,UC-NRLF ^B 2L1 b03 9^. (^ LIBRARY OF THE ' University of California. CALIFORNIA WINE MAKERS' CORPORATION ^Accession 8 73.3.Q Cla&s MANUALS OP HEALTH. FOOD. /f MANUALS OF HEALTH, FOOD. BY ALBERT J. BERNAYS, Ph.D., F.C.S. PEOFESSOB OP CHEMISTET AND OF TEACTICAL CHEMISTRY AT ST. THOMAS'b HOSPITAL MEDICAL AND SUBGICAL COLLEGE, MEMBEB OF THE BOTAL INSTITUTION, ETC., ETC. PUBLISHED UNDER THE DIBBCTION OF THE COMMITTEE OF GENERAL LITERATURE AND EDUCATION APPOINTED BY THE SOCIETY FOB PROMOTING CHRISTIAN KNOWLEDGE. LONl SOCIETY FOR PROMOTING CHRISTIAN KNOWLEDGE. SOLD AT THE DEPOSITORIES : 77, GBEAT QUEEN STREET, LINCOLN* S-INN FIELDS J 4, ROYAL EXCHANGE; 48, PICCADILLY; AND BY ALL BOOKSELLERS. New York : Pott, Young, & Co. The favour with whicli a work of mine on House- hold Chemistry was received in 1851, both by the Press and the Public, is sufficient evidence that there was a demand for a work of the kind. The titles of the several chapters were imitated from the late Professor Liebig's Chemistry of Food. The sixth edition of my book was printed in 1867; in the seventh edition I dropped the articles on food. The present volume is largely based upon my Household Chemistry, supplemented by increased experience, both analytically and otherwise. 87230 Digitized by the Internet Archive in 2007 with funding from IVIicrosoft Corporation http://www.archive.org/details/foodalbertOObernrich CONTENTS. Chap. Page I. Water as an Article of Food 7 II. Starches of different Kinds 16 III. The Sugars 25 IV. The Fats, with the Influence of Cooking... 31 V. The Chemistry of Fermented Liquors 36 VI. The Vegetable Acids 46 VII. Eggs, Albumen, and Milk 50 VIII. Bread and Meats 58 IX. Gelatin and Bones, with something about the Juices of Meats and Liebig's Beef-Tea ... 66 X. The Chemistry of Food 71 XL The Drinks of the Breakfast-table 77 XII. Fruits; a Variety of Drink 86 XIII. Vegetables, and the Part they play as Food 91 XIV. On Fish, Flesh, and Fowl : Modes of Cooking ; Cold Meats and Salads 98 XV. On the relative Digestibility of Food 107 XVL Conclusion 112 ON FOOD, CHAPTEH I. WATER AS AN ARTICLE OF FOOD. 1. The influence of food cannot be understood with- out reference to water and its effects upon the body. Water forms about 79 parts out of 100 of the weight of the blood, and is necessary for the carrying of the food from one part of the body to another. The far- ther necessity for water is shown by the fact that a fullgrown man loses daily about eighty-four ounces, one-half of which is given off by the skin and lungs. 2. The water thus lost by perspiration and other- wise has, of course, to be replaced from without. Now, the skin has a certain, though very limited, power of absorbing moisture. Dr. Madden found that a man in a warm bath absorbed about one ounce and a half of water in half an hour. If the fluid of the body has been previously diminished by exhalation, the absorption is much more active. A man who had lost three pounds by perspiration, during one and a half hour's labour in a dry atmosphere, regained eight ounces in a warm bath in half an hour. This absorb- ent power of the skin may occasionally be turned to account. Thus, a patient, who was quite unable to take food, has been kept alive by baths of milk and water. 3. The skin has a very important duty to perform, b LOSS OF WATER BY THE SKIN. on which health is greatly dependent. This duty is the throwing off of perspiration, and is brought about by the little tubes or " pores " existing in every part of the skin. Commencing at the surface, the tubes pass inwards, twisted like a corkscrew, to the under- side of the true skin, where they end in little balls or glands, in which the perspiratory material is formed. The number of these pores is so great that 3,528 have been counted in a square inch on the palm of the hand. Assuming each of these pores to be a quarter of an inch in length, and the surface of the body of a man to contain 2,500 square inches, the number of pores has been calculated at seven millions, and their length nearly 28 miles ! This length of drainage, this breathing from the skin, is one of the ordained means of throwing off waste material which would be inju- rious to the body, and for keeping it at an equal temperature. The simplest and best means of pre- serving the skin in health is by bathing and washing with soap and water, and rubbing with a rough towel. 4. Every one knows the effect of a " close '^ day, although he may not know the cause. It is simply due to the fact that the air has taken up as much moisture as it can hold, when it is said to be saturated : we then find it difficult to get rid of our own moisture. On the other hand, a dry atmosphere parches the surfaces both of the skin and lungs, and often brings about a chill, owing to the rapid evaporation. 5. As a rule, the amount of water contained in any tissue is in proportion to its vital activity. For instance, the brain, nerves, and muscles are watery in comparison to bones, skin, nails, and hair. In vege- tables we observe the same facts : any portions that have left off playing an active part in growth or in nourishment, become hard and solid, like the heart- WATER AS AN ARTICLE OF FOOD. wood in trees ; and yet we find many vege tables that can bear the loss of their water, either in part or wholly, without being killed. Mosses have been kept dry for years, and yet have lived again under the freshening influence of water. The long sleep of corn seeds for many hundreds of years in mummies, and their germination by heat and moisture, is an instance of the same kind. And even more striking still, because occurring in a more highly organized plant, is the drying up of the beautiful rose of Jericho ; when it is parched by the burning sun, it contracts into a ball, and in that state is wafted hither and thither by the winds, till some friendly moisture again tempts it to expand its leaves and rose-like flowers. Such examples show the necessity of water for anything like vital activity, though life may be sustained, for a time at least, without it. 6. Water forms a large proportioii of our food, as may be seen by the following Table ; — Mushrooms . 96-0 92-0 Lean beef and mutton... Greengages ,c 720 Cabbages .... 71-0 Beer and ale. 91-0 SO-0 Tripe Cream 68-0 Green -top turnips 660 Carrots 87-6 Veal 63-0 Milk 87-5 Sweet potatoes 59-0 Beetroot .... ! 87-0 Pork fat 39-5 Champignons Kohlrabi .... Wheaten bread, crust turnips 860 85-0 and crumb 38-0 White Swede Kidney -beans ) Treacle ) 230 Pears 84-0 Currants .... 81-5 Arrowroot 18-0 Peaches 80-2 Haricots 160 Artichokes . 79-0 Flour and oatmeal 150 Fish 78-0 77-0 Peas 13-0 Salmon Rice 12-5 Potatoes .... 75-0 Lentils 120 Cherries and apricots Butter 7-0 Ox-liver 74-0 Indian corn or maize . . . 60 Eggs 10 WATER FOR DRINKING AND COOKING. 7. Water never occurs in Nature without containing certain gases and salts : it is Nature's great solvent. According to the absence or presence of certain salts, water is either soft or hard. For cooking it is impos- sible to employ too soft a water, especially as regards salts of lime and magnesia (par. 11), such a one as but slightly curdles soap. 8. Mere clearness, or, in other words, perfect trans- parency, although an essential of good drinking-water, is no proof of purity ; and it should also be remem- bered that ordinary filtration cannot remove dissolved impurities. The qualifications of a good drinking- water are peculiar, but may be discerned. If a careful examination be made of the sap of young vegetables, it will be found that only a soft water, containing but small amounts of salts of the metals potassium, sodium, calcium, and magnesium, is present. Also, if inquiry be made into the habits of cattle, it will be found that, where they can choose for themselves, they will select that water which, having no fault on the score of clearness, is soft, and therefore but slightly curdles soap. For what is the object of the water we drink 1 Partly to act as a carrier by which fresh supplies of food are introduced into the body, and its used-up materials removed ; partly to enter bodily into the con- struction of the tissues. As food should be cooked with especial reference to its digestibility, or, in other words, to its solubility, so the water we drink should be com- paratively soft, as then its solvent powers are greatest. 9. Water, to be good for drinking, should be bright and clear as crystal, when poured into a tumbler. Both oxygen and carbonic acid gas should be present in solution, and, for this reason, water should not be allowed to stand long in a warm room, nor in sunlight, nor be drawn long before it is wanted. It should also be cool, and possess no decided taste. WATER AS AN ARTICLE OP FOOD. 11 The best drinking-waters are those from various German mineral springs. Not only are they very refreshing, but they are free from the various con- taminations which are so universal in all our English river- waters, and which render them unfit for drink- ing in times of epidemics. 10. If a person has a tendency to become stout, he should restrict himself in the use of water, as indeed in the use of drinks of all kinds. But, if the body is broken down by excesses of any kind, the copious use of soft water, externally and internally, under proper medical treatment, is strongly recommended. 11. The presence of salts of lime detracts materially from the value of water for cooking purposes. The great disadvantage is this ; that, when it boils, just when the vegetable is beginning to be thoroughly penetrated by it, suddenly there is a plentiful separa- tion of carbonate of lime (a kind of chalk) in every pore. The vegetable is thus hardened by it, instead of being rendered soft and succulent, and the chalk, having found a congenial resting-place, will not be disturbed by any amount of boiling, however long continued. Such water is said to be temporarily hard. One piece of advice can be given : such water can be softened by boiling, and, in such a case, water from the boiler, in which the water has been boiled for at least a quarter of an hour, should be used for cooking ; otherwise the vegetables should be steamed, and not be brought into actual contact with the water, 12. The insides of kettles and boilers used for boil- ing water, should from time to time be examined, as, of course, the salts which are separated, collect at the bottom and form a crust or fur. As this crust is a very bad conductor of heat, it retards greatly the act of boiling. 12 BICARBONATE OP LIME IN WATERS. Such springs as deposit carbonate of lime are often known as **petrifyiDg wells." In Italy, a building- stone in common nse, known as "Travertine," and composed altogether of carbonate of lime, is deposited from "volcanic waters." An example occurs in a lake existing in the Campagna of Rome, at a spot on which the Romans erected baths. "Reeds, lichens, confervse, and a vast mass of aquatic vegetation," says Sir H. Davy, " here find a rich repast, and grow in the utmost luxuriance, forming a number of float- ing islands on its surface" (fig. 1). Fig. 1. 13. It is worthy of remark that one, at leasfc, of the salts combined in water, viz. chloride of sodium WATER AS AN ARTICLE OF FOOD. 13 (common salt)^ is of essential service to digestion. For, not only is this the source partially of the gastric juice, but it is itself a powerful solvent of albumen.* So necessary is salt to health, and especially to the young, that all vegetables should be strewn with salt before they are cooked or steamed. It should not be left to choice whether our children eat salt, or not. 14. The impurities of vegetable and animal origin in water — the so-called organic impurities — are of seri- ous importance, as these are they which often set up changes in the blood. When present, even in minutest quantities, they render water totally unfit for drink- ing. Now, next to long-continued boiling, and in some cases in addition to it, there are few better, and certainly no pleasanter, purifiers of such water than toast. The freshly-made carbon on its surface is but little inferior to animal charcoal. The toast should be thin and crisp, and toasted externally almost to charring ; the resulting toast-and-water (made with boiling water), will then be of a bright amber-colour, and perfectly clear. 15. One piece of advice may be given with reference to tap-waters. The water should be allowed to run to waste for the space of a minute, before any is drawn for use. Thus, whatever may have collected in the pipes will be efiectually discharged. Of course the cisterns should be cleansed every three or four months, as the chief sources of impurity will be found in them, But the sooner the intermittent supply of water in towns ceases, the better. 16. Water, especially when made cheering by car- bonic acid gas, as is the case with many mineral waters, is the only natural quencher of thirst. Though dependent, of course, on the deficiency of * White of egg is the typical form of albumen. 14 WATER A COMPOUND OF OXYGEN AND HYDROGEN. water in tlie body generally, thirst is produced directly by an impression on the nerves of the stomach and throat. Hence it may be satisfied, for a time at least, by a counter-impression on these nerves. On a long summer's walk, there is no better drink than water, and the practice of quenching the thirst in warm climates, by alcoholic drinks, is worse than useless. 17. Water is a compound of two elements. Hydro- gen and Oxygen ; it is an oxide of hydrogen. !N'ow hydrogen is most easily prepared from its oxide, water. If water be boiled in the retort a, fig. 2, Fig. 2. and its steam passed over red-hot iron-filings contained in the gun-barrel 5, hydrogen passes over, and may be collected in the tube c, inverted over water. The iron at a red heat takes the oxygen, and becomes oxide of iron : hydrogen is set free as a colourless gas, which burns in air with a pale flame, and becomes ngain hydrogen oxide, or water. The composition Ox water may be shown by experiment. " If the two poles of a galvanic battery, terminating in platinum ends, be plunged into water (acidulated with about one-third of hydrogen sulphate, so as to make it a better con- ductor of electricity), bubbles of gas are seen to arise WATER AS AN ARTICLE OF FOOD, 15 at each pole or wire. If these gases are collected, by placing tubes filled with the same acidulated water (fig. 3) on the ends of each pole, twice as much gas will be found in one tube as in the other. At the positive ( + ) pole, oxy- gen is collected; at the negative (— ) hydrogen, the latter being in amount double that of the former. This experi- ment shows water to be a compound of two volumes of hydrogen and one volume of oxygen." (See *' Chemistry," in the Manuals of elementary Science, published by the Society for Promoting Christian Knowledge.) 18. Water boils at a temperature of 100° Centigrade, or 212° Fahrenheit. ^'^' ^ When the steam has an elastic force just sufficient to balance and overcome the pressure of the air upon its surface, the water from which the steam rises is said to boil. The temperature of boiling water is a fixed point, and has been adopted as such in all thermometers. And here another fact meets us, which is well worthy of observation, and especially to those to whom the cost of a fire is of importance. It does not matter, except as regards waste, how fierce the fire may be under the kettle or other vessel in which the water may be heated, — it can but boil. When once water boils, it requires but a very small fire to keep it boiling, or on the boil. In the open air, the boiling point cannot be raised, because the pressure of the atmosphere cannot be increased. But, if water be boiled in a close vessel, as in the boiler of the steam-engine, the steam which is pro- duced, having no means of escape until it can lift a certain weight, and continually increasing in quantity, gradually raises the pressure more and more to any B 16 HIGH-PRESSURE STEAM. PAPIN's DIGESTER. point that may be desired ; and, with the pressure, the temperature. Now the steam which rises frotn the water under pressure is called high-pressTire steam. 19. Temperature and pressure are, indeed, in such close relationship, that one might judge of the pressure by the thermometer. The temperature of the steam is always the same as that of the water from which it rises. Advantage is frequently taken of this fact, when a steady temperature above 100°C. is required. It is turned to account in Papin's digester, so much used in the making of soups, and in the extraction of gelatin from bones. This consists of a strong iron saucepan, the lid of which is supplied with a safety-valve, by which the pressure of steam can be regulated, and the vessel prevented from blowing up. Some such apparatus becomes absolutely necessary to persons living on high mountains, as the temperature at which the water there boils is too low for common cooking purposes. CHAPTER U. STARCHES OF DIFFERENT KINDS. 20. Enough will have been said to show the import- ance of water. To those who have been prepared for the study of food by an elementary course of chemistry, it will be no new information to be told that many articles of daily food contain hydrogen and oxygen, not as water, but in the same proportions as we find CAKBON IN STARCH, WITH HYDROGEN AND OXYGEN. 17 them in water. [Water is hydrogen oxide, HgO in it the hydrogen is already completely oxydized, or burnt ; for which reason water can be employed for putting out a fire.] 21. The various starches and sugars afford good illustrations of bodies which consist of carbon and the elements of water ; the latter iu the proportion of two atoms of hydrogen to every one of oxygen. Carbon has been already mentioned in carbonic acid, a chemical compound of carbon with oxygen. It is an element, best represented in the diamond, which is found crystallized in regular forms, all derived from the cube (fig. 4), or the octahedron (fig. 5). Carbon also Figs. 4 and 5. occurs as graphite ; but it is rather in the variety of car- bon known as charcoal that carbon would be separated from a lump of sugar by burning. A piece of wood is known to char, or blacken, when strongly heated ; and so also do sugar, starch, and such-like foods. In toasting, for making toast-and-water, we char the bread ; in fact, produce a surface-charcoal. Thus we may also char meat, when we say it is burnt, because meat contains carbon. 22, Just as a piece of charcoal requires to be heated B 2 18 COMBUSTION OF CARBON IN OXYGEN. to redness before it will burn in oxygen, so it must be understood, that all the varieties of food mentioned in this chapter contain in themselves none of the necessary oxygen for the combustion of the carbon. And just as heat is produced in a fireplace by the burning or oxidation of charcoal, so likewise is heat produced in the human body by the burning of the carbon of the sugars and starches, 23. It must not be thought necessary that a body should actually burn before it can give off heat. We may have true combustion, attended with heat, but without light. In fact the heat of the body is kept up principally by the union of the oxygen of the air with the carbon and the hydrogen of our food. The carbon unites with oxygen to form carbonic acid, and the hydrogen with oxygen to form water. 24. A full-grown healthy man emits 8J ounces of carbon daily from his lungs; not as carbon, but oxydized, as carbonic acid. By the oxygen of the air, every time a breath is drawn, a portion of the carbon of the blood becomes carbonic acid. Breathed air contains one hundred times as much carbonic acid as the fresh air before it ia breathed. This breathed air will neither support combustion, nor serve any longer for respiration. If we breathe through a glass tube into a bottle containing lime-water (made by shaking a little slaked lime with water, and pouring off, after settlement, the clear fluid), the latter becomes milky from the formation of carbonate of lime, or chalk. The act is represented in fig. 6. Now air in its ordinary condition would not produce this change, on account of the exceedingly small quantity of carbonic acid contained in it. Thus is a certain portion of air spoilt by every breath drawn. [Twelve parts by weight of carbon unite with thirty- two parts by weight of oxygen, to form forty-four STARCH AND WOOD MOST ABUNDANT. 