"Incompatibility gives rise to many dangers which may in a great measure be avoided by the use of the utmost simplicity in prescribing. 'The tendency of the present age is toward mono-rather than poly-pharmacy, and prescriptions with the orthodox adjuvans and corrigens are less frequently seen than formerly.' (Piffard.)

"This subject can only be glanced at here. The following simple rules may help the burdened memory of the practitioner: -

"Never use more than one remedy at a time, if one will serve the purpose.

"Never use strong mineral acids in combination with other agents, unless you know exactly what reaction will ensue. They decomnose salts of the weaker acids and from ethers with alcohol.

"Select the simplest solvent, diluent or excipient, you know of, remembering that the solvent power of alcohol and water, for their particular substances, decreases in proportion to the quantity of the other added.

" Never combine Free Acids with hydrates or carbonates.

" Generally do not combine two or more soluble salts.

"The following more or less insoluble salts will be formed whenever the materials of which they are composed are brought together in solutions; the Hydrates, Carbonates, Phosphates, Borates, Arseniates and Tannates of most earthy and heavy metals and alkaloids, and the metallic Sulphides; the Sulphates of Calcium, of Lead and of the subsalts of Mercury: the Chlorides, Iodides and Bromides of Bismuth, Silver, Lead and subsalts of Mercury; the Iodides of Quinine, Morphine and most alkaloids.

"Alkalies precipitate the alkaloids and the soluble non-alkaline metallic salts, and (as also metallic Hydrates and Carbonates) neutralize free acids.

"Silver Nitrate, Lead Acetate, Corrosive Sublimate, Potassium Iodide should nearly always be prescribed alone. The first with Creasote forms an explosive compound. Aconite should never be given in any vehicle except water.

* S. O. L. Potter, M. D.

"Silver Nitrate, and Lead Acetate and Subacetate, although incompatible with almost everything, may be combined with Opium: the latter forming with Opium a compound which, although insoluble, is therapeutically active as a lotion.

"Corrosive Sublimate is incompatible with almost everything, and should be given in Simple Syrup; even the Compound Syrup of Sarsaparilla is said to decompose it.

"Tannic Acid, and substances containing it, are incompatible with albumen and gelatin. Tannic Acid, Iodine and the soluble Iodides are incompatible with the alkaloids and substances containing them, and with most soluble metallic salts. Vegetable Infusions are generally incompatible with metallic salts.

"Glucosides, such as Santonin and Colocynthin, should not be prescribed with free acids or Emulsin.

"Dangerous Compounds, because poisonous, are: Potassic Iodide with Potassic Chlorate; Hydrocyanic acid or Potassium Cyanide with metallic Hydrates, Carbonates, Sub-nitrates or Sub-chlorides, as Bismuth, Carbonate or Nitrate or Calomel.

"Explosions would result from the combination of powerful oxidizers with readily oxidizable substances, as Potassium Chlorate or Permanganate with Tannin, Sugar, Sulphur, Sulphides, Vegetable powders, Glycerine, Alcohol, Tinctures or Ether."