WATER-MOSS, a genus of plants belonging to the cryptogamia class, and to the order of musci. See Botany Index.

FOOD, in the most extensive signification of the word implies whatever aliments are taken into the body, whether solid or fluid; but in common language, it is generally used to signify only the solid part of our aliment.

We are told, that in the first ages men lived upon acorns, berries, and such fruits as the earth spontaneously produces; then they proceeded to eat the flesh of wild animals taken in hunting: But their numbers decreasing and mankind multiplying, necessity taught them the art of cultivating the ground, to sow corn, &c. By and by they began to assign to each other, by general consent, portions of land to produce them their supply of vegetables; after this, reason suggested the expedient of domesticating certain animals, both to assist them in their labours and supply them with food. Hogs were the first animals of the domestic kind that appeared upon their tables; they held it to be ungrateful to devour the beasts that assisted them in their labours.—When they began to make a free use of domestic animals, they roasted them only: boiling was a refinement in cookery which for ages they were strangers to; and fish living in an element men were unused to, were not eaten, till they grew somewhat civilized. Menelaus complains, in the Odyssey, that they had been constrained to feed upon them.

The most remarkable distinction of foods, in a medical view, is into those which are already assimilated into the animal nature, and such as are not. Of the first kind are animal substances in general; which if not entirely similar, are nearly so, to our nature. The second comprehends vegetables, which are much more difficultly assimilated. But as the nourishment of all animals, even those which live on other animals, can be traced originally to the vegetable kingdom, it is plain, that the principle of all nourishment is in vegetables.

Though there is perhaps no vegetable which does not afford nourishment to some species of animals or the like; yet, with regard to mankind, a very considerable distinction is to be made. Those vegetables which are of a mild, bland, agreeable taste, are proper nourishment; while those of an acrid, bitter, and nauseous nature, are improper. We use, indeed, several acrid substances as food; but the mild, the bland, and agreeable, are in the largest proportion in almost every vegetable. Such as are very acrid, and at the same time of an aromatic nature, are not used as food, but as spices or condiments, which answer the purposes of medicines rather than any thing else. Sometimes, indeed, acrid and bitter vegetables seem to be admitted as food. Thus celeri and endive are used in common food, though both are substances of considerable acrimony; but it must be observed, that when we use them, they are previously blanched, which almost totally destroys their acrimony. Or if we employ other acrid substances, we generally, in a great measure, deprive them of their acrimony by boiling. In different countries, the same plants grow with different degrees of acrimony. Thus garlic here seldom enters our food; but in the southern countries, where the plants grow more mild, they are frequently used for that purpose. The plant which furnishes cassada, being very acrimonious, and even poisonous, in its recent state, affords an instance of the necessity of preparing acrid substances even in the hot countries: and there are other plants, such as arum root, which are so exceedingly acrimonious in their natural state, that they cannot be swallowed with safety; yet, when deprived of that acrimony, will afford good nourishment.

The most remarkable properties of different vegetable substances as food, are taken notice of under their different names: here we shall only compare vegetable foods in general with those of the animal kind.

I. In the Stomach, they differ remarkably, in that the vegetables always have a tendency to acidity, while animal animal food of all kinds rather tends to alkalescence and putrefaction. Some animal foods, indeed, turn manifestly acid before they purify; and it has been asserted, that some degree of acescency takes place in every kind of animal food before digestion. This acescency of animal food, however, never comes to any morbid degree, but the disease is always on the side of putrescence. The acescency of vegetables is more frequent, and ought to be more attended to, than the alkalescence of animal food; which last, even in weak stomachs, is seldom felt; while acescency greatly affects both the stomach and system.

With regard to their difference of solution:—Heaviness, as it is called, is seldom felt from vegetables, except from tough farinaceous paste, or the most viscid substances; while the heaviness of animal food is more frequently noticed, especially when in any great quantity. Difficulty of solution does not depend so much on firmness of texture (as a man, from fish of all kinds, is more oppressed than from firmer substances), as on viscidity; and hence it is more frequent in animal food, especially in the younger animals.

