In the classification of the different species of potations, we may, in like manner, be governed by their distinguishing chemical composition. They may be arranged under four divisions,

viz.

CL. I.-Water. Spring, river, well-water, &c.

CL. II.-The Juices and Infusions of Vegetables and Animals. Whey, tea, coffee, &c.

CL. III. Fermented Liquors. Wine, beer, &c. CL. IV. The Alcoholic Liquors, or Spirits. brandy, rum, &c.

Alcohol,

The terms digestible and nutritive must not be considered as synonimous. A substance may be highly nutritive, and yet digestible with difficulty; for it may require all the powers of the digestive organs to convert it into chyle; but still it may afford a highly restorative principle. So it is with some of the fatty and oily aliments; and it has been calculated that an ounce of fat meat is equal in nutriment to four of lean. Again, there are substances, apparently easily digested, which yield comparatively little support to the frame.

A healthy stomach readily and effectually disposes of solid food of a certain specific degree of density, and this may be termed its digestive texture. If the food exceed this, it will require a longer period, and more active powers, to complete its chymification. The same will occur when the food approaches too nearly to a gelatinous condition. It is, perhaps, not possible to appreciate the exact degree of firmness, which will confer the highest order of digestibility upon food. The powers of the stomach may likewise vary in different individuals. But experience teaches that no meat is so digestible as tender mutton, and it is, in this country, more used than any other kind of animal food. Wedder mutton, or the flesh of the castrated animal, is in perfection at five years, and is indisputably the sweetest and most digestible. Ewe mutton is best at two years' old. Beef is not so easy of digestion, yet, though its texture is firmer, it is equally nutritive. Much, however, will depend upon the time which has elapsed since the

* Much is also to be attributed to what may be termed the education of the stomach. The children of peasants feed on fat bacon, and use hog's lard for butter, with ease and pleasure; while these coarse aliments would sicken, and even vomit, those of a higher rank in life. Again, the offspring of the natives of the Polar regions suck pieces of blubber with delight, and their parents eat tallow candles, and drink oil, with rapture. Now all this, we conceive, is owing to the customs of barbarous life, as the reverse is to those of civilized society, and not to any natural difference in the powers of the stomach, which are probably, with certain necessary exceptions, the same in the whole of the human race.-Rev.

death of the animal, and still more upon the method of cookery. It is easy to understand why a certain texture and coherence of the aliment should confer upon it either digestibility, or the contrary. The conversion of it into chyme is effected by the solvent power of the gastric juice, assisted by the churning which it undergoes by the motions of the stomach; and, if the substance does not possess a suitable degree of firmness, it will resist such motions. Thus it is with soups and other liquid aliments, where Nature removes the watery part prior to the progress of digestion. Hence oils are digested with so much difficulty; and it is probable that jellies, and other glutinous matters, although containing the elements of nourishment in the highest state of concentration, are not digested without considerable labour; first, from their evading the grappling powers of the stomach, and, secondly, from their tenacity opposing the absorption of their fluid parts. For these reasons, it is maintained that the addition of isinglass, and other glutinous substances, to animal broths, with a view to render them more nutritive to invalids, is a pernicious practice. The texture of animal food is greatly influenced by the age, sex, habits, condition, diet, and manner of death of the animal. In proportion, generally, to the age, the flesh is coarser and more firm in texture, as almost every individual must have noticed in the eating of birds. If the flesh of mutton and lamb, beef and veal, be compared, they will be found of a different texture ; the two young meats are of a more stringy, indivisible nature than the others, which makes them harder of digestion. Young animals differ, also, from old ones in the distribution of the fat, which, in the latter, is chiefly collected in masses or layers, external to the muscles; while, in the former, it is more interspersed among the muscular fibres, imparting to the flesh a marbled appearance, which is always desirable. The texture of food will likewise vary according to the wild or domesticated state of the animal, since the former is more dense, although very nutritious. Moreover, the sex modifies the quality, that of the female being invariably more delicate and finer grained than that of the entire male, whose fibres are denser. The flesh of hunted animals is peculiarly tender, and the same arises from any lingering death. The administration of vinegar prior to the killing of them has a similar effect. Incipient putrefaction strikingly ameliorates the rigidity of the animal fibre. Yet the circumstances enumerated as influencing the texture of food, and its degree of digestibility, are unimportant, when compared with the modifying powers of cookery. By this process, alimentary substances undergo a two-fold change;-their princi

ples are chemically modified, and their textures mechanically changed. Much, however, will depend upon the manner in which heat has been employed, and this will be generally explicable, by recollecting the kind of fuel most accessible to different countries.

1. Boiling. Here, the principles not properly soluble are rendered softer, more pulpy, and, consequently, easier of digestion. But the meat is deprived of some of its nutritive properties by the removal of a portion of its soluble constituents; the albumen and gelatiu are also acted upon; the former being solidified, and the latter converted into a gelatinous substance. If, therefore, meat be boiled too long or too fast, there will be, where the albumen predominates, as in beef, a hard and indigestible mass, like an overboiled egg; or, where the gelatin exceeds, as in young meats, such as veal, a gelatinous substance alike injurious to the digestive organs. Hence young and viscid food, as veal, chickens, &c. is more wholesome roasted than boiled, and easier digested. Dr. Prout has justly observed, that the boiling temperature is too high for a great many of the processes of cooking, and that a lower temperature and a longer time, or a species of infusion, are better adapted for most of them. Thus it is that "beef tea" and "mutton tea"* are much more calculated for invalids than the broths of these meats. The loss occasioned by boiling partly depends upon the melting of the fat, but chiefly from the solution of the gelatine and osmazone. Mutton generally loses about one fifth, and beef

