an oily concrete substance, deposited in different parts of animal bodies. See Botany Index.

Strong exercise, preternatural heat, an acrimonious state of the juices, and other like causes, by which the oily parts of the blood are attenuated, resolved, or evacuated, prevent the generation of fat; labours of the mind also have this effect, as well as labour or intemperance of the body. Hence rest and plentiful food are sufficient to fatten brutes; but with men it is often otherwise. It is surprising how soon some birds grow fat; ortolans, it is said, in 24 hours, and larks still sooner.

Fats may be divided, from their consistence, into three kinds: (1.) The soft and thin, which grow perfectly liquid in a very small heat; (2.) The thick and consistent, which liquefy less readily; and, (3.) The hard and firm, which require a still stronger heat to melt them. The first is called Pinguedis; the second Avuncia; and the third, Adeps, as taken from the animal; and Sebum, or Secum, when freed from the skins, &c. This use of the names, however, is not constant, some employing them differently.

A great number of fats have been kept in the shops, for making ointments, plasters, and other medicinal compositions; as hog's lard, the fat of the boar, the fox, the hare, dog, wild cat, Alpine moufe, beaver; that of hens, ducks, geese, storks; of the whale, pike, serpents, viper, &c as also human fat.—In regard to all these kinds of substances, however, much depends upon the manner of purifying or trying, and of keeping them.

To obtain fat pure, it must be cut into pieces, and cleaned from the interposed membranes and vessels. It must then be cleansed from its gelatinous matter by washing with water, till the water comes from it colourless and insipid; it is afterwards to be melted with a moderate heat in a proper vessel with a little water; and it is to be kept thus melted till the water be entirely evaporated, which is known by the discontinuance of the boiling, which is caused by the water only, and which lasts till not a drop of it remains; yet it is afterwards to be put into an earthen pot, where it fixes; then it is exceedingly white, sufficiently pure for the purposes of pharmacy or chemical examination.

Fat thus purified has very little taste, and a weak, but peculiar smell. For its analysis and chemical properties, see Chemistry Index.

One of the chief uses of fat probably is, to receive into its composition, to blunt and correct a great part of the acids of the aliment, and which are more than are requisite to the composition of the nutritive juice, or which nature could not otherwise expel. This is certain, that the greater the quantity of aliments taken by healthy animals, above what is necessary for their nourishment and reproduction, the fatter they become. Hence animals which are castrated, which are not much exercised, or which are come to an age when the loss and production of the seminal fluid is less, and which at the same time consume much succulent aliment, generally become fatter, and sometimes exceedingly so.

Although fat be very different from truly animalized substances, and appears not easily convertible into nutritive juices, it being generally difficult of digestion, and apt to become rancid, as butter does in the stomachs of many persons; yet in certain cases it serves to the nourishment and reparation of the body. Animals certainly become lean, and live upon their fat, when they have too little food, and when they have discharges which prevent digestion and the production of the nutritive juices; and in these cases the fatter animals hold out longer than the leaner. The fat appears to be then absorbed by the vessels designed for this use, and to be transformed into nutritive juice.

the sea language, signifies the same with broad. Thus a ship is said to have a fat quarter, if the trussing in or tuck of her quarter be deep.

Fat likewise denotes an uncertain measure of capacity. Thus a fat of shingles contains from 3½ hundred weight to 4 hundred weight; a fat of unbound books, half a mauld or four bales; of wire, from 20 to 25 hundred weight; and of yarn, from 220 to 221 bundles.

VAT, is used also for several utensils: as, 1. A great wooden vessel, employed for measuring of malt, and containing a quarter or eight bushels. 2. A large brewing vessel, used by brewers to run their wort in. 3. A leaden pan or vessel for the making of salt at Droitwich.