a whitish, unctuous, flaky substance, prepared from oil, but chiefly from the brains of a species of whale called *Physeter macrocephalus*.

The method of preparing spermaceti is kept a secret; but the process is said to be this: The brains being taken out of the animal, are then, as some say, melted over a gentle fire, poured into moulds, and when cold melted again; and this process is continued till they are purified. Others say, that after being pressed and drained they are more thoroughly purified by steeping them in a ley of alkaline salt and quicklime. The brains are then washed, and cut into thin flakes or slices with wooden knives. One fish is said to afford some tons of brains. Good spermaceti is glossy and semi-transparent, in fine white flakes; soft and unctuous to the touch, yet dry and friable; in taste, somewhat like butter, and of a faint smell like that of tallow. Some adulterate it with wax; but the deceit is discovered, either by the smell of the wax or by the dulness of the colour. Some also sell a preparation of oil taken from the tail of the whale instead of that from the brain; but this kind turns yellow as soon as exposed to the air. Indeed it is apt in general to grow yellowish, and to contract a rancid fishy smell if not carefully secured from the air. The more perfectly it has been purified at first, the less susceptible it is of these alterations; and after it has been changed, it may be rendered white and sweet again by steeping it afresh in a ley of alkaline salt and quicklime. It melts in a small degree of heat, and congeals again as it cools.

Spermaceti is of use in medicine. Quincy says it is a noble remedy in the asthma, &c., though chiefly used in bruises, inward hurts, and after delivery. For internal use, it may be dissolved in aqueous liquors into the form of an emulsion, by trituration with almonds, the yolk or white of an egg, and more elegantly by mucilages; or made into a lochoch, by mixing two drams of it with a suitable quantity of yolk of egg, then adding half an ounce of fresh drawn oil of almonds, and an ounce of balsamic syrup. Spermaceti is not capable of being dissolved by caustic alkalis, and of forming soaps, like other oily matters: but it is altogether soluble in oils, and unites by liquefaction with wax and resins; and in these forms is applied externally. But it is certain, its greatest property, and that which makes it so much in vogue in many places, is its softening the skin. Whence it comes to be used by the ladies in pastes, washes, &c.

Spermaceti candles are of modern manufacture: they are made smooth, with a fine gloss, free from rings and scars, superior to the finest wax-candles in colour and lustre; and, when genuine, leave no spot or stain on the finest silk, cloth, or linen.

A method has been lately proposed by Mr Smith Gibbs of Magdalen college, Oxford, to convert animal muscle into a substance much resembling spermaceti. The process is remarkably simple: Nothing more is necessary than to take a dead carcass and expose it to a stream of running water: it will in a short time be changed to a mass of fatty matter. To remove the offensive smell, a quantity of nitrous acid may then be poured upon it, which uniting with the fetid matter, the fat is separated in a pure state. This acid indeed turns it yellow, but it may be rendered white and pure by the action of the oxygenated muriatic acid. Mr Gibbs brought about the same change in a much shorter time. He took three lean pieces of mutton and poured on them the three mineral acids, and he perceived that at the end of three days each was much altered; that in the nitrous acid was much softened, and on separating the acid from it, he found it to be exactly the same with that which he had before got from the water; that in the muriatic acid was not in that time so much altered; the vitriolic acid had turned the other black.