This section is from the "Encyclopedia Of Practical Receipts And Processes" book, by William B. Dick. Also available from Amazon: Dick's encyclopedia of practical receipts and processes.
42. Proportion of Ingredients used for making Tinctures. Tho following are the proportions usually employed for the most important perfume tinctures:
Tincture. Troy. Alcohol.
Vanilla............Vanilla bean, rasped.....1 lb........8 pts.
Musk..............Grain musk..............2 drachms.8 pts.
Frangipani.......Powder a la frangipani. 1 lb.......6 pts.
Rhodium.........Rhodium-wood, rasped. 1 lb........2 qts.
Civet...............Civet, orris-root........1/2 oz......2 qts.
Tonquin ..........Tonka bean..............1 lb........8 pts.
Orris..............Orris - root...............7 pts......8 pts.
Alkanet - red col..Alkanet.................1/2oz......1 qt.
Turmeric - yellow.Turmeric................1/2 oz......1 qt.
43. To Prepare Emulsions. These are milky liquids, formed by the mechanical admixture of oil, balsam, or resin, with water, by means of some other substance that possesses the property of combining with both. There are numerous preparations of the kind in pharmacy and medicine, which, in the later pharmacopoeias, have received the name of "mixtures." There are also several emulsions employed as cosmetics, either alone, or as vehicles for other ingredients. The common name of emulsions is "milk" but the term is often incorrectly extended to opaque white liquids of an entirely distinct character.
The successful preparation of emulsions is a matter requiring some little skill and care. In some instances, as with the almond, the two substances necessary to produce a perfect emulsion are presented by nature, ready to our hand, in the same vegetable production; nothing more is necessary than to reduce it with the pestle, and triturate it with water, gradually added. In other cases, and which are far the more numerous, we have to operate on oily or resinous ingredients in their common form. These we are enabled to suspend in water, or mechanically combine with it, by the intervention of thick mucilage, almonds, or yolk of egg. It is found that 1 drachm (6O grs.) of the first - made with equal parts of good gum-arabic and water (powdered gum is sometimes used instead of mucilage)— 1 ounce of the second, (usually about 26 in number), and one of the last, will form 2 drachms of oil or resinous matter into an emulsion with about 1 fluid ounce of water, gradually added; and such an emulsion, if properly made, will then, in most instances, bear further dilution with water. (The yolk of an ordinary-sized hen's egg is referred to. It should be remembered, that emulsions formed with yolk of egg will not keep long, owing to the putrescible nature of the latter.) Of these, mucilage is the medium most commonly employed. According to Montgomery, for conversion into permanent emulsions, " oils require about three-fourths their weight ; balsams and spermaceti, equal parts; resins, twice their weight; and musk and ambergris 5 times its weight." In some cases instead of the above substances, a little liquor of potassa is employed, when a saponaceous emulsion is formed, which differs considerably in its properties from an emulsion of the same ingredients produced by means of a bland medium.
In making an emulsion, the gum, or other medium employed, should be first put into the mortar, and rendered thoroughly homogeneous with the pestle. If almonds are used, they should be treated as noticed under " almond-paste " (see No. 1123 (Almond Paste)), a few drops of water being added to prevent "oiling," and to reduce them to a smooth, soft paste. The oil or resinous matter may then be gradually added and rubbed in, carefully observing not to add it more quickly than it can be subdued by the pestle; and if, during this part of the manipulation, the mixture should begin to exhibit a "breaking" or "curdling" appearance at the edges, a few drops of water must be immediately incorporated with it, before adding the remainder of the oil. If this be not done, the emulsive mixture in the mortar will, in general, suddenly lose its tenacious consistence, and the process will fail. After the whole of the oil, balsam, or resinous matter is thoroughly incorporated, the water or other aqueous vehicle intended to form the bulk of the emulsion, should be added gradually and with care, each portion being perfectly blended with the liquid mass in the mortar, by patient trituration, before adding the next. If any alcoholic liquid is employed, it should be added at the very end of the process, and then only very gradually, as otherwise it will cause the separation of the ingredients.
It must be observed that soluble salts, spirit, acids, and astringents, are, as a rule, incompatible with the emulsive form. If saline matter must be introduced, it should only be added in a very minute quantity, and in the state of solution, to the ready-formed emulsion; and in this case emulsion of almonds is the most suitable vehicle. (See No. 1125 (Cold Cream).) Spirits and acids act by precipitating the mucilaginous matter, or yolk. Even the addition of a very little lemon juice, or of a portion of slightly acescent syrup, will often entirely destroy an emulsion. This inevitably occurs with emulsions made with liquor of potassa, or other alkaline medium, owing to the absolute incompatibility of acids and alkalies in the same liquid.
It is found that volatile oils arc more readily made into emulsions if mixed with an equal volume of some simple fixed oil, as that of the almond or olive, before proceeding to operate on them.
All emulsions should be well shaken before use. (Cooley.)