The subject of human food may perhaps be most conveniently considered under the following five heads:
I. The chemical composition and the physiological action of the various proximate principles of animals and vegetables commonly employed as food. II. The varieties of animals and vegetables used as food in this country, the different alimentary products obtained from them, and their various composition. III. The modes of preparing food for use, and the rationale of their respective actions. IV. The modes of preserving articles of food from decomposition. V. The principles of diet, and some dietary tables.
I. The chemical composition and the physiological action of the various proximate principles of animals and vegetables commonly employed as food.
The different proximate principles (i.e., specific unions of some of the elementary bodies of chemistry) of animals and vegetables that may be used as food, and become converted into blood for the purpose of keeping up in adults the constant waste of the tissues, and for the same purpose also for affording the additional matter that is required in growing individuals, have been, since the publication of Dr Prout's treatise, usually arranged into three classes and water. These three classes are—the saccharine, the members of which are composed of carbon, hydrogen, and oxygen, the two latter being combined in the same proportion that they are in water; the oleaginous, which likewise consists of the same elements, but in which the hydrogen and oxygen are not in the same proportion that they exist together in water; and the albuminous, which are essentially composed of the four elements of carbon, hydrogen, oxygen, and also nitrogen, the last-named element being almost invariably in the proportion of about fifteen per cent. But, besides these four elements, the human body, and therefore the nutritious parts of animals and vegetables that keep up that body, contain, although in small proportions, sulphur, phosphorus, sodium, chlorine, &c. The manner in which these elementary bodies are, in animal and vegetable structures, combined, is certainly not ascertained, and the subject will be partially considered by-and-by, when noticing Mulder's theory of proteine compounds, but they may, for all practical purposes, be stated to be combined with the albuminous proximate principles.
A. Saccharine proximate principles derived from vegetables.—1. Cellulose. The basis, or skeleton, as it were, of vegetable structures, is either cells, or vessels that are in fact composed of a number of ruptured or elongated cells. The walls of these cells are composed of the proximate principle under notice—cellulose. In order to separate it from the other constituents of the vegetable, it is necessary to cut the stem into small bits and digest them (for the purpose of separating the other constituents of the wood) successively in alcohol, ether, potassa water, hydrochloric acid, and water. Collodine is not soluble in any of these, while the other constituents of the stem are, and hence cellulose is left behind. It is a white substance, but is changed into a violet colour if iodine be added to it. Its composition is as follows: 24 atoms of carbon, 21 of hydrogen, and 21 of water. By the action of acids or of heat it is converted into starch, and therefore if a little sulphuric acid be added to it, the violet colour produced by the iodine (see next paragraph) is converted into a blue. Substances that contain a very large proportion of cellulose are not employed as human food, but such (as hay and straw) are much used in feeding cattle and horses; and when this is done, it is probable that the cellulose is converted into starch by the hydrochloric acid of the stomach. Cellulose is apt in old plants to part with a portion of its oxygen, and is then converted into a principle named lignine. This is known from cellulose by its solubility in caustic potassa water. As its hydrogen and oxygen are not united in the proportions that they are in water, it is not exactly a saccharine proximate principle. It exists in potato skins, the peel and core of fruit, the seed-coat or skin of nut kernels, &c., and it seems doubtful if it can afford food. The principle said to have been detected in mushrooms (and which perhaps also occurs in other cellular plants)—fungine, is probably a variety of lignine or of cellulose. Brannock however, reports that it contains nitrogen. 2. Starch. In plants that have come nearly to maturity, starch is probably the proximate principle that, next to cellulose, is most abundant. It is also contained in large quantities in many ripened, indeed in most ripened
---
1. The body of man, as will be more fully explained in section v., consists of carbon, oxygen, hydrogen, nitrogen, sulphur, phosphorus, chlorine, iron, sodium, calcium, potassium, magnesium, and fluorine. As the body cannot form an element, of course the food must contain and consist of these elements.
2. Johnston.
3. Anal. Chem., 79. Food.
or matured ones. It is easily obtained from flour (or ground cereal grains); the tubers of potatoes; the stems of the sugar-palm, &c., &c. If any vegetable structure that contains starch be washed with cold water upon a sieve, a milky fluid passes through, which, when set aside, deposits a white powder. This is starch. Starch is, when pure, without taste, colour, or smell. It does not dissolve in cold water, but does so very readily in hot; and, when this is the case, it forms, upon cooling, a gelatinous mass. When moistened with a solution of iodine, it strikes a blue colour. Its formula is $12$ carbon, $10$ hydrogen, and $10$ oxygen; or $24$ carbon, $20$ hydrogen, and $20$ oxygen. It therefore differs from the cellulose, from which it is probably derived, in containing one atom less (or the atoms that contain one atom less) of water. The rationale of the action of sulphuric acid, when it converts cellulose into starch, is that it abstracts from it this one atom of water. There are two varieties of starch, called taucine (obtained from the dahlia, and other roots), and tichen starch (which is procured from the lichen). They differ from common starch in their action upon iodine, in their relations to water, and in a very slight degree in the proportion in which their elements are arranged. But for all practical purposes these variations may be disregarded.
3. Dextrine. If starch be heated up to a temperature of $300^\circ$, or if diluted sulphuric acid be added to it, or indeed if it be boiled in ordinary water for some time, a proximate principle—dextrine—is obtained, which differs from starch in being soluble in cold water. This change of starch into dextrine is naturally brought about during the germination of those seeds that contain starch. In this case the change is brought about by the contact of a peculiar nitrogenous principle—diastase—soon to be noticed. This principle may be separated from barley that is being converted into malt in the malt-house, and if a little of this separated principle be added to any starch, it (the starch) is soon converted into dextrine—a substance that, although having the same chemical composition as starch, unlike that principle, is soluble in cold water. This conversion of starch into dextrine is brought about in nature by the action of diastase during the germination of those seeds that contain starch. The albuminous proximate principle of diastase will be afterwards noticed, and if a little of it be added to starch, the starch is speedily converted into dextrine. If sulphuric acid be added to dextrine, the dextrine is converted into another proximate principle of this group—sugar. The formula of dextrine is of course the same with that of starch.
4. Gum. Many vegetables secure gum, of which proximate principle there are two varieties, which merely differ in the one, arabiné, dissolving in cold, and the other, cerasine, requiring hot water for its solution. The chemical composition of gum is identical with that of dextrine and of starch, but gum differs from the latter in not giving the blue colour with iodine, and from the former in not readily giving up some of its oxygen and hydrogen to sulphuric acid, being thereby converted into sugar.
5. Cane Sugar. Many plants, as the sugar-cane, the maple, the beetroot, &c., contain another proximate saccharine principle, cane sugar. This is soluble in water, forming with it an oily compound—syrup—from which, however, the sugar gradually separates in crystals, which are commonly known as sugar-candy, and which sugar-candy has an extremely sweet taste. Its formula is $24$ carbon, $18$ oxygen, and $18$ hydrogen. If diluted sulphuric acid, as before mentioned, be added to starch, first dextrine is obtained, and then cane sugar. And when cane sugar is itself heated with dilute sulphuric or other acids, it is blackened by it, and becomes converted into another form of sugar, next to be noticed.
6. Grape Sugar. This is found in the grape, apple, and many other fruits, and is produced from cane sugar by the action of acids and heat. In this latter mentioned manner it is extensively produced, when a solution of malt, &c., is fermented by the brewer or distiller. Grape sugar is neither so soluble in water nor so sweet as cane sugar. Its formula, too, is different, being $24$ carbon, $22$ hydrogen, and $22$ oxygen; and it may be readily distinguished from cane sugar by not being blackened when boiled with diluted sulphuric acid. Other subvarieties of sugar may be omitted. One called pectine is contained in many fruits and roots, and contains an excess of oxygen. Combined with sugar, it forms a jelly.
7. Alcohol. Correctly speaking, this proximate principle does not belong to the purely saccharine group, for its atoms of hydrogen are in excess over those of oxygen. Neither does it, like all the above mentioned saccharine proximate principles, exist ready formed in plants, although by art, when the plant has been some time dead, they can be converted into alcohol. In order to procure alcohol there must be a solution of grape sugar (or of cane sugar, dextrine, or starch, under those conditions in which these respective principles may become converted into grape sugar), a certain temperature, and the presence of some albuminous matter, as gluten (as in grapes), or yeast, as in beer-making, or the like. When these conditions occur, carbonic acid is given off, and alcohol is left in the water. The following is the change that occurs:—1 atom of grape sugar and 2 of water are composed of $24$ carbon, $24$ hydrogen, and $24$ oxygen. If we subtract from this $4$ atoms of carbonic acid, which contain $8$ of carbon and $16$ of oxygen, we have left $2$ atoms of alcohol, which together contain $16$ atoms of carbon, $24$ of hydrogen, and $8$ of oxygen. The formula of alcohol is therefore $8$ of carbon, $12$ of hydrogen, and $4$ of oxygen. Obtained in this manner alcohol is always much diluted, constituting wine, beer, &c. To obtain it in a purer form it requires to be distilled and rectified.
B. Saccharine proximate principles derived from Animals.—1. Milk Sugar. If the milk of any mammiferous animal be taken, and the curd separated, as is done in ordinary cheese-making, and then the whey boiled so as to evaporate a considerable portion of the water, the remaining whey gradually deposits a number of crystals, which, on examination, are found to be a variety of sugar, to which the name of milk sugar is given. It is not so sweet to the taste as either cane or grape sugar, neither is it so soluble in water, and it is harder and grittier when chewed than they are. Its formula is $24$ carbon, $19$ hydrogen, and $19$ oxygen. By the action of acids it is converted into grape sugar, and is then susceptible of the alcoholic fermentation. Milk sugar is never sold in this country except for scientific purposes; but in Switzerland it forms an article of commerce, and it is the source of the alcoholic drink of some nomadic tribes. In this last-mentioned case the lactic acid (see p. 758) is allowed to separate, the free lactic acid then converts this sugar into grape sugar, and the albuminous principle of the curd or cheese acts as a ferment. The physiological action of all the saccharine proximate principles is the same, and consists altogether, or mainly, in affording carbon, and this almost solely for the purpose of keeping up the animal heat, and not for the purpose of depositing fat. Man requires to keep up a temperature of about $100^\circ$ Fahr., which is one much higher than that of the atmosphere that surrounds him. In order that he may do this his economy is able to take the carbon of his food, including, of course, the carbon of the saccharine principles that constitute his food, and combine it, just as wood, or coal, or coke are combined in a common fire, with oxygen (which oxygen man and animals take in at the lungs from the air). The result is, in this as in all ordinary cases of combustion, the formation of carbonic acid by the union of the carbon of the food and the oxygen of the air; and this carbonic acid, when the elements that composed it have served their purpose of heating the body, is cast out at the lungs. The amount of pure carbon necessary to be taken in as food by an ordinary-sized adult man for the purpose of burning in him is about eleven ounces a-day. But some of this may be derived, and in many cases is, from the oleaginous proximate principles now to be noticed.
C. Oleaginous proximate principles derived from Vegetables.—Plants usually, and, as far as regards those used as food, almost without an exception, contain a considerable quantity of oily matter. This is usually deposited around the seeds, as in the husks of cereal grains, or among the cellular tissues as in turnips, potatoes, grass, &c. When fixed oily matter is present in considerable quantity in a vegetable, it may be generally separated by means of pressure, or, if that is not convenient, by being dissolved out by means of ether, and the other afterwards evaporated. Volatile oils are readily obtained by distillation with water. The fatty matters that can be thus obtained from plants may, for all practical purposes, be ar-
---
1 Alcohol is, however, sometimes produced in nature. Very ripe gooseberries, and probably grapes, and many other very ripe but ungathered fruits contain it. ranged into three, viz.—1. Elaine, which is a liquid, and may be readily procured from the solid constituent of olive and other oils by freezing. The part, in such a case, that is left fluid is the elaisine. There are two sub-kinds of it, one that is not acted upon by the air, and another that, when exposed to the air, absorbs oxygen, and undergoes other changes, the result of which is to convert it into a resin, or oxygenated oil. This latter is the drying oil of painters. The composition of the two kinds is identical, their formulae being 94 carbon, 87 hydrogen, and 15 oxygen. 2. Margarine. This is the solid portion that is left when most vegetable oils are frozen. It is white, hard, and brittle, and melts at 118°. The composition is 74 carbon, 74 hydrogen, and 12 oxygen. 3. Stearine. This is very analogous to the preceding, and is obtained by freezing some vegetable oils (not, however, many), of which it constitutes the solid part. It differs from margarine in containing less oxygen, and in requiring a higher temperature (129°) to melt it. These oleaginous principles are usually mixed together in vegetables, and likewise contain small quantities of some essential oil peculiar to each plant, to which the colour and sapid taste are often owing.
D. Oleaginous proximate principles obtained from animal articles of food.—1. Elaine. This is the liquid part of almost all animal fats, and is quite identical with vegetable elaisine. 2. Margarine. This is the solid part of the fat of man, the goose, cows, &c. It is the same as vegetable margarine. 3. Stearine. This is the solid part of the oily matter of cattle, sheep, pigs, and other animals, and in no respect differs from stearine obtained from vegetables. Animal oils, like vegetable oils, often contain a minute proportion of some oil peculiar to the animal, upon which their peculiar odour, sapid taste, &c., depend. These three oleaginous proximate principles of vegetables and animals are now, however, known to be compounds of elaisine, margarine, and stearine acids with oxide of glycerine. For the properties and compounds of these substances see Chemistry. The physiological action of the oleaginous proximate principles of plants and animals whose structures are used as food is, like those of the saccharine group, to furnish carbon partly for the purpose of being consumed as food, and partly to furnish fat. Indeed, under ordinary circumstances, they only fulfill the latter indication. Nations the members of which, as Greenlanders, &c., have a small supply of saccharine proximate principles either to eat or to convert into alcohol, consume a large amount of animal fat. They have little or no vegetable fat; and something of the same kind has been observed to be the case with individuals in other nations who can obtain saccharine proximate principles, but who, from some reason or other, do not.
E. Albuminous proximate principles obtained from vegetable articles of food.—1. Vegetable Albumen. If the expressed juice of many plants, as of the potato, turnip, carrot, the seeds of the cereal grains, &c., be filtered, and the fluid that remains be exposed to a heat of 180° Fahr., a portion of it coagulates and falls down in flakes. This is albumen, and may be collected upon a filter. Albumen may be distinguished from other nitrogenous proximate principles by coagulating at a heat of about 180°, by drying into a hard white mass, by being soluble in alkalies and by being precipitated from these alkaline solutions by all acids save the phosphoric and acetic. It is believed that albumen exists in plants in two states, one a soluble one, and another not so. Albumen essentially contains carbon, oxygen, hydrogen, and nitrogen. The exact proportions of these are perhaps not very accurately ascertained. The following is the result of an analysis by Jones:—Carbon, 54.74; hydrogen, 7.77; nitrogen, 15.85; oxygen, 21.64 = 100.