*Nothing can more strongly evince how much the English language demands strict revision and consequent improvement than the introduction of these barbarous phrases into the present work. Tea, in common conversation, implies an infusion of that Chinese plant in hot water :how, then, can the infusion of beef, mutton, and sage, in a similar menstruum, be denominated tea, without a ludicrous absurdity? What should we think of a man who spoke of mutton-partridge, simply because his mutton was cooked as partridges are?-He would be thought mad, something like my Lord Peter, in the Tale of a Tub, who swore that a loaf of bread was both mutton and wine! Yet is this a case exactly analogous. If the ridiculous terms, here reprobated, sprang from the poverty of the language some excuse might be admitted, but it is not so; for beef, mutton, or sage-infusion would be perfectly correct, and unobjectionably short. It is now 115 years since Swift published a letter to Harley, Earl of Oxford, then Lord Treasurer, concerning the imperfect state of our language, and complaining that, in many instances, it offended against precision, seuse, and grammar. What would the Dean have said, had he been told that, in the year 1826, a doctor of the University of Cambridge, and certainly one who has done her no discredit, would use, in a scientific work, such phrases as beef, mutton, and sage-tea.-Rev.

one fourth of its original weight. Boiling is particularly applicable to vegetables, rendering them more soluble in the stomach, and depriving them of a considerable quantity of air, which is so injurious to weak stomachs. But, even in this case, the operation may be carried to a hurtful extent; for instance, potatoes are frequently boiled to a dry and insipid powder instead of being preserved in a soft, gelatinous state, which retains their shape. Again, the cabbage tribe, and carrots, are commonly not boiled long enough, and in this condition they are highly indigestible. The quality of the water employed must also be attended to; for mutton, boiled in hard water is more tender and juicy than when soft is used; while vegetables are made harder, and less digestible.

2. Roasting. By this process the fibrine is corrugated, the albumen coagulated, the fat liquified, and the water evaporated, The surface first becomes brown, then scorched; and the tendinous parts are rendered softer and gluey. The meat should not be over-done, nor under-dressed; for though it may contain more nutriment, it will be less digestible from the density of its texture. Animal matter loses more by roasting than boiling. It has been stated, that by this latter process mutton loses one-fifth, and beef one fourth; but by the former these meats lose about one-third of their weight. In roasting, the loss arises from the melting of the fat, and the evaporation of the water; while the nutritious matter remains condensed in the cooked, solid; whereas, in boiling, the gelatine is partly abstracted. Roasted are, therefore, more nutritious than boiled meats; because it has been computed that, from the dissipation of the nutritive juices by boiling, one pound of roasted contains as much nourishment as two of boiled meat.

3. Frying. This is, perhaps, the most objectionable of all the culinary operations, since the heat is applied through the medium of boiling oil, or fat, which is rendered empyreumatic, and consequently extremely liable to disagree with the stomach.

4. Broiling. Here the sudden browning or hardening of the surface prevents the evaporation of the juices of the meat, and imparts to it a peculiar tenderness. It is the form selected by those that strive to invigorate themselves by training.

5. Baking. The peculiarity of this process depends upon the substance being heated in a confined space, which does not permit the escape of the fumes arising from it. The meat is, therefore, from the retention of its juices, made more sapid and tender; but baked meats are not so easily digested, on account of the greater retention of their oils, which are, moreover, in an empyreumatic state. Such dishes accordingly require the

stimulus of various condiments to increase the digestive powers of the stomach.

Of Condiments. These are substances which, in themselves, are incapable of nourishing, but which, in concert with food, promote its digestion, or correct some of its deleterious qualities. The existence and necessity of such agents are far more universal and important than has been generally supposed.* The bitter principle which exists in grasses and other plants appears to be equally essential to the digestion of herbivorous animals. It acts as a natural stimulant; for a variety of experiments has shewn that it passes through the body without suffering either diminution, or mutation. No cattle will thrive upon grasses which are destitute of a portion of this vegetable principle; this fact has been most satisfactorily proved by Mr. Sinclair, in that magnificent work, the "Hortus Gramineus Woburnensis." The value of slight bitters, and of condiments has been felt and acknowledged in all ages. From the different nature of condiment, it has been usually divided into three classes; viz. the saline, the spicy or aromatic, and the oily.

1. Salt appears to be a necessary and universal stimulus to animated beings; and its effects upon the vegetable and animal kingdoms have furnished the most interesting inquiries to the physiologist, chemist, physician, and agriculturist. It appears to be a natural stimulant to the digestive organs of all warmblooded animals, and they are instinctively led to immense distances in the pursuit of it. To point out the advantages of salt as an article in diet, or to dwell upon the miseries that have sprung from the want of it, would be, indeed, a superfluous labour, since they are too notorious to be either questioned, or denied.

2. Vinegar. This acid, in small quantities, is a grateful and wholesome stimulant. It will often check the chemical fermentation of certain substances within the stomach, and prevent vegetable matter in its raw state from inducing flatulence, yet the use of it demands caution, and it is obviously noxious in some morbid states of the system. Fatty and gelatinous substances frequently appear to be rendered more digestible in the stomach by the addition of vinegar, although it is difficult to offer either a chemical or physiological explanation of the fact. The native vegetable acids may also be occasionally substituted. The addition of lemon juice to rich and glutinous soups makes

See the Author's Pharmacologia, Ed. VI. Vol. I. p. 145.