Pharmaceutical. This results when substances are mixed and do not produce clear solutions, owing to their different solubility in men-struums - insoluble powders or oil will not mix with water, nor will water with solutions of resins without precipitation - acid quinine solutions with licorice solutions precipitate glycyrrhizin - alcoholic solutions with aqueous solution of hydrated chloral separate the latter on top. In all such cases it is better pharmacy to suspend the separated ingredients by the addition of a mucilage or some emulsifying agent. Under this head it is well to remember the following classes:
3. Spirit of nitrous ether with strong mucilages, tincture of guaiac, solution of potassium bromide or iodide.
4. Alcoholic liquids, tinctures, and fluidextracts with those made with diluted alcohol; also with strong solutions of acacia.
5. Infusions in general with metallic salts - due to gelatinization and behavior of tannic acid.
6. Antipyrine with alkaloids, tincture of odine, corrosive mercuric chloride, Lugol's solution, spirit of nitrous ether, ferric salts, hydrocyanic, tannic, and nitric acids, phenol, permanganates, salicylates, hydrated chloral, orthoform.
7. Pepsin with alkalies, alcoholic liquids, mineral salts, tannates, heat (100° C; 212° F.).
8. Salicylic acid with iron compounds, alkali iodides, spirit of nitrous ether.
Therapeutical. This results where two drugs of opposite medicinal properties are given together - the one neutralizing somewhat the other; astringents with purgatives; aconite or veratrum viride with digitalis; atropine, belladonna, hyoscyamus, or stramonium with caustic alkalies, pilocarpine, physostigmine (eserine), or morphine; acids with alkalies; arsenic with hydrated ferric oxide; phenol or lead salts with magnesium or sodium sulphate; cannabis with strychnine, picrotoxin, or acids; cocaine or gelsemium with morphine; conium with strychnine, picrotoxin, or stimulants; corrosive mercuric chloride with tannin or vegetable astringents; homatropine with physostigmine (eserine); opium and its alkaloids with potassium permanganate, belladonna, hyoscyamus, or stramonium; oxalic acid with calcium carbonate; silver nitrate with sodium chloride; strychnine or picrotoxin with hydrated chloral and potassium bromide; tartar emetic with tannin. Sometimes physiological antagonists are prescribed together purposely, in order to have the action of the one to guard that of the other, as atropine with morphine (hypodermically).