2. Gluten. If the flour of wheat or other cereal grain, or indeed of many other parts of several plants, be made into a dough with water, and the dough well washed, the saccharine and oleaginous matters, and also the albumen, are carried away by the water, and a stiff tenacious substance is left. This is gluten. It is, as the mode of obtaining it sufficiently indicates, insoluble in water, but it is partly so in alcohol. The portion that does so dissolve in alcohol is called gluten, and sometimes vegetable fibrine. The chemical composition of gluten is very analogous to that of albumen, out of which it is probably formed. Gluten does not coagulate at a heat of 180°; it dissolves in acetic acid, and may also be distinguished from other proximate albuminous principles by its great tenacity. 3. Vegetable Casein. After boiling the sap of some plants, as of potatoes, pears, &c., and straining the liquid that remains from the albumen that is by the heat coagulated, if a little hydrochloric (or other acids) be added, a white powder gradually falls to the bottom. This is caseine. Its chemical composition probably differs but slightly from those of albumen and gluten, but it may be known by its coagulating in many acids. 4. Theine. If tea, coffee, or cocoa be boiled in water, and the solution treated with sugar-of-lead, this proximate principle, theine, which had been combined with tannic acid, is thrown down in brilliant long crystals of a silvery lustre. It is composed of carbon, oxygen, hydrogen, and nitrogen, but the latter is in greater proportion than in any other albuminous compound (it actually contains 29 per cent. of this element), and, as we shall afterwards see, this accounts for the nutritious effect of tea, &c., in individuals who consume little food of other descriptions. 5. Diastase. If pounded malt be infused in cold water, the solution considerably evaporated, and then alcohol added, a white powder falls down, to which the name of diastase is given. Diastase exists in all germinating seeds or tubers, and is probably during germination the last product obtained from the above-mentioned albuminous principle caseine. If a little of this diastase be applied to starch it has the remarkable property of converting it, first of all into (soluble) dextrine, and eventually into grape sugar. Diastase is an albuminous proximate principle, but its exact composition is not known, one reason for this being that it is very readily decomposed and separated into inorganic compounds, one of these being ammonia. The very important action that it has in ripening and maturing vegetable productions is ascertained, but in this place we have only to consider its action in fermentation. It is not known if diastase in itself furnishes nutriment or not.
F. Albuminous proximate principles obtained from animal articles of food.—Animal Albumen. This constitutes the white of the egg, or it may be readily obtained by heating the serum of the blood up to 180° (Fahr.), upon which it coagulates and falls down in flakes. It is also abundant in almost all animal tissues. It is probably exactly identical in all its properties with vegetable albumen. 2. Fibrine. If recently drawn blood be whisked with a birch wand, a white fibrous matter attaches itself to the twig. This is fibrine. It may also be obtained by a little management from any muscular structure. It differs (besides in other respects) from albumen in coagulating at ordinary temperatures, and from gluten (to which principle it is very analogous) in coagulating at all. Its formula is carbon 52, oxygen 23, nitrogen 16, and hydrogen 7. It is probably formed in animals out of albumen. 3. Gelatine. This may be obtained by boiling bones, skin, cartilage, &c., in water, and putting the solution to cool. It is distinguished from the two former substances by dissolving readily in hot water, and by this solution forming a jelly-like mass when cold. It also combines with tannin and forms the impervious compound called leather (which contains also fibrine). Gelatine is probably formed out of fibrine, and in its chemical constituents is nearly identical with that compound, but it contains a little more oxygen. It is important to recollect that pectose, which is sometimes called vegetable gelatine, is not an albuminous compound at all. 5. Kreatine. Some years ago Chevreul announced the presence in butcher meat of a crystallizable principle to which he gave the name of kreatine. It is, however, almost certainly the product of decomposition, and in no degree nutritive. 6. Osmazome. Cooked animal meat has a very different smell and taste from the same when raw. If the former be treated with alcohol, an odoruous and sapid extract is obtained, to which the name of osmazome has been given. If this be a proximate principle, it is almost certainly an albuminous one, but it is very doubtful if it is such. It is perhaps a compound of lactesce with the salt employed in cooking, but it may be that part of it is a resin obtained by the deoxidation of some of the fat during the application of heat. 7. Proteine, and the ashes of vegetable and animal structures that are used as food. If the structures of vegetables and animals that are used as food be examined, they are found to consist of an aggregation of several of the above proximate prin-
---
1 Annalen der Chemie.
ciples (or of slight modifications of them that are purposely omitted), of water, and of a small quantity of salts, or of the acids and bases that form salts. If any of the substances that we use as food be exposed to considerable heat, the water is first driven off, the four elements in the proximate principles just noticed enter into new combination (carbonated hydrogen, ammonia, &c., &c.), and pass off into the air, but a small quantity of ash is left behind. In plants this ash is found to consist of sodium, potassium, chlorine, phosphorus, sulphur, calcium, magnesium, iron, silicon. In animals the constituents of the ash are the same, with the exception that animals contain no silicon. In the undestroyed structures of vegetables and animals these constituents of the ash probably exist as chlorides, phosphates, and sulphates of soda, potassa, &c. (or chlorides, phosphates, and sulphates of sodium and potassium), iron, &c. It has been maintained that the albuminous proximate principles are in reality compounds of a peculiar substance, to which the name of protein has been given, and that the difference of the albuminous compounds essentially consists in their being respectively combined with varying portions of these constituents of the ash. This opinion is perhaps not supported by sufficient evidence, but the elements that form the ash may be considered as in some way or other united during life with the albuminous proximate principles of vegetables and animals.
G. Acids found in the recently dead structures of plants and animals that serve for food.—1. Acids derived from vegetables.
1. Acetic acid. This acid and the following (the lactic) resemble the saccharine proximate principles in being composed of carbon, hydrogen, and oxygen, and in the hydrogen and oxygen being in the same proportions as they exist in water. But they differ in this that they have an acid reaction, reddening litmus paper, and forming neutral salts with alkaline bases. Acetic acid as formed during the germination of seeds, is a product, at least often, of incipient putrefaction in many plants, particularly in those that had contained much sugar, but it probably also is contained in many living juices. Acetic acid (undiluted) consists of 4 carbon, and 3 respectively of hydrogen and oxygen. One of its chemical characteristics is that its solution gives a white precipitate (acetate of silver) with lunar caustic, and that this precipitate is little soluble in water. Acetic acid is also obtained abundantly from the fermentation of weak alcohol and the destructive distillation of wood. 2. Lactic acid. If chopped cabbage, flour, grapes, or many other vegetable substances, be allowed to ferment, the starch or sugar is decomposed, and lactic acid is formed. The composition of it is carbon 6, hydrogen 6, and oxygen 6. It is also formed in animal structures that are beginning to undergo putrefaction. It perhaps never occurs in a living plant or animal. It appears, however, to be certainly an aliment. 3. Tartaric acid. This and the following consist of carbon, hydrogen, and oxygen, but they have the last-mentioned element in excess. They have acid reactions, but may be regarded otherwise as corresponding with the oleaginous principles of food. Tartaric acid exists in the juice of the grape, tamarind, and other fruits. In combination with potassa (argol), it is deposited in wine-casks and bottles. Its composition is carbon 4, hydrogen 2, and oxygen 5. 4. Malic acid. This acid exists in large quantities in apples, pears, and other fruits, particularly before they are ripe, or in those varieties of them that never become very ripe or sweet. Its composition is carbon 4, hydrogen 2, and oxygen 3. b. Acids derived from animals.—1. Lactic acid. If milk be allowed to stand for a while, it becomes sour. This is owing to its sugar, or a part of its sugar, having become converted into lactic acid, a substance identical with that noticed above, as being formed by the decomposition of cabbage, &c. It is also formed in flesh undergoing incipient putrefaction. 2. Butyric acid. This acid exists in butter, a substance that contains likewise two other acids, the consideration of which may be here omitted. 3. Ironic acid. This acid perhaps exists in flesh just beginning to putrefy.
H. Composition and physiological action of the different parts of animals and vegetables usually employed as food, and which contain two or more proximate principles.—a. Vegetable structures. The various nutritive principles are generally so much combined in vegetables that a very few lines may suffice for this section. The stem of young edible plants is usually composed of cellulose, oil, some sugar and starch, and a small quantity of albuminous matter. The seed of the cereals, besides starch, a little sugar, and gum, contains a large amount of albuminous matter, surrounded by a husk that is very rich in oil. Esculent roots and tubers generally contain an admixture of albuminous matter, saccharine (usually starch), and oleaginous, the two last usually preponderating. Ripe fruits, besides albumen and oil (this in general very sparingly), contain sugar in considerable amount, and usually one or more acids. Unripe fruits consist almost entirely of cellulose and acids. All of these have also a large quantity of water mixed up with their structures. b. Animal structures.—1. Bone. This substance consists of about 33 per cent. of albumen and gelatine, principally the latter, and about 67 of phosphate of lime and other commonly-termed inorganic matters. The long bones also contain marrow, a substance which is a mixture of elaine and stearine. The bones of young animals contain a much larger proportion of the gelatine than those of old ones of the same species. 2. Cartilage. This consists almost entirely of gelatine and albumen, and is analogous to bone that has been deprived of its inorganic matter. 3. Cellular Tissue. This consists of cells that are composed of an albuminous principle, probably gelatine, and which inclose elaine and margarine. When the cells are very much filled with the fatty matter, the compound is named adipose tissue, or commonly fat, and a variety of it is. 4. Muscle. The flesh of animals consists of muscle proper or lean, and also, in all or nearly all animals relished as food, of fat, which is deposited in the cellular tissue surrounding the fibres, and also that surrounding the entire muscles, which then often becomes adipose tissue. Some albumen, too, derived from the blood is contained amongst it, and of course various saline matters. As before mentioned, the creatine found in dead meat is probably the first stage of decomposition, and the oesmazome present in cooked meat developed by that process. Muscle contains about 74 or more per cent. of water. 5. Glands and Viscera. The tongue, the kidney, the sweetbread, and other internal organs, are used for food. They generally contain a good deal of albumen and fibrine. Sweetbread contains 6 per cent. of gelatine; liver has a peculiar brown oil, and the kidneys certainly often appear to retain urine. 6. Nervous Matter. Nervous matter contains albumen, various fatty matters, a peculiar acid that contains about 2 per cent. of nitrogen, various saline ingredients, and about 80 per cent. of water. Nervous matter is very little employed as food, being only occasionally used as a garnish. 7. Blood. Blood constitutes so great a proportion of the structure of animals, that some is almost invariably retained in the muscular structure. But blood is only used by itself as an article of food in the form of black puddings, which consist essentially of cooked hog's blood. Blood in composition and in nutritive quality is analogous to flesh.
II. The varieties of animals and vegetables used as food in this country, the different elementary products obtained from them, and their various composition.
A. The varieties of Alimentary Vegetables.
a. Cereal Grains.—1. Wheat (Triticum). The grain of wheat has for a very long time constituted an important article of food, and in England has for about three centuries been the staple grain. The kind usually cultivated is the Triticum sativum. A bushel of it should weigh, if very good, about 64 lb. Wheat in the form of flour is sometimes manufactured as macaroni and vermicelli; but its almost universal use is as bread. (See BAKING). The following is the composition of first-class wheaten flour:—Water, 14·0; albuminous compounds, 14·6; oil, 1·2; saccharine compounds, 66·9; cellulose, 1·7; ash, 1·6. The greater part of the ash is made up of phosphorus, potassium, and magnesium. The bran contains much less saccharine matter, but absolutely more oil and more albuminous matter; and "seconds" of this must stand intermediate between fine flour and bran. The cheaper price of seconds and bran, therefore, appears to be somewhat arbitrary and improper, and brown bread is probably more economical than that made from fine flour. The objection to it is probably that bran does not leaven particularly well. 2. Oats (Avena sativa). In Scotland, the climate and soil of which seem peculiarly adapted to its cultivation, this cereal has long constituted the staple article of diet. This is also the case in the high-lying land in the West Riding of Yorkshire and the adjacent parts of Lancashire. A bushel of good oats weighs about 45 lbs. Oats are made into flour or meal, and before being submitted to the mill they are always kiln-dried, to facilitate the separation of the husk. The proportion of husk in perhaps about a quarter per cent. When the husk is separated, but before the grain is ground, the seeds receive the name of groats. When ground the dust constitutes oatmeal, and it is found in practice that oats afford about half their original weight of meal, the loss being the water expelled by the kiln-drying, the husk, and the chaff. The following is Norton's analysis (the arrangement being altered) of oats that had been dried to 21/2°. Perhaps in this drying the loss of water would be about 20 per cent. Albuminous compounds, 19-61; saccharine do., 65-68; oleaginous do., 7-33; husk, 2-23; ash, 2-60. The proportions of ash, principally phosphates and sulphates of lime, potash, and magnesia, are much larger than those of oatmeal. Oatmeal, therefore, contains considerably more nutritious matter than the same weight of wheat flour. The husks consist mainly of cellulose, and are almost never used as human food. 3. Rye (Secale cereale) has been cultivated from time immemorial, and was for long much used for breadmaking in this country, as it still is (constituting the staple) in Russia, many parts of Germany, &c. A bushel of rye weighs about 54 lb. Rye grain is very coarsely powdered, and the mixture of flour and bran made into fermented bread, which is distinguished from other bread by its black colour. The following is an analysis of rye flour, the water having been previously expelled. Albuminous compounds, 10-5; saccharine do., 78-0; oil, 3-5; salts, 6-0, principally phosphates of potash, soda, and magnesia; loss, 2-0=100. These three cereal grains constitute the basis of the food of the modern European nations. In order that wheat may produce a good crop, it requires land rich in alumina, and also considerable summer heat, while barley thrives best on sandy soils. The oats do best with a dampish and somewhat cold climate, and almost prefer a thin soil lying over limestone and metamorphic rocks. 4. Barley (Hordeum distichon). Barley is occasionally made into bread; and it is also used, when deprived of its husk, for making soup. But by far the most important use of barley is that it may be converted into malt (i.e., that its starch may be converted into sugar), for the purposes of brewing and distillation. The reason it is thus selected is, that of all grains, if put under the conditions favourable to germination, its diastase soonest converts the starch into sugar. A common weight of a bushel of good barley is 56 lb. It contains about 68 per cent. of starch, upon which its value to the maltster or distiller mainly depends. 5. Rice (Oryza sativa) supplies in the Eastern world the place occupied in the Western by wheat, oats, and rye, and is also pretty extensively used on a small scale in this country. The following analysis of rice is abstracted from Payen:
- Albuminous principles, 7-5; saccharine do., 87-3; oil, 0-8; salts, 0-9; woody tissue (cellulose), 3-4. Thus, save in saccharine proximate principles, rice is far less nutritious than any of the preceding.