19 parts by weight of carbonic acid. Carbonic acid, a com- pound of one atom of carbon with two atoms of oxygen, is represented by the symbol CO2.] 25. Not that the starches (and sugars) are alone of use in keeping up the heat of the body (animal heat), though this is their chief function. They are also concerned in the pro- duction of fat ; and from this fact we obtain a hint to be moderate in the use of such foods, if we are naturally in- clined to stoutness. 26. Next to wood, starch is the most abundant product of the vegetable kingdom. The seeds of the various grasses contain it largely, as do also those of peas, Fig. 6. Fig. 7. Tubers of the Common Potato. 20 VARIETIES OF STARCH GRANULES. beans, lentils, ex- TROSE, CoH^2^6)^20.] Many ripe fruits, of an acid character, such as pine-apples, strawberries, peaches, apricots, and citrons, contain sucrose, as well as laevulose. The latter sugar is not nearly so sweet as sucrose. The conversion of lsevulose into dextrose is often witnessed in honey, which undergoes a change by long keeping into a mass of crystalline dextrose ; if such honey be washed with alcohol, laevulose is removed in solution. 43. Lactose is the chemical name for "sugar of milk," the word being derived from lac, milk. It is the sweetening principle which, in cow's milk, amounts to between 4i to 5 per cent. After the milk has been curdled, and the curd separated, the whey holds the sugar in solution j it is evaporated to the consistency of syrup, small sticks of wood being introduced as centres round which the lactose crystallizes. Sugar of milk is seen in white semi-transparent masses, which are hard and gritty between the teeth, and require from Rye to six parts of cold water for solution. Of course, then, it does not possess anything like the sweetening power either of sucrose or dextrose. Never- theless its value as an article of food is as great as that of starch or of sucrose, taken weight for weight. [Lactose, C12H24O12, is insoluble in alcohol and ether. Its composition shows it to consist of carbon and the elements of water.] SUGARS IN FRUITS, VEGETABLES, AND SEEDS. 31 44. The following amounts of sugar have been found in various products taken in 100 parts. Muscovado sugar 96-0 Treacle 790 Figs 62-5 Cherries 18*1 Peaches 16*5 Apricots and greengages 11*6 Pears ) « . Buttermilk) ^^ Gooseberries 6*2 Carrots 6'1 Parsnips 5-8 Oafcmeal 5*4 Skim-milk 6*2 Milk 4-9 Barley-meal 4*8 Wheaten flour 4*2 Wheaten bread 3-6 Potatoes 3'2 Turnips 31 Peas 2-0 Maize ) - "^ CHAPTER IV. *IilE FATS, WITH THE INFLUENCE OF COOKING. 45. However disinclined the reader may be to enter into any study of the chemical composition of food, he must become acquainted with the classification usually adopted, or he would fail to understand the nature of the various foods. 46. Starches, sugars, and fats are bodies, which consist of the three elements, carhon, hydrogen, and oxygen. The starches and sugars, as we have seen, consist of carbon and the elements of water ; but the fats contain not nearly sufficient oxygen to burn their hydrogen, let alone their carbon, so that the oxygen and the hydrogen are not in the proportions to form water. To do this, there must be two atoms of hydrogen for every atom of oxygen. 47. Starches, sugars, and fats are called respiratory c 32 RESPIRATORY OR CARBONACEOUS FOODS. or carbonaceous foods. They are respiratory, because they more readily keep up the auimal heat of the body ; carbonaceous, because carbon is the chief element, and to distinguish them from those which contain nitrogen. The respiratory foods assist in keeping up the supply of energy, and play their part, together with the nitrogenous, or nitrogen-containmg materials, in forming a proper diet. For it may be safely said, neither is the one without the other : they are never quite separated the one from the other, except by the art of man. 48. Lean meat would afford the best illustration of nitrogenous food, and yet even the leanest sort con- tains some fat. While it is necessary to distinguish between carbonaceous and nitrogenous foods, we return to the subject of this chapter — the fats. 49. There are certain general characters attachiug to the fats and oils. They are lighter than, and perfectly insoluble in water, but soluble in ether and in benzol. They possess different degrees of solidity. They have the property of staining paper, and render- ing it semi-transparent. 50. Oils consist chiefly of olein, which is a colourless liquid, and remains so at temperatures above the freezing-point of water. Olive-oil, which is so much used in making salads, furnishes the best idea of olein. Now olein is also contained in the solid fats, and their hardness depends upon the greater or less amount of olein present in them ; the more there is of olein, the less solid is the fat. 51. Stearin is the most abundant of the solid con- stituents of fats. In mutton suet we find three distinct fats — stearin, olein, and palmitin; but stearin is the chief. When heated with about ten times its weight of ether, the whole dissolves ; but the stearin crystallizes out, on cooling, in pearly scales. THE FATS, WITH THE INFLUENCE OF COOKING. 33 52. Palmitin, which has been mentioned in the former paragraph, is contained abundantly in palm- oil, from which it has received its name ; it is also a chief constituent of cocoa-nut oil. It resembles stearin, but has a lower melting-point, and a some- what different chemical composition. The principal solid constituent of butter is palmitin, just as olein is its chief liquid component. 53. Lard is the soft fat of the pig, in which the olein predominates over the stearin and palmitin. 54. Fats and oils may be heated to about 260°C. without undergoing any great change ; but above that temperature they give off vapours of a most irritating character. 55. The fat best known in cooking, and the most esteemed, is butter. It is obtained from milk, chiefly from cows, which contains on an average 3 per cent, of it. As is well known, it is separated from the milk by churning. If the butter is for keeping, the more completely the butter-milk has been removed the better, and the addition of a little salt is a distinct improvement. The odour and flavour of the butter are not due to the olein and palmitin, of which it chiefly consists, but to the presence of small quantities of other fats, especially of butyrin. Unless it contain a little water — say 8 per cent. — butter is not so palatable as it might be ; as water is cheap, it is more than probable that a larger quantity will be met with, even to the extent of 22 per cent. It is con- sidered to be adulterated when mixed with more than 15 per cent., although it is obviously adulterated when it contains as much. 5G. Cream contains about 30 per cent., Cheshire cheese 25 per cent., while cheese from skim-milk only contains about 7 per cent, of butter fat. 57. In vegetables, the amount of fat naturally c2 34 AMOUNTS OF FAT IN DIFFERENT FOODS. present signifies little or nothing. It becomes, how- ever, a matter of great importance in animal food, and, indeed, in all kinds of food in the cooking of which the temperature is raised much above the boiling-point of water. Fats are not so easy of digestion when they have been strongly heated. By far the most wholesome form in which butter can be employed at table is as melted. 58. " ' " " ' amount of fat in different kinds of food. Per Butter 85 to Bacon Pork (fat) Mutton (fat) The following Table will give some idea of the Beef (fat Cheese, Cheddar Egg, yolk of Tripe Veal Eels , Egp:, white and yolk Maize Mackerel Skim-cheese cent. 94-00 6700 50-00 40-00 3000 16-00 1400 1000 800 7-00 Per cent. Herring 600 Salmon 5-50 Ox-liver 4-00 Milk 3-CO Codfish >. Rye / Peas r \ 200 Barley-meal V Wheaten flour J Rice 0-70 Parsnips 0-50 Soles 0-25 59. All the fats above-named are compounds of fatty acids with glycerin. Thus, stearin is a stearate of glycerin, olein, an oleate of glycerin, palmitin, a palmitate, and butyrin a butyrate of glycerin. When a mixture of stearin and water is forced under strong pressure through tubes heated nearly to redness, the fat is broken up into glycerin and stearic acid ; the glycerin dissolves in the water, the fatty acid does not. Palmitin, the solid portion of palm-oil (which is obtained by heating the crushed fruit of a palm-tree), is thus broken up into the fatty acid, palmitic acid, and into glycerin. As palmitic acid possesses a higher melting-point than the palmitin from which it GLYCERIN IN FATS AND OILS. 35 is derived, it is more valued in the manufacture of candles. [Glycerin is the sweet principle of fats and oils. As its name indicates, it is a sweet {glykys^ sweet) syrup-like liquid, heavier than water, and capable of being mixed with it in any proportions. The chemical composition of fats may be judged by the following symbolical representations: — glycerin, C3llg03, the basis of all these fats, is combined respectively with butyric acid, C^HgO^, palmitic acid, C^eH3202, STEARIC ACID, C^gll3g02, and with oleic acid, CigHs^Og. But it must not be imagined that any of these fats consists simply of one molecule (as the smallest quantity imaginable of these substances would be written) of glycerin and one of the fatty acid ! No ; three atoms of the acid and one atom of glycerin, by the loss of three atoms of water, become respec- tively butyrin, palmitin, stearin, and oleic. So we should write butyrin, Q^.Oj^^^O)^, or Cj^IIggOg ; palmitin, C3H5O (Ci(jH3iO)3, or C^^H^gOc ; stearin C3HA,(Ci8H350)3, or C,,HnoO,; olein, C3HA (Ci8H330)3, or CgyH^^j^Og. It will be understood, at least, that in any of these compounds there is only oxygen enough to burn 12 atoms of hydrogen, as 6 atoms of oxygen are contained in 6 atoms of water, or HYDROGEN OXIDE, HgO.] 60. As an article of diet the fats are of nearly double the value of sugar and starch. And, when perfectly dried, they are two and a half times as valuable. In cold weather, food rich in fat is gene- rally acceptable, and, from its composition, the reason is clear. There is a large amount of hydrogen upon which the oxygen of the air can readily act ; by its oxidation more heat is produced than by starch and sugar, weight for weight, as would be understood at once by using starch or sugar, as against fat 36 FERMENTATION. GLUCOSE INTO ALCOHOL. for fuel. With what a bright, cheery flame would a lump of bacon burn ! What a dull kind of fuel, com- paratively, would starch be. And yet, and for the same reasons, both would make a good fire. CHAPTEK V. THE CHEMISTRY OF FERMENTED LIQUORS. 61. The foundation of all beverages is necessarily water. Entering largely into the composition of the human body, it is the only natural solvent of foods and quencher of thirst. And yet, man, at an early period of his existence, learned to be dissatisfied with it, and turned his ingenuity to produce some more stimulating liquor. " Man," says Pliny, " is so skilful in flattering his vices, that he has even found means to render water poisonous and intoxicating." 62. The only substance capable of immediate fer- mentation, that is, of producing by its change spirit of wine or alcohol, is glucose or grape-sugar. Starch can, by art, be rendered soluble, converted into dextrin and dextrose (par. 41), and lastly fermented. So that the starches and sugars may, one and all, under favour- able circumstances, be fermented. 63. Yery beautiful and instructive is the process of fermentation. The glucose receives nothing from the ferment : nothing, that is, of a material nature : nothing that it requires for the formation of alcohol, carbonic acid and water. Although glucose contains only water ready made, it has all the materials for making the carbonic acid and alcohol. Something, THE CHEMISTRY OF FERMENTED LIQUORS. 37 however, it does receive. Like water altered in its physical condition by heat, or steel by magnetism, it receives what, in the language of philosophy, is called force. Popularly, glucose may be said to be roused, in presence of a ferment, by a shake, which compels it to re-arrange its elements in some new form. 64. But, although glucose and a ferment are the only substances requisite for the process, the fermentation will go on only under certain conditions, and these conditions are two, — the presence of water, and a certain fixed temperature. It is not enough that the temperature be sufficiently high, but it is especially desirable, for the perfection of fermentation, that it be as nearly as possible the same throughout. In fermenting grape-juice, the most favourable tempera- ture is found to be 21° C. 65. The ferment is not in the juice of the grape, nor does the juice ferment until it has been exposed to the air. The albumen (par. 109) in the juice furnishes the food to the fungus (or ferment), the germs or seeds of which are carried about in the air, and the fungus grows at the expense of its food. When once fermentation has commenced, the air is no longer necessary. Now the glucose rapidly changes ; heat is disengaged, and car- bonic acid is set free. The escape of carbonic acid after a time is lessened, the sweetness of the juice disappears, and the liquid acquires a spirituous flavour from the presence of alcohol. [In order to understand the formation of alcohol, a slight chemical explanation is needed. Glucose, C6Hi20^,H20, contains water, HgO, and the elements of alcohol and carbonic acid, twice told. Alcohol, CgHoO, and carbonic acid, COg, will be found twice over in the chemical formula for glucose, after the removal of its water, which, by the way, it may be 35 FORMATION OF ALCOHOL FROM GLUCOSE. made to lose when dried at the boiliDg-point of water — Two of alcohol j ^'^^^ 2H6O p ^^ > Two of Carbonic Acid, CeH,,0„ To speak more accurately, glucose breaks up, by the action of a ferment, into two molecules of alcohol, two molecules of carbonic acid, and one molecule of water. The molecule is the smallest quantity of an element, or of a compound in a free state.] 6Q, To describe all the subsequent processes would be beyond the scope of an elementary work such as this. Suffice it to say that, in ordinary cases, the wine is left in the cask till its fermentation is complete ; but if it be desired to produce an effervescing wine, such as Champagne, and the sparkling wines of the Rhine and the Moselle, it is bottled before the fer- mentation is completed. The process is continued in the bottles, the carbonic acid being retained in the wine, where it must remain, under pressure, till the removal of the cork allows it to make its escape with effervescence. A good substitute for the expensive effervescing wines is an admixture of the light French wines with good mineral water. 67. When the quantity of the sugar in the grape predominates over that of the albumen (par. 109), the result is a more or less sweet wine. But when the albumen is in excess, the fermentation is more com- plete, and the wine has a dry character. It must not, however, be supposed that any wine is absolutely free from sugar, but some contain it in very minute quan- tities, and hence are the best adapted for certain classes THE CHEMISTRY OF FERMENTED LIQUORS. 39 of invalids. Such wines are those of Bordeaux and Burgundy, Hock and Moselle, which are even stated by some writers to contain no sugar at all. 68. The blue colouring matter of the grape resides in the skins. The juices of both red and white grapes, under ordinary circumstances, make white wines, be- cause the colouring matter of the skins is insoluble in water. It is, however, soluble in alcohol ; if, there- fore, red wine is to be made, the expressed juice is allowed to ferment in contact with the skins, until the formation of alcohol has extracted the colouring matter. 69. But something more than colouring is thus ex- tracted. The time that the husks are in soak allows of the solution both of a salt of iron, and a peculiar kind of tannin. These, but especially the latter, give tonic 2)roperties to the wine, — a pint of Bordeaux con- taining a strong medicinal dose of iron. As time passes, a considerable portion of the tannin becomes insoluble, and is deposited, together with colouring matter, as "crust" in port and other coloured wines. 70. Free acids and acid salts are contained, more or less, in all wines, tartaric acid, cream of tartar, and acetic acid being the chief. These acids are, to most people, very digestible; they are present in smaller quantities in old wines, as alcohol causes the gradual separation of the tartaric acid in the form of cream of tartar, or acid tartrate of potash. 71. The fragrance, or "bouquet," of wines is due, mainly, to a peculiar ether, called Pelargonic ether, which forms gradually and very slowly in the wine. 72. The colour of dark sherry is artificial, being derived from caramel, or burnt sugar (par. 38). 73. The quantity of alcohol in wine may vary very much, both with the nature of the grape, the season, and the aspect of the vineyard. The majority of 40 ALCOHOL ABSOLUTE AND AS PKOOF-SPIRIT. French, wines contain 10 per cent. ; but Burgundy may contain, naturally, even 13*5 per cent. Most wines are fortified, that is, made stronger by means of alcohol : thus some kinds of " Port " contain 20 per cent, of absolute alcohol. One of the worst features of wines is the uncertainty as to the quantity of alcohol, and the amount of acidity which they possess. One of the greatest services which our wine-merchants could render would be to inform the public upon these points. And one of the greatest benefits which the people could confer upon themselves would be to admix strong wines with wholesome water. [Alcohol, C2H6O, is a colourless, limpid liquid, of agreeable vinous odour, and somewhat pungent taste aud smell. Its specific weight, as compared with water, is 0*793 ; it is therefore lighter than water. It is very inflammable, and burns with a bluish, sootless flame, into carbonic acid and water. Alcohol is a great solvent. Eau de Cologne and the various per- fumed waters, the so-called essences, are solutions of essential oils in alcohol. Yarnishes consist of resins dissolved in spirit of wine, and tinctures consist of bark, iodine, &c., dissolved in the same liquid. Absolute alcoliol, as the strongest alcohol is called, can only be prepared by long treatment of strong spirit of wine with quicklime, and distillation. Except as a means of expressing the strength, no such thing as absolute alcohol can be considered as present in wine.] 74. Proof-spirit is, as nearly as possible, a mixture of one-half water with one-half alcohol (par. 89). 75. Pure or absolute alcoliol is an undoubted poison. It possesses a strong attraction for water, which it abstracts from the tissues of the body with such avidity as to destroy their vitality ; and, if taken into the stomach, it will rapidly cause fatal inflammation. But in wine the alcohol is strongly diluted, and its mani- THE CHEMISTRY OF FERMENTED LIQUORS. 41 fest effects are produced on the nervous system ; to this it is a stimulant, producing, in small quantities, a cheerful flow of spirits, in large, the too well-known phenomena of intoxication. The difference between wine " as making glad the heart of man," and wine " as a mocker," is almost too great to need enforcement. 76. Whether persons in robust health require the con- stant stimulus of wine or beer may be more than ques- tioned ; but one thing is certain, viz., that, with wine or beer, a more moderate allowance of food should suffice. In truth, however, few of our dwellers in towns are robust. The impurity of the air, and especially of the drinking-water, the habits of town life, the demands on the nervous system in the struggle for existence, and many other causes in operation in large towns, render the very moderate use of wine or good unadul- terated beer beneficial. 77. In many cases of small or defective appetite, the benefit of wine cannot be questioned ; in such cases it is a medicine, as all food should be. Wine and beer are clearly lawful only so far as they minister to health, energy, and virtue. 