No. I. can be made a good mixture by the addition of acacia. Make a mucilage of 2 drachms of the powdered gum with 1/2 ounce of chloroform-water; dissolve the iodide in the rest of the water, and mix the mucilage with it; then mix the tincture of guaiacum with the other tinctures and add to the whole of the watery mixture with gentle agitation. It may be noted that recently prepared tinct. guaiaci ammon. poured into water containing 25 per cent, of fresh acacia mucilage forms a nice milky emulsion, but an old sample of tincture with stale mucilage produces an unsightly curdy mixture. In the case of No. II. the taraxacum extract is a good substitute for mucilage. Rub the extract down with about 2 ounces of the water, pour in the mixed tinctures, nearly fill the bottle with aq. chlorof., and add the ammon. chlor. dissolved in the rest of the aq. chlorof.

If this be mixed in different ways it will present different appearances. The principle to be borne in mind here, as in all similar cases, is that it is far easier to keep a substance in solution than it is to take it up again after precipitation. In the instance before us it is evident that the substances should be mixed in the order of their percentage of alcohol- that is, the spirit of nitre should be mixed with the tinct. tolut, and the tinct. camph. co. added gradually with agitation.

The best plan for No. I. is to mix the tincture and the spirit, and dissolve the thymol in the mixture. Then mix the magnesia with 10 drachms of water, and pour the spirituous mixture into it. Light magnesia must be used. Mucilage is inadmissible owing to the alcoholic strength of the preparation. The light carbonate of magnesia is largely employed in making the quasi-emulsion inhalations of such essential oils as oleum pini sylvestris and oleum pini pumilionis. These are generally dispensed by mixing with a small quantity of the light carbonate in a mortar and adding the water. In this way the use of spirit, which might be therapeutically inapplicable in some throat cases, is avoided. No. II. prescription requires the addition of 1/2ounce of acacia mucilage.

One mixture of a resinous tincture with water may be mentioned as a useful cosmetic, making, it has frequently been stated, a perfectly suspended milky compound. It is known asLait Virginal, and is composed of tinct. benzoini 3ij, and aquae rosae This cannot be made into an inseparable mixture without the addition of a few drachms of acacia mucilage.

Tincture of tolu is frequently prescribed in cough-mixtures, and it is desirable that the tolu should be dispensed in a permanent milky condition. If senega or quillaia is in the mixture, the dispenser will bear in mind that the saponin in these bodies is one of the best emulsifying agents, therefore the tincture of tolu should be added to the senega or quillaia preparation. The properties of these saponin emulsifiers are discussed later.

Fiat mistura.

There is insufficient quillaia here to keep the tolu suspended. A dispenser made a good mixture by the addition of pulv. tragac. co. 3j. This was mixed with 2 ounces of chloroform-water, the elixir and tincture of quillaia added, then the tincture of tolu, and lastly the salts dissolved in the rest of the water.