7. Indian corn (Zea mays) is the staple of North America, Mexico, &c., and has been at times of scarcity in our own country, being frequently imported into this country. It is also cultivated, but precariously, cultivated in England. According to Payen, 14 per cent. of water having been previously expelled, the grain contains more than 12 per cent. of albuminous matters, nearly 72 per cent. of saccharine, and the immense proportion of 9 of oleaginous. It is, therefore, extremely nutritive.
b. Viniferae Vegetables.—1. Grapes (Vitis vinifera). The grape vine is one of the oldest of our cultivated plants, the main object of its culture having been, as now, to obtain from its juice a wine, which is the staple drink of millions of men. Like the wheat plant, its native habitat is unknown, and if neglected by man it degenerates. The limits to the culture of the vine in Europe are (Boussingault) where the mean temperature is from 50° to 62°, and where the mean heat of the summer is from 65° to 67°. Ripe grape juice, when expressed, is found to contain grape sugar, gluten and albumen, tartaric acid and potassa, a volatile oil, tannin, colouring matter, and water. Of dried grapes or raisins there are two kinds, the smaller or Corinthian currants, and the larger, of which there are many varieties.
c. Sugar-yielding Vegetables.—1. Sugar-Cane (Saccharum officinarum). Its ripe juice consists of sugar, gum, acetic acid, malic acid, potassa, &c., after being boiled with lime, and then evaporated, the raw or muscovado sugar being obtained. The impurities are got rid of by means of refining, and crystallized sugar is the result. A portion of the sugar, however, will not crystallize, and constitutes the tenacious fluid called molasses or treacle. Cane sugar is now enormously consumed as an article of food. Although the dietary action of sugar is unquestionably mainly to supply carbon for the purpose of respiration, it would also certainly seem to be able to afford fat. During the time of taking the crop in Jamaica, and when the labour is severe, the work-people use it liberally, and "every negro on the plantations, and every animal, even the dogs, grow fat."
a. Selection of Sugar-yielding Vegetables. Fruits.—1. Apple (Pyrus Malus). A great many varieties of apples are cultivated, some of which, perhaps, differ a little in the relative proportion of their constituents. Their average composition is probably about 85 or 80 per cent. of water, 10 of saccharine (a portion of this, however, gum), rather more than one of malic acid, and a small quantity (perhaps not yet ascertained) of albuminous principles. They likewise contain a volatile matter, salts, and some tannin, as is indicated by the black colour of the juice when cut with a steel knife. In many parts of France and the States of America, apples constitute an important article of food, but unless the amount of albuminous matter is greater than is known, they can only afford carbon to the system. 2. Pear, &c. (Pyrus communis). The pear does not materially differ in chemical constitution from the apple. The varieties of smell and taste probably are dependent upon a little peculiar volatile oil. A jargonelle yields one-fifth of albuminous matter. Plums, cherries, oranges, &c., consist mainly of water, with a small portion of saccharine, a still less of albuminous principles, malic and other acids, and various essential oils upon which their flavours and colours depend. 3. Gooseberries, Currants, &c. (Ribes). All these are tolerably nutritious, containing nearly seven per cent. of saccharine proximate principles, and almost one of albuminous.
d. Products obtained by art from Sugar-yielding Vegetables. With the exception of cane sugar, the products artificially obtained from the preceding sugar-yielding plants are in this country of no more dietetical consequence than the original structure of the vegetables themselves. The theory of the preparation of their products will be found in Section III. In this place their chemical composition, their physiological actions, and their more important varieties, are described. 1. Wine. This beverage consists of grape-juice, the sugar of which has, by the action of its albumen, been made to ferment, to evolve carbonic acid, and to leave behind alcohol. As grape-juice essentially contains tartaric acid, so does wine essentially contain it, and this possession of tartaric acid is in fact the distinguishing mark of wine from other fermented drinks. Wine also contains a volatile oil, which seems to vary much in grapes grown in different climates and on different soils, and this oil is technically called its bouquet. Wine also contains a colouring matter, often tannin, free acids, &c. Wines may be arranged into three classes.—a. Thoroughly fermented wines, in which all the sugar, or nearly all of it, is converted into alcohol and carbonic acid, and the latter product allowed to escape into the air. This class includes port, sherry, burgundy (still), claret, hock (which, however, contains an excess of tartaric or other acid), madeira, and the like. b. Wines not thoroughly fermented, and in which a considerable portion of the sugar remains as undecomposed sugar, or a very tolerable fructosan. Canadian wine, &c. c. Wines thoroughly fermented, but in which some of the carbonic acid is not allowed to escape into the air, but retained in the liquid, as in champagne and sparkling moselle. The proportion of alcohol in different kinds of wine is variable both in the different kinds of wine and in different years. Port usually contains about 25 per cent., claret about 15, and hock and champagne about 12 per cent. In France, however (where the chemical changes that take place in wine-making are thoroughly understood), if the juice of the grape contain too little sugar, beetroot sugar is added, and thus the average strength of French wine is kept up. The great dietetical use of wine, in a mere animal point of view, is to supply carbon for the purpose of preserving the animal heat, and it will be observed that alcoholic compounds are more permanent than most other saccharine or oleaginous matters, and less bulky than these. The action of wine upon the nervous system is also an important one, but one that need not here be entered into. An average yield of wine per acre in France is 170-9 gallons. 2. Cider and Perry. These are produced by converting the sugar of apples and pears into alcohol. This is effected by bruising them, and then mixing up in one pulp the saccharine and albuminous proximate principles. See CIDER. They both, however, differ from wine in containing malic instead of tartaric acid. Besides alcohol, malic acid, and water, cider and perry contain volatile oil, colouring matter, &c. The physiological action of these beverages is probably identical with that of wine, but malic acid fermented drinks are not so much relished as tartaric acid ones. Cider and perry contain from 8 to 9 per cent. of alcohol. 3. Beer, Ale, and Porter. These consist of solutions of the sugar of malt, which has been converted by fermentation into alcohol. They also contain the soluble principles of malt, and for long have been flavoured.
---
1 It is not perhaps sufficiently borne in mind that all articles of food approach more or less to the liquid form, and in this respect only differ from one another in the proportion of water which they contain. And this difference is by no means so great as is generally supposed. Butcher meat may be put down generally as containing about 75 per cent. of water, and beer 95 per cent., turnip nearly 90, &c. &c. with infusion of hops. When coloured black or dark brown by means of charged malt, porter is obtained; when not so coloured, the strong kind constitutes ale, and the weaker beer. All malt fermented liquors differ from wine and cider in containing neither tartaric nor malic acid. London porter contains on an average about 4 per cent. of alcohol; stout, nearly 7; ale, perhaps nearly the same; and porter 2 more or less. Beer that cannot be distinguished from the above is made by employing common sugar instead of sugar of malt. The physiological action of malt liquor is identical with that of wine and cider. (See BREWING.) 4. British Wines. These are the fermented juices of native fruits, to which, as they seldom contain enough sugar to afford the requisite amount of alcohol, sugar is generally artificially added. Most of our fruits contain malic acid, and therefore domestic wines resemble cider; but if argol be added during the fermentation, they then become analogous to grape wine. The demand for them not being at least openly (for a great deal of supposed continental wines of home origin), very great, they are sold at a high price, but they might be produced nearly at cost price. Their physiological action is the same as that of other fermented drinks. 5. Alcohol and spirits. Since the alcohol can be separated from any of the wines, beers, or malt liquors, by a little skillful application of heat, and then condensed in proper vessels. This separated alcohol can also be freed from essential oils and other impurities; and when so freed and mixed with one-half of water, it constitutes proof-spirit, which has a specific gravity of .950. Proof-spirit, however, is not used dietetically, but several varieties of it either naturally or artificially flavoured are extensively consumed. The most important of these are— a. Brandy. When wine is distilled, there comes out along with the alcoholic quantity of water, and of the flavouring matter of the wine. This is brandy. It contains 53 per cent. of alcohol. A fictitious brandy is made from cider, malt, and from fermented potatoes, the latter constituting British brandy. b. Rum and Whisky. These are the distilled spirits of the fermented juice of the sugar cane and of malt (or such as the distiller calls it). Both these are of strength of 11 overproof, and consume (as always in the case of newly-imported rum) much more; and the physiological action of all of them is to supply carbon to the system. They perhaps contain too the carbon in far too concentrated a form for actual use until diluted. They are also powerful stimulants upon the nervous system, this action being probably the result of their carbon-supplying properties. c. Liqueurs. Among these may be noticed—gin, which is spirit flavoured with sugar, and in the better kinds juniper berries, but in the inferior oil of turpentine; curaçao, which is a solution in alcohol of sugar and peach-stones, or other analogous stone fruits, which undergo decomposition with some of the water present, and form a little prussic acid; crème d’absynthe, which is essentially a solution of wormwood in alcohol, sugar, and water. The physiological action of liqueurs is essentially the same as that of spirits. d. Vi- mepor. This is a diluted solution of acetic acid, generally obtained by the farther fermentation of alcohol, but sometimes now by the destructive distillation of wood. Vinegar, properly speaking, is soured wine or ale (alegar), but in practice a solution of sugar is employed to prepare commercial vinegar. This first becomes a solution of alcohol, and then, by obtaining more oxygen, a solution of vinegar. At sea, and in many parts of the continent, vinegar or sour kraut is found very useful as affording a supply of carbon. It has probably also another action; for it contains a supply of vegetable albuminous matter, and thus the longitudinal preservation of health. (This subject will be noticed in Section V.) In this country it is chiefly valued for its antiseptic properties.
e. Leguminous Plants. The leguminous plants used as food in this country agree in their seeds being when ripe exceedingly nutritious, and also in affording an agreeable although less nutritive food when immature. 1. Bean (Vicia faba). The ripened seed of the bean is scarcely ever now avowedly used as human food, although it is a very common practice among millers to mix bean-flour with that of wheat. Bean-meal is extremely nutritious, containing 22 per cent. of albuminous proximate principles, 45 of saccharine, and about 3 of oleaginous. A bushel of good beans weighs 65 lb. Immature beans contain much more water and less albuminous matter. 2. Pea (Pisum sativum). Ripe peas ground into meal, and baked with water or milk, were formerly a very common article of food in Scotland, but peas bread or bannocks are now almost entirely confined to Selkirkshire and a few other localities. Ripe peas are extremely nutritious, containing 22 per cent. of albuminous proximate principles, 45 of saccharine ones, and 2 of oleaginous. They are much used for soup, and very extensively and very beneficially in the royal navy along with fat pork. In this case, contrary to the vulgar opinion, the peas afford the nitrogenous (or what is incorrectly called the nutritious matter, per excellence), and the flesh the carboniferous matter. Beans and peas, perhaps, contain somewhat less phosphates than the cereal grains. 3. French Beans (Phaseolus vulgaris). This, the kidney bean, and another variety, the scarlet, are much cultivated abroad for their ripe seeds, which are very nutritious, but in this country their pods before they are ripe are eaten. They probably contain a very small quantity of salts.
f. Brassicae Vegetables. All the edible members of the cabbage family are wholesome articles of diet, and nutritious, considering the very large proportion of watery fluid which they contain; insomuch as they contain an admixture of saccharine, oleaginous, and albuminous proximate principles. They generally contain a large proportion of sulphur, and, when boiled, this usually combines with the hydrogen, and sulphured hydrogen being formed, and then given rise to the disagreeable smell of water in which cabbages &c., &c., has been boiled. 1. Cabbage (Brassica, various species). Under this head may be comprehended the kinds used for their leaves, kail, hearling cabbage, savoys, and Brussels sprouts, all of which are merely modifications of the same original stock. They contain about 92 per cent. of water, some albuminous principles, some saccharine, and a considerable quantity of oleaginous. Their ash is usually great, and contains a good deal of sulphur, chlorine, phosphorus, soda, potassa, and lime. If cabbage be sliced and pressed, its saccharine principles become converted into lactie acid, and sour kraut is produced. It is a nutritious, and, as will appear in Section V., a wholesome winter dish, but it is little used in this country. 2. Cauliflower. The flower of this species of cabbage is the part used. It is remarkable for containing an immense amount of albuminous matter. 3. Turnips (Brassica rapa). A turnip contains about 89 per cent. of water, 7 of saccharine principles, less than 1 of albuminous, and about 3½ of oil. Its ash is rich in phosphorus. Sea-kale and other vegetables of a somewhat analogous nature are omitted, being only used on a small scale, and being not by accurate analyses of them.
g. Root Crops. 1. Potato (Solanum tuberosum). It is lonely in popular language that the potato can be called a root. It is a tubercle or tuber attached to the root and subterranean stem. A well-grown potato contains about 75 per cent. of water, nearly 20 of saccharine compounds, about 1½ of albuminous, and a small quantity of oleaginous. Its ash, which constitutes on an average at least 1 per cent., contains a very large quantity of potassa, and a considerable amount of phosphorus and sulphur. Potatoes have also been stated to contain citric acid. Potatoes are a nutritious article of food, and capable alone of maintaining life; but their saccharine principles are so much in excess that they ought to be eaten along with articles of food abounding in albuminous and oleaginous principles. It may be here mentioned that pigs fed upon potatoes only become fat, and acquire more fat than the oil of the potatoes can be expected to afford. This is a strong reason for admitting that saccharine proximate principles can be decalcified in the animal economy, and deposited as oleaginous. 2. Beet (Beta vulgaris). The white beet, or mangold-wurzel, is seldom grown for human food, and is not palatable; but the red kind is a common article of diet. This contains about 2 per cent. of albuminous compounds; the amount of oily matter has not yet been ascertained, but the saccharine proximate principles amount to the very large proportion of 15 per cent. For the last-mentioned cause beet (a white variety) is largely grown in France and Belgium, for the purpose of extracting sugar from it. Did the excise regulate it as beer it, it is calculated that sugar might be produced from beet by the farmer of this country, and sold with a profit at 2½d. a pound. If desired, too, all the fermented and distilled drinks of this country might be made from beet sugar in place of barley and other corn. The ash of beet consists mainly of potassa, but it also has something like 10 per cent. of silica. It also contains a considerable portion of other alkalies and alkaline earths, and very little acid. 3. Carrot (Daucus carota). The root of the carrot contains 80 per cent. of water, about 18 of saccharine proximate principles, 1 of albuminous, and a little oil. It has also a volatile oil, and some malic acid. Its ash is considerable, and has much potassa and common salt. 4. Parsnip (Pastinaca sativa). This is a very nutritious root, as it contains 18 per cent. of saccharine principles, and more than 2 of albuminous. The amount of its oleaginous contents and of its ash do not seem to have been ascertained. Owing to its large quantity of sugar it is sometimes fermented; and from this liquid a spirit is also distilled. 5. Girasole, vulgarly Jerusalem Artichoke (Helianthus tuberosus). The tubers contain 1 per cent. of water, 18 of saccharine proximate principles, and 1 of albuminous, and some fat. It has also some citric acid. The ash is pretty considerable. Skirret, scorzonera, and some other roots now little used as food are common in all European countries. These plants are extensively employed as food in many continental states, but are in this country principally used as flavouring agents. They contain albuminous and saccharine matter (probably in very considerable quantity), and a peculiar volatile oil to which they owe their flavour and pungency. This oil appears to relieve the oppression of very hot weather. They contain citric acid, and their ash is rich in Food.