78. Cider and Perry are the fermented juices of apples and pears. In time, longer or shorter accord- ing to the temperature of the cellar, a part of the sugar is changed into alcohol, and an agreeable, though to some persons very unwholesome beverage, is ob- tained. Other home-made wines are prepared from the juice of gooseberries, currants, and elderberries. The acids in these wines are principally citric and malic. To make them even palatable they must be strongly fortified, and they thus often partake more of the character of spirits than of wines, and they are ^ then, of course, injurious. 79. Beer is a kind of wine made from malt, and is one of the oldest of fermented liquors. The grain 42 BEER. MALT-INFUSION. YEAST. employed is barley, which is " malted," in order to de- velop the peculiar ferment (diastase, an albumen-like substance), which has the property of converting starch into soluble dextrose (par. 41). The process consists in forcing the germination of the seed, and so bringing about by art what is accomplished on a grand scale in Nature in the germination of every seed and bud. 80. If a little malt be infused (soaked) in warm water, it will convert a very large amount of starch, first into dextrin (par. 28) and then into dextrose. It is sufficient to mix some warm gelatinous starch with a small quantity of malt-infusion, to insure its be- coming, in a few minutes, thin like water, and, after a few hours, sweet like sugar. The liquor strained from the malt husks, called the '^ wort," is now boiled with hops, and rapidly cooled by running it into capacious wooden coolers ; it is then mixed with yeast, and suffered to flow into the fermenting-vat. A great amount of froth is thrown up, arising from the escape of carbonic acid ; the liquor loses much of its sweet- ness ; from being turbid it becomes clear, and acquires a new taste and intoxicating properties from the forma- tion of alcohol. The fermentation is stopped, when necessary, by separating the yeast and drawing off the beer into casks. 81. The yeast above- mentioned consists of a multitude of small, oval, organized bodies (fig. 17), which do not exceed -2^0 of an inch in diame- ter, and are seen to con- sist of nucleated cells. It is a fungus, to which the term Torula cerevisice has been applied, and is ob- Fig 17. THE CHEMISTRY OF FERMENTED LIQUORS. 43 tained abundantly during fermentation in the manu- facture of beer. 82. Various beers, though made from malt and hops, differ very widely in their properties. The amount of alcohol may be as low as l| per cent, in small-beer, or even as high as 8| per cent, in Burton ale. Stout may contain 6 per cent., porter 5 per cent., or more, of alcohol reckoned as absolute (par. 73). 83. Bottled ales are more acescent, from the presence of much free carbonic acid, and are gene- rally more alcoholic than draught ales. 84. Every kind of beer contains small quantities of acids: besides carbonic acid, acetic (par. 95) and lactic (par. 167) acids are present. When beer has become sour through the conversion of alcohol into vinegar, it may be corrected and fitted for use by the addition of sodium bicarbonate. 85. Dr. Carpenter, the great apostle of teeto- talism, says : " There is another class of cases in which we believe that malt liquors constitute a better medicine than could be administered under any other form ; those, namely, in which the stomach labours under a permanent deficiency of digestive powers. . . . There are many cases in which no form of medical treatment seems able to develop in the stomach that spontaneous power, which it has either completely lost, or which it never possessed, and in which the artificial excitement of an alcoholic stimulus affords the only means of procuring the digestion of the amount of food which the system really requires." 86. The chemistry of the manufacture of ardent spirits is so similar to that of brewing, that little requires to be said. The distiller, who prepares spirits from grain, uses a very large quantity of grain with the malt, the diastase (par. 79) of which is ' sufiicient to convert the starch first into dextrin, and 44 VARIOUS KINDS OF SPIRITS. PROOF-SPIRIT. then into dextrose. The ** wash," as it is called in the language of the trade, is made to ferment as rapidly as possible by means of yeast added in large quantities, and is then distilled. Whisky is prepared from barley and oats. Gin and Hollands are dis- tilled from barley, and flavoured with juniper-berries and other substances. Arrack is made from rice, a grain which contains a larger amount of starch than any other natural product. Rum is from the fer- mented juice of the sugar-cane. Brandy is obtained by the distillation of wine, and that made from white wines has the finest flavour. The win«s from the countries bordering on the Mediterranean supply the largest proportion of brandies. 87. Yinous fermentation may be produced even in milk, and such a spirit is prepared by the Tartars. The milk-sugar changes into glucose, and this by a ferment into alcohol, carbonic acid, and water (par. 65), 88. With reference to the quantity of alcohol contained in spirits, it may be stated that few that are sold contain more than 49 per cent, of absolute alcohol. In mercy to the drinking public they generally con- tain much less ; but they may contain more ; and this uncertainty is an additional reason for the exercise of the greatest caution in their use. The alcohol from spirits is more readily absorbed than that in wine ; hence is their stimulating power greater. Whisky is more wholesome (if the word can in any sense be allowed) than brandy, because its effects are more readily got rid of. 89. The term proof-spirit, already alluded to, is one applied by the Excise. Proof-spirit is defined by an Act of Parliament to be " such as shall, at the temper- ature of 10° -5 0., weigh exactly twelve-thirteenths of an equal measure of distilled water.'' It consists of alcohol 49-24, and of water 50*76 by weight [and THE CHEMISTRY OF FERMENTED LIQUORS. 45 shows a dilute alcohol of specific gravity, 0-919 at 15°-5 C.]. The name takes its origin from the very rude "proof" formerly in use, in which gunpowder was moistened with the spirit of wine to be tried, and the alcohol ignited ; if it fired the powder it was said to be over-proof ; but if the spirit burnt off and left the powder damp, it was considered to be under proof. Every additional 0*5 or J per cent, of absolute alcohol is said to be one degree above proof. 90. Apart from ill-health, the chief excuse for drinking spirits is due to the character of the water- supply. For wine much may be said. The late Professor Liebig is enthusiastic about its use. He says : " As a restorative, or means of refreshment, where the powers of life are exhausted, of giving animation and energy where man has to struggle with days of sorrow, as a means of correction and compen- sation when misproportion occurs in nutrition, and the organism is deranged in its operations, and as a means of protection against transient organic disturb- ances, wine is surpassed by no product of Nature or art." 91. This is said by Liebig of the wines of the Rhine, Moselle, and France, — wines which are not so alcoholic as some of the Ports and Sherries. Like all other gifts of God to His creatures, wine has been abused ; nevertheless, it seems to admit of no doubt that, when used in moderation, it adds very greatly to the reasonable enjoyment of mankind. At any rate, as long as wines occupy such prominence among articles of consumption, as they undoubtedly do at the present day, a few pages devoted to their consideration can scarcely be thought to be out of place.* * It would be of great advantage to the public if our wine- merchants would publish, with their prices, the alcoholio contents of their wines. And it would be well for the advance 46 CHANGE OF ALCOHOL INTO ACETIC ACID. CHAPTER YI. THE VEGETABLE ACIDS. 92. Fkom ancient times it has been well known that the juices of frnits, after becoming vinous (alcoholic) from fermentation, were subject to another change by which they were rendered sour. The acid formed has been long known by the name of vinegar, its produc- tion being common among the Egyptians before the time of Moses. Whilst the presence of oxygen or of air is absolutely necessary to the formation of vinegar, the vinous fermentation, when once commenced, is better carried on with exclusion of air. 93. All liquids capable of vinous fermentation may be made to produce vinegar ; but in all such cases the sugar is first converted into alcohol, and alcohol, by oxidation, into acetic acid, the acid of pure vinegar. 94. [Alcohol, CgHgO, by oxidation becomes ACETIC ACID, C2H4O2. By the loss of two atoms of HYDROGEN, Hg, which are oxidized, and become WATER, H2O, and the addition of an atom of oxygen O, alcohol becomes acetic acid.] 95. And yet pure alcohol will no more become acetic acid by simple exposure to air than will a solu- tion of pure sugar change into alcohol and carbonic acid. There must be some carrier of the oxygen of the air. 96. The best vinegar is made from wine. The wine is mixed with a little vinegar, and exposed to of the good canse of temperance, if all wines containing more than 20 per cent, of proof spirit were admixed with water before drinking. The uncertainty as to the alcoholic contents of wines, and even beers, is a fruitful cause of intemperance, and a complete explanation of the evil, without any refer- ence to adulteration. THE VEGETABLE ACIDS. 47 the air in casks partly filled with the pressed husks of grapes. From time to time the liquid is drawn out from below, air supplies its place, the husks become warm by absorbing oxygen, which they give up to the alcohol, when the wine is again poured into the cask. This process is repeated until the vinegar is made ; its strength may be increased by the addition of more or less brandy to the wine. Free access of air, a temperature not below 24° C, and exposure of a large surface of liquid, are the chief conditions of success. 97. Acetic acid is a clear, colourless liquid, which crystallizes below 15° C. in colourless scales. In this condition it blisters the skin ; but ordinary vinegar only contains about 5 per cent, of acetic acid, and is then possessed of a pleasant, sour taste. In small quantities good vinegar promotes digestion, serves to flavour food, and to excite the nerves of taste. 98. Acetic acid is contained in wines, but tartaric acid is the chief acid ; and then, not as tartaric acid, but as a salt of potassium, the so-called "cream of tartar." This salt has an acid taste, and is but little soluble in water. In alcohol it is even less soluble, so that it is found collected as a crust in the wine-casks. From cream of tartar, all the tartaric acid of commerce is produced. As this cream of tartar is very digestible, a wholesome drink for summer use may be prepared by dissolving a drachm in one pint of water, sweetening according to taste, and flavouring with lemon. (If the drinking-water should be of doubtful character, it is better to use boiled water for the manufacture of this drink.) [Tartaric Acid, C^H^Pe, is also the sour principle of tamarinds and pine-apples. When pure, it forms clear, colourless crystals, very soluble in water, and possessed of a sour taste. It is employed in making 48 CREAM OF TARTAR, CITRIC ACID, ETC. effervescing draughts, as it drives out carbonic acid from sodium carbonate, and forms sodium tartrate. POTASSIUM HYDROGEN TARTRATE, C4H,K06, is cream of tartar.] 99. Currants, both red and white, contain two acids, citric and malic. The same two acids are also contained in strawberries, gooseberries, cherries, and raspberries, in the cranberry, and the whortleberry ; but the chief source of citric acid is the lemon and the citron, although it is also contained in the orange. It is even more digestible than tartaric acid, and serves equally in the making of effervescing draughts. [Citric Acid, CGlIg07,H20, as it is sold in the form of large transparent crystals, closelyres embles tartaric acid. It has an agreeable acid taste, and is very soluble in water.] 100. Malic Acid derives its name from Prunus malus, the apple, in which fruit the acid is found. It is also contained in garden rhubarb, and largely in the berries of the mountain ash. The dried leaves of tobacco are rich in a salt of malic acid. It is only made upon a very small scale, but its sour taste is well known and liked in a sour apple. [Malic Acid, CJIgO^, differs but little from tar- taric acid, and is easily converted into it by chemical means.] 101. Oxalic acid accompanies malic acid in the garden rhubarb, in sorrel and in the shamrock, known by the botanical name Oxalis acetosella. It is pos- sessed of a pleasant, sour taste, but is nevertheless poisonous when taken in quantity. Salts of oxalic acid are called oxalates ; that of potassium is sold in the shops under the name of " salts of lemon." [Oxalic Acid, C2H2O4, 2H2O, resembles Epsom salts in appearance. The best antidote to poisoning by this acid consists in a dose of magnesia or of chalk.] THE VEGETABLE ACIDS. TANNIN. 49 102. Scattered through the vegetable kingdom, in the bark and leaves of many trees and shrubs, is an astringent principle, which goes by the name of tannin, or tannic acid. It is obtained in a state of purity from the gall-nut, and is possessed of a very astringent taste, well understood by the manner in which it draws the mouth together. Coffee and tea contain also a kind of tannin, but the properties are different. Thus, the tannin of tea will give a blue- black colour with a salt of iron, but that of coffee will not. A cup of strong, rough congo owes its astrin- gency to tannin. [Tannin, C27H22O17, has already been mentioned as an important constituent of red wines (par. 69). It presents the appearance of a yellow powder, very soluble in water. Black ink is tannate of iron, a stain from which upon linen is best extracted by means of oxalic acid.] The most remarkable property of tannin is its power of combining with gelatin, and forming leather. A solution of tannin will immediately precipitate as a solid body the gelatin contained in soups, and will have an effect of hardening meat, and rendering it less digestible. 103. Yegetable acids are exceedingly numerous ; but the only ones of any importance in fruits and vegetables, leaves and seeds, are those just mentioned. In moderation, all but oxalic acid are peculiarly wholesome, and the quantity of the latter in the cooked rhubarb of a pie or pudding is too small to affect the health. The introduction of the orange has had much to do with the better health of our people ; indeed, it would be well if larger quantities were consumed, and an orange, while in season, took the place of beer at dinner. D 2 50 CARBONACEOUS AND NITROGENOUS FOODS. CHAPTEE VII. EGGS, ALBUMEN, AND MILK. 104. It is a very common thing to classify foods, and to divide them into carbonaceous (respiratory) and nitrogenous (plastic). Carbonaceous foods would be such as have been already considered ; namely, compounds of carbon, hydrogen, and oxygen. In Nature, these are always more or less associated with nitrogenous matters ; it is by arfc, more or less, that they are separated. It is true that in milk we have water, butter, and sugar, but we have also casein (nitrogenous). In bi^ead we have water and starch, but also glutin and albumen. Oatmeal contains starch, water, and fatty matters, in addition to fibrin. Lentils abound in starch, but also in legumin. Vegetables, such as cabbages, greens, turnips, and carrots, are chiefly valuable on account of their juiciness, and do not yield more than 2 per cent, of nitrogenous materials. 105. Nitrogen is a component of the air. That the atmosphere does not consist wholly of one kind of matter is readily shown by the following experiment: a float made of cork, into which is fitted a tiny porce- lain basin, containing a piece of phosphorus about the size of a pea, is placed in a soup-plate full of water, and over it is inverted a deflagrating jar, open at the bottom and carefully stoppered. On removing the stopper, the water will stand on a level inside and outside the jar. The phosphorus is then inflamed by means of a heated wire introduced through the neck of the bottle, and the stopper immediately replaced. The phosphorus burns brilliantly for a time, producing white vapours of phosphoric acid, soon dissolving in the water, which then rises in the jar (fig. 18), till NITROGEN IN AIR : HOW DETECTED. 51 it fills one-fifth of the space previously occupied by the air. By the combustion, there- fore, of the phosphorus, some- thing has been removed from the air in the jar equal to one- fifth of its whole bulk. The matter so removed is oxy- gen ; the gas left behind is nitro- gen. More accurately, the atmo- sphere when dry consists of 79 per cent, by measure of nitrogen, and of 21 per cent, by measure of oxygen. Like oxygen, nitro- gen is a colourless, tasteless, and ^'^S- 18. inodorous gas ; but it does not support either respira- tion or combustion. Its presence in such large pro- portion in the atmosphere is a proof that it is not injurious to respiration, while it serves to check the activity of breathing as well as of combustion . From the difficulty with which it enters into combination, nitrogen is admirably adapted for this purpose ; in- deed, there is no other gas which could be made to take its place. lOG. Nitrogen is always in combination with the elements of the carbonaceous group. In its separate form, mingled with the air, it cannot take the place of food. It must be in chemical combination with Carbon, Hydrogen, and Oxygen, if it is to do us any service. The difference between mixture and combination is thus well seen. In a mixture, bodies retain their individual characters ; in a combination, these are lost. All kinds of food which contain nitrogen are solids ; nitrogen itself is a gas. 107. The best proof of the presence of nitrogen in a body is furnished when, in heating it with quicklime, it gives oft* ammonia. Now ammonia is a com- 52 A CERTAIN AMOUNT OF NITROGEN REQUIRED. pound of nitrogen and hydrogen, and is well known as hartshorn. It is one of the most valuable of ma- nures to plants, and supplies them with nitrogen ; but it cannot serve as food to man or beast. Decay and putrefaction minister to the life and growth of vege- tation ; indeed, the very value of manures depends upon the amount of ammonia which they contain or afford. 108. Amongst nitrogenous foods, one of the most useful and handy is an egg. Taking it as weighing 1| oz., it would yield about 2 per cent, of nitrogen, or nearly 18 grains. Now, as about 200 grains of nitrogen are required daily by a grown-up person doing but little active work, it would follow that, if he lived upon eggs (a most absurd supposition), he would require 11 per day. If an egg be carefully analyzed, it would be found to consist of 70 per cent, of water and 30 per cent, of solid matters. The solids would be divisible into white of egg and yolk ; the latter consists of similar material to the white, but contains the tasty principle — an oil rich in phosphoric acid, and admirable as a restorative. In the yolk, the oil amounts to about one-third of the weight of the total solids, and is to be classed among the respiratory kinds of foods. 109. Albumen is the most noteworthy principle of the egg, and it is a substance of such importance as to be worthy of a more extended description. The best understood character of albumen is its property of becoming solid and insoluble in water on the appli- cation of heat. This coagulation or curdling begins at 60° C. If the quantity is large the white sets, as in an egg which has been hard-boiled ; if the quantity be small, the liquid containing albumen simply becomes cloudy. In carrots and turnips and cabbages, wherein the quantity is very small, the water in which they are boiled simply becomes unclear or turbid ; in the EGGS. ALBUMEN. SULPHUR IN ALBUMEN. 