Digestion is explain'd by doctor Arbuthnot to be a fermentation begun, because, he says, there are all the requifites of fuch a fermentation, because that requires a greater time than the continuance of the aliment in the ftomach. Vegetable putrefaction, for the reafons he gives, resembles very much animal digestion. By mastication, faliva, the attrition of the folid parts, or inward coats, of the ftomach, the gall or bile, the pancreatick juice, and the action of a disfolvent liquor, asfifted with heat, the aliment is converted into a fort of chyle (a refemblance of milk or whey), and, passing through the mefentery, is receive'd into the veins, by means of the thoracick duct and the lacteals, becomes finally blood. As the nutriment, therefor, of the body depends entirely on the quantity of chyle, animals, which take a largeër portion of aliment by the mouth, may be lefs nourish'd than those which take a fmalle: for, according to the force of the chylopoëtick organs, a largeër or lefs quantity of chyle may be extracted from the fame quantity of food* There is, of course, no esfential difference in the quality of chyle,

Esfay concerning aliments, p. 1, 4, 8, 19, &c. See, allfo, doctor Cheynes Natural method of curing diseafes, p. 22, &c.

whether produce'd by the digestion of animal fubftanceës, or by that of vegetables, though there may be much in the quantity.* All animals, in fact, are made, immediately or mediately, of vegetables, or of animals that are fed on vegetables; and vegetables, therefor, are proper enough to repair animals, as being nearly of the fame specifick gravity with animal substanceës, fpirit, water, falt, oil, earth. † Animal fubftanceës, doctor Arbuthnot obferves, are more nourishing, and more eafeyly transmutable into animal juiceës, than vegetable; and, therefor, he fays, a vegetable diet is more proper for fome conftitutions, as being lefs nourishing; though he allows fome vegetables, as carrots and turnips, are fattening to animals which live onely on vegetables and, elsewhere remarks, there may

* Animal fubftanceës differ from vegetables in two things: firft, in that being reduce'd to afhes, they are perfectly infipid: all animal falts, being volatile, flying off with great heat: fecondly, in that there is no fincere acid in any animal juice, (P. 64). Animal fubftanceës, therefor, are all alkalescent; of vegetable fubftanceës, fome are acid, other alkalescent, (P. 105).

† lbi, p. 42.

be a stronger broth made of vegetables than any gravy-foup.*

In the memoirs of the royal academy for the year 1730, M. Geoffroy has giveën a method for determineing the proportion of nourishment, or true matter of the flesh and blood, contain'd in any fort of food. He took a pound of meat that had been free'd from the fat, bones and cartilageës, and boil'd it for a determine'd time, in a clofe vesfel, with three pints of water; then, pouring off the liquor, he aded the fame quantity of water, boiling it again for the fame time, and this operation he repeated fix feveral times, fo that the laft liquor appear'd, both in fmel, trial and tafte, to be little different from common water. Then, puting all the liquor together, and filtrateing, to feparate the too grofs particles, he evaporateëd it over a flow fire, til it was brought to an extract of a pretty moderate confistence. This experiment was made upon feveral forts of food, the refult of which is contain'd in the following table:

* Ibi, p. 181, 180.

According to this table, the proportion of nourishment contain'd in thefe foods wil be as

So that common household bread has nearly

three times the nutritive quantity of food above any other fpecies.

*Doctor Cheynes Natural method of curing diseafes, p. 54.

The reflections of M. De Saint-Pierre, respecting the use of bread, become of fuch abfolute necesfity over all Europe, may be here subjoin'd: "Who would believe," he fays, "that it is an aliment of luxury? Of all those which are ferve'd up on the table of man, though it be the most common, and even when markets are at the lowest, there is none which costs fo dear. The grain of which it is made, is of all vegetable productions, that which demands most culture, machinery and handleing. Before it is caft into the ground, there must be ploughs to til the ground, harrows to break the clods, dunghils to manure it. When it begins to grow, it must be weeded; when come to maturity, the fickle must be employ'd to cut it down; flails, fanners, bags, barns, to thrash it out, to winnow it, and to ftore it up; mils to reduce it to flour, to bolt it, and to fift it; bake-houfees, where it must be kneaded, leaven'd, bake'd, and converted into bread. Veryly man never could have existed on the earth, had he been under the necessity of deriveing his first nutriment from the corn plant. It is no where found indigenous. Nay, its grain, from the form and fize, appears much better adapted to the beak of granivorous birds than to the mouth of man. Not fo much as the twentyeth part of mankind eats bread. Allmost all the