sulphur and phosphorus. The most important of them are the onion and the leek. In this country garlic, rosemary, eschalote, and chives, are little grown. 1. Asparagus vegetables. Asparagus, artichoke, and spinach are nearly entirely composed of water, but they have some saccharine principles, and also peculiar ones to which they owe their characteristic flavour. They probably contain acids. 2. Salad vegetables. Lettuce, celery, endive, &c., perhaps contain a larger proportion of nutrient matter than is generally thought, as they constitute an important article of diet in most southern continental countries. They probably are mainly useful in affording carbon, and thus allowing the eater to dispense with an equivalent of fermented drink. But there does not appear to be any recent analysis of them. 1. Nuts. Nuts are little employed as an article of diet in this country, but in many continental states they form a staple article of food, and are very nutritious. The sweet acorns of the oak, and chiefly those eaten, and contain 47 per cent. of saccharine proximate principles, 15 of albuminous, and 3 of oleaginous. The nuts chiefly eaten in this country are the hazel, the walnut, and the chestnut. 2. Olive oil and vegetables.—1. Olive tree (Olea europaea). The expressed oil of the olive is the only vegetable oil that is dietetically used in an isolated form in this country. The oil is imported from the south of France and Italy, and also, but of inferior quality, from Spain. It consists of oleins and margarine, the former being most abundant. Its alimentary action is to supply carbon. On the Continent it is extensively used with bread and a great many dishes, but in this country its use is confined for the most part to salads. In many parts of Italy and Greece ripe olives are salted, and form a staple food. Unripe olives pickled in an aromatic solution of salt are imported as a luxury to this country. n. Beverage vegetables.—1. Tea (Thea viridis and Thea Bohemica). The prevalent opinion is that black tea is the produce of T. Bohemica, and green of T. viridis, and that the different varieties of each sort depend upon modes of preparation. Notwithstanding the immense consumption of infusion of tea and the very important place that it has taken among the dietetics of this country, there is no accurate analysis of its composition, and consequently of its physiological action, by no means definitive. Tea certainly would appear to contain at least a third of an nutritive principle, about 6 per cent. of saccharine proximate principles in the form of gum, 2 or 3% of volatile matter, upon which its fragrance depends, and 6 of albuminous matter, including about a half per cent. of the peculiar principle called theine. From 45 to 60 per cent. are cellulose or lignin. Even from this very imperfect analysis it will be apparent that an infusion of tea is a nutritious agent, according to the system saccharine and albuminous, and perhaps oleaginous proximate principles. Daily experience proves this; for many people who lead a sedentary life, i.e., who require not very rapid supplies of food, particularly of nitrogen and carbon, keep up their flesh and strength upon a diet of which tea is the principal or a principal part. Indeed a pint of tea of ordinary strength will contain nearly 1 per cent. of albuminous and saccharine compounds, which is not much less than weak soup has. But the principle tea has perhaps some nutritive action with which we are not yet familiar; and this probability is increased when we consider that both tea and chocolate contain it. Liebig's conjecture is that it serves to form bile; but this hypothesis is not likely to find much favour with those English physiologists who regard that bile as an excretion. The action of tea upon the nervous system will be noticed in Section V. Green tea differs from black in containing more volatile oil and more tannin, although this latter is denied. The different commercial kinds of black and green teas differ from one another in their mode of preparation, and in the consequent amount of volatile matter &c., they possess. The following are the most important of them. a. Varieties of Black Tea. a. Bohemian. This, and particularly the kind called Canton bohea, is the refuse and large and coarse leaves of the other black kinds, and is often employed to adulterate other sorts. b. Congou is the full-developed leaf, and is the kind generally used in this country. c. Souchong is another full-developed black-tea leaf, and is distinguished from the previous by the greener colour of its infusion. d. Pekoe is prepared from the undeveloped or unexpanded leaf-bud of the black tea. It is considered the best kind, but is difficult to procure unmixed. b. Varieties of Green Teas.—a. Tsehong is a common kind not much used. It consists of the expanded leaf. b. Hyson consists of the expanded leaf, but is the finest variety of the second or third order. It is a common tea, usually drunk in this country. c. Gunpowder consists of the unopened buds of the young crop of the green tea plant, and, like the pekoe, it is the best of its kind. According to Mr Portman the green tea is a leaf derived in the process of drying by a mixture of indigo, turmeric, and gypsum. 2. Coffee (Coffea arabica)—the berries of the coffee plant with the husk removed. The following analysis of coffee is by Payen:—Cellulose, 34; water, 12; fat, 13; dextrine and other saccharine principles, 15; caseine, legumine, 10; nitrogenous substance, 3; caffeine (theine), 8; oil, 3; ash, 6; other matters, 3. According to this analysis coffee is an extremely nutritious substance. The roasting process, preparatory to its infusion, has no effect upon its nutritive properties, but merely communicates the characteristic flavour and smell. Of the several kinds, the Mocha coffee is the most esteemed. 3. Chicory (Chicorium Intybus). The roasted root of this plant when ground is either mixed with coffee or used alone. We have no recent analysis of it, but we know that it contains a good deal of saccharine principles, and a bitter extractive matter upon which its flavour seems to depend. Experience also teaches that it is perfectly wholesome, and to many people it forms a very palatable beverage. (See Chicory.) 4. Chocolate (Theobroma Cacao). The kernels of the seeds of this plant contain more than 50 per cent. of oleaginous matter, nearly 17 of albuminous, and 18 of saccharine principles. It also possesses a principle called theobromine, analogous to theine. Chocolate is consequently one of the most nutritious articles of food which we possess; but its large quantity of oil makes it indigestible to many persons. It is now advantageously substituted in the navy to supply carbon, in place of the large quantity of rum formerly allowed. There are several modes of preparing the chocolate. The roasted and ground kernels, made into a paste with vanilla, &c., and dried in moulds, constitute chocolate proper. In order to dissolve it, although boiling water it requires the somewhat tedious process of milling, or a patent preparation (there are two or three varieties of it). Fry's chocolate, can be dissolved in water at once. The kernels of the roasted seeds constitute nib coca of the shops. The entire roasted seeds of both kernels and their husks ground down, make cocoa.
B. The varieties of Animals used as Human Alliment.
a. Quadrupeds. The various proximate principles that enter into the several structures of the quadrupeds used as human food are enumerated at p. 753. Herbivorous quadrupeds may almost always be eaten without danger. Sometimes, however, articles of food derived from quadrupeds do become poisonous, or at any rate injurious. The following cases have occasionally been noticed to do so: a. Bacon, and other cured or cooked meat. There are several instances on record of bacon having become somewhat poisonous, although it never perhaps destroyed life. It would appear that decomposition ensues, and that creatine or some analogous compound combines with the salt or with the nitre used in the preserving, and that a deleterious compound is thereby produced. Such an accident, however, is extremely rare. b. Sausages poison. Sausages, at least in Germany, have pretty often acquired poisonous properties, and have occasionally destroyed life. This has generally occurred in long-kept sausages, and usually in the spring season. The decomposing sausages become acid and soft, and acquire a nauseous taste and smell. When, however, they begin to emit sulphuretted hydrogen their poisonous property is lost, but until then they are stated to be very deleterious. On the nature of this sausage poison nothing is known. c. Cheese. Cheese has occasionally in Germany, and perhaps also in Cheshire, acquired poisonous properties, owing probably to some modification of an acetous fermentation. These very rare, and sometimes perhaps not very well-founded, cases of poisoning prove what a certainty in general food derived from quadrupeds may be used. 1. The Ox (Bos taurus). The flesh of the mature ox, or beef, constitutes the greatest by far the greatest proportion of animal food that is eaten. That of the ox is never most esteemed, next that of a heifer that has never been a milk cow, next that of a milk cow, and lastly that of a bull! It may be, however, that part of the dislike felt to the beef of cows and bulls is attributable to these animals not generally being slaughtered until they become so old that the cartilaginous matter dispersed among the muscles is tending to become ossous, and that other earthy deposits are being formed, the result of which is that the meat becomes ill-flavoured and tough. Occasionally some of the small breeds, as the Shetlands, are kept on grass for five years or longer, but by far the greater proportion of oxen are now slaughtered when they are in their third year, and some, as most shorthorns, before they are two years old. In this latter case, and indeed practically in almost all cases, they are now fattened more or less upon turnips, often with the addition of a little oil-cake. And it is quite certain that oxen put up to fatten in hams in October, and slaughtered in a few months, i.e., entirely fattened without grass, afford as good beef as those altogether or entirely (as in the old way) fattened upon grass; and this is exactly in accordance with what our knowledge of the proximate principles of the food of cattle would teach. The order of the different breeds varies a little. That of the Shetland breed is perhaps the most compact, or finest grained as it is called. Next to the Shetland beef, that of the West Highland breed, and of the Welsh (the latter, however, rarely well enough fattened), is probably best; next that of the Galloways, Angus, and those of the Devon breed; and lastly the Herefords and shorthorns. But the last, or shorthorns, will always, in arable districts, form the preponder-
aling breed, from the readiness with which they become maturely fat at an early age upon turnips. Every hundred pounds of a fat ox give its butcher meat (including bones) 57.7 per cent.; tallow, 8.0 per cent.; hide, 5.5 per cent.; entrails and offal, 28.8 per cent. Some of the larger breeds grow to an immense size, attaining a weight of a hundred stones or more; but the beef of such is not in such estimation as that of the smaller kinds. Shetland oxen perhaps do not average twenty stones. The flesh of young bovine animals, which is known as veal, differs from beef in containing less fibrine, and in most parts of it containing considerably more globuline. It has also an appreciable quantity more water, and the meat is whiter owing to the portion of blood lost among its fibres containing a smaller quantity of red globules. About London a calf is usually slaughtered when ten weeks old, when it will weigh as many imperial stones of veal (the offal being omitted). As gelatine is longer in being converted into chyme than fibrine, veal is less readily digested than beef; and the same may be said of the flesh of most young animals.
2. The Sheep (Ovis aries). Mutton differs probably in only some trifling peculiarities from beef. Among these is that its retained blood contains fewer globules, and is therefore not so dark-coloured. Sheep are occasionally kept for four or five years, and occasionally longer, before they are considered fit for the butcher; but the great majority of those sent to the market (and their meat cannot be distinguished from older ones) are not much more than two years old. By far the best mutton is that of the wether, next that of a young ewe, then of an old ewe, and the worst of all that of a tup. The offal of a sheep is to the purchaser as good as food as one to three. Perhaps 120 pounds may be stated as the weight of an ordinary sheep's carcass. Of the various breeds, the Leicester sheep is the largest, and the one that comes earliest to maturity; but its flesh contains a larger and indeed excessive quantity of oleaginous matter, mixed with the muscular fibre; and this renders the meat heavy and unpalatable. But as Leicester sheep soon become fat, even at a very early age, and attain, moreover, a very large size, the breed is a favourite one with the farmers. The Cheviot and Southdown (the two breeds are dietetically analogous) are smaller than the preceding, have darker meat, less fat, and are in every respect superior. The black-faced and Welsh varieties are still smaller, have less fat, and their flesh is much darker. Their flesh, too, has a particular, and, to most people, a very agreeable flavour, owing probably to some peculiar oil in the fat. If well fed, they are, contrary to a popular opinion, in perfection when about two years of age. The flesh of lambs differs from that of sheep in containing more gelatine and water, and less fibrine. It is therefore less easy of digestion.
3. Goat and Kid (Capra hircus). Formerly goat-flesh was much used, and in modern Italy and the Peninsula it still is; but in this country the use of goat-flesh is confined to a few localities in the Highlands and in Wales. Kid-flesh is probably very analogous to that of lamb.
4. Deer (Cervus). Three kinds of venison are used as food in this country—that of the fallow-deer, which is considered the finest; that of the larger stag; and that of the roebuck. All venison is darker than any other meat, owing, probably, to its containing more blood capillaries; and in flavour it resembles that of black-faced sheep. Fallow-deer and stag are considered to be in perfection at four years of age, and are not good food for three or four months after August. Venison has less fat than even black-faced mutton. 5. Hog (Sus scrofa). Of all quadrupeds whose flesh is employed as food, the hog is perhaps the most profitable. In the course of a twelvemonth it attains a large size (often 20 stones, or indeed much more). From its sedentary habits it wastes far less flesh, and consumes less of the carbon of its food, than any other of our domesticated animals, and has likewise a far less proportion of offal to usable meat than any other animal. Thus a pig that, when alive, weighed 199 lbs., yielded a clean carcass that weighed 130 lb. (Septum). A well-fed hog, too, contains a large proportion of oleaginous matter separate from its muscles; and its physiological action when employed as food, in the form of bacon, is mainly to supply carbon. This fat also, when separated from its cellular tissue, differs from that of other animals fats in containing more oleine, and is hence much used in cooking. For the same reason the bacon of hogs when salted is less dry than that of any other cattle's meat. Fresh pork contains about 10 per cent. of albuminous matter, 1½ of salts, and more than 78 of water.
6. Hare (Lepus timidus). From its very active habits, the hare consumes the carbon of its food, and hence deposits no fat. For some reason or other, partly from its never having been bled, the blood is retained in great quantities among the muscles, and this makes the flesh very dark-coloured, but at the same time renders its infusion in soup very nutritious. Hares are not good food from February to August, that being their breeding-time. Hares weigh from 3 or 4 lbs. to 10 or 12. The Alpine hare (Lepus variabilis) is smaller than the common hare, from which it may at once be known by its shorter ears and white fur in winter; and the colour of its flesh is intermediate between that of the common hare and the rabbit.
7. Rabbit (Lepus europaeus). The wild rabbit, like the hare, has no fat, and its flesh is much whiter. It is used almost all the year round. A common weight is about 3 lbs. Two rabbits grow to a much larger size, and often contain mat. Of two good rabbits the eatable portion amounts perhaps to 50 per cent. of the original weight of the animal.
8. Bird. In birds that use active flight, or have been intended to do so, as partridges, fowls, &c., the pectoral muscles are whiter and drier, and are considered better than those which move the legs; but the reverse of this is usually held to be the case in aquatic birds, as ducks, which use principally the leg muscles. The cooking of the entrails of a woodcock, and the inducing in the goose an enlarged and diseased state of the liver, are also practices, but surely not very commendable ones of epicures.
1. Fowl (Gallus domesticus). As compared with beef, the flesh of the fowl contains a little less water, only a fraction per cent. less of albuminous matter, and a greater proportion of salts. Hence, as a flesh-forming product, fowl is more nutritious than beef, but it is deficient in oleaginous or carbon-supplying matter.
2. Turkey (Meleagris gallopavo). Young turkeys about nine months old often weigh from 15 lb. upwards. In chemical composition, and in physiological action the flesh of a turkey is probably nearly identical with that of the common fowl. There are three varieties of turkeys—the black, the white, and the mottled gray. Of these the black is the hardestiest, and is also thought to yield the best food.
3. Guinea-fowl (Numida meleagris) very much resembles the turkey in the properties of its flesh, but owing probably to its semi-wild habits, it has somewhat of a game flavour, and is used as a substitute for game when game is out of season.
4. Peacock (Pavo cristatus). The flesh of the old peafowl is coarse and ill-flavoured, but the young bird is palatable, though rarely used as food.
5. Partridge (Perdix cinerea). The flesh of this and the four following birds has a peculiar flavour, arising doubtless from something introduced into their system by their food. There are two kinds of partridge, the common one and the red-legged partridge. They are only used from September to February. In common with other game, partridges, when long kept, acquire a peculiar smell and bitter flavour, both probably owing to creatine. A partridge, with its feathers and entrails, weighs generally somewhat less than 1 lb. 6. Woodcock (Troglodytes terres). This beautiful and delicate bird is in season from the 20th of August to the end of December. It feeds pretty much on mountain rushes, heath tops, and birch tops, which probably contribute partly to its peculiar flavour. A cock weighs about 1 lb. The female (called a grey hen) weighs about 2 lb.
7. Pheasant (Phasianus colchicus). Except in its larger size, this bird resembles dietetically the partridge. It is in season from the 1st of October to the 24th of February.
8. Grouse and Ptarmigan (Lagopus scoticus and subsp.). The red and white grouse live very much upon heather, which communicates to their flesh its peculiar flavour. Each weighs when killed about 1¼ lb. The capercailzie, Tetrao urogallus, (sometimes called woodland grouse) is perhaps extinct in the country, but sometimes appears in the market. One will weigh from 7 to 12 lbs.
9. Quail (Coturnix vulgaris). This small bird resembles the partridge in flavour, and is in season from May to October.
10. Duck (Anas brachyrhynchos). The flesh of aquatic birds is still darker than that of the game birds noticed above, this being owing to their muscles retaining more blood. Also, when in condition, they have a good deal of fat underneath their skins. As their lean is quite as nutritious as that of fowls and game, and as they contain this oleaginous matter in addition, they are more valuable as nutritive agents. The duck is in best condition in autumn; but ducks are sold earlier. A common weight of a full-grown tame duck is 2½ or 3 lb. The wild duck is smaller. Wild ducks that are tame, and that have usually a fishy taste, derive from the food. The widgeon (Anas penelope) is a species of wild duck. Its flesh is dark and dry, and is by many esteemed, but it is often fishy. Its average weight is 1¾ lb. The teal (Anas crecca) is a still smaller kind of wild duck, the flesh of which is thought much superior to that of the widgeon. It is below 1 lb. in weight. Wildgrouse and teal are fat and in season at the end of the year.