53 juice of meat, where there is much albumen (par. 116), distinct coagulation takes place ; but even in this there is but little compared with white of egg. 110. If the heat of boiling water (100° C.) be allowed to penetrate, both the white and yolk become solid ; in five minutes' time from the placing in boiling water, an egg becomes hard throughout. Now, the setting of the yolk depends upon a variety of albumen, known as vitellin. 111. The tastelessness of the white without the yolk is a well-known fact, and alluded to in the Book of Job : "Is there any taste in the white of an eggV But the value of an egg as an article of food may be adjudged by the fact that, by the help alone of air and warmth, the flesh, bones, membranes, and feathers of the fowl are produced. 112. The presence of sulphur in albumen ought also to be remembered, as it makes itself seen in the blackening of a silver spoon when left in an egg. And the well-known ill-savour of a putrid egg is equally due to the sulphur, which, with hydrogen, produces hydrogen sulphide, or rotten-egg gas. On account of the action of sulphur upon silver, it is usual to gild the bowls of silver egg-spoons. Omitting the soda which is contained in albumen, and which occasions the bluiug of a piece of red litmus-paper when inserted into the white of egg, and taking the phosphorus into account, the following will give the composition of perfectly dry albumen in 100 parts : — Carbon 53-5 Hydrogen 7'0 Nitrogen 15*6 Oxygen 22*0 Sulphur , l'(y Phosphorus 0*4 100-0 54 OVALBUMEN IN AN EGG. [Albumen varies greatly according to the source from whence it is derived. Ovalbumen, as that from the ovum, or egg, is called, is an albuminate of sodium, and may be represented by the formula C^2HiiiNa Ni8S022,H20. It occasions a precipitate in solutions of metallic salts, and therefore raw eggs, beaten up, are a most valuable household remedy against poisoning by salts of lead, mercury, and copper. Strong alcohol also coagulates and hardens it, as does also creasote. Albumen is coagulated by ether, and does not pre- cipitate salts of lead and copper, and is thus mainly distinguished from ovalbumen.] 113. Albumen constitutes about 7 per cent, of the blood, and is an essential of the brain, liver, &c. It is not found in the refuse of the body, except in disease. 114. As an article of food, what cannot be said in praise of an egg 1 With milk it gives custard-pudding ; it may be eaten raw, soft-boiled, hard-boiled, poached, in the form of omelets, in soups, in many ways — and yet others would remain to be told. lb is impossible to exaggerate its value. Eaten with bread and butter, or with toast, an egg may be made to go as far as five eggs eaten by themselves, and the appetite, on account of the variety thus introduced, would not tire. The starch of bread and toast would increase the quantity of respiratory food contained in the yolk, whilst the albumen of the white and yolk would be supplemented by the nearly equally valuable gluten of the bread and toast. The same may be said of eggs and bacon. Eggs are also useful as vehicles for salt, which greatly promotes digestion generally, as well as the digestion of the albumen itself. 115. It has been already stated that albumen is contained in blood ; it is therefore a constituent of the juice of meats. The quantity of albumen in certain animal foods has been found as follows : — ALBUMEN IN MEAT. EXTRACT OF MEAT. 55 Albumen per cent. In beef 2-02 In chicken .S'OO In veal 3-02 Albumen per cent. In pigeon 4'05 In sweetbread 14-00 In ox-liver 20-19 These quantities of albumen are exclusive of fibrin (par. 142). 116. If an extract be made of finely-minced meat with water, a reddish-coloured fluid is obtained, having the taste peculiar to the blood of the different classes of animals. When heated to between 65° and 70° C. (depending upon strength ; as tlie more dihited with water the higher is the temperature required), the albumen which it contains coagulates, and carries with it the colouring matter. The clear liquid, or broth, will be found distinctly acid. But the great point to be remembered is, that if the juices of meat be extracted with cold water, all the albumen is transferred to the water. Now, since meat, taken as food, is again to become flesh in the body, it should, as far as possible, contain all the original constituents of the raw meat. So, when the meat is to be eaten, the albumen should be retained in it ; for not only does it preserve the fibrin from becoming hard, but it gives to it softness and delicacy. The best method of boiling meat intended for food, is to introduce it at once into boiling water. If the boiling be kept up for five minutes, and then so much cold water added as Co reduce the temperature to 75° C, and the whole kepi; slowly simmering until it is cooked, all the conditions are united which give to the flesh the quality best adapted for its use. When it is introduced into the boiling water, the albumen immediately coagulates from the surface inwards, and in this state forms a crust which no longer permits the outer water to penetrate into the meat. But the temperature is 56 MILK CONTAINS BUTTER, LACTOSE, AND CASEIN. gradually transmitted inwards, and there accomplishes certain changes. 117. Tripe is rich in nitrogenous material, and con- tains a considerable proportion of albumen. When properly cooked, it is very digestible, and, from its cheapness, offers to the poor a valuable kind of food. 118. And now as to milk. In addition to car- bonaceous material, such as butter and lactose (sugar of milk), milk contains about 4 per cent, of a nitrogenous substance called casein. Every one knows that, when milk becomes sour, it coagulates. This coagulation is owing to the separation of the casein with the butter, and is not the effect of heat, as is the case with albumen. Milk when simply boiled is covered with a skin, or scum, of oxydized casein. A minute quantity of vinegar, or acetic acid, separates the curd or casein, and this carries the butter down with it. Advantage is taken of this in the manufac- ture of cheese, which consists principally of casein and butter. Coagulation is accomplished by means of " rennet," the inner membrane of the fourth stomach of the calf after it has been salted and dried, and a clear, straw-coloured liquid, the whey, is left. The cause of the coagulation is not known, but the result is a very valuable article of food — cheese. 119. JSTew cheese has but little flavour, as is per- ceived in fresh cream-cheese. As the latter is often made from skim- milk, from which the cream has been abstracted, the cheese contains but little butter, and consists mainly of casein. Even new cheese has but little flavour, and it is only with the lapse of time that certain acids are developed, possessed of smell and taste, which give pungency and flavour. 120. The composition of cows' milk is as follows. It has a specific gravity of 1 -030 to 1 -034. Cream amounts to about 10 per cent. COMPOSITION OF MILK AND CHEESE. 57 Water 875 Fat 3-5 Casein and insoluble salts 4'0 Sugar and soluble salts 5'0 100-0 121. If human milk is to be imitated, good cows' milk requires to be diluted by one-third of lukewarm water, and sweetened by means of one quarter of an ounce of sugar to each pint of milk and water. 122. Half a pint of new milk would supply as much nitrogenous material as a good-sized egg ; the value of milk may therefore be easily understood. 123. The reader will observe a considerable differ- ence between milk and cheese. The latter may con- tain in different specimens : — Water .... Cheddar. 36-0 Cheshire. ... 300 .. ... 39-5 .. ... 260 .. ... 4-5 .. Skim< . 44-0 Casein Butter ..... Salt 28-4 311 4-5 . 44-8 . 6-3 . 4-9 100-0 1000 100-0 The most valuable of the three cheeses would be the Cheddar, as the Cheshire and the Skim-cheese are really too rich in nitrogenous material, without very large admixture with carbonaceous food. The Cheshire is obviously greatly superior to the Skim-cheese, as the butter is four times as largely present. 124. A small piece of cheese, as large as a hazel- nut, acts as a digester of food ; but after a hearty meal cheese is too tempting to be placed upon the dinner-table. To give variety to food in a poor man's house, macaroni and cheese are most admirable, and would supply a supper at an inexpensive rate. Macaroni may be looked upon as high-class bread, and should be introduced into every household at 58 CASEIN CONTAINS LESS SULPHUR. least once a week. One pound of Cheddar cheese would afford about 300 grains of nitrogen ; it will therefore be easily understood why cheese is so highly regarded by the hard-working labouring man. 125. The most digestible form of cheese is cream- cheese, when kept sufficiently long to possess a dis- tinct flavour, but before it has begun to decompose. Casein contains less of sulphur than does albumen, and no phosphorus ; otherwise their composition differs but little. It may be prepared by coagulating skim- milk by means of dilute sulphuric acid. The curd, after well washing with water, may be dissolved in sodium carbonate, and allowed to stand for twenty-four hours to give time to the butter to collect on the surface ; this is then skimmed off, and the casein again precipitated by sulphuric acid. After washing with water, the casein should be purified by digestion with ether, in order to remove remaining traces of butter. (For Sulphur and Phosphorus see Chapter X.) 126. The solubility of casein in water is not de- stroyed by alcohol ; hence a moderate quantity of beer is a good accompaniment of a meal of bread and cheese. Water is, however, a better drink. CHAPTER VIII. BREAD AND MEATS. Among the more substantial articles of food, bread and meat occupy a very high place. 127. The valuable grain called wheat is the pro- duce of several kinds of the genus Triticum, winter- wheat and spring-wheat being the most common. Like rye, oats, barley, and rice, it belongs to the FIBRIN. GLUTIN. CASEIN. 59 natural family of the grasses {Graininew), a family which includes some of the most useful, and the longest-cultivated plants in Europe. As a great poet says : " A cornfield represents God's battalions against hunger." 128. Wheat is composed principally of a floury portion, which is enclosed by an integument, or shell, amounting to about 14 per cent, of the whole grain. The flour consists of starch (par. 26) and gliitin, with small quantities of gum, albumen, and certain salts. 129. As starch is the main carbonaceous, so is glutin the main nitrogenous constituent of wheat or flour. Glutin is to biead what casein is to milk : in their absence, neither bread nor milk could be considered nutritious in respect to nitrogen. Glutin is readily obtained, by kneading a mass of dough in a muslin bag under a running tap, by which means the starch is carried off, leaving a greyish, glutinous, highly- elastic substance ; it resembles birdlime in appearance, and is perfectly insoluble in water. The glutin from wheaten flour is singularly tenacious, and renders it peculiarly well adapted for making bread. 130. Glutin is composed of three distinct nitroge- nous substances, one of which, fibrin, corresponds to the fibrin of meat (par. 142), and is seen in greatest perfection in oatmeal. A variety of vegetable casein is also present, together with the glutin, which gives to the whole its adhesive or sticky properties. Vege- table casein, as well as animal casein, contains no phosphorus. 131. In making bread, the flour is mixed with half its weight of water, and thoroughly kneaded into dough, with the addition of salt (sodium chloride), to make it tasty and wholesome, and of yeast (par. 81) to make it ferment. The water, yeast, and flour being 60 BAKING OF BREAD. CRUST AND CRUMB. mixed, the mass is left to rest for some hours at a temperature of about 21° C. Fermentation commences almost immediately ; the dextrose, which is produced. from the starch by the action of the ferment, is quickly changed into alcohol and carbonic acid. The carbonic acid thus set free at all parts of the dough, causes it to rise, and to increase greatly in bulk. The dough is then cut into loaves, and baked in an oven at a temperature of 230° C. to 260° C. ; the heat causes a still further expansion of gas in the dough, which also loses a portion of its water, and thus prevents any great rise of temperature in the crumb. Accord- ing to experiments made by the author, the crumb is rarely heated to 94° C, but ihe crust is greatly altered. Much of the starch becomes changed into dextrin,[and is soluble and more digestible, as it partakes of the character of biscuits. The lightest part of the loaf is that which has not been compressed by the oven- plate. By the act of baking, the starch granules lose the property of forming a gelatinous paste with water, and form, together with the glutin, distinct but irregular cells, which are among the best characteristics of a well-baked loaf. The oven should have been sufficiently heated to harden the sides of these cells, so as to retain their form after the loaves have been removed. 132. The amount of water, in the crust and crumb together, is equal to 38 per cent, of its weight. The difference between fresh and stale bread is not owing to the quantity of water (as the loss on the part of the stale loaf is not more than 1 per cent.), but rather to the condition of the starch. Stale bread may be readily changed into the condition of fresh by enclosing it in a tin case, and replacing it in the oven for a short time. 133. The presence of dextrin (par. 28) in the crust LEAVEN A FERMENT. SECONDS FLOUR. 61 of bread is easily proved. If a loaf be wetted with a moist sponge, and returned to the oven, it will soon possess a shining coat, as though glazed with gum ; the water has dissolved a portion of the dextrin. In the making of toast, much more of the starch is thus changed, and this is no doubt one of the reasons of its greater digestibility. 1 34. A thin slice of well-made toast, a little burnt upon its surface, has been already suggested as a cheap means of filtering water, and of preparing toast- and- water (par. 14). But it must be made with boiling water, or, at least, from water which has been boiled. 135. Leaven is sometimes employed instead of yeast. It is merely dough kept in a warm place until a portion of its gluten becomes changed by atmo- spheric air, through the instrumentality of germs, into a ferment. " A little leaven leaveneth the whole lump," and brings about the same changes as yeast. As it frequently sets up an acid fermentation, and makes the bread sour, it is not much used in England. 136. Pure white bread is not so nutritious as that made from seconds-flour. This, to well-fed persons, is of no importance, as they make up with meat and eggs what the breadjmay lack in glutin. But, to the poor, it is a matter of interest. Indeed the entire removal of the bran, except to persons in deli- cate health, is decidedly objectionable ; the latter is rich in fat, as well as in phosphates, and, if only finely ground, renders bread more tasty. 137. In bread made by the ordinary process of fer- mentation, a certain loss is occasioned by the conver- sion of some of the starch into dextrose, and then into alcohol and carbonic acid. To obviate this waste, several plans have been suggested. By Dr. Dauglish's 62 BREAD CONTAINS NITROGEN. process, carbonic acid gas is pumped into the dough, and is made to produce the same effect mechanically, as is done by the loss of a certain weight of starch. Or the carbonic acid is obtained from sodium bicar- bonate, by means of tartaric, or some other acid. In the baking of cakes, ammonium carbonate and sodium bicarbonate are similarly employed, but not quite with such good results. 138. One pound of bread will supply between 90 and 100 grains of Nitrogen, and about twenty times as much Carbon. With bread at 2d. per lb., it will be seen how cheaply our needs in respect to nutrition may be supplied. It may be calculated that 2 J lb. of bread would supply our daily wants, at least as regards the most costly element, nitrogen, and we can obtain very considerable variety in tlie use of flour. "With dripping, butter, lard, or suet, we can make pies and pudding-crusts; those made with suet are the most digestible. 139. Macaroni is a very admirable variety of a rich form of bread, and, with cheese, is much to be recom- mended. It is a manufacture of wheat which for a long time was peculiar to Italy. Strictly speaking, the name only applies to wheaten paste in the form of pipes, varying in diameter from an ordinary quill up to those now made of the diameter of an inch ; but there is no real difference between it and the fine threadlike Vermicelli. Only certain kinds of wheat are applicable to this manufacture, and these are the hard sorts which contain a large per-centage of glutin. The wheat is first ground into a sort of meal, from which the bran is removed — in that state it is called Semola ; during the grinding it is necessary to employ both heat and moisture. The semola is worked up with water into a dough, and, for macaroni and ver- micelli, it is forced through gauges, as in wire- and OATMEAL. BREAD AND MEATS. 63 pipe-drawing. If the taste of macaroni with cheese be objected to, there are many kinds of puddings in which it can be advantageously employed. 140. Whilst on the subject of flour, there is no meal so much to be recommended for cheapness and excellence as oatmeal. One pound of oatmeal con- tains about 140 grains of nitrogen. When cooked with water^ and eaten as porridge with milk, it affords variety in diet, and is very wholesome withal. Or it can be eaten with salt, or with sugar and butter, or with treacle, and should be a welcome addition to the small variety in food in which most people indulge. 141. If to bread we add meats, we shall have con- sidered the chief portion of the subject of food. 142. The components of lean meat, so far at least as regards its nitrogen ized constituents, are very similar to those of vegetables. Muscular fibre, mus- cular tissue or Syntonin, is composed chiefly of fibrin. A thin slice of lean beef, washed in cold water until perfectly white, and then, when dry, with ether, until all the fat has been removed, affords a good example of insoluble animal fibrin ; whilst that portion of the glut in of wheaten iiour which is insoluble in hot alcohol and in ether, represents the best idea of vege- table fibrin. 143. The fibrin in blood amounts to 0*25 per cent. Because, in muscle, it arranges itself in bundels of fibres, it is called fibrin. There are two varieties of fibkin, one soluble, the other insoluble. The soluble variety is met with in the blood, and is readily obtained by beatincj freshly - drawn blood with a bundle of twigs ; in the moment of coagulation, the fibrin attaches itself in white, elastic fibres, and may be afterwards washed clean by knead- ing in water. E ^^u^ * ^ A ^^^>^ 64 BLOOD FIBRIN IS OXYDIZED ALBUMEN. [In regard to its chemical composition, fibrin differs but little from coagulated albumen, as will be seen at once by comparison of their constituents. Carbon 52*7 Hydrogen 6*9 Nitrogen 15*4 Oxygen 23-5 Sulphnr 1*2 Phosphorus 0'3 Fibrin. Albumen. 53.5 70 15-5 220 1-6 0-4 1000 1000 Blood fibrin would seem to be oxidized albumen Blood fibrin decomposes hydrogen peroxide ; albu- men does not. Both fibrin and albumen are soluble in dilute solutions of potash, but, on neutralizing the solution with acetic acid, fibrin is precipitated, and not albumen. Solutions of fibrin and of albumen in acetic acid are precipitated on addition of yellow prussiate of potash.] 144. That which we call butcher's meat, is the muscular substance, with more or less of bone and fat. It may be said to consist of : — Juice of meat 71 Muscular tissue 16 Bones 10 Fat and cellular tissue 3 100 145. With an increase of fat, the quantity of water present in meat decreases; well-fed and fatteued meat contains for equal weights about 40 per cent, more of dry animal matter than non-fattened meat. The following analyses by Breunlin exhibit the diflference between the meat of fat and non-fatted bullocks ; — ALBUMEN AND FIBRIN IN MEATS. 65 Fattened. Non-fattened. Juice 39-48 ... 61-12 Muscular tissne 36-65 ... 30-81 Fat 23-87 ... 