is to thoroughly mix the articles together, and then add the sugar, in the form of a dense syrup, made with but two-thirds of the usual quantity of water required for simple syrup, mix it quickly, and, while yet warm, roll the mass into long cylinders, and, when nearly dry, cut them of the required size" (W. Procter, Jr.). It may be added that troches are not now used as freely as they were when the foregoing was written. Sugar and gelatin-coated pills, triturations, and tablets have largely superseded them.