11. Goose (Anser palatinus). In common with that of most aquatic birds, the flesh of the goose seems to contain some peculiar matter, perhaps oleaginous (although this is quite contrary to what happens in birds), but the nature of which is unknown. A goose weighs (without feathers and offal) 6½ lbs. and upwards. The Solan goose, as it is called (Pelicanus bosseanus), is really a pelican. It is caught on the Bass rock in the Firth of Forth and in the Hebrides. It is salted and smoked. The flavour is very fishy. One weighs about 7 lbs. A very analogous bird is the pelgie, which is also salted, but, like the solan goose, it has very fishy taste, and its use as food is almost wholly confined to the poor. They are chiefly captured for the sake of their feathers.
12. Pigeon (Columba). The flesh of the different kinds of pigeon, and of the lark (a bird be- Food.
logging to a different natural family), intermediate between that of poultry and game both in colour and flavour. As rich in albuminous matter it probably ranks high. The flesh of the pigeon indeed contains 21½ per cent. of albuminous matter, and is therefore, as a flesh-forming article of diet, not only more nutritious than beef, but indeed more so than any article of animal food. Only the young (before they fly) of the domesticated pigeons are used at table. 13. Woodcock (Scolopax rusticola). This and the following four birds are waders, and their food consists of aquatic insects, small fish, and the like. Their flesh is considered delicate; but it has not been subjected to analysis. A woodcock weighs 12 oz., and is in season from October to March. The common snipe, jack-snipe, plover, and landrail, are only considered fit for table when fat, which is at the beginning of winter, and during that season. The buzzard, of the family of CROWS, is now nearly or altogether extinct in this country. A few are sometimes yet caught in France, and sell very high. 14. Rook (Corvus frugilegus). The only precious bird that is used for food is the young rook, and this but to a small extent. Its flavour is peculiar, and to many persons far from agreeable. 15. Eggs. The eggs of birds are a rather important article of diet. They resemble one another very much in composition and in their physiological actions, but the several kinds probably do not materially differ from each other, save in containing some small amount of a peculiar volatile oil. A bird's egg essentially consists of shell, a membrane lining it, a white or albumen, and a yolk. Besides these, the yolk contains a membrane, the chalaza, which, as a digestive agent, may be altogether overlooked. The shell is composed of a little animal matter, and phosphates of lime and magnesia, with 97 per cent. of carbonate of lime. The white of a common hen's egg is composed of water, 80°; muscus, 4½; albumen, 15½. It also contains about 4 per cent. of inorganic ingredients (omitted in this analysis). These are sulphur, phosphorus, chlorine, potassa, soda, lime, and magnesia. The yolk contains, water, 53¾; albumen, 17½; oil, 28½. This oil contains 90 per cent. of oleic and only 10 of stearine. There is also a colouring principle, and nearly 6 per cent. of ash, the composition of which is the same as that of the white, but it contains a greater proportion of phosphorus and (according to Liebig) iron. From these analyses it will be seen that eggs are extremely nutritious, being rich in albuminous and oleaginous compounds. The eggs of different birds probably contain a little volatile oil peculiar to each species, by which the characteristic flavour is produced.
c. Reptiles. Although several species of reptiles are used as food in other countries, the only one ever employed in this country is the green turtle (Testudo mydas), which is now regularly imported from the West Indies. It is particularly valued for its green gelatinous substance, commonly but erroneously termed its fat. In this country turtle is almost exclusively made into soup, but in the West Indies it is made into steak, &c. Turtle contains much gelatine and little fibre. It probably, in a nutritive point of view, resembles, but is inferior to, veal. Vipers were formerly used in this country as a remedy for consumption, and a receipt for making viper-broth was once contained in the pharmacopoeia. A species of frog is used as food on the Continent, but it is perhaps never eaten in this country. Indeed here the animal is rare.
d. Fishes. Fish constitute an important and economic article of food. The result of various analyses of fishes is to indicate that their muscles contain nearly but not quite as much of albuminous proximate principles as the flesh of quadrupeds, and fully as much of saline ingredients. Hence as flesh-producing articles of diet, they are nearly equal to meat. In the case of the salmon, trout, salmon, &c., contain also much oleaginous matter; but in others, as cod, haddock, &c., the oil is entirely confined to the liver. This latter class of fishes does not afford so much carbon to the system for respiratory purposes. Fish are in season before spawning, and for some time after they have spawned they are not good; but as most fish resort to the deep water after spawning, they are seldom caught in this state. Not only is recently-spawned fish flabby and tasteless, but it is sometimes positively unwholesome. Fish in tropical countries have sometimes proved poisonous, probably from the nature of their food. It is, however, certain that in this country no fish in season is unwholesome, although the barbel and the pike have for long been considered injurious. The following is a short account of the various species of fish commonly employed as food in Great Britain. 1. Lamprey (Petromyzon marinus). The sea lamprey is an oily and fibrous fish, whose bones are composed of cartilage (having no osseous matter). It is about two feet long. It ascends the rivers from the sea to spawn in spring, and is then in season. It is considered a great delicacy. It is not a common fish in Britain, only occurring, at least abundantly, in some southern rivers, but in many European rivers they occur so plentifully that they are salted and barrelled. There is also another smaller species. 2. Dog-fish (Squalus canicula). This is a member of the shark family, and is very often caught in the herring-sets on the Scottish coasts. It is an oily and fibrous fish, and has a cartilaginous skeleton. Dog-fish are dried and used as winter food by the poorer people of the northern coasts. From their composition they are very nutritious, but they have a strong, disagreeable taste. 3. Skate (Raja batis). The larger skate live in deep water, and are seldom caught; but even the smaller ones in the shallows have been known to weigh 200 lb. Those commonly taken weigh perhaps from 6 to 20 lb. The flesh, from its containing oil, is very nutritious. Skate is in season from July till nearly the end of winter. 4. Thornback (Raja clavata) may be known from the skate by having spines upon the back, and it is smaller, seldom exceeding two feet in length. The young ones are called malle. The flesh resembles that of skate. 5. Sturgeon (Acipenser sturio). This fish sometimes ascends our rivers, and gets entangled in the salmon-nets. These generally are from 4 to 8 feet long (sometimes longer), and occasionally weigh 300 lb. Sturgeon is in season in winter and spring. The skeleton is gelatinous. Its flesh nearly resembles the taste of veal, and is much esteemed. The salted roe of the sturgeon constitutes caviare. It is sometimes imported to this country from Russia. 6. Salmon (Salmo salar). The salmon begins to enter the rivers for the purpose of spawning in autumn, and the parent fish return to the sea during the months of February, March, and April. The hatched young ones follow in April, May, and June. The salmon is in greatest perfection when ascending the rivers; but there is such a demand for them, that it becomes necessary to make enactments rendering the taking of salmon illegal only in certain seasons. All salmon fisheries north of the Tweed close on the 1st of February, and close on the 14th of September. The Tweed fishing opens on the 15th of February, and closes the 15th of October. As the spawn is deposited from October to February, this keeps up the breed; but it is plain that some of these fish will be caught when they are not in season, being weakened by the spawning. From 6 to 10 lb. is a common weight of a salmon, though sometimes this fish attains a much greater weight. An salmon contain oleaginous principles mixed among its albuminous, it is very nutritious. A young salmon returning for the first time to its native river, and weighing from 3 to 6 lb., is a grilse. 7. Bell trout (Salmo erizo). This fish is not in much esteem. Its flesh is white. 8. Sea trout, or salmon trout (Salmo trutta). This fish is about 18 inches long, and weighs about 3 lb. Its flesh is red, and is considered very good. Its migrations and seasons are much similar to those of the salmon. 9. Trout (Salmo fario). This well-known fish is a permanent resident in our rivers. There are several sub-varieties of it, which differ in size. In life it being more or less of a reddish hue; but, in general, it is simply white. The Gillaroo trout differs from the common trout in having a very thick stomach. Trout are in season from February to August, and when full grown are about a foot long, and weigh about 1 lb. Sometimes, particularly in weirs, they attain a much larger size. The char, another variety of the salmon, only occurs in one or two lakes. 10. Smelt (Osmerus eperlanus). This little fish is generally about 8 or 9 inches long, and weighs less than ½ lb. It is remarkable for the great transparency of its body, particularly of its head, and for a peculiar odour, which is thought to resemble that of a cucumber. It is a sea fish, but enters the estuaries to spawn, and stays there from autumn till March. It is in season in November, December, and January. 11. Grayling (Salmo thymallus) is a migrating fish, leaving the sea in the end of autumn to ascend clear rivers, for the purpose of spawning. It should be stated, that there is some doubt if it really does live in the sea. It is in best season at mid-winter, in which month firm and white, is considered to have a very fine flavour. It weighs about as much as a trout. The above six fishes belong to the salmon family, and by naturalists are considered species of the same genus. Salmon. 12. Herring (Clupea harengus). This fish is one of the most useful that approaches our shores. Immense shoals of it appear off the Shetland Islands in April, and are succeeded by a still more immense shoal in June. These shoals extend southward on the east and west coasts of Scotland, and in localities on the eastern coast of England. Their purpose in approaching the estuaries and coasts is to spawn; and, like other fish, they are then in best season. The herring contains a large quantity of oleaginous matter mixed with its albuminous principles, and is very nutritious. A herring is about a foot long, and seldom weighs quite a pound. Herrings are extensively employed both pickled and dried. 13. Pilchard (Clupea pilchardus) very much resembles the herring, but has a rounder body and no teeth. It appears in vast shoals off the Cornish coast in July, and is occasionally caught in more northern seas. The flesh contains more oil than that of the herring. In Cornwall, during their season, they are so extremely cheap as to be sometimes used as a manure. The sardine, which in a pickled state is imported from the Mediterranean, seems to be a small pilchard. The fry of the herring and pilchard are sold indiscriminately under the name of sprats. There is, however, a distinct small species, the Clupea sprattus. All these are pickled red with cochineal or red lead, and sold as pickled anchovies. They may be distinguished by always retaining more or less of their backbone in an oiled state. 14. Shad (Cephalos albus) ascends the Severn and Thames to spawn, and is in season in July. It is in no esteem. The white bait is by many considered to be its fry, although naturalists maintain that it is a distinct species. 15. Anchovy (Cephalos exsiccatus). This little fish is abundant enough on our own coasts for our own supply, but it is imported in a pickled state from the Mediterranean. During the pickling it is boiled, and its backbone is quite dissolved. 16. Pike (Esox lucius) is a fresh-water fish that inhabits our rivers and lakes. A full-grown one weighs from five to a great many pounds, and when under 2 lb. is called a jack. The pike affords a very dry food, and has no oil. The sea pike or gar (Belone vulgaris) is pretty often caught on our coasts, but is not esteemed. Its backbone, as in the viviparous Blenny, becomes green by boiling. 17. Carp (Cyprinus carpio). This fish, before the railways conveyed salt-water fish to inland parts, was in greater esteem than it is now, or probably ever will be again in this country. It is the fish that is most commonly bred in ponds. It weighs from 3 to 20 lb. Carps are in season from June to October. Other fishes of the same family as Cyprinus are all freshwater ones, are sometimes used as food, and may be here mentioned. The barbel inhabits English rivers, and grows to two or three feet long, but it is considered very indifferent food. The little gudgeon is caught during summer in shallow streams, and is regarded as very good. The tench is perhaps the best dietetical fish of the family; it sometimes attains a weight of 4 or 5 lb., but is usually under 1 lb. It is in season from May to October. The bream is another fresh-water fish that inhabits some of our lakes and sluggish rivers. In appearance it almost resembles a flat fish. It is not much esteemed in this country, but in France it is. It spawns in July, and is in season two or three months before, but some regard it as in best season in September just after it has recovered its strength. It weighs from \( \frac{1}{2} \) lb. to 3 or 4 lb. The chub, the roach, and the dace are all river fish, and in little estimation. Their flesh appears to contain an excess of water which perhaps renders them insipid. Walton, however, maintained that the chub owed its bad reputation to ignorant cookery. 19. The Cod family. Members of this very important group afford large and most valuable supplies of food, both in a fresh and salted state. They all contain a due proportion of albuminous matter, but their general effect has no oleaginous principle, all that oil being contained in their livers; although perhaps the milk contains a little. a. Cod (Morus vulgatus, or Gadus morhua, or Merluce). This, one of the most numerous of fishes, is abundant on many of our coasts, and (salted) is exported in abundance from Zetland, Iceland, and Newfoundland. It spawns in spring, and is therefore in season in the winter months, but it appears to recover from spawning sooner than almost any other fish, or at least large fish, and is good during the greater part of summer. It weighs from 6 to 20 lb., and occasionally more. Young cod, or codlings, are far more watery and insipid than the mature cod. Indeed many that are sold as such are really young cod-fish. The swimming bladders of the cod are also salted, and used as food. They consist almost entirely of gelatine. b. Haddock (Morhus capensis, or Gadus capensis) is much smaller than the cod, seldom being longer than 1 ft., or weighing more than from 2 to 3 lb. Its flesh, however, is more delicate than that of the cod. Haddocks are in season from May to September. They are used fresh, slightly salted, or smoked (then called Finnan haddock). c. Ling (Morus vulgaris, or Gadus Morhus) is taken in considerable quantities on our northern and north-eastern coasts. It is much smaller than the cod, and, like it, is eaten both fresh and salted. Contrary to the general opinion, it is in both ways superior to the cod. It spawns in June, and is in season up to the end of May; and it may be known by the sound, by its liver being white. It seems probable that a great many of the so-called cod sounds are ling sounds. The ling attains the same weight as the cod. Dried cod is very often sold as dried ling. d. Turbot and Hake (Bromius vulgaris, and Merluccius vulgaris, or Gadus Resinosa and Gadus Merluccius). The first of these is common in the northland and the other in the south. They are both caught along with ling and cod, and are about the same size. They are generally dried and salted. Another species of the same family, and of the same genus as the turbot, is the coal-fish, which in certain localities, as the Scottish islands, is extensively used. It has various names. In Scotland a young one is called a polley and an old one a sette. Considerable quantities of cod, ling, tusk, hake, and coal-fish are salted and dried, and largely exported. It is called stock-fish; and as most of the water is expelled it is an extremely concentrated and nutritious article of diet, though not very digestible. e. Whiting (Merluccius vulgaris, or Gadus Merlangus) is the most delicate fish of its family. It spawns from March to September, and is therefore in best season during the two first months of the year. It is however pretty good towards the end of the year. In the south of England it is frequently salted, and is there called "back-bone." A whiting is usually about a foot long, and seldom weighs more than 1 lb. 20. The Flat fish. These fishes belong to the Pleuronectidae, and are easily recognised by their flattened form, and by having both their eyes on one side. They are much esteemed for their delicate flavour. The oleaginous principles are confined to their livers, and hence they only furnish albuminous matter, but they contain (at least