8-07 100-00 100-00 146. Albumen and fibrin are, then, always met with together in various kinds of meat. In veal, chicken, and beef, we have about 20 per cent, of fibrin to from 2 to 3 per cent, of albumen ; whilst in sweet- bread we have about 8 per cent, of fibrin to 14 per cent, of albumen. As has been already remarked, since meat, taken as food, is again to become flesh in the body, it should as far as possible contain all the original constituents of the meat. According to the usual plan of boiling meat, the albumen is coagulated, and thrown away in the water, and the fibrin much hardened in consequence. Now meat intended for boiling should be immersed in boiling water, so that the outer part has its albumen coagulated, and thus the juices prevented from passing into the water. As soon as this is accomplished, which takes, place in the first ten minutes, the water should be somewhat cooled down (from 100° C. to 80° C.) by the addition of a small quantity of cold water, and the cooking completed by gentle simmering. The water should only be just on the boil, for which purpose a very small fire is neces- sary. As regards the water in which the meat has been cooked, it should be so reduced in bulk by evapo- ration, as to be just sufficient to serve as gravy, or to be used as stock for soup. 147. So then, if the meat is to be eaten, the juices are to be kept in the meat ; but, if beef-tea is wanted, the chief goodness of the meat should be in the tea. According to the late Professor Liebig, the great master on the subject of food, finely-minced meat should be extracted with its own weight of cold or E 2 66 GELATIN AND BONES. lukewarm water : digested for an hour, all the albumen and the other soluble and tasty ingredients will be removed into the tea. On straining through a sieve and slight washing with water, the beef- tea may be heated, flavoured according to taste, and served with the albumen, — coagulated indeed, but still nutritious as in a boiled egg. CHAPTER IX. GELATIN AND BONES, WITH SOMETHING ABOUT THE JUICES OF MEATS AND LIEBIG's BEEF-TEA. 148. If the value of a nitrogenized substance could be judged by the amount of nitrogen which it con- tains, then indeed would gelatin stand very high. Isinglass is an example of the purest kind of gelatiu, and glue of au inferior sort. 149. Isinglass is prepared from the inner mem- brane of the floating bladder of the sturgeon. Glue is made from bones. Not that the bones contain gelatin, but it is the result of the long-continued action of boiling water upon such bodies as skin, the organic (destructible) matter of bones, &c. 150. Now the composition of bone is somewhat as follows : — Animal matter yielding gelatin 30 58 Calcium phosphate 57*67 Calcium carbonate 7'00 Magnesium phosphate 2*10 Calcium fluoride 2*65 10000 GELATIN PRECIPITATES TANNIN. 67 151. When boiled for several hours even, bones give but a small proportion of gelatin ; but, if placed with water in a Papin's digester and heated to about 150° C, gelatin is very largely, if not completely, dis- solved. The more the bones are broken, the thicker is the jelly which is obtained, and also at an expense of less firing. 152. Gelatin is readily soluble in warm water; even one per cent, will cause water to gelatinize on cooling. Its solution is tasteless, and without odour. Alcohol precipitates it, and so also, but more com- pletely, does tannin; indeed leather is a compound of tannin with gelatin. From albumen and fibrin gelatin may be readily distinguished, in that it is not precipitated from its solution in acetic acid by yellow prussiate of potash. [See par. 143, enclosed in brackets.] 153. Gelatin contains more nitrogen and less car- bon than either albumen, fibrin, or casein ; like the latter it contains no phosphorus, but it contains more sulphur than casein. The composition of gelatin, it may be as well to contrast with casein, albumen, and fibrin. Gelatin. Casein. Albumen. Fibrin. Carbon 504 ... 53*83 ... 63-50 ... 62-70 Hydrogen ... 6-5 ... 7-15 ... 7*00 ... 6-90 Nitrogen 16-9 ... 15-65 ... 16-50 ... 15-40 Oxygen 25-6 ... 22'52 ... 22-00 ... 2350 Sulphur 0-6 ... 0-85 ... 1*60 ... 1-20 Phosphorus none ... none ... 0-40 ... 0-30 100-0 10000 100-00 100-00 Clearly then, chemical analysis can tell us only the constituents of food ; experience and judgment are required to make use of such analysis. For, if one thing be more certain than another, it is, that equal bo GELATIN, A SOLVENT OF PHOSPHATES. weights of properly cooked gelatin and albumen are not equally nutritious. 154. To a person in delicate health, gelatin is rather a vehicle for food, than food. Jellies may be sweeteiied with sugar, made tasty with wine, and give, as it were, some solidity to water ; they may convey the sensation of food. Gelatin is at its best when it contains the juices of meat. 155. Nevertheless, as a solvent of phosphates (the earthy material of bones), gelatin is of great value, especially to children the nutrition of whose bones is defective. But it can only partially replace albumen and fibrin. It is as an aid to nutrition, as giving variety to our food, as affording bulk and giving the stomach something to do, that gelatin is most valuable. 156. To persons in health, and in houses where price is of great importance, the bones from joints, (fee, should be broken up and boiled in water, in a Papin's digester for a couple of hours, and the gelatin- soup thus obtained should be rendered tasty by frag- ments of well-roasted fresh meat, and the addition of various vegetables, such as celery, carrots, onions, &c. 157. Taste being the best test of good cookery, it is obviously of the highest importance in cooking to retain, as far as possible, the sapid (tasty) principles. The practice of boiling meat with large quantities of water, which is thrown away, and with it the whole, or nearly the whole, of the soluble matters, is clearly objectionable. With the albumen and gelatin which would thus be lost, we have already become familiar ; but these are not all. 158. There is also in the water a highly- nitrogeni zed substance, by name kreatin, so called from the Greek kreas, flesh, because contained in meats. One pound of fresh beef or mutton yields about 5 grains of kreatin ; the same weight of fowl about half as much again. It is liebig's beef-tea, boke-earth. 69 obtained most cheaply from codfish. It presents a bril- liantly crystalline appearance, and its solution in water has a weak, bitterish taste. What part it plays we can- not tell ; but as we find kreatin in the juice offish, flesh, and fowl, we may suppose it to have its uses. Any- how, no one but a thoroughly self-satisfied and ignorant person would believe it to be unimportant, because the quantity is small. In Liebig's beef-tea it is always met with, as that contains all the soluble constituents of meat which are not removed or obtained by boiling. Thus there is neither albumen nor gelatin in Liebig's extract, but kreatin and inosin. The kreatin may be likened to quinine ; the inosin to sugar. Inosin is also called muscle-sugar. It is contained most largely in the heart, and identically the same substance is contained in the kidney-bean. Inosin has a sweet taste, and a chemical composition similar to that of dextrose, except that it contains more water of crystallization. [Kreatin, C4H9N3O2, H2O, crystallizes in trans- parent prisms, which require 75 parts of water for solution. By the loss of water it becomes changed, into KREATININ, O4H7N3O, and is thus found in the liquid excretion. Inosin, CgH^gOc,, 2H2O, also crystal- lizes in prisms. When heated below the boiling-point of water, it loses water, and has the same compo- sition as dextrose (par. 41).] 159. Without attempting to enter deeply into the subject, it may be safely asserted that the various salts contained in our food are essential to the nourish- ment of the body ; in other words, all foods worthy of the name contain certain salts. Calcium phos- phate, or bone-earth, is necessary to the building-up of the bones. Unless, therefore, our food contains phosphates, no skeleton can be formed. Now, as a fact, it may be borne in mind that the albuminoid group of foods contains either phosphorus or phosphates, or 70 PHOSPHORUS IN ALBUMEN. SODIUM CHLORIDE. both. Albumen and fibrin both contain phosphorus ; casein does not, but then it is always associated largely with phosphates. [Neither albumen nor fibrin can be thought of with- out PHOSPHORUS as an essential component ; but if we examine more closely the liquids in which albumen is found, and which change albumen into fibrin, we shall always meet with phosphates. In the juice of flesh, we find potassium hydrogen phosphate, and such juice is acid to test-paper ; but in the blood, which turns red litmus-paper blue, we find tri-sodium phosphate.] 160. In all vegetables containing much nitrogen, such as the cereals (wheat, oats, barley, &c.), and the leguminosse (peas, beans, lentils), the albuminoid materials are always accompanied by these phosphates. 161. Liebig's beef-tea contains these phosphates most abundantly, and is therefore of great use in the making of gravy, and of soups, where the ingredients which are wanting, such as albumen and gelatin, are otherwise obtained. 1 62. Besides the phosphates, common salt, or sodium chloride, is contained in all juices, especially in the blood. This salt is necessary to the production of hydrochloric acid in the gastric juice, and of soda in the bile (par. 176). The power possessed by salt of preserving meat is well known ; but salting takes somewhat from the nutritive value of meat, because it dissolves and removes in the brine some of the albumen, the phosphates, kreatin, and other valuable ingredients of the juice. 163. All foods containing much starch, as well as all highly albuminoid, should be eaten with salt. The more thoroughly the salt is incorporated with our food, the better, and therefore it should be introduced a3 such in the process of cooking (par. 176). THE CHEMISTRY OF FOOD. 71 CHAPTER X. THE CHEMISTRY OF FOOD. 164. Starches, sugars, and fats are bodies which consist of the three elements carbon, hydrogen, and oxygen. Cellulose belongs to the same class ; so also does alcohol. Without disputiDg whether alcohol is food or not, although it is held to be such by the author, starch, sugar, fat, and alcohol belong to the respiratory or carbonaceous class. They are respira- tory foods, because they more readily sustain the animal heat ; and the more useful, in proportion to the amount of hydrogen unburnt, or requiring oxygen from without. The difference between starch and a fat is at once seen by comparing the composition of each in 100 parts. Starch. Butyrin. Carbon 44.-5 ... 65*2 Hydrogen 6'2 ... 11*6 Oxygen 49-3 ... 232 1000 100-0 165. As a heat-producing agent, dry fat is two and a half times as valuable as the same weight of starch or sugar. In cold countries the value of fat food is well understood, but it is dilB&cult to persuade young people to place a proper value upon it. In the form of butter and cream, it is generally esteemed, but fat is not sufficiently valued in its property of promoting digestion, and enabling the body to appro- priate nitrogenous food. 16G. Many articles of food can be made more 72 NITROGENOUS, ALBUMINOUS, ETC., MATERIAL. effective by tlie use of some kinds of fat. This is especially the case with the meat of poultry, rabbits, and many kinds of fish, as soles, whiting, plaice, haddock, cod, and turbot. Sprats, eels, herrings, pil- chards and salmon are, on the contrary, more or less rich in fat. Among vegetables, pease and beans are especially improved by the admixture of fatty food, and none is more suitable, or more economical, than fat bacon. The richness of good cocoa and of choco- late is also due to fat, as cocoa naturally contains as much as 50 per cent, of a solid fat known as cocoa- butter. 167. The sugars are the main source of lactic acid, a constituent of the gastric juice, and best known in sour milk, as giving to the latter its acid taste. Lactic acid has the same percentage composition as lactose, or sugar of milk, and is consequently a compound of carbon with the elements of water. Sauerkraut con- tains lactic acid. [Lactic acid, CoHgOs, is a clear, syrupy liquid, of sharp acid taste.] 168. Albumen, glutin, fibrin, and casein are the most important nitrogenous constituents of food. To these may be added, but in an inferior sense, gelatin. Inasmuch as albumen is the most valuable, the name albuminous is often given to this class of foods ; plastic material is also a changeable term for nitro- genous foods. The properties of these different compounds are given in Chapters VIIL and IX., and require no repeti- tion. They all of them contain sulphur as an essential element (par. 53) ; albumen, glutin, and fibrin con- tain phosphorus, as well as sulphur. 169. [Sulphur, S, is an element well known in its free state. In commerce it is met with as brimstone, and it is much valued as a medicine, under the name of flowers of sulphur. When pure, sulphur is of a SULPHUR AND PHOSPHORUS IN PLASTIC FOODS. 73 pale yellow colour, heavier than water, and quite insoluble. It melts at 150° C. When further heated in air, or in oxygen, it burns into sulphurous acid, SO2, a gas possessed of most suffocating odour. An important fact remains for consideration. All articles of food which contain sulphur are liable to become corrupt and abominable, injurious to health, and offensive to the sense of smell. Hydrogen unites with the sulphur of albuminoid bodies, especially in absence of air, and forms the offensive and injurious gas known as hydrogen sulphide, II2S. Because emitted from a putrid egg, it is commonly called rotten eg^ gas. Care should therefore be taken not to allow any refuse to accumulate from which this gas can be emitted ; and this remark applies not merely to the accumulation of refuse animal, but also vegetable matters. As regards the former, the dressing of meat is left to the butcher ; but, as regards vegetables, how much better it would be for the community if they were as carefully trimmed before brought to market, or, at least, into our homes. The chief contamination of the air by our dust-bins would then be avoided, as the refuse vegetables are the main cause of the nuisance, and the necessity for removal would be obviated.] 170. [Phosphorus, P, is also an element, but never found in nature in the free state. It is a pale, wax- like, lustrous solid, nearly twice as heavy as water, and, like sulphur, insoluble. It melts at 44° C, and should always be handled under water, because so inflammable. Phosphorus forms a compound with hydrogen, called HYDROGEN PHOSPHIDE, PH3, a gas possessed of the smell of putrid fish. This gas is given off in the putrefaction of albuminoid bodies. It may be produced by boiling phosphorus in a solution of caustic potash (fig. 19); at the same time a very small 74 NITROGEN IN VARIETIES OF FOOD. quantity of a liquid hydrogen phosphide is produced, which renders the gas spon- taneously inflammable. The appearance is most beautiful, from the formation of widen- ing rino[s of snow-white phos- PHORIC ACID, P2O5.] 171. Although casein does not contain phosphorus, it always removes from milk phosphate of lime, the chief Fig. 19. constituent of bones (par. 1 50). Nitrogenous matters always contain either phosphorus or phosphates, and are ne- cessary for the repair of tissue. 172. The following table gives, with some approach to accuracy, the amount of nitrogen which could be afforded, respectively, by one pound weight of different articles of food. Nitrogen per lb. In grains. Skim-cheese 364' Ordinary cheese 315* Roast beef 260- Pease 252* Red herrings 217* Boiled lean beef 215* Boiled mutton 190* Oatmeal 140* W^heaten flour . . , Maize 120- In grains. Fat pork 106' Bread, wheaten | q^. Pearl barley j Average bacon 80" Rice flour 68" Milk 44' Potatoes 24' Beetroot 17' Whey 15' Cabbages 14' 173. It does not follow, for instance, that one pound of roast beef should really afford 260 grains of nitrogen to the system. The whole of it would not be assimi- lated ; but the student may obtain from such a table a notion of the quantity of nitrogen which each pound could give under the most favourable circumstances. NITROGENOUS FOOD. ASH IN FOOD. 75 174. It is very important properly to adjust the admixture of foods, so that the plastic should not be much in excess of our wants, as regards nitrogen, and also that the carhonaceous or respiratory should be in fair proportion. The nitrogenous may he in the proportion of one-fourth to one-sixth of the respira- tory or carbonaceous food. 175. Now the quantity of nitrogen in food must not be mistaken for nitrogenous or nitrogen-yielding food. As has been already stated, all nitrogenous food consists of at least five elements; viz., carbon, hydro- gen, nitrogen, oxygen, and sulphur ; and, in the case of albumen, glutin, and fibrin, with addition of the element phosphorus. 176. If ou.r food consisted of these elements alone, the act of combustion would convert them entirely into gaseous compounds, and they would pass, as such, into the air. But it is a well-known fact that an ash is left, when food is burnt ; and the more of plastic food there is, the greater is the amount of ash. Thus, pease and lentils, when burnt, leave 2*3 per cent, of ash, and these are notedly high in their standing among plastic foods. About 70 per cent, of the weight of a bone (par. 150) consists of incombustible ash. In the juice of flesh we find phosphates (par. 159), and an abundant supply, when required, in Liebig's beef-tea (par. 161). Common salt, too, or sodium chloride, which is found in every secretion, constitutes about one-half of the weight of the ash of blood. Its constant presence in all animal and vegetable fluids, and in the ash of every kind of natural food, shows the importance of a proper supply. A grown man requires from 150 to 200 grains of salt per day. All vegetables should be salted before they are cooked, as they are thereby rendered more tasty and 76 USE OF SODIUM CHLOEIDE IN OUR FOOD. more wholesome. Not that the quantity of salt in the blood is increased by the salt we eat, but we find digestion promoted by its presence. [Sodium chloride is a compound of the metal SODIUM or natrium, Na, with chlorine, CI. The chemical symbol for salt is therefore NaCl. By the action of vitality, the sodium chloride, in presence of water, is broken up into hydrochloric acid, which is found in the gastric juice, and into soda, or sodium oxide, which is a component of the bile. The same compound, soda, may be produced by burning sodium under water, as suggested in the experiment repre- sented by tig. 20. The test-tube h, held in the Jeft hand, and previously filled with, and kept with its mouth under water, becomes filled with hydro- gen when a piece of so- dium fastened to a wire is allowed to enter the water in the basin a ; the water is driven out of the tube into the basin, and soda is found in solution, in the place of the insoluble metal.] Liebig says that, for all purposes of nutrition, a diet free from salt is no better than eating stones. With abundance of nitrogenous matter, absence of salt is equivalent to starvation. Excess in food is much less injurious when we partake freely of salt, and it is of first importance that choice of salt at meals should not be left to the young. Oxide of iron is always contained in the ash of blood and of muscle, and also, in minute quantities, in the ash of milk. Defect in iron has often to be supplied by medicine, as it is necessary to the making THE DRINKS OF THE BREAKFAST-TABLE. 77 of blood and muscle. Certain meats, as veal and fish, are deficient therein, and the want must be made up by vegetables and bread. 177. It is obvioua that, whilst the study of Che mistry will give us the necessary knowledge of the composition of food, it requires experience to guide us. Defect here, and excess there, can only be reme- died by proper admixture. Want of space will only allow of indications as to what we should eat and what we should drink. CHAPTER XI. THE DRINKS OF THE BREAKFAST-TABLE. 178. After the detailed account of water, as an article of food, given in Chapter I., a few words will suffice concerning its special relations to the hreak- fast-tahle. 