With regard to mixture:—There is no instance of difficult mixture in vegetables, except in vegetable oils; while animal foods, from both viscidity and oiliness, especially the fatter meats, are refractory in this respect. Perhaps the difference of animal and vegetable foods might be referred to this head of mixture. For vegetable food continues long in the stomach, giving little stimulus: Now the system is affected in proportion to the extent of this stimulus, which is incomparably greater from the animal viscid oily food, than from the vegetable, firmer, and more aqueous. However, there are certain applications to the stomach, which have a tendency to bring on the cold fit of fever, independent of stimulus, merely by their refrigeration: and this often arises from vegetables; as we see, in those hot countries where intermittents prevail, they are oftener induced from a surfeit of vegetable than of animal food. A proof of this is, that when one is recovering of an intermittent, there is nothing more apt to cause a relapse than cold food, especially if taken on those days when the fit should return, and particularly acescent, fermentable vegetables, as salads, melons, cucumbers, &c., acido-dulces, &c., which, according to Dr Cullen, are the most frequent causes of epidemics; therefore, when an intermittent is to be avoided, we shun vegetable diet, and give animal foods, although their stimulus be greater.

II. In the Intestines. When the putrescence of animal food has gone too far, it produces an active stimulus, causing diarrhoea, dysentery, &c. But these effects are but rare; whereas from vegetable food and its acid, which, united with the bile, proves a pretty strong stimulus, they more frequently occur; but luckily are of less consequence, if the refrigeration is not very great. In the autumnal season, when there is a tendency to dysentery, if it is observed that eating of fruits brings it on, it is rather to be ascribed to their cooling than stimulating the intestines.

As to stool.—Wherever neither putrefaction nor acidity has gone a great length, animal food keeps the belly more regular. Vegetable food gives a greater proportion of succulent matter; and, when exsiccated by the stomach and intestines, is more apt to stagnate, and produce slow belly and costiveness, than animal stimulating food; which, before it comes to the great guts, where stoppage is made, has obtained a putrefactive tendency, and gives a proper stimulus: and thus those who are costive from the use of vegetables; when they have recourse to animal food are in this respect better.

III. In the blood-vessels. They both give a blood of the same kind, but of different quality. Animal food gives it in great quantity, being in great part, as the expression is, convertible in succum et sangvinem, and of easy digestion; whereas vegetable is more watery, and contains a portion of unconquerable saline matter, which causes it to be thrown out of the body by some excretion. Animal food affords a more dense stimulating elastic blood than vegetable; stretching and causing a great resistance in the solids, and again exciting their stronger action. It has been supposed that acescency of vegetable food is carried into the blood-vessels, and there exerts its effects; but the tendency of animal fluids is so strong to alkalescence, that the existence of an acid acrimony in the blood seems very improbable. Animal food alone will soon produce an alkalescent acrimony; and if a person who lives entirely on vegetables were to take no food for a few days, his acrimony would be alkalescent.

IV. We are next to take notice of the quantity of nutriment these different foods afford. Nutriment is of two kinds: the first repairs the waste of the solid fibres; the other supplies certain fluids, the chief of which is oil. Now, as animal food is easier converted, and also retained longer in the system, and as it contains a greater proportion of oil, it will afford both kinds of nutriment more copiously than vegetables.

V. Lastly, As to the different degrees of perspirability of these foods. This is not yet properly determined. Sanctorius constantly speaks of mutton as the most perspirable of all food, and of vegetables as checking perspiration. This is a consequence of the different stimulus those foods give to the stomach, so that persons who live on vegetables have not their perspiration so suddenly excited. In time of digestion, perspiration is stopped from whatever food, much more so from cooling vegetables. Another reason why vegetables are less perspirable is, because their aquo-saline juices determine them to go off by urine, while the more perfectly mixed animal food is more equally diffused over the system, and so goes off by perspiration. Hence Sanctorius's accounts may be understood; for vegetable aliment is not longer retained in the body, but mostly takes the course of the kidneys. Both are equally perspirable in this respect, viz., that a person living on either returns once a day to his usual weight; and if we consider the little nourishment of vegetables, and the great tendency of animal food to corpulency, we must allow that vegetable is more quickly perspired than animal food.

As to the question, Whether man was originally designed for animal or vegetable food, see the article CARNIVOROUS.