some of them) more than 20 per cent. of it. a. Plaice (Platessa vulgaris). This and the two following plates are known from the other flat fish by each jaw having a single row of oblique teeth, a spine at the beginning of the anal fin, and a rounded tail. The body is rhomboidal, and the eyes are generally on the right side. The plaice has a smooth body, with six tubercles on its head. It is considered one of the most flabby and worst of the flat fishes. It weighs from \( \frac{1}{2} \) of a lb. to 3 or 4 lb. b. Flounder (Platessa plebeja). The body of the flounder or fluke is smooth, except that it has a band of sharp spines on the side lining the mouth, at the junction of the anal and dorsal fins with the body. It is in season from January to March, and from July to September. c. Bat (Platessa Lemonada) has scales, and is rather lean and thinner than the flounder. It spawns in May, and is out of season in that and the following month. d. Halibut (Hippoglossus vulgaris) may be known by its slender pointed teeth, its elongated body, and lamated tail. It is a large fish, sometimes weighing 200 lb. Its flesh is white and good, although by many not much esteemed. In Scotland it is very frequently sold as turbot. Halibut is best in season in March, April, and May. e. Turbot (Rhombus maximus). The genus rhombus may be known by their thick-set pointed teeth, eyes being generally placed on the left side, and entire mouth. The turbot itself is the most esteemed of all the flat fishes, and may be known by its numerous round and hardish tubercles, particularly on its coloured side. Its under side is cream-coloured, and on this side it has no scales. It has no red spots, which at once distinguishes it from the plaice. It is often two feet long, and weighs from 12 to 20 lb. It appears to be in season all the year round. Its flavour, which is so much esteemed, probably depends upon the crustaceans animals upon which it feeds. Turbot is the dearest of all fish. Among the Scotch fishermen it is called the bonanza fish. f. Brill (Rhombus vulgaris) may be distinguished from the turbot (which as food is altogether) by its not having the tubercles on its coloured side, and by its colouring, which is fuscous, being spotted with brown, yellow, and white. It has scales, too, on both sides. Brill is considerably smaller than turbot, from 1 to 3 lb. being a common weight. It is exposed for sale nearly at all seasons indiscriminately. Its Scotch name is Roman fish. g. Sole (Solea vulgaris). The genus Solea is distinguished from the foregoing by its twisted mouth, and by the jaws of the eye side having no teeth. The sole inhabits the sandy shores of our island, and its meat is very much esteemed, being firm, white, and delicate. It spawns towards the end of February, and is out of season for a few weeks afterwards. A sole weighs from 2 lb. upwards. 21. Eel (Anguilla vulgaris) is one of the fishes that contains oil amongst its muscular texture. In shape it resembles a snake. Its scales are not visible to the naked eye. It is considered to afford good food, but to be difficult of digestion. It is always in season. A pound is a common weight of an eel, although eels very often attain a much larger size. The conger-eel (a permanent inhabitant of salt water) may be known by the margins of its fins being black. It grows to an enormous size, sometimes attaining a weight of 100 lb. In the Peninsula it is fried and powdered for the purpose of putting into ragouts, but it is seldom eaten in Scotland. The little sandeel, common on our sandy shores, is properly a lancelet. 22. Wolf or Cat-fish (Amurichthys vulgaris) may be recognised by its very ugly appearance, and by its dorsal fin extending the whole length of the back. It furnishes, nevertheless, very good food. In Scotland it is improperly sold as John Dory—a fish altogether different. Its common weight is 3 or 4 lb. 23. Perch (Perca fluviatilis). The common perch may be known by the spines of its first dorsal fin. It spawns in the beginning of May, and is out of season for a few weeks afterwards. It is considered one of the best of our fresh-water fishes. Sometimes it attains a weight of several pounds, but one pound is perhaps more than an average. 24. Gurnard (Trigla cuculus). This (like other members of the genus) is common on the English and Irish coasts, weighs about 3 lb., is in season from October to the end of winter, and is considered to afford good food. 25. Red Mullet (Mullus surmuletus) is taken on the south-western coasts of England, but rarely on our northern shores. It is about a foot long, is in best season in May and June (although sold at all seasons), and is regarded as very excellent food. The grey mullet (Mugil cephalus) is a fish of a different genus, and is common on the south and west coast of England. It is 14 feet long, and its flesh is esteemed. The roe is sometimes made into caviare. It is one of the few fishes that are sometimes artificially fattened. 26. Mackerel (Scomber vulgaris) one of the most beautiful and delicious of our fishes, is in season from May to the end of summer. It is more common in the southern than in the northern part of our For some reason not well understood, it is apt to become rapidly paler after it is taken from the sea. An ordinary length is from 12 to 15 (sometimes even 20) inches, and the weight from 1 to 1½ lb. The common mackerel or common tenny (Scomber Thunnus) is sometimes taken on the western coast of Scotland. It is from 3 to 6 feet long, and like sturgeon its flesh resembles that of quadrupeds. It is much esteemed in France. 2. John Dory or Doré (Zeus Faber) is not a common fish, but is occasionally caught on the Cornish and Devonshire coasts. It is a very ugly animal—its head being disproportionately large for its body. It is very much esteemed. It is in season at the end of spring, and commonly weighs 4 or 5 lb. Unless kept for a day or two after being caught, it is tough.
c. Invertebrated Animals.—a. Crustaceous animals having shelly coverings and feet—1. Lobster (Astacus marinus or griseus). This animal, improperly called a shell-fish, inhabits all the northern seas. The full-grown ones are in season from October to May, but smaller ones are eaten all the year round. Lobsters are of a blue-black colour, but when boiled they change to a brighter red. The male is known by its narrower tail, and is most esteemed, particularly during winter, but the female is found superior for some culinary purposes. The muscular parts of the lobster and of the true sea-eating animals contain (we have no exact analysis) fibre, lime, and a peculiar principle to which they probably owe their flavour, and also perhaps their indigestibility. The common crayfish (Astacus pallipes) is similar but inferior to the lobster. 2. Crab (Cancer pagurus). The crab is very abundant on all our rocky shores. It is in season all the year except May, June, and July, although individuals may be obtained fit for the table at any season. The male is usually preferred. 3. Shrimp (Crangon vulgaris). This little animal is common on our sandy shores. It is nearly transparent; but when boiled it becomes of a brownish-red colour. 4. The prawn (Palaeomera serrata) is analogous to the shrimp, but considerably larger. b. Molluscous animals without feet. 1. Oyster (Goreus edulis). This much-esteemed animal is in season from September to April. In May it spawns, and requires all the summer to recruit its condition. Oysters are abundant on our shores, where they stick to rocks or other solid bodies, but they are often collected and fattened in beds. They contain about 12 per cent. of albuminous matters, and are therefore moderately nutritious. 2. Cockle (Cardium edule). This little bivalve burrows into the sand about low-water mark. It is in season in spring, and in autumn. The periwinkle, the whelk, and the periwinkle and whelk, are analogous molluscous animals which are sometimes used as food, chiefly by the common people. 3. Mussels (Mytilus edulis). The sea-mussel lives in flocks on hard ground above low-water mark. It has a peculiar beard by which it sticks to the sand or rock. It is in season in autumn and in spring. It is occasionally poisonous.
f. Insects.—Perhaps with the exception of the locust and some larva no insect is used by man as food. Honey, however, the produce of the bee, is largely used by man. It is probably somewhat modified from its original state in the flower by secretions from the bee. Honey consists of two kinds of sugar, one that will crystallize and therefore be separated in the solid form, and one that will not. It also contains colouring and odorous matter (and some other matters) derived from the flowers upon which the bees feed, and its flavour consequently varies with the plants from which it is gathered. Fermented honey is mead—a drink now little used. Honey may be used as sugar, and supplies the system with carbon.
g. Aqueous Aliment.—Water. As nearly four-fifths of the body of man consist of water, this fluid is a necessary ingredient in his food. All the so-called solid matter that he eats, as has been before stated, contains water abundantly. It is almost certain that a portion of the water taken into the stomach is decomposed, in the system, and yields oxygen and hydrogen. Spring water usually contains a small quantity of saline ingredients derived from the rocks through which it has flowed. When it contains much lime or magnesia it is said to be hard. It often too contains a little organic matter.
h. Condiments. Only one condiment, common salt (the action of which is inexplicable, none of the theories proposed regarding it being satisfactory), is absolutely necessary, but in civilized countries several others are used for the purpose of promoting the appetite and stimulating the digestion. And notwithstanding the stereotyped outcry, there can be no doubt but that if used in moderation they are conducive to health. 1. Common salt is obtained from sea-water and also from salt mines, which are portions of beds of extinct seas. It is indispensable to all food, but it is not known whether it acts as food itself (to afford sodium and chlorine) or for some other purpose. Perhaps it is necessary to form the hydrochloric acid of the stomach. However this may be, every adult man consumes a considerable quantity of it. Two kinds are known in commerce, bay salt or large crystallized salt, and white, basket, or small crystallized salt. Salt is also used for preserving articles of food, and for this purpose the large or bay salt is preferred. Many specimens of salt contain magnesia, but it is essentially composed of chlorine and sodium. The notion that salt or salted meats produce scurvy is erroneous. When this disease breaks out at sea it is not the presence of salted food but the absence of fresh vegetables that excites it. 2. Vinegar. What is sold in the shops as vinegar is diluted acetic acid. Four strengths are sold, called Nos. 18, 20, 22, and 24; No. 22 is the best for domestic purposes. Vinegar is often adulterated with sulphuric acid. A small quantity of it is probably assimilated and supplies the system with carbon. It is frequently flavoured with capsaicin, tarragon, &c.; and pickles, although the vegetables in them go for something, are essentially spiced vinegar. The use of vinegar as an antiseptic will be afterwards considered. When fresh vegetables cannot be regularly obtained, as in voyages, a liberal allowance of vinegar is found very conducive to health (see Section V.). Lemon-juice, which is a diluted solution of citric acid, is also used advantageously for the last-mentioned purpose. 3. Spices. Nearly all the spices are natives of tropical countries, contain aromatic and stimulating essential oils, and yield little or no nutriment, but are unquestionably useful in artificial states of society as promoting appetite and digestion. The most important of these are the peppers, cinnamon, cloves, cardamom, nutmeg, mace, ginger, and pimento. 4. Seasoning and Salting Herbs. These resemble the preceding, but are natives of our own climate. They all contain an essential oil, and unquestionably are, if taken in small quantities, useful. The most common of them are mustard, horse-radish, parsley, tarragon, thyme, sage, mint, savory, and tansy. Capers, which belong to this class, are imported in a salted state from the Levant. 5. Sauces and Compound Condiments. These are also useful flavouring ingredients. Catsup is the seasoned juice of mushrooms, and sometimes of green walnuts. Soy ought to be the juice of the Dolichos Soja, a Japanese plant, but is usually a mixture of fermented pease-juice, catsup, and spices. Anchovy sauce is a solution of anchovies and spices. Curry-powder is a mixture of turmeric, pepper, coriander, ginger, and other flavouring ingredients. The various sauces of the shops have for their base catsup, and their difference consists in their seasoning ingredients.
III.—The Modes of Preparing Food for Human Use, and the rationale of their respective actions.
Most animal and vegetable articles of food are exposed to heat before being used. The effect of this is in albuminous compounds to coagulate the albumen, to promote the formation of osmazome and creatine, and to expel a portion of the water (and fat, if any be present). Heat applied to starchy compounds (if, as is always the case, water be present) causes them to swell, and the starch grains split, and form more or less of a homogeneous mass, and in this way they become more palatable, and also in a state that the digestive juices can act better upon them. And vegetables too, in some manner which it is not easy to explain, lose by the application of heat a great part of their acidity, and sometimes sugar is formed in the process. The operations of cooking may be divided generally into roasting, baking, broiling, frying, boiling, and stewing, and to these may be added the making of bread, the processes connected with viscous fermentation, distillation, and vinegar-making. 1. Roasting. Professor Wallace many years ago made some experiments relative to the loss of weight sustained during this process, and he found that taking 10 lb. joints, the average loss of 100 lb. of beef in roasting was 32 lb., of necks of poultry 27 lb., of kidneys 31 lb., of legs of mutton 24 lb., but in Professor Wallace's experiment fattest meat was probably used than what is customary now, and he did not ascertain the amount of bone. The inquiries of Donovan are more instructive, and the conclusion that he came to is that the loss in roasting in the best piece of beef (as the sirloin), is 19½ per cent., in a three-quarter of lamb 22½, in a goose 19½, in a turkey a little more, in a duck 27½, and in a chicken 14½ per cent. The proportion of the bones in a roasted joint of meat, as ascertained by the same experimenter, is also important. He took a piece of the longer ribs of beef that weighed 11½ lb. This when roasted lost 2 lb. 6 oz., of which 28 oz. were water and 10 fat, &c. The meat was then dissected from the bones, and these were found to weigh 16 oz. Consequently, of the original joint which weighed more than 11½ lb., there was less than 8 lb. of meat; so that if it was bought at 8½ a lb., the roasted beef that could be actually consumed would cost more than 18 a lb. Part of a sirloin of beef that weighed 12 lb., lost by roasting 44 oz., of which 27 were water and 17 fat, &c. The bones weighed 2 lb., and the beef that was actually suitable for eating weighed 7½ lb. Hence if the cost of the joint were at the rate of 8½d. per lb., the value of the roasted meat would be 16½d. per lb. A leg of mutton that weighed when bought 94 lb., lost when roasting 1 lb. of fat, &c., and 14 oz. of water. The bone weighed 16 oz. Only 8 lb. 6 oz. were left, and if the butcher had charged 8d. per lb., the cooked meat would cost more than 1l.d. per lb. Lamb, it was found, lost a little more by roasting than mutton. A goose (not stuffed) roasted for roasting weighed 5½ lb. When roasted it was found to have lost 18 oz., and the bones weighed 4 oz. The edible part that remained, therefore, if the goose sold at 1s. 6d. would be worth 1s. 8d. A turkey properly trussed weighed, including its liver and gizzard, 6 lbs. 11 oz. It lost 20 oz. in roasting, and its skeleton weighed nearly 14 oz., the weight of its edible part being 4 lb. 10 oz. Had the original price of the turkey been 5s., the value of the roasted meat would be 1s. 1d. According to the same authority, a duck when prepared for roasting weighed 1 lb. 10½ oz. In roasting it lost 64 oz., and the bones weighed 4 oz. The edible portion was therefore only about 1 lb.; and if the duck cost 2s. or 1s. 8d., the food it yielded would be this sum per lb. A fowl weighing 1½ lb. lost 3 oz. when roasted, and its skeleton weighed 3 oz. The edible portion therefore was 164 oz. At the price fowls commonly sell at, the cost of the roasted meat would be 1s. 6d. per lb.
2. Baking. The difference between roasting and baking consists in this, that in baking there is no free current of air allowed, the result of which is, that less water is evaporated, and that less oil is expressed out. Hence baked meat is less dry roasted by the hot air, and partly boiled in its own juice and fat. Wallace found that 100 lb. of meat lost in baking 39 lb., being 2 per cent, more than the same quantity, in his experiments, lost when roasted. 3. Bread-making. This is a very rapid mode of roasting, by means of applying more intense heat, the substance to be cooked being placed immediately over instead of before the fire. The albumen at the outside of meat so cooked is immediately coagulated, and a little crust formed, which (unless the meat be pricked with a fork), prevents the escape of much water, fat, or gelatine.
