The mistura ferri composita will exemplify the subject. It is infinitely preferable to prepare it for stock in a concentrated form of four times the strength, and to keep the ferrous sulphate apart until required.

Beat the myrrh well, divide the beaten mass with the powdered sugar, and make into an emulsion with half the rose-water. Next add the carbonate of potassium dissolved in the remainder of the water, and add the spirit last.

Recollect that potassium carbonate is a hostile ingredient in an emulsion when present with a second emulsifying agent. Proceeding in this way an excellent emulsion is produced in an extemporaneous manner; but there is a better mode.

Beat the myrrh as usual, divide with sugar, add the potash, and make a thick creamy emulsion with just sufficient water.

Let this stand, covered from the air, overnight, and the following morning finish the operation. A few minutes' trituration will restore the whiteness, and such a mistura ferri will keep for some years without alteration. [Note.- Since Mr. lnce made these remarks the B.P. formula has been altered in quantities, and his ' better mode' has been adopted in principle.]

Ammoniacum and asafetida must both be converted into hydrated masses. Let them, before being manipulated, soak in a small quantity of water, when they are readily reduced to a pulpy condition, and form tolerable emulsions afterwards without any additional emulsifying agent.

Egg Emulsions require a skilful hand, and may be presented as permanent combinations. The first and last requisite is that the dispenser should abstain from the slightest mechanical force. Example :

Break the egg-shell cleverly on the side-edge of a 2-ounce measure, into which let the albumen run. Entirely clear away the albumen (a fertile source of failure when this precaution is neglected). Keep the albumen to be used as liquid gum, and also for sugar-coating pills. Render the yolk (thrown into the mortar) perfectly smooth under the pestle with rapid circular motion; add the oil by degrees; if occasionally too thick, thin with a little water. Add the syrup next; then wash out the measure with a little water. Add the tincture last, and finally wash out the measure with the remaining water, and the process is complete.

Yolk of egg is supreme with regard to spermaceti, once a very favourite remedy with the accoucheur.

Break down the spermaceti; make it quite smooth in the syrup, then proceed as usual. All these egg emulsions keep. When a dilute acid forms an ingredient in an emulsion, it should be added last, and there should be no fear of imperfect combination.