179. For making tea or coffee, the water must be absolutely boiling hot. Now water is said to boil when the steam which comes from it has the same elasticity as the air ; so then, boiling depends upon atmospheric pressure, and may be higher or lower than 100° C, according as the pressure is raised or diminished. 180. If water be very hard (pars. 11 and 12), either thoroughly boiled water should be employed, or water just on the boil ; that is to say, either water from which carbonate of lime has already been separated, or hard water only jus*t boiling, before the separation of carbonate of lime has commenced. 181. All vessels in which it is desirable to keep the 78 DESCRIPTION OF A TEA- PLANTATION. water hot, such as the tea-kettle and tea and coffee- pots, should be as bright and burnished as possible. The Scotch fashion of covering the teapot with an ornamental loosely-fitting wrapper, or *^ cosy," is to be commended, as it keeps in the heat for a long time. 182. The introduction of tea has been one of the greatest boons to European nations. It has tended greatly to diminish the use of spirituous liquors, and has therefore largely contributed to promote tem- perate habits. According to Beckmann, tea was first introduced into Europe by a Kussian embassy, at the commencement of the seventeenth century. The plant is a native of China, and of the Northern pro- vinces of Hindostan. It also grows abundantly in Japan and in Cochin-China. Its cultivation is carried on over large tracts of country. The shrub in culti- vation about Canton is known to botanists as Thea bohea, while the more northern variety, from which the green tea is made, has been called Thea viridis. Both black and green teas can, however, be made from either at the will of the manufacturer. There are, of course, many varieties : for, as the tea-plant is multiplied by seed, it is not to be expected that the produce should be altogether identical with the parent. 183. The young tea-plantations are made in spring, and are well watered by the rains which fall at the beginning of the summer monsoon in April and May. When seen at a distance, it looks like a shrubbery of evergreens ; the leaves are of a rich dark green, and afford a pleasing contrast to the strange and often barren scenery around. The toa-plant belongs to the same family as the well-known Camellia ; but it is in every way smaller, and the leaves less thick and glossy. The young plantations are allowed to grow METHOD OF ROASTING THE LEAVES OF TEA-PLANT. 79 unmolested for two or three years, the natives being aware that the practice of plucking the leaves is very prejudicial to the health of the shrubs. The length of time which a plantation will remain in full bearing depends on a variety of circumstances, but, with the most careful treatment consistent with profit, the plants will not do much good after they are ten or twelve years old : they are often dug up and the space re-planted before that time. 184. In the making of green tea the leaves are spread out thinly on flat bamboo trays for the course of an hour or more, in order to drive off all super- fluous moisture. In the mean time the roasting-pans have been heated with a brisk wood fire. A portion of leaves are now thrown into each pan and rapidly moved about, and shaken np with both hands. They are immediately affected by the heat, begin to make a crackling noise, and become quite moist and flaccid, while at the same time they give out a considerable portion of vapour. The}^ remain iu this state for four or five minutes ; they are then drawn quickly out, rolled up in balls, compressed, to squeeze out their moisture, and then again thrown into the pan. Here tlie leaves are kept in rapid motion by the hands of workmen. In about an hour or more they become well dried, and their colour, which naturally is of a dullish green, is permanently fixed. 185. If, however, the leaves are to be converted into black tea, — first, they are allov/ed to lie spread out in the factory for some time after being gathered, and before they are roasted ; secondly, they are tossed about until they become soft and flaccid, and then left in heaps ; thirdly, after being roasted for a few mi- nutes and rolled, they are exposed for some hours to the air in a soft and moist state ; and, fourthly, they are at last dried over charcoal fires. The difference F 80 CHEMICAL CONSTITUENTS OF TEA. in the manufacture of black and green teas is there- fore most marked. 186. This is a description, culled from Mr. Fortune's work on China, of the manufacture of tea as it ought to be sold in the British market. But its adultera- tions are as numerous as they are for the most part harmless. 1 87. The properties of tea depend chiefly on the presence of a volatile oil, and of thein, together with tannin and certain salts. 188. As the volatile oil is easily lost, and acts as a powerful stimulant, tea should be infused, and never boiled. In China, it is true, the dried leaf is not used until, by keeping a twelvemonth, it has lost much of this oil ; but there is no fear to us from the presence of too much oil, which at the utmost^ amounts to 0*8 percent, in green tea. The aroma is best brought out by placing the leaf in a pot, heating it before the fire, and then filling up with boiling-hot water. 189. Tannin (par. 102) in tea may amount to as much as 18 per cent. It is a very powerful astringent. The quantity of it in the infusion depends upon the length of time the tea is allowed to draw : hence it is advisable to pour the made tea into a second pot, if it is to be kept for a length of time. Would that the caterers at our places of public entertainment would bear this in mind, for nothing can exceed the mawkish taste of the article there offered, or furnish a better excuse for taking alcoholic drinks ! 190. But the valuable properties of tea, next to the essential oil, depend upon the presence of thein (par. 197), which exerts a stimulant and a tonic action upon the nerves, resulting in a general feeling of refreshment and invigoration. In delicate and nervous persons strong tea produces wakefulness and restless- TEA AS A COLD DRINK. COFFEE. 81 ness, often with palpitation of the heart, aud other symptoms of distress. 191. Cold tea makes an admirable summer drink, and affords one of the best methods of employing London water after it has been boiled. The celebrated Dr. Johnson says that he is a hardened and shameless tea-drinker, who for twenty years diluted his meals with only the infusion of this fascinating plant ; whose kettle had scarcely time to cool ; who with tea amused the evening, with tea solaced the midnight, and with tea welcomed the morning. 192. The taste for coflfee is in England not so gen- eral as that for tea. It was first introduced amongst us in the year 1652, when a coffee-house was estab- lished in London by a Greek in the neighbourhood of Cornhill. 193. Coffee belongs to the same natural family which supplies us with ipecacuanha, quinin, and cin- chonin. The plant is a native of the Ethiopian high- lands, and is now extensively cultivated in Arabia, the East and West Indies, and America. It is an evergreen, and grows to a height of about 16 feet. The leaves are oblong-ovate, sharp-pointed, very glossy, and upwards of 2 J inches long. The flowers are white and fragrant, but fade rapidly. Fig. 21 gives a good representation of the coffee-plant : a, corolla and stamens ; 6, style and stigmas ; c, the berry, and d, the berry with the two seeds exposed. The fruit somewhat resembles the cherry, and grows like the flower, in clusters ; when ripe it is shaken from the tree, and laid on mats exposed to the sun. As soon as it is dry, it is spread i?.pon a floor, and the husks are broken off with a heavy roller. The berries are then winnowed, and further exposed to the sun. Each shrub will afford from one to two pounds of the F 2 82 COFFEE AND THE COFFEE PLANT. berry. Mocha coffee is the most highly esteemed, and affords the most as^reeable beverage. 194. Coffee swells greatly during roasting, and loses about 20 per cent, of its weight. It becomes brown and friable, and exhales a rich aroma; at the same time a pleasant bitter principle is pro- duced, which is not contained in the raw coffee. The sugar in coffee amounts to upwards of seven per cent, and is of the same character as sucrose. Or- dinary roasted coffee contains caramel (par. 38), derived partly from the natural, and partly from added sugar. 195. The aroma acts as a stimulant, and the effect of an overdose is similar to that of oil of tea ; and yet coffee only contains 0*003 per cent. ! There is no tannin in coffee, but in its place a peculiar acid, the caffeic, which is a variety of tannin in combination Fig. 21. CAFFEIN. EFFECTS OF COFFEE. THEIN. 83 with caffein. In making coffee, if an agreeable flavour be desired, the berries should have been freshly roasted, finely ground and infused : it is then less astringent, less acid and more digestible ; but, owing to the large quantity of fixed fat (13 per cent.), coffee is not so easily digested as tea. 196. A cup of strong coffee is far more stimulating than tea ; when taken freely, it produces dryness of the skin, thirst and feverish symptoms. The effect on the brain is striking. It prevents drowsiness ; hence is it called by the French *^ liqueur spirituelle." It accelerates the circulation of the blood, and sometimes occasions giddiness and palpitation of the heart. In tropical climates it is valued for its stimulating powers, being regarded almost as a specific against the enervat- ing effects of heat. Liebig says of coffee : " Persons of weak or sensitive organs will perceive, if they attend to it, that a cup of strong coffee after dinner instantly checks digestion. It is only when the absorption or removal of it has been effected, that relief is felt. For strong diges- tions, which are not sufficiently delicate reagents to detect such effects, coffee, after eating, serves, from the same cause, to moderate the activity of the stomach, exalted beyond a certain limit by wine and spices. Tea has not the same power of checking digestion." 197. Thein in tea, and caffein in coffee, are iden- tical in chemical composition, and are active alkaloids, like quinin. In tea, it may amount to 3 or even 4 per cent. ; in coffee to less than one (0*8) per cent. It crystallizes in long, white, silky needles, sparingly soluble in cold water and in alcohol. When heated, it fuses and sublimes, and for this reason may often be extracted from coffee-roasters. The effects of this alkaloid are a result of a stimulant and tonic action 84 COCOA AND CHOCOLATE CONTAIN THEOBUOMIN. on the nervous system generally. [Thein, CgHj^N^O^, H2O, is identical with caffein, CgHj^N^Os, HgO.] 198. Cocoa and chocolate are not sufficiently valued as articles of diet. Although in one important respect resembling tea and coffee (with regard to the alkaloid theobromin), they are both meat and drink in the way of direct nutrition. The name of the cocoa-tree, Theohroma cacao would seem to embody the opinion of the great botanist Linn^us as to its value ; the word Theobroma signifying '' food for gods." Accord- ing to Johnston, it grows wild in several countries of the torrid zone of America, especially in Guiana, Mexico, and the coast of Carraccas. The tree has large leaves, and the flowers grow on short stalks direct from the stem. The fruit is a large leathery capsule, having nearly the form of a cucumber, and containing from twenty-five to thirty seeds. These are covered with a thin husk, which is removed before the seeds are broken into the familiar form of cocoa- nibs. 199. The nibs yield about 55 per cent, of cocoa- butter, a white, solid fat, not liable to become rancid. In the so-called homoeopathic cocoa this fat is entirely removed. The nibs also abound in glutin (par. 129), to the extent of 17 per cent. ; but this is almost entirely removed in the ordinary mode of preparing cocoa. Gum, sugar, starch, and cellulose amount to 22 per cent. 200. Theobromin in cocoa amounts to about 1*2 per cent. In composition it closely resembles caffein and thein, and has similar properties. [Theobromin, C7H8N4O2, is an alkaloid, slightly bitter in taste, sparingly soluble in boiling water, and still less so in alcohol and ether.] 201. Chocolate is generally prepared by grinding the roasted nibs into powder between hot rollers. COCOA AND CHOCOLATE. TEA AND COFFEE. 85 This powder is made into a paste flavoured with vanilla, sweetened with sugar, and generally dete- riorated with flour or starch. Humboldt gives this testimony in favour of chocolate, that, before the con- quest of Mexico, it formed the principal food of the Mexicans. They held the cocoa-tree in such estima- tion, that its kernel served as current coin ; and this custom still continues. By being mixed with milk, as it generally is, it is made still more palatable a^ well as nutritious, and is strongly recommended as an adjunct of the breakfast-table. 202. As the late Professor Johnston remarks : '' Everywhere, in fact, un-intoxicating and non- narcotic drinks are in general use among tribes of every colour, beneath every sun, and in every con- dition of life. The custom, therefore, must meet some universal want of our nature, some physiological function which science has not explained ; and, con- sidering that these beverages contain essentially the same chemical compounds, it is remarkable that they should have been selected from the whole range of the vegetable kingdom. What constitutional cravings common to us all have prompted to such singularly uniform results ! Through how vast an amount of unrecorded individual experiences must these results have been arrived at ! Coffee has followed the banner of the Prophet wherever, in Asia or Africa, his false faith has triumphed. Tea, a native of China, has spread over the hill-country of the Himalayas, the table-lands of Tartary and Thibet, and the plains of Siberia ; has climbed the Altais, overspread all Russia, and is equally despotic in Moscow as in St. Peters- burg. In Central America, the Indian of native blood, and the Creole of mixed European race, indulge alike in their ancient chocolate. In Southern America, the tea of Paraguay is an almost universal beverage." 86 USE OF BOILING WATER. MILK AT MEALS. 203. One advantage of all these drinks consists in the great fact that they must always be made with "boiling water, and thus provision made for the great want of many places, a wholesome drinking-water. One thing should be remembered in connection with the use of hot beverages : not to speak of the damage inflicted on the teeth by repeated alternations of hot and cold, excessive heat materially impairs the diges- tive power of the stomach, permanently weakening its structure. It is a matter of common observation, that cooks are noted for bad teeth. This may be accounted for from their love of hot tea, and their opportunities for eating scalding-hot food. 204. The very best beverage for breakfast and tea for children is milk, in some form or other. With the prevalence of foot-and-mouth disease, and the possible adulteration with tainted water, it should always be boiled. The same may be said of skim- milk as a common drink for adults in the place of water. 205. It may be necessary to repeat that skim-milk contains all the plastic material of fresh milk, and has only been deprived of the greater portion of its fat. It is a most valuable article of food. CHAPTEE XII. FRUITS, A VARIETY OF DRINK. 206. All fresh fruits contain much water, and may be regarded as acid juices more or less sweetened, APPLES AND PEARS. VEGETABLE ACIDS IN FRUITS. 87 witiii nioi e or less of nutriment. If not perfectly ripe, fruit should always be cooked before it is eaten ; else it is unfit for food. Unripe fruit may be com- pared to bad water, laden with organic matters in a state of change, the evil effects of which can only be destroyed by heat. More especially is this the case with fruits like the melon, which contains 96 per cent. of water : except when ripe, it should never be eaten, and, like all watery fruits, should be eaten with bread, so as to separate the tough cellular structure, to pre- vent its forming indigestible pads. 207. The apple is both wholesome and nutritious. The tree itself, Frimus malus, is a native of Britain, being far from uncommon in woods and hedges, though the wild apples or crabs are small, dry, sour, and unpalatable. By sowing and re-sowing the seed, crossing and re-crossing the sorts thence produced, the many known varieties of apples are procured. Heat, when applied in roasting, baking, or boiling, tends to break down the interstices of the cells of the apple, to diffuse the acid and tlie sugar more uni- formly through the mass, to disperse some of the moisture, and to render the whole more easy of di- gestion. 208. One of the properties of sugar is especially worthy of remembrance, when the sweetening of a fruit-pudding or pie is in question. The presence of vegetable acids (pars. 98, 99, 100) soon determines the change of sucrose (par. 36) into dextrose (par. 41), — a sugar possessing far less of sweetening power. It is consequently a waste of a portion of the sugar to sweeten before cooking. 209. The pear grows wild in our woods and copses, but it there yields fruit of a very inferior description, and very unlike the juicy produce of the orchard. From a deficiency of acid, this fruit is less wholesome 88 CUKRANTS, CHERRIES, PLUMS AND DAMSONS. for delicate stomachs than the apple. In both cases, where health is studied, the skin as well as the core is to be rigidly avoided. 210. Black and red currants are natives of Britain, as are also gooseberries. Cold as are some of the countries of Northern Europe, large and beautiful berries may be obtained. Even in the barren dis- tricts of Finland, and on the Alpine heights, goose- berries with ruddy tints have been met with. A tra- veller in Kamschatka found himself in a large forest, many of the trees being finely grown ; and amongst the underwood he perceived some bushes of large red berries, which, to his great astonishment, he dis- covered to be red currants of a very large size and high flavour, but possessing a much more acid taste than those of our gardens. 211. Cherries were obtained from Cerasuntis, a city of Pontus, in Asia Minor ; hence the botanical name, Prunus Cerasus. LucuUus, after the war with Mithridates, introduced them into Italy : they were so pleasing as to be rapidly cultivated, and Pliny testifies that, twenty-six years afterwards, the cherry- tree passed over into Britain. The whole race of this tree was afterwards lost, and is said to have been restored by the gardener of Henry VIII., who brought it from Eland ers. 212. Just as the cherry has become indigenous, the plum is common in its wild state, and has been much improved by cultivation. The sloe may be the original stock from whence all the varieties of the plum have originated. The damson, or damascene, was brought from Damascus. The most unwholesome portion of wall-fruit is the skin, which is quite as indigestible as wood. 213. Ripe grapes are among the most palatable, wholesome, and nutritious of all fruits. The weight GKAPES AT HAMPTON COURT. ORANGES. 89 of grapes which every vine can properly produce is proportioned to the thickness of the stem immediately above-ground. At Hampton Court there is a vine which yields about fourteen hundredweight of very fine grapes in a good year. The grapes produced in Palestine are very large ; the famous bunch of Eshcol, which required to be borne by two men, greatly sur- prised and pleased the Israelites when they first be- held in a barren and sandy desert, the fruits of the long-promised land they were to occupy. Even now, in the present neglected state of the country, some bunches of grapes are found to weigh twelve pounds. 214. The quantity of sugar in the grape is very large, varying from 10 to 20 per cent. Dried grapes or raisins are greatly valued. The so-called Mus- catel raisin consists of the bunch dried whilst yet hanging on the vine. Sultanas come from Turkey. 