4. Boiling. The following experiments of Donovan's show the loss sustained by boiling various articles of food, and consequently the value of the soup. A piece of flank of beef weighing 10 lb., had 8 oz. of bone. It was boiled and found to lose 23 oz. Supposing, therefore, it cost 6d. per lb., its price when cooked would be 7½d. A leg of mutton weighed 9½ lb. When boiled its bone including its shank weighed 1 lb., and the loss of the meat was 1 lb. 2 oz. If it cost 8d. a lb., it would be worth when boiled 10½d. A ham without its shank that weighed 8 lb., was boiled and skimmed losing 8 oz. by boiling was 1 lb., and its skin likewise losing (a part of its rind) 1 lb. The meat that was left therefore amounted to 6 lb. Had the ham cost 10½d. per lb., when cooked it would be worth 1s. 1¼d. per lb. A piece of bacon that previously weighed 4 lb., lost by boiling 4 oz. The bone weighed 2½ oz., and the skin and lard by boiling amounted to ¾ lb. The edible portion weighed 3 lb. 1 oz. If it originally cost 2d. a lb., the meat when cooked would be worth 10½d. per lb. A turkey that weighed 4½ lb., and which cost 3s. 6d., lost 12 oz. in boiling; and its bones weighed 10 oz. The edible portion therefore amounted to 3 lb. 2 oz., and had cost at the rate of 13½d. per lb. A chicken that weighed 1½ lb., lost 3½ oz. by boiling, and its bones weighed 4 oz. This left 12½ oz. of meat, which, if the chicken cost 1s. 6d., was worth nearly 2s. per lb. A turbot that weighed 9 lb. and cost 7s., lost in boiling 8 oz. and its bones weighed 21 oz. Hence its edible part after cooking amounted to 11½d. per lb. The following table prepared from the same source shows the average loss from roasting and boiling:
| Loss in roasting beef | Loss in boiling salt beef | |----------------------|-------------------------| | 19½ | 15 | | mutton | mutton | | 24½ | 10 | | turkey | turkey | | 20½ | 16 | | chicken | chicken | | 14½ | 13½ |
a. Soup-making. Soup is a decoction in water of a good deal of gelatine, some fibrine, albumen, phosphate of lime, other salts, and oxammonia. The fibrine, however, rises to the surface and is skimmed off. Of course, vegetables, as will be seen by a reference to their chemical composition, yield exactly the same kind of soup as butcher meat or fish. In practice, however, a mixture of animal and vegetable matter well boiled is found to afford the most economical soup. Animal soup probably contains little albumen, but when vegetables are boiled down, their albuminous proximate principles are quite mixed up with the fluid. This is probably the reason that the vegetable or nearly vegetable soups so much employed by the labouring classes in Scotland and France are found to produce in their consumers such a high degree of material vigour. Soup also contains some creatine and certainly generally lactic acid; and Liebig affirms that the addition of the latter (in the form of sour krent) improves the flavour of the soup; but the experience of English gastronomists at least scarcely confirms this opinion. The same distinguished chemist also affirms that chloride of potassium improves the piquancy of soup. 4. Steaming. By this method of preparing meat, less of the principle of the meat are absorbed by the surrounding menstrum, and the greater portion of the gelatine in particular remains among the coagulated albumen. Hence stew-
ing is an economical form of cooking. 5. Frying. In this culinary process it is probable that a portion of the glycerine of the fat is decomposed, and that a new substance or principle is formed, which principle seems somewhat difficult of digestion. 6. Bread-making. Common fermented wheaten bread is made by mixing flour, water, salt, and some albuminous matter, either yeast or leaven (e.g., a piece of old bread), and placing the compound in a warmish situation. Two catalytic actions very soon begin; a portion, and the greater portion, of the sugar, is converted into alcohol and carbonic acid; the greater part of the former of these compounds is evaporated (by the after heat of the baking), but the carbonic acid gas is retained among the tenacious gluten, and produces the vesicular structure that characterizes ordinary fermented bread. Then some of the starch is likewise converted into sugar. If the alcoholic fermentation be allowed to go on too long, it runs into the acetone, and the bread consequently becomes sour. It is said that the salt employed in the mixture, besides communicating flavour, communicates stiffness to the dough, probably by abstracting some of its water. After these changes have taken place the bread is baked, the result being that a considerable quantity of water and the alcohol are driven off and the albumen is coagulated. 100 lb. of flour produce 139½ lb. of bread; but the apparent gain is derived from the water that is used—the flour being diminished in quantity by the conversion of part of it into alcohol and carbonic acid. The baker often adds potato-flour and also alum to his dough. The latter adulteration makes the loaf whiter, but is highly injurious to the consumer. Brown or household bread differs from white bread, in the flour of which it is made containing more or less of bran. Rolls are made to ferment more rapidly than loaf bread by adding more ferment, and hence are more porous. None but wheat flour is used in this country for making leavened bread, but formerly rye or black bread, still so common abroad, was extensively employed. For many years occasional attempts have been made to make bread spongy by adding to the dough, in place of yeast, hydrochloric acid and carbonate of soda. Carbonic acid is given off, which mixes among the gluten and makes the bread light, and chloride of sodium or common salt is left behind. In this manner the waste caused by the conversion of the sugar into alcohol is avoided. Properly prepared gingerbread is rendered porous in a similar manner. Carbonate of potassa is frequently added to the dough. Treated with free acid which combines with the potassa salt and liberates the carbonic acid. Some kinds of light bread are rendered porous by adding carbonate of ammonia to the dough, the ammonia of which is expelled by the heat of the oven; and some cakes are made light by the addition of carbonate of magnesia. Wheat flour is also used unfermented in various ways—as in pastry, biscuits, macaroons, &c., &c. (See Baking). 7. Wine and Vinegar Making. Grape wine is now rarely made in this country, as the grape grown out of doors rarely contains sugar to afford an alcoholic mixture that is strong enough. Raisin wine, however, it is believed, is pretty extensively made, and the greater part of it sold as sherry. Domestic wines are made by fermenting the juices of currents, gooseberries, and other fruits, with the addition of sugar and tartaric acid, and frequently a little spirit. Vinegar is oxidated alcohol, and is usually prepared by fermenting a saccharine solution, and then exposing the diluted alcohol thereby obtained to the air.
IV.—The Modes of Preserving Articles of Food from Decomposition.
The elements that compose all living structures, vegetable or animal, are grouped together in obedience to certain laws of vital affinity. But this obedience is transitory, and whenever life departs from an animal or plant, they tend to, and ultimately always do, return to the dead world, and become subject to the laws of chemistry. The series of changes that they undergo in thus passing from one arrangement of their elements to another is termed putrefaction, and consists mainly in the following processes:—The carbon absorbs oxygen from the air, and carbonic acid is formed and given off; some of the hydrogen and oxygen unite together and form water, and another portion of the hydrogen unites with the nitrogen (if any be present) and forms ammonia, while another portion of it unites respectively with carbon, phosphorus, and sulphur, the results being carburetted, phosphuretted, and sulphuretted hydrogen gases, the last of which communicates a great part of the disagreeable odour of putrefying food. Very probably, too, creatine, &c., are formed and decomposed during the putrefying process. An albuminous substance putrefies the most rapidly, owing to its albuminous compounds acting catalytically as a ferment. A purely saccharine or oleaginous substance putrefies much more slowly. Sugar is only resolved into water and carburetted hydrogen, and hence has little bad smell. It often happens that previously converted into vinegar. In order, however, that putrefaction take place, two conditions are necessary—in the first place, water must be present, and it is indispensable, at least for rapid putrefaction, 1st, That the alimentary matter be exposed to oxygen, or, what comes to the same thing, to air. This enables us to understand why one article of food putrefies so much sooner than another. If a piece of meat, for example, be exposed to the atmosphere, say in the month of September, along with a bone and a potato, the meat being fully exposed to the air, and containing a large proportion of albumen, moisture, and water, soon putrefies; while the other two, the one containing little water and the other protected from the air by its skin, retain their structure for a number of months. 2d, Heat, in virtue of the power it possesses of removing its atoms from one another, strongly predisposes to putrefaction; so also does the presence of any other putrefying substance, which seems to act catalytically. This action may be counteracted by excluding the air or the water, and also by the use of certain antiseptic substances, as salt, sugar, vinegar, &c., the action of most of which, however, is to be explained by the property that they possess of acting upon air or of abstracting water. If meat appear likely to become tainted, it may be preserved for a few days by any of the following means:—It may be kept enveloped in a wet cloth, which in consequence of the evaporation produces cold; it may be slightly smeared over with pyrolygous acid; it may be surrounded by a little powdered charcoal, which absorbs the sulphured hydrogen and other decomposing gases; or it may be kept in an atmosphere of creosote. This last seems to be a most effectual plan, and Dr Stenhouse of Glasgow reports most favourably of its success, not only with himself, but also with a butcher who tried it. 3d. Airless localities, such as casks, jars, &c., afford tolerable for a very considerable time, by evaporating the water they contain by the action of heat. Indeed something of this kind is occasionally witnessed in nature; and in hot sandy deserts where rain seldom or never falls, the bodies of camels and of travellers are found undecomposed, and have probably been so for ages. Advantage is seldom taken in this country to preserve vegetables in this manner, although the kiln-drying of wheat and other grains is partly a process of this nature, and the usual manner of preserving sweet or pot-herbs is essentially so. Abroad, and sometimes perhaps here, apples and pears are sliced and put into a heated oven, so as to expel the water, and the fruit thus dried may be kept for a considerable time. The flesh of mammals is rarely so preserved in this country, but the Indians thus prepare pemmican, an imitation of which made of beef, but which is generally also smoked, has been employed in our Arctic expeditions. It was in this way the buccaneers preserved their beef. Portable soup is essentially a dried meat. It is made by preparing a strong beef soup from a bony piece, as the leg of an ox, skimming off the fat, and then evaporating the water. According to Liebig, the test for distinguishing the true extract of flesh from the spurious imitation which consists almost entirely of gelatine, is that 80 per cent. of the true extract is soluble in alcohol, and only 4 per cent. of the gelatinous cake. Many articles may be preserved from putrefaction by means of solidifying the water they contain by applying cold. Water becomes solid at 32°, and when the water of a structure has been thus converted into ice all putrefaction is impossible. Thus the fossil meat that was found imbedded in Siberia was quite fresh although it had probably been so imbedded for thousands of years. This mode of preserving food, however, is not applicable to vegetables, for the starch of a frozen vegetable is almost certain to be converted by frost into sugar. But in cold countries, as in the north of Russia, Canada, &c., it is very extensively used as a means of preserving fish, whole animals being often frozen, and thus kept throughout winter. If, however, frozen meat be not gradually and slowly thawed by being at first immersed in cold water, putrefaction comes on so rapidly that the meat is unpalatable. In this country butcher meat is seldom or never preserved in this manner; but fish, especially salmon, is so on a very large scale. Every salmon-fishery of any consequence in Scotland has an ice-house, and the salmon intended for the English markets are packed in the ice and thereby frozen or nearly frozen. In this manner they reach their destination in a fresh state. The fishermen also preserve their own catch in a similar manner.
Articles of food may also be preserved from putrefaction by excluding them from air. This has long been done in a great variety of ways. The oldest and most imperfect of these is potting, which is usually performed by beating up the meat into a paste, then putting it into jars and covering it up with clarified butter. Another variety of meat similarly preserved is the common sausage. The exclusion of air, however, is only partial, and consequently sausages do not keep very long. This defect is obviated in the Bologna sausage by smoking the meat of which it is made. Long ago, Mr Boyle tried the experiment of keeping food in an exhausted receiver, and he found that no putrefaction took place; but the plan of preserving food by thoroughly excluding the air was scarcely carried into practice until 1810, when M. Appert (who seems to have been quite ignorant of Boyle's experiments) published his plan of effecting this, and received a reward for it from the French government. Since then his method, with some modifications of detail, has been extensively pursued. It consists in first coagulating the albumen of the animal and vegetable structure to be preserved by boiling it, and thus attaining two ends, the coagulated albumen being far less disposed to putrefy than uncoagulated, and a great portion of air being driven out; secondly, in putting the coagulated food in jars or bottles (the latter in the case of liquids), and plunging these into boiling water, which expels a great portion of the remaining air contained in the food. Some air indeed always remains, but the oxygen of most of it combines with carbon and forms carbolic acid; why, it is not very easy to say. The jars are then hermetically sealed, and their imperviousness to air tested. At present, instead of bottles the canisters are employed, and these have the additional advantage of collapsing a little from atmospheric pressure. As, however, some air is left, the food eventually putrefies. Meat prepared in this manner sells from 1s. 3d. to 2s. 2½d., soup from 2s. upwards per quart, and milk at about 1s. a pint. The various plans followed for the preservation of eggs all depend upon the exclusion of air. A simple plan is to stop up the pores of the shell by smearing the eggs with some unctuous substance, as suet. Another mode is to pack the eggs in bran, salt, &c. A third is to boil them for a few seconds, and thus form a small layer of coagulated albumen underneath the shell. It should be observed that eggs are very apt to contract an unpleasant flavour from the readiness with which they absorb offensive effluvia. Thus, when packed in old straw, their flavour is frequently much worse than that of food preserved by the more effectual means of salting of salt. This plan has been practised from time immemorial, and in this country, before the turnip culture allowed the farmer to furnish continuous supplies of butcher meat, was even much more extensively used than now. One part of the action of the salt is to abstract a great part of the water, another is to abstract the juices from the outside (thereby forming brine), and thus to envelope the meat in a hardened case which more or less excludes the air; but there is probably some other property of the salt of an antiseptic nature, the exact nature of which is not known. All articles of food preserved by salt retain a portion of the salt in their texture, they are always a little firmer in their structure than the same foods unsalted. In the ordinary manner of salting animal food, about one-third of the juices, including some of the soluble albumen, passes off into the brine. If this statement be correct salted meat is of course much less nutritious than fresh. Liebig proposes to employ a salt that contains chlorides of calcium and magnesium. The lime and magnesia, according to him, unite with the phosphates of the tissue and cover the meat with a crust or white film of phosphate of lime and magnesia which actually keeps in the place. It is generally considered among practical salters that the salt which occurs in large crystals or bay salt is preferable to the finer kind, and as bay salt is not so pure as the fine, this would appear to confirm Liebig's hypothesis. In salting a piece of meat or of fish, the salt is generally rubbed in, and the brine allowed to run off, and in this case it is then dried and frequently smoked. When the food is kept immersed in the brine it is said to be pickled. Vegetables are sometimes salted dry, but generally pickled. It is also very common to add nitrate of potassa or saltpetre in the salting of flesh. This substance acts as an antiseptic by abstracting water, but it also forms a compound of a red colour with meat. Sugar, another antiseptic, is also now commonly added to the salt and salt brine, and frequently also spices for the purpose of communicating a flavour. 5. Articles of food may be preserved from putrefaction by means of sugar alone. Sugar is a powerful antiseptic, part of its action being owing to its abstraction of water; but it also possesses a peculiar but inexplicable power of preventing a substance with which it is placed in contact from obtaining oxygen. Sugar, however, although much employed mixed with salt, is seldom used alone to preserve animal food; some fish, as salmon and mackerel, are occasionally so preserved, but the great application of sugar in this respect is to vegetables. Sugar is also employed in making syrup (strong enough to prevent it running into the alcoholic fermentation); sometimes the water of the syrup is evaporated, the result being a dry confect or a candy; sometimes a portion of the water of a fruit is evaporated, and then sugar added, the result being a jam when it is pretty moist, and a marmalade when it is drier; and sometimes only the juice of a fruit is preserved, and in this case the product is called a jelly. Honey is equally efficacious as sugar in these respects, but it is seldom so used. Fruits preserved by means of honey used formerly to be called confections. 6. Articles of food may also be preserved by means of pyroligous and acetic acids. Under this head may not only be included the direct application of the acids, but also the employment of creosote and of wood smoke. The action of all these is the same, and consists in coagulating the albumen at the surface, and thereby preventing the access of air. The application of creosote to meat to protect it for a few days has been noticed above; but if meat be dipped in it and then dried, it may be kept for a very long time without decomposing; but this process is rarely adopted in this country. The smoke of burning wood, however (which contains creosote), is very much employed to cure both meat and fish. These substances are usually first salted and then exposed to the smoke of bark or oak-wood, to which juniper, rosemary, &c., are sometimes added. Bacon, hams, tongues, pieces of beef, herrings, salmon (then called kippered salmon), are extensively treated in this manner, and haddock (then named Finnan or Flodden) is sometimes smoked and eaten alone, without any application of salt. It is now known, that if a piece of meat or fish be slightly smeared over with pyrolytic acid, or dipped in it for a few seconds, it is protected from putrefaction, and has the same flavour as smoked food. Common vinegar obtained from alcohol is not used for preserving any article of food derived from a mammal, but it is used to coagulate the albumen of some fish, as salmon and herrings, and of some molluscs, as oysters. The antiseptic properties of vinegar, however, are principally taken advantage of for the purpose of preserving vegetables. As vegetables contain much water, it is necessary either to use a strong vinegar, or to abstract a portion of the water of the vegetable intended to be acted upon. In practice the latter is done by adding salt to the vegetable, and pouring off the brine that is in that manner obtained. Sour kraut so much used abroad, is also in part a pickle, but the cabbage of it would seem to undergo also a fermentation of its own, in which probably lactic acid is formed. 7. Articles of food may also be preserved in alcohol, which acts by coagulating the albumen; but owing to its expense it is never applied to animal food, and only on a small scale for preserving some of the finer fruits.