With regard to the effects of these foods on men, it must be observed, that there are no persons who live entirely on vegetables. The Pythagoreans themselves ate milk; and those who do so mostly, as these Pythagoreans, are weakly, sickly, and meagre, labouring... ing under a constant diarrhoea and several other dis- eases. None of the hardy, robust, live on these; but chiefly such as gain a livelihood by the exertion of their mental faculties, as (in the East Indies) factors and brokers; and this method of life is now confined to the hot climates, where vegetable diet, without incon- venience, may be carried to great excess. Though it be granted, therefore, that man is intended to live on these different foods promiscuously, yet the vegetable should be in very great proportion. Thus the Lap- landers are said to live entirely on animal food: but this is contradicted by the best accounts; for Linnæus says, that besides milk, which they take sour, to ob- viate the bad effects of animal food, they use also cala- menyanthes, and many other plants, copiously. So there is no instance of any nation living entirely either on vegetable or animal food, though there are indeed some who live particularly on one or other in the great- est proportion. In the cold countries, e.g. the inha- bitants live chiefly on animal food, on account of the rigour of the season, their smaller perspiration, and little tendency to putrefaction.

Of more importance, however, is the following than the former question, viz. In what proportion animal and vegetable food ought to be mixed?

1. Animal food certainly gives most strength to the system. It is a known aphorism of Sanctorius, that pondus addit robur; which may be explained from the implication of the blood-vessels, and giving a proper de- gree of tension for the performance of strong oscilla- tions. Now animal food not only goes a greater way in supplying fluid, but also gives the fluid more dense and elastic. The art of giving the utmost strength to the system is best understood by those who breed fighting cocks. These people raise the cocks to a certain weight, which must bear a certain proportion to the other parts of the system, and which at the same time is so nicely proportioned, as that, on losing a few ounces of it, their strength is very considerably im- paired. Dr Robinson of Dublin has observed, that the force and weight of the system ought to be deter- mined by the largeness of the heart, and its proportion to the system: for a large heart will give large blood- vessels, while at the same time the viscera are less, par- ticularly the liver; which last being increased in size, a greater quantity of fluid is determined into the cel- lular texture, and less into the sanguineous system. Hence we see how animal food gives strength, by fill- ing the sanguiferous vessels. What pains we now bestow on cocks, the ancients did on the athlete, by proper nourishment bringing them to a great degree of strength and agility. It is said that men were at first fed on figs, a proof of which we have from their nutri- tious quality: however, in this respect they were soon found to fall short of animal food; and thus we see, that men, in some measure, will work in proportion to the quality of their food. The English labour more than the Scots; and wherever men are exposed to hard labour, their food should be animal.—Animal food, although it gives strength, yet loads the body; and Hip- pocrates long ago observed, that the athletic habit, by a small increase, was exposed to the greatest haz- ards. Hence it is only proper for bodily labours, and entirely improper for mental exercises; for who- ever would keep his mind acute and penetrating, will exceed rather on the side of vegetable food. Even the body is oppressed with animal food; a full meal al- ways produces dullness, laziness, and yawning; and hence the feeding of gamesters, whose mind must be ready to take advantage, is always performed by avoiding a large quantity of animal food. Farther, With regard to the strength of the body, animal food, in the first stage of life, is hardly necessary to give strength: in manhood, when we are exposed to active scenes, it is more allowable; and even in the decline of life, some proportion of it is necessary to keep the body in vigour. There are some diseases which come on in the decay of life, at least are aggravated by it; among these the most remarkable is the gout. This, when it is in the system, and does not appear with in- flammation in the extremities, has pernicious effects there, attacking the lungs, stomach, head, &c. Now, to determine this to the extremities, a large proportion of animal food is necessary, especially as the person is commonly incapable of much exercise.

