Alum dissolves in twelve times its weight or less of water: on setting the solution to exhale slowly in a moderately warm air, the salt concretes into crystals of eight or more triangular sides. The solution changes the colour of the blue flowers of plants, or their juices, to a red or purple, as acids do; and like them also, it coagulates milk and the serous humours of animals. The whey obtained by boiling a pint of cow's milk with two drams of powdered alum, is sometimes given in uterine haemorrhages, and recommended also in the diabetes (a), in doses of a quarter of a pint, three or four times a day. This liquor, like other aluminous solutions, is not a little ungrateful: nor does this method of obtaining the solution admit of so much precision, as could be wished for in a medicine of such efficacy in regard to the dose: a considerable part of the alum being retained in the curd, which tastes rather more strongly aluminous than the whey. The whey may be made more elegant by a proper addition of sugar, and of dried red rose buds.

This salt, exposed to the fire, easily liquefies, bubbles up in blisters, emits watery vapours amounting to about one sixth of its weight, and then turns to a light spongy unfusible mass, which seems on tailing to be almost insipid, but gradually dissolving in the mouth, discovers at length the same taste as the alum at first. This dried, or burnt alum, as it is called, is sometimes employed for drying foul ulcers, and consuming proud flesh, which it does with great mildness, but it is said to have an inconvenience of leaving a hardness upon the part.

The burnt alum, urged with a strong fire, gives out an acid spirit exactly similar to that obtained by the same means from vitriol; the matter which remains, if the fire has been sufficiently intense and long continued, is the pure earth of the alum, white, light, and insipid. If any of the alum still retains its acid, which a considerable part commonly does though a pretty strong fire had been continued for some days, this part may be extracted, by boiling in water, from the pure indissoluble earth.

(a) Mead, monita & praecepta med. p. 165.

Alumen uftum Ph. Lond.

The earth of alum may be separated also by dissolving the alum in water, and adding a solution of any pure alkaline salt, or rather a volatile spirit: the liquor grows instantly milky on this addition; and on standing for a little time, the aluminous earth falls to the bottom, its acid being absorbed by the alkali. This earth, freed from the saline matter by repeated ablutions with boiling water, dissolves readily in all acids: solutions of it in the nitrous and marine are more styptic, and more nauseous than alum itself: solutions of it in vegetable acids, though strongly styptic, are of a milder and less ungrateful kind, and promise to be, in many cases, medicines of no small utility.

Ambragrisea. Succinum griseum. Suc-cinum cinereum. Ambarum. Ambergris: a marine bitumen; very light, so as to swim both in water and in rectified spirit of wine; growing soft in a gentle warmth; when warmed, of a fragrant smell; soluble in boiling spirit of wine, from which, if the saturated solution be set in a very cold place, or if a part of the menstruum be exhaled, a proportionable quantity of the ambergris concretes into a whitish unctuous substance.

The greatest quantities of ambergris are met with in the Indian ocean: pieces have likewise been now and then discovered in our own (a) and other northern seas. It is found floating on the surface of the sea, or adhering to rocks, or thrown out upon the shores, and sometimes in the stomachs of large fishes. It is usually in small masses, though there are accounts of very large ones, weighing more than an hundred (b) pounds, opake, rugged, of a greyish or ash colour intermingled with yellowish and blackish specks or veins, of a loose texture, friable in a certain degree like wax, breaking rough and uneven, and frequently containing pieces of shells and other like matters. It is said to be at first soft; and when found in this state, to be often adulterated by incorporating different substances with it; an abuse which may in good measure be distinguished by the appearance and texture of the mass, and with more certainty by its differences from true ambergris in solubility, volatility and smell.

Ambergris has scarcely any particular taste; and very little smell, unless heated, or much handled; in which circumstances, its smell is very fragrant, and to most people agreeable: set on fire, it smells like burning amber. It softens betwixt the fingers, melts in a small degree of heat into the appearance of oil, and in a strong one proves almost totally volatile. Dis-tilled, it yields an aqueous phlegm, a brown coloured acidulous spirit, a deeper coloured oil, at length a thick balsam, and sometimes a small portion of a concrete salt. The spirit, oil, balsam, and salt, are similar to those obtained by the same treatment from amber: except that the oil is of a more grateful smell.

(a) Charleton, de animal. append. de fossilib.

(b) Chevalier, description de la piece d'ambregris, etc. pesant 182 livres.

It dissolves in pure spirit of wine, almost totally, but sparingly, and not without the assist-ance of a boiling heat. Neumann observes, that pure spirit may be made to take up about one twelfth its own weight of the ambergris: that spirits impregnated with a little essential oil, whether by the addition of the oil itself, or by distillation from oily vegetables, dissolve it more readily than pure spirit: that spirits drawn over from fixt alkaline salts, extract a deeper tincture, but dissolve no more, than those which have been rectified without that addition: and that the dulcified acid and alkaline spirits have very little effect on it.

Ambergris is, in general, one of the most agreeable of the perfumes, and the least apt to disorder weak constitutions, or such as are liable to be offended by substances of that class. Taken internally, from two or three grains to a scru-ple, it is accounted a high cordial, corroborant, and antispasmodic; in which light it is prescri-bed by Riverius in hypochondriacal affections. A solution of it made in a very highly rectified spirit distilled from roses, is recommended by Hoffman, in his physicochemical observations, as one of the most effectual corroborants of the nervous system. The orientals are said to look upon it as an aphrodisiac, and suppose that the frequent use of it contributes to longevity.

The faculty of Paris directs a tincture to be drawn, by digesting two scruples of ambergris in two ounces of a high rectified spirit impregnated with roses. They have also a compound tincture made from the same quantity of ambergris, with half as much musk, ten grains of civet, six drops of oil of cinnamon, and four drops of oil of rhodium, digested together, in four ounces and a half of a spirit impregnated with roses and orange flowers. This compound tincture is a very high perfume: a few drops of it give a fine scent to a large proportion of in-odorous matters. It is used also for heightening the natural odours of other bodies, as aromatic waters, spirits, etc. the principal secret, for this purpose, consists in adding the perfume so sparingly, that while it heightens and improves the smell of the substance it is joined to, it may not betray its own. The most advantageous way of preparing these kinds of tinctures, in regard to the ambergris, appears to be, to make the spirit boil or simmer with it first, that this ingredient may be completely dissolved before the more soluble ones are added. The vapour, which exhales during the coction, caught and condensed in proper vessels, has little flavour of the ambergris: water, distilled from it in the same manner, proves considerably impregnated with its fragrance.

Tinct. feu essentia am-brae Ph. Paris.

Tinct. feu essentia re-gia Ph. Paris.