V.—The Principles of Dietetics.
The human body consists of the following elementary bodies variously combined together,—oxygen, hydrogen, nitrogen, carbon, sulphur, phosphorus, potassium, sodium, calcium, magnesium, chlorine, and iron. These are probably arranged so as to form water, albuminous proximate principles, oleaginous ones, and to a very small extent saccharine ones, all these being grouped together so as to form flesh, glands, bones, &c. All these elements must be taken into the human body in the form of food, and they must exist in the combinations that they have acquired in vegetables or in animal flesh that has been nourished on vegetables, either directly or indirectly, through the medium of a herbivorous feeding animal. But even when an adult man has taken into his stomach the amount of the above elements that he requires, either in the form of vegetable or animal nutriment, and has by means of his organs of digestion and assimilation converted them into his own oleaginous, albuminous, and other principles, these elements can only remain a part of his frame for a very limited time. After a short interval they become putrid and poisonous, and are cast out as excrements. The weight of these excretions corresponds each day in a healthy individual, exactly with the weight lost by the feet through under the guidance of appetite, is taken up in the same period, with this exception, that a larger amount of carbon in the form of wine, alcohol, fat, &c., may be likewise received into the system to serve as fuel, combine with oxygen, and so keep up the animal heat. In a growing person, as a child, there is required an amount of food which, besides replenishing the daily waste, will also afford material for the new structure that is daily being added to the bulk. It may be also stated, that the rapidity with which the structures are wasted and the carbon consumed, depends very much on the amount of exercise that is taken; and accordingly the daily quantity of food varies in different individuals, and in the same individuals in different circumstances.
From the structure of the teeth, and from the relative conformation of the stomach and intestines, comparative physiologists judge that man is omnivorous, and facts in his habits certainly confirm the conclusion. Many men, as the natives of Bengal and other countries, live entirely upon vegetables; and others, as the Esquimaux, altogether upon animal food, while most examples of the human species use a mixed diet of animal and vegetable matter. In the majority of people it is most convenient to obtain a portion of their supply of carbon from fermented drinks, and from drinks distilled from such. The number of people who abstain from fermented drinks, however, proves that the requisite amount of carbon may be obtained from saccharine or oleaginous compounds, the deficiency being in general, probably, made up from the latter. There appears, nevertheless, to be little doubt but that, in order to attain the full perfection of the mental and bodily faculties, an admixture of animal and vegetable articles of food is essential; and also that a portion of the carbonaceous supply should be derived from alcoholic drinks. Those who live almost entirely upon animal food become stunted in growth, and liable to ravages of scurvy, and their mental and moral faculties are blunted and sensually those who consume only vegetables are generally inactive and listless, and incapable of either active bodily or mental labour; and independently of other objections, there is reason to fear the offspring of those who abstain entirely from fermented drinks, because in their education or two generations in mind and body. It is probably in this last-mentioned manner that the decadence of the different Mohammedan nations and races is to be accounted for, at least in part.
The subject of digestion will be fully treated of in another place; but it is necessary here to notice some facts connected with it that have a more immediate bearing upon dietetics. Plants, and the classes of animals living fixed to a spot, appear to be almost constantly taking in food, and have no receptacle in which to close it. The higher animals, as man, have however such, or a stomach which receives and contains the various articles of food for some time before they are assimilated. The relative capacity of this stomach varies much in the different classes of animals. In the carnivorous, who live upon food that contains little water, and is therefore concentrated, it is small; in the herbivorous, with the members of which the contrary is the case, it is very large, while in man it is midway between the two. The proximate principles of animals and plants, when taken into this stomach, are acted upon by the gastric juice there secreted, (and which juice contains water, hydrochloric acid, and pepsin,) and converted into a pulpy mass, chyme, from which the albuminous, oleaginous, and saccharine principles (the last of which is called chyle) are absorbed and poured into the blood to be expended in nourishing and warming the body. The length of time that it takes for food to be converted into chyme varies according to the kind of food taken, in different individuals, and in the same individuals at different times; for digestion, although an organic process, is nevertheless influenced by states of the nervous system. Dr Beaumont made some experiments upon a man who had an opening into his stomach from his side—the consequence of a wound. He ascertained the length of time occupied by various articles of food to become digested. The following are extracts from his table, but they only give approximate results, and it is certain that many of them did not hold good in the majority of people:
| Article | hr. min. | |------------------|----------| | Boiled rice | 1 | | Boiled eggs | 3 | | Boiled pork | 1 | | Boiled mutton | 3 | | Roasted mutton | 3 | | Fried fish | 3 | | Cheese | 3 | | Mutton soup | 3 | | Bread | 3 | | Broiled veal | 4 | | Boiled fowl | 4 | | Roasted do | 4 | | Roasted salt beef| 4 | | Boiled pork | 4 | | Fried veal | 4 | | Boiled cabbage | 5 | | Roast pork | 5 |
From more satisfactory and often repeated dietetic experiments it appears certain that food is more rapidly converted into chyme when cooked than when raw, although some people appear to be able to digest fruit, salads, and raw oysters with rapidity. Salted meat appears to be longer of digestion than unsalted, and so also do pickled vegetables than fresh ones. Animal food is certainly more rapidly digested when in a state of incipient putrefaction than when subject to the contraction of toxicity. The meat of young animals takes longer to become converted into chyme than that of old of the same kind, owing to the gelatine that it contains requiring a long time to digest. The old opinion that cooked vegetables are more difficult of digestion than cooked animal substance would seem to be quite unfounded.
With regard to the intervals between meals and the times of taking food, strong statements have been made by writers upon dietetics which have no very exact foundation. Some carnivorous animals, as serpents, only require a meal once in several weeks, but carnivorous mammals seem to need a supply of food once in the 24 hours. Dogs, for example, require feeding once a day; but it is found with regard to them, and also to hyenas, &c., kept in zoological gardens (but it must be remembered that these animals get very little real active exercise), that two meals a day decidedly injure their health. On the other hand, graminivorous animals, as sheep, oxen, &c., eat almost incessantly. The conformation of the digestive organs of man, and his omnivorous habit, would indicate a mean between these two. But he has unquestionably a singular power of accommodating himself to circumstances with regard to the interval between his meals. It is plain that one meal a day was and even yet is not a very uncommon regimen. But now, especially among those classes that labour principally with their minds, the principal meal or dinner is taken late in the day, and a smaller meal or breakfast is taken immediately after rising. Members of those classes who physically labour also take at least two meals, but such often work for an hour or two before breakfasting, and appear none the worse for their procrastination. But most of the members of the first-mentioned class feel their energies and strength not entirely restored until some food has been taken, and that if they do not breakfast immediately after dressing, they experience a sensation of lassitude and muscular debility during the whole day. If only two full meals are taken in the day, and the one immediately after rising in the morning, it seems unreasonable enough to eat the latter, or dinner, in the evening. It is sometimes assumed that digestion should never stop in the human stomach, so that as breakfast is soon digested dinner should be taken in the middle of the day, but there seems to be no good reason for admitting this as a general rule. Many people, however, do feel exhausted if they do not take in the middle of the day a small lunch, and experience shows that if too much albuminous matter be not then taken into the system the habit is at any rate quite innocuous. The meal called tea, taken soon after dinner, is in fact a part of dinner. To those who dine late, suppers, beyond very slight ones, seem unnecessary, and are certainly often injurious.
There is another important alimentary law which applies to human dietetics. It is, that without a due and pretty regular allowance of fresh vegetable food, not only does the strength become impaired, but the very dangerous disease of scurvy is induced. Before the present system of agriculture was established this pestilence was rare in early spring and latter part of winter, and still later it played fearful ravages among sailors during long voyages. Since, however, there have been supplies of potatoes and other vegetables during winter on land, and since some vegetable juices have been regularly supplied to sailors, the disease has nearly vanished, and has only occurred occasionally where fresh vegetables have been for some time neglected to be consumed.
The following then may be laid down as established facts regarding the philosophy of the food of man—1. Articles containing albuminous proximate principles must be frequently received into the system to supply the continual waste of the economy, and these may be derived from either the animal or vegetable world. A mixture of the two, although the amount of nutriment and relative digestibility be nearly equal, seems the best. 2. A large amount of food rich in carbon must be also regularly taken into the system for respiratory purposes, and this may be done by means of oleaginous animal or vegetable principles, or saccharine principles, or by means of substances derived from saccharine ones. 3. It is indispensable to take, besides, some fresh vegetables or vegetable acids. 4. Almost all articles of food are more digestible when cooked than when raw. 5. The hours of taking food and the intervals between meals are, with a moderate limit, of little consequence; and an approximation to regularity from day to day seems to be the most important matter to aim at.
ADULTERATIONS OF. It has long been known that very fraudulent, and sometimes very unwholesome, adulterations of food are extensively practised; but until lately it was not easy in all cases to pronounce decidedly on the nature of the fraud that had been committed. Now, however, by means of the microscope and the chemist's test tube, there is little difficulty in so doing, and many important disclosures have by their use been made. The proprietors of the Lancet employed Dr Hassall (one of the most accomplished of the microscopic observers of our day) to thoroughly investigate the subject, and his reports have appeared from time to time in that periodical. As he published the names of the different tradespeople from whom he bought spurious or adulterated articles of food, and as none of them have succeeded in disproving (and indeed very few have ventured to contradict) any of the statements, the thorough accuracy of the report may be relied upon, and the facts in this article are based upon it. Although Dr Hassall purchased the articles of food that he examined from London shopkeepers, there can be no doubt that the same adulterations will be found in the provinces. Indeed, the great adulterators are the wholesale houses, who supply indiscriminately London and country shopkeepers.
1. Adulterations of articles of food not avowedly of a manufactured nature.—Milk, usually supposed to be much adulterated, is comparatively little so. In towns water is generally added to it, and a portion of the cream is likewise abstracted; but chalk, gum, &c., are very rarely employed (as has often been alleged) to give the appearance of greater strength. Salted butter is frequently melted, and when in that state has water added to it. In this manner fifty per cent. of water may, it is said, be incorporated. Lard is mixed up with water, potato flour, and refuse mutton fat, and the amount of the potato starch has sometimes been known to amount to twenty per cent. Oatmeal, in London, and perhaps elsewhere, is extensively mixed with barley meal; the latter, as it contains so much more water, only selling for about half the price of the former; but wheat flour, unless it contains alum (as it perhaps does), seems quite pure. Arrowroot is adulterated to a large extent. Of 50 samples, bought from London shops, Dr Hassall found 22 to be impure; of these, 10 scarcely contained any arrowroot at all, but were made up of sago, tapioca, and potato starch; while in the others there was a considerable admixture of these cheaper articles. Raw sugar has many impurities, among which the immense number of acari with which it swarms are the most disgusting, but it is also extensively mixed with flour (apparently to make impure dark sugar appear like purer and lighter-coloured), and perhaps with other foreign ingredients. Lead-sugar seems sufficiently pure. Tea is in a lamentable state, for it is meddled with by both the Chinese and those through whose hands it passes here. With regard to black tea, Dickson maintains that the Chinese mix with their exports of tea to this country many millions of pounds of leaves of other plants, which they mix with genuine tea plants. In other respects, however (and even, perhaps, in this), the Chinese do not adulterate the common black teas, as Congou, Souchong, and ordinary Pekoe; but other descriptions, as scented Orange Pekoe and Caper, are, almost without exception, impure, the former by being glazed with black-lead, and the Caper by being extensively mixed with Paddy and Lie tea (i.e., an imitation of tea leaves obtained from other plants), or by not containing any tea leaves at all, but altogether other leaves sprinkled with tea dust, and made up into little masses by means of gum, and which masses are glazed with plumbago, turmeric or Prussian blue, and the whole sprinkled over with mica, &c. But imitation black teas are also entirely made up of the leaves of indigenous plants of this country, as those of sycamore and horse-chestnut, broken down, sprinkled with catechu (to communicate tannin), dried, and coated with gum. But a still more common imposition is to purchase exhausted tea leaves (which are sold at about 3½ d. a lb.) from hotel-keepers and the like, and attempt to imitate fresh tea by admixture with catechu, gum, sulphate of iron (to strike a dark colour with the catechu), Prussian blue, logwood, black-lead, tate, &c. Some of these adulterations—as the Prussian blue, for example—are calculated to have serious effects upon the health. Green teas are more adulterated than black ones, a really unadulterated specimen being very rarely to be met with. They are mixed in China with leaves of other plants, are subsequently glazed with gum, Prussian blue, turmeric, and various other substances, some of which are very unwholesome. Imitation green teas of British manufacture are also occasionally, perhaps even often, exposed for sale. Coffee, until the government interfered to prohibit the sale of a mixture of coffee and chicory as "coffee," almost invariably contained a large, and sometimes an amazingly large, admixture of chicory. Several contained in addition roasted corn, beans, potatoes, sometimes red ferruginous earths, and other impurities. Ground chicory itself, so much employed to secretly mix with coffee, is itself an article extremely adulterated. Nearly a half of the specimens examined were largely so, the substances employed for the purpose being roasted wheat, ground acorns, mangold-wurzel, carrots, mahogany sawdust, and ferruginous earths—the two latter for the purpose of communicating colour. Cocoa and chocolate are no better, the great majority of samples of them being largely mixed with sugar, and with potato, and other starch; but a worse adulteration is, that they also contain colouring earthly matter (usually, probably, of a ferruginous nature, but which sometimes perhaps have for ingredients red lead and vermillion, two very dangerous ingredients), and tallow and other fats seem to be sometimes mixed with them. The acknowledged substitutes for tea, coffee, and cocoa, as Revalenta, Semola, Prince of Wales' Food, &c., &c., are very familiar substances. Dr Barry's much vaunted "Revalenta" is a mixture of pounded lentils and barley meal, and the syrup that accompanies it is treacle. Bullock's "Semola" is the gluten of wheat with a little starch; and "the Prince of Wales' Food" is potato flour. Ground ginger is very commonly, and very largely adulterated. Dr Hassall found three-fifths of his samples to be so, the substances admixed being sago-meal, potato flour, common flour, ground rice, cayenne pepper, and mustard husks.