Animal food, although it gives strength, is yet of many hazards to the system, as it produces plethora and all its consequences. As a stimulus to the stomach and to the whole system, it excites fever, urges the circula- tion, and promotes the perspiration. The system, however, by the repetition of these stimuli, is soon worn out; and a man who has early used the athletic diet, is either early carried off by inflammatory diseases, or, if he takes exercise sufficient to render that diet saluta- ry, such an accumulation is made of putrescent fluids, as in his after life lays a foundation for the most inve- terate chronic distempers. Therefore it is to be ques- tioned, whether we should desire this high degree of bo- dily strength, with all the inconveniences and dangers attending it. Those who are chiefly employed in mental researches, and not exposed to too much bodily labour, should always avoid an excess of animal food. There is a disease which seems to require animal food, viz. the hysteric or hypochondriac; and which appears to be very much a-kin to the gout, affecting the alimentary canal. All people affected with this disease are much disposed to aescency: which sometimes goes so far, that no other vegetable but bread can be taken in, without occasioning the worst consequences. Here then we are obliged to prescribe an animal diet, even to those of very weak organs; for it generally obviates the symptoms. However, several instances of scurvy in ex- cess have been produced by a long-continued use of this diet, which it is always unlucky to be obliged to pre- scribe; and when it is absolutely necessary to prescribe, it should be joined with as much of the vegetable as possible, and when a cure is performed we should gra- dually recur to that again.

2. Next, let us consider the vegetable diet. The chief inconvenience of this is difficulty of assimilation; which, however, in the vigorous and exercised, will not be li- able to occur. In warm climates, the assimilation of ve- getable aliment, is more easy, so that there it may be more used, and when joined to exercise gives a pretty tolerable degree of strength and vigour; and though the general rule be in favour of animal diet, for giving strength, yet there are many instances of its being re- markably produced from vegetable. Vegetable diet has this advantage, that it whets the appetite, and that we can hardly suffer from a full meal of it. Besides the disorders it is liable to produce in the prime via, and its falling short to give strength, there seem to be no bad consequences it can produce to the blood vessels; for there is no instance where its peculiar acrimony was ever carried there, and it is certainly less putrefiable than animal food; nor, without the utmost indolence, and a sharp appetite, does it give plethora, or any of its consequences; so that we cannot here but conclude, that a large proportion of vegetable food is useful for the generality of mankind.

There is no error in this country more dangerous, or more common, than the neglect of bread; for it is the safest of vegetable aliments, and the best corrector of animal food; and, by a large proportion of this alone, its bad consequences, when used in a hypochondriac state, have been obviated. The French apparently have as much animal food on their tables as the British; and yet, by a greater use of bread, and the dried acid fruits, its bad effects are prevented; and therefore bread should be particularly used by the English, as they are so voracious of animal food. Vegetable food is not only necessary to secure health, but long life; and, as we have said, in infancy and youth we should be confined to it mostly; in manhood, and decay of life, use animal food; and near the end, vegetable again.

There is another question much agitated, viz. What are the effects of variety in food? Is it necessary and allowable, or universally hurtful? Variety of a certain kind seems necessary; as vegetable and animal foods have their mutual advantages, tending to correct each other. Another variety, which is very proper, is that of liquid and solid food, which should be so managed as to temper each other; and liquid food, especially of the vegetable kind, is too ready to pass off before it is properly assimilated, while solid food makes a long stay. But this does not properly belong to the question, whether variety of the same kind is necessary or proper, as in animal foods, beef, fish, fowl, &c. It doth not appear that there is any inconvenience arising from this mixture, or difficulty of assimilation, provided a moderate quantity be taken. When any inconvenience does arise, it probably proceeds from this, that one of the particular substances in the mixture, when taken by itself, would produce the same effects; and indeed it would appear that this effect is not heightened by the mixture, but properly obviated by it. There are few exceptions to this, if any, e.g. taking a large proportion of acetic substances with milk. The coldness, &c., acidity, flatulency, &c. may appear; and it is possible that the coagulum, from the acceescy of the vegetables, being somewhat stronger induced, may give occasion to too long retention in the stomach, and to acidity in too great degree. Again, the mixture of fish and milk often occasions inconveniences. The theory of this is difficult, though, from universal consent, it must certainly be just. Can we suppose that fish gives occasion to such a coagulum as runnet? If it does so, it may produce bad effects. Besides, fishes approach somewhat to vegetables, in giving little stimulus; and are accused of the same bad effects as these, viz. bringing on the cold fit of fever.

