These are made by mixing the Oil with a certain proportion of the emulsifying agent, adding Water, and triturating the mixture in a mortar or agitating it in a flask.

There are various methods, but these are general rules:

The emulsification of the oil should be complete before the mixture is made up to the required measure.

When alcoholic liquids are to be added, they should first be diluted as much as possible.

Salts should be dissolved before being added.

No heat should be employed, as the oil separates when an emulsion is heated.

Emulsions should be freshly prepared and be preserved in a cold place.

The most common emulsifying agent is Powdered Gum Acacia (Acacia puly.). The Oil is thoroughly mixed by trituration in a mortar with one-fourth its weight of powdered Acacia. To this one and a half times as much water as of gum is added at once, and the mixture is rapidly triturated with a rotary motion of the pestle until it becomes stiff and assumes a milk-white color. This so-called "mother-emulsion" may now be diluted to the required measure, and other substances, flavors, etc. be added.

Powdered Tragacanth may be used in the same way or in the form of mucilage, but it does not produce so permanent emulsions as does gum acacia.

The Mucilages of Acacia and of Irish Moss are not so satisfactory as powdered gum: while they produce a good emulsion, the division of the oil-globules is not so thorough as in the preceding: emulsification being incomplete, the mixture more rapidly separates into a heavier, watery liquid and a lighter, thick, gelatinous emulsion, which requires thorough mixing before use.

Extract of malt is an excellent emulsifying agent when its use is admissible. The Oil should be added to the Malt Extract contained in a capacious mortar, and incorporated in small quantities at a time. A good article will emulsify an equal volume of cod-liver oil.

Condensed Milk and Egg-yolk produce the most perfect emulsions, and also the most palatable, but they rapidly ferment and spoil.

Glycerin and sugar added to emulsions for the purpose of preservation and palata-bility induce separation, and their use is not advisable.

Emulsification "by intervention" is the best and only reliable method to be employed with Ethereal Oils and all substances of themselves not emulsifiable. The process is illustrated in the official Chloroform Emulsion.

Oil of Turpentine, for example, is emulsified by dissolving the Turpentine Oil in a bland fixed oil (Almond Oil), incorporating an equal weight of powdered Acacia, adding Water, and proceeding as with an ordinary emulsion.

Pancreatin emulsionizes fats in preparing them for digestion, but it does not produce a permanent emulsion when used artificially. While, therefore, not a reliable emulsifying agent, it aids the assimilation of oils, and its addition to emulsions is sometimes therapeutically desirable. As it is more active in alkaline media, the Emulsion should be prepared with a little Sodium Bicarbonate.

The addition of Alkalies to emulsions should be avoided. Soaps are not Emulsions, nor is the use of Soap-bark to be recommended.

The official emulsions are:

Unofficial Emulsions of the National Formulary. Emulsions should, of all pharmaceuticals, be prepared within a reasonable period previous to the time of dispensing. A true emulsion should contain the oil simply suspended in the form of a mechanical mixture, which, from its very character, cannot withstand the effects of variation in temperature any better than a natural emulsion, such as milk or emulsions of almonds, gum-resins, etc., and consequently quickly degenerates or spoils.

An emulsion may be perfect - that is, the oil-globules entirely extinguished - yet a separation similar to that occurring in milk will take place, which, though in its first stage not so objectionable, will eventually impair the medicinal value of the preparation. These reasons are, it is believed, sufficient to condemn the various "ready-made" or patent emulsions, and to justify the physician in prescribing such as are kept on hand by the pharmacist, in smaller quantities, prepared according to these formulas.

A typical formula for emulsions, with Acacia, is -

Emulsify by trituration in a mortar, and add the flavoring.

The following are flavors employed: (1) Gaultheria, (2) gaul-theria and sassafras, (3) aromatic spirit, (4) gaultheria, bitter almond, and coriander, (5) gaultheria, sassafras, and bitter almond, (6) gaultheria and bitter almond, (7) oil of neroli, bitter almond, and cloves. Unless otherwise specified, that designated as No. 5 may be employed in these Emulsions.

The following formulas may be useful as indicating the form of prescription for any combination desired. Hypophosphite Salts or any medication desired may usually be dissolved in the water directed in the formula, should a preparation be indicated different from any of the following emulsions of the N. F.:

Emulsio -

Olei Morrhuae cum Calcii et Sodii Phosphatibus. - Calcium Phosphate, Sodium Phosphate, of each, 1 grain in 1 fluidrachm (0.06 in 4 Cc).

Olei Morrhuae cum Calcii Lactophosphate. - Calcium Lactophosphate, 3 grains in 1 fluidrachm (0.2 in 4 Cc).

Olei Morrhuae cum Calcii Phosphate. - Calcium Phosphate, 2 grains in 1 fluidrachm (0.12 in 4 Cc).

Olei Morrhuae cum Extracto Malti. - Contains 40 per cent. Extract of Malt.

Olei Morrhuae cum Hypophosphite. - The Hypophosphite Salt or any combination of the following: Calcium, Potassium, Sodium, or Iron, to be directed by the prescriber, 8 grains to the fluidounce (0.5 in 30 Cc).

Emulsio -

Olei Morrhile cum Pruno Virginiana. - Wild Cherry (Fluid Ext.), 1/2 fluidrachm to 1 fluidounce (2 Cc. in 30 Cc). Olei Ricini. - 1 fluidounce (30 Cc.) contains 2 1/2 fluidrachms (10 Cc.) Castor Oil, disguised by the addition of Vanilla. Olei Terebinthinae. - Contains 1 fluidrachm (4 Cc.) Oil of Turpentine I fluidounce (in 30 Cc), prepared according to the following formula:

Make an emulsion by trituration in a mortar.

Phosphatica (Phosphatic Emulsion). - Prepared with Glycerite of Egg-yolk, and contains in 1 fluidounce (30 Cc) Cod Liver Oil, 2 fluidrachms (8 Cc.); Dilute Phosphoric Acid, 22 1/2 minims (1.5 Cc.); Jamaica Rum, flavored with Bitter Almond and Orange Flower Water.