215. Although of less importance to us in England, the date is of great value throughout Asia and Africa. It is the fruit of a palm, and sweet to a high degree, from the presence of 58 per cent, of sugar. 216. The fig is the sweetest of fruits, and comes from one of the most beautiful of trees. It is apt to cloy. 217. Mulberries bring us back to juicy fruits. They contain 85 per cent, of water and 9 per cent, of sugar, and suflScient acidity to be pleasant to most palates. 218. Strawberries and raspberries are about equal as to water, but the former are always sweeter, and contain less free acid. Both fruits are very refresh- ing, and much appreciated. 219. Amongst the most useful and grateful of fruits introduced to us in modern times, is the orange. The Portuguese are supposed to have imported it into Madeira, and into all countries washed by the Mediterranean. No single kind of food has had so much to do with the removal of scurvy as this deli- 90 TABLE OF CONSTITUENTS OF FRUITS. cious fruit, together with its allies, the lemon and the citron. 220. Many of these fruits contain a notable quan- tity of sugar, nitrogenous matter, acids, and salts, as may be judged from the following table, compiled from the labours of Fresenius : — Nitrogenous Water. Sugar. Acid. matters. Salts. Mulberries... 85'0 . . 90 .. . 1-86 ... 0-40 . .. 0-56 Grapes 79-8 . . 13-8 .. . 1-12 ... 0-80 . .. 0-12 Blackberries 86*4 . . 4-4 .. . 1-18 ... 0-60 . .. 0-41 Pears 850 . . 8-0 . . trace — ... 0-28 Apples 85-0 . . 7-5 . . 1-04 ... — .. 0-44 Cherries 80*5 . . 8-7 . . 1-27 ... — .. 0-56 Strawberries 87'4 . .. 7-5 . . 1-13 ... 0-36 . .. 0-60 Raspberries 86-5 . . 4-7 . . 1-35 ... 0-54 . .. 0-48 Gooseberries 85'5 . .. 8-0 . . 1-35 ... 0-44 . .. 0-31 Currants ••' 85-2 . . 6-4 .. . 1-84 ... 0-49 . .. 0-57 Greengages 79*7 . . 3-4 .. . 0-87 ... 0-40 . .. 0-40 Apricots ... 83-5 . . 2-7 . . 1-60 ... 0-41 . .. 0-72 Peaches 85-0 . . 1-6 . . 0-60 ... 0-46 . .. 0-42 The nitrogenous matters in pears, apples, and cherries are not stated. The quantities of water and of sugar vary according to season, &c. But the analyses will convey a useful lesson as to the com- position of many fruits. When in season, these fruits may be made to supply substitutes for alcoholic drinks and tainted water. Indeed, fruit is the most natural, healthful, and delicious part of our diet, and ought to form a much larger proportion of it than is usual, especially among the poorer classes. Preserved fruits are to be obtained at very reasonable prices, and, thanks to the removal of the duty on sugar, are now generally sold free from adulteration. Bread and butter should be eaten with ripe fruits, if they are to serve the purpose of nutrition, and the part of a meal. 91 CHAPTER XIII. VEGETABLES, AXD THE PART THEY PLAY AS FOOD. 221. It has probably been observed that flesh, cor- responding in composition to that of the human l3od3% contains 79 per cent, of water. Now the liquids taken at a meal should be in quantity, such as, when added to that contained in, the solid food, would raise the whole amount to this percentage. In fact, however, instinct urges us usually to take more than the above-prescribed dose. On this point the conclusions of pure chemistry must not be too rigorously interpreted. Genuine science need never override common sense and experience, which must be allowed some sway, not to contradict, but to modify, if need be, and reduce to their true value the dictates of science. 222. Every kind of natural food is bulky ; that is, it contains much that is not in the ordinary sense nutritious. Vegetables, for example, contain a very large proportion of water and woody fibre : bulk seems, however, essential to the proper action of the stomach, which cannot digest more than a very limited quantity of concentrated nourishment. This is one reason why pease and beans are not readily digested in any quantity, their nitrogenous matter being too abundant. 223. Of foreign vegetables now established among us, many originally came from Southern climates, especially from Italy, and the number of them has greatly increased in the course of the last two cen- turies. The kitchen-gardens of England were, until about the end of the sixteenth century, as scantily supplied with vegetables as the pleasure-orrounds were with shrubs and flowers. ^' It was not." says Hume, ** till the end of the reign of Henry YIII., that any 92 VEGETABLES USED TO BE VERY HARE. salads, artichokes, carrots, turnips, or other edible roots, were produced in England/' The little of these vegetables that was used, was imported from Holland and Flanders ; and Queen Catherine, when she wanted a salad, was obliged to despatch a messenger thither. The most important vegetable of the present day, the Potato, was brought to England in 1586, by Sir Walter Raleigh ; but its culture for the next century must have been but partial, as the market-price was then one shilling per pound. Brocoli and Cauliflower were introduced from the Levant into Italy about the end of the sixteenth century, and at the close of the seventeenth into England. The Turnip was in culti- vation in the seventeenth century; and it is stated that when in the years 1629 and 1630 there was a dearth in England, very good bread was made with boiled turnips, kneaded up with an equal quantity of wheaten flour. Among the .kitchen vegetables, of which uncertain traces are to be found in the works of the ancients, is Spinach. Its native country is unknown. The name first occurs in the year 1351 among the lists of food used by the monks on fast-days. The extent to which the Homans carried their enthusiastic affection for Leguminous * plants, is shown by the fact, that illus- trious families did not disdain to borrow their names from them. Fabius, Cicero, and Lentulus thus give renown to the humble names of beans (Faba), pease (Cicer), and lentils (Lenticula). 224. Potatoes deserve, perhaps, chief mention among ordinary vegetables. They contain, it is true, 75 per cent, of water when raw, but this very succulence adds to their value. They should be cooked in their skins, as they thus not only lose but little moisture * Leguminosoe is the botanical name for the family to which pease, beans, lentils, &c., belong. COOKING OF POTATOES. MASHED POTATOES. 93 (3 per cent.), but are then more easy to steam, and more mealy when brought to table. The starch which they contain is a first-rate vehicle for salt, and a good absorbent of fat. Except when eaten in large quan- tities (which is as objectionable as making rice a chief portion of diet), they cannot afford the nitrogenous (par. 47) materials in anything like sufficient quantity, unless eaten with lish or flesh, or with highly nitro- genous food like eggs, pease, and beans. With skim- milk as a drink they do well ; in fact, all they need is admixture with more nitrogenous food, of which potatoes contain only 2 per cent. It would require about 3^ lbs of cooked potatoes to supply the same amount of nitrogen as can be obtained from one pound of good wheaten bread. 225. As regards the cooking of potatoes, it is necessary to add a word ; they should not be boiled, but steamed. Waxy potatoes should, if bought, be somewhat dried before they are steamed, by placing them in the hot ashes. If peeled, they lose 14 per cent, of water ; a matter of no great importance in itself, as potatoes contain so large a quantity, but serious to the poor, because so much waste is incurred in the act. When steamed in their skins, they should be scrupulously clean ; and if the cook does not possess a steamer, the principle may be carried out by placing only a small quantity of water at the bottom of the saucepan, and with closed lid allowing the steam to do the work. Baked potatoes are somewhat more nutritious than steamed, as they lose more water, and they are certainly more wholesome. If persons are at all delicate, potatoes should always be served mashed, as it is a great mistake to suppose them easy of digestion unless well masticated. Under- done potatoes are among the most objectionable forms of food. 94 CABBAGES, CARROTS, TURNIPS, AND BEET-ROOT. 226. Cabbages, although in themselves of little value as food, are of great importance in admixture. As the common cabbage contains about 92 per cent, of water, it occupies a lower rank as a vegetable than the potato ; its succulence is, however, a great recom- mendation, especially when eaten with dry salt mpats, which supply the necessary nitrogen ; or with bacon, which makes it rank high as respiratory food ; thus is the requisite bulk obtained at no great cost. With regard to nitrogenous matters, the cabbage stands upon exactly the same level as the potato. In Germany, cabbage is made into very nutritious food by the introduction of boiled chestnuts ; these are peeled, rasped, mixed with the cooked cabbage, and flavoured with butter and salt. 227. Carrots and turnips are about of similar value as to nitrogenous matters ; that is to say, they are equally low. Turnips contain only 2 per cent, of sugar ; carrots 6 per cent. In other respects, when tender, they are about equally digestible. Owing to the large amount of water which they contain, they are well suited for admixture with salt meat. Parsnips are about intermediate between carrots and turnips. 228. Beet-root stands higher as respiratory food than carrots, on account of the considerable amount of sugar which it contains. But, as to nitrogen, its value is small, even less than that of a potato. One pound of beet-root would be equal to one moderate- sized eggj with reference to nitrogen. Nevertheless, it is an admirable vegetable when boiled, cut in slices and served hot, with thick gravy or melted butter. 229. Onions, to thoce who do not dislike their odour, are admirable as giving flavour to many foods which would be otherwise tasteless and unsatisfying. The Spanish peasant dines frequently on bread and raw •aNIVEBSiTT CUCUMBERS, PEASE, BEANS, AnW lifflT'lLS. 95 onion ; and, although this is not suggested for imita- tion, it is worthy of record as a fact. A very small piece of meat may be made serviceable to many mouths, by admixture with certain vegetables flavoured with onions. If the water in which the onions are boiled is thrown away, and renewed more than once, much of the strong-smelling and indigestible oil is removed, and the chief offence done away. 230. Lastly, onions suggest cucumbers. These are least unwholesome when cut at the time they are eaten. No plan of preparation is worse than that of cutting them into thin slices, allowing the juice to drain, and then to serve them with vinegar, salt and pepper. Cucumber salad is then often most indiges- tible. The large amount of water which it contains makes cucumber a pleasant accompaniment with bread and cheese, especially when freely eaten with salt. 231. It will be expected, in speaking of vegetables, that something more should be said about those which contain less water, and therefore stand higher as regards nutrition. We should distinguish between such as are real substitutes for meats, on account of their high nitrogenous values, and such as turnips, parsnips, carrots and cabbages, which afford a pleasant form of water, some bulk, and but little nourishment. Thus pease, beans, and lentils stand very high as nitrogenous foods, and should be eaten for the purpose of economizing the more expensive meats. However well cooked, they are not so digestible as meat ; they are not only too dry, but too nitrogenous. They all contain a large percentage of starch, and therefore take rank not only as plastic (par. 104), but also as respiratory food. Nevertheless, the nitro- genous is so very considerable, that such require large admixture with other kinds of food. Pease and beans, when properly cooked and eaten in moderation, go G 96 VEGETABLES LESS DIGESTIBLE THAN MEATS. well with bacon, fat pork, and potatoes. Hence, also, melted butter is used with them, as it renders the starch more palatable. Grreen pease, French beans, and Scarlet runners, are much more easily digestible than when in the form of dried pease and beans : one pound of pease may afford 252 grains of nitrogen. Pease meal is best em- ployed in making soup, puddings, and such-like, and is a much-valued article. 232. The reader must have missed his way if he has not perceived that vegetables contain plastic and respiratory material of similar quality to that which is met with in animal food. Flesh has its counterpart in the casein of pease, beans, and lentils ; in the glutin of bread, and in the fibrin of oatmeal. The fat of meat is represented by the various star^ches, the sugars and cellulose. The very juices of meats have a certain counterpart in the juices of vegetables. Anyhow, vegetables ought to form a considerable proportion of our food, including, of course, bread and its like, as important and primary articles. 233. But, inasmuch as vegetables of every kind are less digestible than many, even most, meats when properly cooked, persons with small appetites ought to make animal food the leading principle in their diet. And again, all who have a tendency to become stout should be very careful as to their choice of vegetables, and should avoid the starchy constituents nearly as much as the different fats and oils. 234. Considering the enormous number of aliments in the world, and the present great facilities of inter- communication, it is wonderful that so little variety is met with in the dietaries of the poor. For, to a certain extent, the gratification of the appetite is not only a legitimate pleasure but a veritable duty, as it conduces to the health of the body. Most persons are aware of liebig's opinions on food admixture. 97 the appetizing effects of a diet grateful to the palate, and there is nothing more acceptable than frequent change. The strongest illustration is afforded by the positive disgust created by the constant use of the same food, which is indeed so great that, even when it is eaten, the stomach refuses to digest it. 235. Even though it may involve a repetition of certain statements, the following quotation will aptly conclude this chapter, showing, as it does, the im- portance of proper admixture, and the value attaching to vegetable as well as to animal food. " It is obvious," says Liebig, " that by a due admix- ture of plastic and respiratory food, we can obtain a diet of a composition analogous to that of milk or of wheaten bread. By the addition of bacon or fat pork to pease, beans, or lentils ; of potatoes to beef; of fat bacon or ham to veal ; of rice to mutton ; we increase in each case the proportion of non -nitrogenous matter. A glance at these relations is sufficient to convince us that, in choosing his food (when a choice is open to him), and in mixino the various articles of food, man is guided by an unerring instinct which rests on a law of nature. " This law prescribes to man, as well as to animals, a proportion between the plastic and non-nitrogenous constituents of his whole diet, which is fixed within certain limits, within which it may vary according to his mode of life and state of body. This proportion may, in opposition to the law of nature and instinct, be altered beyond these limits, by necessity or compulsion ; but this can never happen without endangering the health, and injuring the bodily and mental powers of man." G 2 98 MODES OF COOKING FISH. FAT FISH. CHAPTER XIY. ON FISH, FLESH, AND FOWL : MODES OF COOKING. COLD MEATS AND SALADS. 236. The introduction of fish, as part of our diet, is very much to be commended. But it is not fitted to take the place of flesh-meat entirely, except once or twice a week. Salmon, being a red-blooded animal, does not indeed differ much from meat, but it requires greater skill in cooking, and the employment largely of butter and eggs, to make fish generally a substitute. Fish digests very rapidly, and soon leaves a sense of emptiness, which is far from pleasant to a hard-working man. Nevertheless, to those who live well, it would be of considerable advantage to make a fish-dinner, at least occasionally. 237. Where the fat in fish is fairly diffused through- out the muscular portion, the meat is more satisfying ; but when the fat, as in cod-fish, is mainly stored up in the liver, and the meat is very dry, a rich butter is required to make the dish perfect. Oyster-sauce, the mpst nutritious of dressings, generally accompanies cod, and gives to it that which it lacks. What differ- ences in respect to fat, there may be in the varieties of fish, the following table will make manifest. The statements are according to Payen, and give the quantity per cent. Fat per cent. Soles 0-248 Whiting 0-383 Conger-eel 5-021 Mackerel 6-758 Eels 23-861 EFFECTS OF FRYING, BROILING, AND BOILING. 99 Sprats, herrings, and pilchards are also rich in fat, and are rightly much esteemed, on account of their tastiness and nutritive value. Indeed, fresh, as well as salted, herrings are among the most valued of foods, on account also of the quantity of nitrogen which they can afford. A dried herring will give as much as 40 grains of nitrogen, and a fresh one, of average size, about 30 grains ; so that a bloater is a good addition to bread-and-butter at the breakfast or supper table. 238. The fresher the fish, the more digestible it is. It only requires some judgment to know when certain kinds are in season, and to purchase accordingly. Then alone are they probably in the best condition for eating ; and then alone can they be considered economical food. When the flesh is firm, fish-meat is in its highest condition. 239. As regards cooking, the remarks made about the effects of heat upon fat (par. 57), require expan- sion. The heat of frying renders fat most difiicult of digestion, and should be avoided in the case of delicate persons. The fried fish, as often sold in the fish-shops of London, is very indigestible : the smell ought to be sufficient to give warning of the act of burning, and of the fact of the decomposition of the fat. And if rancid fat is used into the bargain, it is not easy to express in words the injurious consequences possible to some constitutions. Broiling is a good process of cooking, where that is possible ; but it involves a clear fire, free from smoke, careful attention in the way of turning, and some good sweet fat, though not at all necessarily butter. Lard is far better than much of the so-called butter which is sold at the present day. Some people, however, can only eat fish which has been boiled, and such is easiest of digestion, although not so savoury. lOG POULTEY LESS SATISFYING THAN FLESH MEAT. 240. Poultry is perhaps intermediate in value between fish and flesh-meat. It is certainly not so satisfying as flesh-meat, and as a substitute, is too expensive for people of ordinary means. Not that poultry is deficient in nitrogen, but rather in fat, and in iron. The fat is easily supplied, but the fact remains, that what would appear an unnaturally largo quantity, would have to be eaten by a person of good appetite in order to produce the sensation of a full meal. On account of the want of fat, boiled chicken is always eaten with melted butter, and generally with fat bacon or pork sausages. Koast chickens and tongue, together with a good gravy from beef, also practically make up for the above-mentioned defici- encies. As regards phosphates, the young meat from fowls is peculiarly advantageous, and superior to that from flesh. The want of iron can be made up by good gravy. The part, tlierefore, of poultry, as an article of diet, can be readily understood. 241. Ducks and geese are more tasty, but not nearly so easy of digestion. The fat is far more abundant, and is therefore liable to be injured by fire ; besides which they possess a strong flavour, not relished by all. Addition of sage and onions, by its stronger flavour, may easily overcome the natural taste, but then such seasoning is not very acceptable, and certainly neither agreeable nor digestible. 242. Rabbits resemble poultry, and are as easy of digestion. They also require some addition in the way of seasoning, as they are otherwise very insipid. Fried bacon and sausages are good accompaniments, and make up for defect in fat. If boiled, and served with a good white sauce, or with parsley and butter, the want of fat and flavour is also supplied. 