Thus much may be said for variety. But it also has its disadvantages, provoking to gluttony; this, and the art of cookery, making men take in more than they properly can digest: and hence, perhaps very justly, physicians have universally almost preferred simplicity of diet; for, in spite of rules, man's eating will only be measured by his appetite, and satiety is sooner produced by one than by many substances. But this is so far from being an argument against variety, that it is one for it, as the only way of avoiding a full meal of animal food, and its bad effects, is by presenting a quantity of vegetables. Another mean of preventing the bad effects of animal food, is to take a large proportion of liquid; and hence the bad effects of animal food are less felt in Scotland, on account of their drinking much with it, and using broths, which are at once excellent correctors of animal food and preventives of gluttony.

With regard to the difference between ANIMAL FOODS, properly so called, the first regards their solubility, depending on a lax or firm texture of their different kinds.

I. SOLUBILITY of animal food seems to deserve less attention than is commonly imagined; for there are many instances of persons of a weak stomach, incapable of breaking down the texture of vegetables, or even of dissolving a light pudding, to whom hung beef, or a piece of ham, was very grateful and easily digested. None of the theories given for the solution of animal food in the human stomach seem to have explained the process sufficiently. Long ago has been discarded the supposition of an active corrosive menstruum there; and also the doctrine of trituration, for which, indeed there seems no mechanism in the human body; and, till lately, physicians commonly agreed with Boerhaave in supposing nothing more to be necessary than a watery menstruum, moderate heat, and frequent agitation. This will account for solution in some cases, but not entirely. Let us try to imitate it out of the body with the same circumstances, and in ten times the time in which the food is dissolved in the stomach we shall not be able to bring about the same changes. Take the coagulated white of an egg, which almost every body can easily digest, and yet no artifice shall be able to dissolve it. Hence, then, we are led to seek another cause for solution, viz. fermentation; a notion, indeed, formerly embraced, but on the introduction of mechanical philosophy, industriously banished, with every other supposition of that process taking place at all in the animal economy.

Many of the ancients imagined this fermentation to be putrefactive. But this we deny, as an acid is produced; though hence the fermentation might be reckoned the vinous; which, however, seems always to be morbid. Neither indeed is the fermentation purely acetous, but modified by putrescence; for Pringle has observed, that animal matters raise and even expedite the acetous process. The fermentation, then, in the stomach is of a mixed nature, between the acetous and the putrefactive, mutually modifying each other; though, indeed, in the intestines, somewhat of the putrefactive seems to take place, as may be observed from the state of the feces broke down, and from the little disposition of such substances to be so, which are not liable to the putrefactive process, as the firmer parts of vegetables, &c. Upon this view solution seems to be extremely easy, and those substances to be most easily broke down which FOOD

which are most subject to putrefaction. See ANATOMY, and GASTRIC Juice.

But solution also depends on other circumstances, and hence requires a more particular regard.

1. There is a difference of solubility with respect to the manducation of animal food, for which bread is extremely necessary, in order to keep the more slippery parts in the mouth till they be properly comminuted. From want of proper manducation persons are subject to eructations; and this more frequently from the firm vegetable foods, as apples, almonds, &c. than from the animal, though, indeed, even from animal food, very tendinous, or swallowed in unbroken masses, such sometimes occur. Manducation is so much connected with solution, that some, from imperfectly performing that, are obliged to belch up their food, remanducate it, and swallow it again before the stomach can dissolve it, or proper nourishment be extracted. Another proof of our regard to solubility, is our rejecting the firmer parts of animal food, as bull beef, and generally carnivorous animals.

2. Its effects with regard to solubility seem also to be the foundation of our choice between fat and lean, young and old meats. In the lean although perhaps a single fibre might be sufficiently tender, yet these, when collected in fasciculi, are very firm and compact, and of difficult solution; whereas in the fat there is a greater number of vessels, a greater quantity of juice, more interposition of cellular substance, and consequently more solubility. Again, in young animals, there is probably the same number of fibres as in the older, but these more connected; whereas, in the older, the growth depending on the separation of these, and the increase of vessels and cellular substance, the texture is less firm and more soluble; which qualities, with regard to the stomach, are at that time too increased, by the increased alkalescence of the animal. To this also may be referred our choice of castrated animals, viz. on account of their disposition to fatten after the operation.

3. It is with a view to the solubility, that we make a choice between meats recently killed, and those which have been kept for some time. As soon as meat is killed, the putrefactive process begins; which commonly we allow to proceed for a little, as that process is the most effectual breaker down of animal matters, and a great assistance to solution. The length of time during which meat ought to be kept, is proportioned to the meat's tendency to undergo the putrid fermentation, and the degree of those circumstances which favour it: Thus, in the torrid zone, where meat cannot be kept above four or five hours, it is used much more recent than in these northern climates.

4. Boiled or roasted meats create a difference of solution. By boiling we extract the juices interposed between the fibres, approximate them more to each other, and render them of more difficult solubility; which is increased too by the extraction of the juices, which are much more alkalescent than the fibres: but when we want to avoid the stimulus of alkalescent food, and the quick solution, as in some cases of disease, the roasted is not to be chosen. Of roasted meats it may be asked, which are more proper, those which are most or least roasted? That which is least done is certainly the most soluble: even raw meats are more soluble than dressed, as Dr Cullen was informed by a person who from necessity was obliged, for some time, to eat such. But at the same time that meats little done are very soluble, they are very alkalescent; so that, wherever we want to avoid alkalescence in the prime vita, the most roasted meats should be chosen. Those who throw away the broths of boiled meat do very improperly; for, besides their supplying a fluid, from their greater alkalescence they increase the solubility of the meat. Here we shall observe, that pure blood has been thought insoluble. Undoubtedly it is very nutritious; and though out of the body, like the white of eggs, it seems very insoluble, yet, like that too, in the body it is commonly easily digested. Moses very properly forbade it the Israelites, as in warm countries it is highly alkalescent; and even here, when it was used in great quantity, the scurvy was more frequent: but to a moderate use of it, in these climates, no such objection takes place.

5. Solubility is varied from another source, viz. viscosity of the juice of aliment. Young animals, then, appear more soluble than old, not only on account of the compaction and firmness of texture in the latter, but also their greater viscosity of juice. And nothing is more common, than to be longer oppressed from a full meal of veal, than from the same quantity of beef, &c. Upon account, too, of their greater viscosity of juice, are the tendinous and ligamentous parts of animals longer retained than the purely muscular, as well as on account of their firmness of texture. Even fishes, whose muscular parts are exceedingly tender, are, on account of their gluey viscosity, longer in solution in the stomach. And eggs, too, which are exceedingly nourishing, have the same effect, and cannot be taken in great quantity: For the stomach is peculiarly sensible to gelatinous substances; and by this means has nature perhaps taught us, as it were by a sort of instinct, to limit ourselves in the quantity of such nutritive substances.

6. With regard to solution, we must take in the oils of animal food; which, when tolerably pure, are the least putrescent part of it, and, by diminishing the cohesion of the fibres, render them more soluble. On this last account is the lean of fat meat more easily dissolved than other lean. But when the meat is exposed to much heat, this oil is separated, leaving the solid parts less easily soluble, and becoming itself empyreumatic, rancescent, and of difficult mixture in the stomach. Fried meats, from the reasons now given, and baked meats, for the same, as well as for the tenacity of the paste, are preparations which diminish the solubility of the food. From what has been said, the preparation of food by fattening it, and keeping it for some time after being killed, although it may administer to glutony, will yet, it must be confessed, increase the solution of the food.

II. The second difference of animal food is with regard to ALKALESCENCY.

Of this we have taken a little notice already under the head of Solubility.

1. From their too great alkalescence we commonly avoid the carnivorous animals, and the ferox; and choose rather the granivorous. Some birds, indeed, which live on insects, are admitted into our food; but no man, without nausea, can live upon these alone for any length of time. Fishes, too, are an exception to this rule, living almost universally on each other. But in these the alkalescence does not proceed so far; whether from the viscosity of their juice, their want of heat, or some peculiarity in their economy, is not easy to determine.

2. Alkalescence is determined by difference of age. The older animals are always more alkalescent than the young, from their continual progress to putrefaction. Homberg always found in his endeavours to extract an acid from human blood, that more was obtained from the young than from the old animals.

3. A third circumstance which varies the alkalescence of the food, is the wildness or tameness of the animal; and this again seems to depend on its exercise. Dr Cullen knew a gentleman who was fond of cats for food; but he always used to feed them on vegetable food, and kept them from exercise; and in the same manner did the Romans rear up their rats, when intended for food. In the same way the flesh of the partridge and the hen seems to be much the same; only, from its being more on the wing, the one is more alkalescent than the other. Again, tame animals are commonly used without their blood; whereas the wild are commonly killed in their blood, and upon that account, as well as their greater exercise, are more alkalescent.

4. The alkalescence of food may be determined from the quantity of volatile salt it affords. The older the meat is, it is found to give the greater proportion of volatile salt.

5. The alkalescence of aliment may also, in some measure, be determined from its colour, the younger animals being whiter and less alkalescent. We also take a mark from the colour of the gravy poured out, according to the redness of the juices judging of the animal's alkalescence.

6. The relish of food is found to depend much on its alkalescence, as does also the stimulus it gives and the fever it produces in the system. These effects are also complicated with the viscosity of the food, by which means it is longer detained in the stomach, and the want of alkalescence supplied.

Having mentioned animal food as differing in solubility and alkalescence, which often go together in the same subject, we come to the third difference, viz.

III. Quantity of Nutriment. Which is either absolute or relative: absolute with respect to the quantity it really contains, sufficient powers being given to extract it; relative, with respect to the assimilatory powers of those who use it. The absolute nutriment is of some consequence: but the relative, in the robust and healthy, and except in cases of extraordinary weakness, may, without much inconvenience, be disregarded. In another case is the quantity of nourishment relative, viz. with regard to its perspirability; for if the food is soon carried off by the excretions, it is the same thing as if it contained a less proportion of nourishment. For, giving more fluid, that which is longer retained affords most; and, for the repair of the solids, that retention also is of advantage. Now, gelatinous substances are long retained; and, besides, are themselves animal substances dissolved; so that, both absolutely and relatively, such substances are nutritious. Of this kind are eggs, shell fish, &c. In adults, though it is disputed whether their solids need any repair, yet at any rate, at this period, fluid is more required; for this purpose the alkalescent foods are most proper, being most easily dissolved. They are, at the same time, the most perspirable; on one hand that alkalescence leading to disease, while on the other their perspirability obviates it. Adults, therefore, as writers justly observe, are better nourished on the alkalescent; the young and growing, on gelatinous foods. All this leads to a comparison of young and old meats; the first being more gelatinous, and the last more alkalescent. This, however, by experience, is not yet properly ascertained. Mr Geoffroy is the only person who has been taken up with the analysis of foods. See Memoires de l'Academie, l'an. 1731 & 1732. His attempt was certainly laudable, and in some respects usefully performed; but, in general, his experiments were not sufficiently repeated, nor are indeed sufficiently accurate. He has not been on his guard against the various circumstances which affect meats; the cow-kind liking a moist succulent herbage, which is not to be got in warm climates; while the sheep are fond of dry food, and thrive best there. Again, some of his experiments seem contradictory. He says, that veal gives more solution than beef, while lamb gives less than mutton, which is much to be doubted. If both he and Sanctorius had examined English beef, the result probably would have been very different as to its perspirability, &c. Besides, Mr Geoffroy has only analyzed beef and veal when raw; has made no proper circumstantial comparisons between quadrupeds and birds; and has examined these last along with their bones, and not their muscles, &c. by themselves, as he ought to have done, &c. If a set of experiments of this kind were properly and accurately performed, they might be of great use; but at present, for the purpose of determining our present object, we must have recourse to our alkalescence, solubility, &c.

IV. The fourth difference of animal food is, The Nature of the Fluids they afford. The whole of this will be understood from what has been said on alkalescence; the fluid produced being more or less dense and stimulating, in proportion as that prevails.

V. The fifth difference of animal foods is with respect to their

Perspirability. The sum of what can be said on this matter is this, that such foods as promote an accumulation of fluid in our vessels and dispose to plethora, are the least perspirable, and commonly give most strength; that the more alkalescent foods are the most perspirable, though the viscid and less alkalescent may attain the same property by long retention in the system. The authors on perspirability have determined the perspiration of foods as imperfectly as Mr Geoffroy has done the solubility, and in a few cases only. We must not lay hold on what Sanctorius has said on the perspirability of mutton, because he has not examined in the same way other meats in their perfect state; far less on what Keil says of oysters, as he himself was a valetudinarian, and consequently an unfit subject for such experiments, and probably of a peculiar temperament.

As to the effects of Food on the Mind, we have already hinted at them above. It is plain, that deli-