243. As regards flesh-meat, much has been already ROAST AND BOILED MEATS. VEAL AND PORK. 101 said (Chapter YIII.). Eoastmeat is more nutritious, weight for weight, than boiled, because meat in roast- ing loses more than in boiling. Beef loses less in weight than mutton, partly because of the less fat contained in it, partly because the flesh is more dense. When beef is lean, it may lose even 30 per cent, in boiling ; much, however, must depend upon the absence of fat. One pound of boiled beef, according to the late Dr. Edward Smith's experiments, may give 215 grains of nitrogen ; one pound of roast beef 262 grains. Esti- mating mutton with its usual amount of fat, one pound of boiled mutton may afford 192 grains of nitrogen. Lamb is more watery than mutton, and digests more easily. Considering how rapidly lamb grows into mutton, and the serious price of meat, it is more than doubtful whether it should be eaten except by invalids. 244. Veal, as generally eaten, having been deprived of the blood and its salts, is less digestible than beef or mutton, and should be served with a good gravy made with gravy-beef, or with Liebig's extract of flesh. The salts lost by the veal could thus be re-supplied ; but, whether it be wise first to remove, and then to add what we remove, is for a discerning public to settle. The same objection applies to veal as to lamb, as regards the slaughter of young animals. In the form, of roast- veal, properly seasoned, and partaken of with ham in order to supply the want of fat and a harder fibre for admixture, this kind of meat is at its best and is most valued. Calves' feet afford perhaps the purest form of jelly. The latter owes its property to a substance called gelatin (par. 148). 245. Pork is so much richer in fat than mutton or 102 TRICHINA SPIRALIS IN PORK. beef, and is so much more difficult to masticate on account of the texture of the meat, that even its nitrogen does not go so far, as a nutrient, as the quantity present in it would indicate. One pound of fresh pork is said to contain only 79 grains of nitrogen. Pickled pork is more digestible than either boiled or roast. The latter is said by Dr. Beaumont to require five and a quarter hours for digestion, whilst pickled will probably be digested in about three hours. Salted, as ham and bacon, pork offers one of the most aofreeable varieties of food. '■' There is, however, a greater danger in the use of pork than of any other kind of meat, since, so far as is known, it is more frequently diseased, and the nature of the disease is such as to be very injurious to man. Thus, measly pork is known to have produced fatal results to many of those who have incautiously eaten it ; and although the characteristics of the disease may be recognized by those who understand it, they are neither known nor observed by the great majority of the poorer classes. Further, the terrible pest of the small worm called the Trichina spiralis, is much more frequent in this than in other kinds of flesh in its uncooked state ; and the power which the creature has to penetrate the tissues of the body of those who eat it, has been vividly described by German and American writers. " Many instances of this terrible disease, isolated or in numbers, have now been recorded, and particularly in Germany. Of 103 healthy people who ate diseased pork which had been made into sausage-meat, at Hel- stadt, in Prussia, 20 died within a month. ... In all the fatal cases the worm was found to have penetrated the whole muscular system, and upwards of 50,000 were computed to exist on a square inch." — Dr. Ed. Smith on Foods. PERFECT COOKING OP PORK ESSENTIAL. 103 The best precaution against any such mishap con- sists in perfect cooking. There should never be the appearance of raw or underdone meat, either in the case of pork or veal. 246. With reference to sausages, they are un- objectionable if their origin can be fairly traced. Certainly meats can thus be made available which would otherwise probably be wasted. It is in sausages that diseased meat would most probably be met with. 247. From the very nature of meats, and from the abundance of nitrogenous constituents, the necessity for the use at the same time of bread and of various vegetables may be inferred. Bread is a necessary of the dinuer-table, whether the diet be liberal or lean. From its porousness, aud its easy digestibility, it is admirably adapted for admixing with and separating the denser meats. lb is, besides, useful in retaining moisture, as well as nutritive in the sense of nitro- genous. One pound of bread contains more nitrogen than a pound of pork, and this element is the most costly to purchase. 248. Such condiments as pepper, mustard, and spices act as stimulants of the digestive organs. They often give an appetite by the flavour they confer upon food, and are certainly aids to digestion. Mustard is an annual cultivated for the sake of its seeds. There are two kinds, the black and the white, and these are generally mixed together. Although the powdered seed has little odour when dry, in the moist condition it exhales a pungent, penetrating odour, very irritating to the eyes and nostrils. The peculiarity of mustard is, that the essential oil, for which it is so highly valued, does not exist ready- formed in the seed, but is developed on the addition of water. It is even possible to render the ferment, which is present, altogether inactive, by means of 104 CONDIMENTS OF VARIOUS KINDS. boiling water, teaciiing the lesson that mustard for the table should be made with warm, bub not boiling water. Oil of mustard consists mainly of sulpho- cyanide of allyl, the chemistry of which compound is too intricate for a work of this kind. Horseradish is the root of Gochlearia armor oda, and is much cultivated on account of its grateful qualities. The fleshy root has a pungent taste, and emits, w^hen crushed or scraped, the odour of mustard. When distilled with water, the same oil as from mus- tard is developed. Mustard is far more wholesome, as the scraped root may adhere in the same way as the skins of plums, and produce indigestion, if not worse results. Pepper grows in abundance on the Malabar coast, whence, as well as from the Malay Peninsula, Sumatra, and other islands, it is now imported. The berries are gathered before they are ripe, and dried in the sun : they then become black and wrinkled from the drying up of the pulpy part, which covers a round greyish-white seed. White pepper is the same berry allowed to ripen, when its pulpy part is easily removed by soaking in water and subsequent rubbing. The essential constituents of pepper are : — an acrid resin, a volatile oil possessing the flavour of the pepper, and a substance called piperin, possessed of the composi- tion, but with none of the properties, of morphia. 249. Vinegar has already been mentioned in Chap- ter YI. It is certainly one of the most valuable of condiments, and could least easily be dispensed with. A weak solution of sugar is easily changed into vinegar, through the aid of the vinegar plant (Fenicillium glaucum) : the same plant will continue to grow, and may be used again and again. The pleasantest vinegar is white wine vinegar. In some form or other it has most wide applications. It SALADS OF GREAT IMPORTANCE TO HEALTH. 105 prevents the decomposition of animal and vegetable substances, and enables us to keep mackerel, salmon, and other meats, even in the warmest weather, and at a time when vinegar is most grateful. Cabbage is more tasty when eaten with it, and with salads of various kinds it is of first importance. 250. Space is wanting to do much more than men- tion salads as a pleasant variety of food, as helping to give bulk in an agreeable form, and in eking out small quantities of meat. From time immemorial the lettuce has occupied a most distinguished place in the kitchen garden. The Jews eat it, without preparation, with the Paschal lamb. The opulent Greeks were very fond of the lettuces of Smyrna, which appeared on their tables at the end of a feast ; the Romans decided that this favourite dish should be served in the first course with eggs- The lettuce possesses a narcotic property, of which ancient physicians have taken notice. Galen mentions that, in his old age, he had not found a better remedy against the wakefulness he was troubled with. Our ancestors served salads with roasted meats, roasted poultry, &c., and they had a great many which are no longer in vogue. Lettuces, endives, watercress, beet-root, radishes, onions, and such-like, constitute the basis of the various salads, and are rendered of high nutritive value by the introduction of potatoes, haricot beans, French beans, and similar foods. In Germany, charm- ing variety is given to salads, by making some more nutritive substance than lettuce the basis. Thus we have bean-salad, potato-salad, lierring-salad, endive- salad, and others. The vegetables are covered with oil, acidulated with vinegar, which makes them very agreeable to the palate, and also more digestible. 106 USE OF GARLIC. MUSTARD AND CRESS. Garlic was known in the most remote ages. It was a prevailing opinion that the effects of foul air were neutralized by garlic. It is called the physic of the peasantry, especially in warm countries, where it is eaten before going to work, in order to guarantee them from ill effects. The odour is intensely dis- agreeable, but the common experience is borne out by science. If it were made the rule that garlic should be eaten by all or none, the objection to it would cease. Mustard and cress are also not to be despised, as furnishing some variety to the breakfast and tea- table. And if only for the encouragement to be given to the cultivation of small plots of garden ground, it would be impossible too much to exalt the value of such foods. Nothing does a man greater good than a little gardening. Parsley, mustard and cress, sage, onions, thyme, and mint are easily grown ; add to these lettuces, radishes, scarlet-runners, French beans, and cabbages, and already the sameness of many a man's diet vanishes. 251. Enough has been said to give the reader a general idea of the differences in fish, flesh, and fowl. We have yet to learn something as to diets in common use, and their digestibility : then, alone shall we possess an adequate idea of the parts played by science and experience. No attempt has been made to give receipts for cooking, as these are to be met with in cookery books. CARBONACEOUS AND NITROGENOUS FOODS. 107 CHAPTEE XV. ON THE RELATIVE DIGESTIBILITY OF FOODS. 252. The conversion of vegetable food into flesh is a more difficult proceeding than the assimilation of flesh. On this account vegetable-feeders have more complicated digestive organs than those which feed on flesh alone. Thus considered, herbivorous animals may be said to prepare food for the carnivorous, or omnivorous. 253. As the bulk of the body consists of so large a proportion of water, so the solid food taken also con- tains more or less, but not sufficient to supply the waste : hence the necessity for drink. 254. The sources of loss are more numerous than those of supply. In fact the alimentary canal is mainly charged with the function of waste. External circumstances determine in great measure the quality and quantity of food ; but the mental or bodily activity of the individual, and the temperature in which he lives, ought to be leading guides. When the tem- perature is high, carbonaceous foods are least required, as they are more easily productive of heat. 255. Although foods are divided into carbonaceous or respiratory, and nitrogenous or plastic, all proper nutriment contains both kinds. Without nitrogen, no nourishment can be afibrded to the tissues : the carbon, hydrogen, and oxygen in the nitrogenous compound may, however, also be employed for heat as well as for nutrition. Food must be used to sapply the quality of the waste, as well as the quantity. The best proportions in a mixed diet would embrace 69 parts of starch and sugar, 9 parts of fat, and 22 parts of nitroj^enous material. 108 A MIXED DIET IJf MODERATE QUANTITIES. 256. Even when the food is well selected, much depends upon ourselves as to the profit we shall obtain from it, as well in keepinsf up the heat of the body as in nourishing it. A mixed diet in moderate quantities is best suited to a healthy frame. Excess is every way injurious, both in eating and in drinking. Unless food be properly masticated, much of it is absolutely wasted, besides being a fruitful cause of indigestion. Apart from cooking, '' the early stage of preparing the food for nourishment is dependent on muscular action, and we shall find that the succeeding steps also require mechanical assistance to supplement the chemical action of solution. The stomach and intestines are, therefore, essentially muscular organs as well as organs of secretion. " TPie form of the stomach is seen in the accom- panying illustration. It is a large, sacculated cavity, capable of great distension ; stretching across the upper part of the abdomen, and chiefly under the lower part of the left ribs. Its left, or cardiac, ex- tremity is large, where the oesophagus terminates ; its right extremity — the pylorus — is smaller, and guarded by a thick ring of muscular fibres and a valve of mucous membrane, so as to prevent the food during digestion from passing too soon into the intestine. The stomach has a large supply of blood-vessels, and derives its nerves from two sources. " The mucous membrane is covered with cylin- drical epithelial cells, and studded all over with the minute orifices of numberless tubular glands, some of which are branched at their extremities ; it is from these that the gastric juice, or dissolving fluid of the stomach, is poured out at the period of digestion ; and in such quantity that it has been calculated to amount, according to circumstances, to ten or fifteen pints, or even more, during twenty-four hours. Eut the active FROM F. LE GROS CLARK'S PHYSIOLOGY. i09 ingredients iu tlii.^ fluid are, as in the saliva, a very small pei'ceiitage of tbe whole, between live or six in one hundred, the re- maining ninety-four parts being water. It is clear, without odour, and with very little taste. It is acid, front the pre- sence of hydrochlo- ric acid ; but the most important and abundant constitu- ent is called pepsin, in which, combined with the acid, the solvent property of the gastric juice es- pecially resides. " The muscular action of the stom- ach aids this pro- cess importantly, by keeping its contents constantly moving to and fro, and thus bringing each part successively into re- lation with the sol- vent fluid ; just as we should stirabout anything which we wish to dissolve. In this way the food is converted into what is called chyme, and is then permitted to pass the pylorus into the intes- Alimentary Canal {in siht). 1. Oesophagus. 2, Stomach. 8. Duodenum. 4. Small iutestine. 5. Caecum. 6, 7, 8. Colon. 9. Sigmoid flexure. 10. Rectum. 110 TABLE OF DIGESTIBILITY OP FOOD. tine."— ^ee " Physiology." by F. Le Gros Clark, F.R.S., in "Manuals of Elementary Science," S.P.C.K. 257, With reference to the digestibility of food, the following Table, compiled from the well-known experiments of Dr. Beaumont, will afford some notion. Eelative Digestibility of Animal and Vegetable Substances. Articles of Diet. Pigs' feet Tripe Eice Eggs (whipped) Apples (sweet)... Salmon-trout ... Venison steak ... Brains Time of How cooked. Chymiiication. Hours. Mins. Sago Ox -liver Codfish (cured) Tapioca Barley Apples (sour) Cabbage with vinegar.. Eggs Turkey Gelatin Goose Pig Potatoes Beans Parsnips Spongecakes Potatoes ' Chicken Beef Beef Mutton Boiled .. Raw Raw Boiled .. Broiled Boiled .. 1 30 1 45 Broiled Boiled Boiled , Boiled ^ ^ w Raw I Raw J Roasted 2 l5 Boiled 2 25 Boiled ^ Roasted Roasted | Boiled ^ 2 30 Boiled Boiled Baked J Baked 2 33 Fricasseed > „ .^ [ 2 4d Boiled ... Roasted Boiled ... RESPECTIVE WEIGHTS OF STOMACHS. Ill Table of Digestibility — continued. Articles of Diet. How cooked. Apple dumpling Boiled "^ Indian corn cake Baked ) Indian com bread Baked Carrot Boiled Mutton Roasted .... Oysters Stewed ~^ Cheese Uncooked . Hard-boiled. Time of Cliymificatioii Hours. Mins. Eggs , Fried ... Wheaten bread Baked ... Potatoes Boiled ... Turnips Boiled ... Beef Fried ... Fowls Boiled... Fowls Roasted Ducks Roasted Cabbage Boiled ... Pork Roast ... Tendon Boiled . . . ^ 3 3 15 3 30 4 15 30 258. As to the necessity which exists for cooking our food, and of employing the stomachs of animals to digest for us what we ourselves cannot do, nothing more striking can be mentioned than the weights of the stomachs respectively of man, pig, sheep, and ox. In the man, the stomach weighs 6 oz. In the pig, „ „ 14 oz. In the sheep, „ ,, 39 oz. In the ox ,, ,, 51 oz. 112 MIXED DIET NECESSARY TO HEALTH. CHAPTER XYT. CONCLUSION. 259. For the maintenance of robust healtli, nothing is equal to the "regime" adopted by men who are training for running or rowing. The basis of the system is to promote, in every way, the rapid change and renewal of every portion of the body, increasing its vita] activity, and making it live fast. This is done by constant, regular and vigorous exer- cise, aided by baths and shampooing, to encourage the action of the skin on the one hand, and a fall nourish- ing diet on the other. The effects on the system are truly wonderful : the muscles become large and hard ; the skin clear and firm, so that it is not readily bruised ; the general system becomes light and active, able to bear great exercise, not to say fatigue, and even the mind partakes of an unusual joyousness, being rendered clear and vigorous. Such rude health is perhaps rare, especially among the inhabitants of towns. There, unfortunately, we have more oppor- tunities of seeing the effects of insufficient nutrition ; exhibiting itself after a time in scrofula, scurvy, and other low forms of disease. 260. Curious experiments have been at times per- formed by physiologists on the effects of different kinds of nutriment in a pure state. All such experi- ments tend to one conclusion : that a mixed diet is necessary to health. Even albumen, the type of nourishment, is found insufficient of itself to support life. One of the most lingular effects of a restricted diet seems to be, to render the stomach incapable of digesting even that little with which it is supplied. 261. Of the influence of different kinds of food on QUANTITY OF FOOD REQUIRED VARIES. 113 the development of the body, there is no more curious example than that afforded by the history of bees. Every one is familiar with the vast difference between the ordinary working bee and the queen-bee ; the former is simply a bee whose development in certain respects is imperfect. This difference is brought about entirely by food. If, by any accident, the queen should die, or be lost, the bees select two or three of the eggs, which they hatch in large " royal " cells, and subse- quently bring up the maggot on a jelly-like, stimulating food, very different from that which they supply to their other babies. 262. The quantity of food required for the main- tenance of the human body in health varies with age, sex, constitution and habits of life. The only sure guide is the appetite, })rovided its dictates are honestly interpreted. There can be little doubt, how- ever, that most persons in easy circumstances eat more than is nece:-'sary, and therefore more than is good, otherwise they would not increase in bulk and weight between the ages of twenty-five and fifty. If the food is eaten slowly and thoroughly masticated, then a feeling of genial satisfaction will give a fair indication to the system to be content : beyond this, a sense of satiety is induced, which ought to warn us that the point of healthful indulgence has been exceeded. 263. With reference to the dietaries of large bodies of men, it is not iifficult to form some general estimate of the necessary amount of food, especially after the admirable labours of Dr. Lyon Playfair and of the late Dr. Edward Smith. The foil )wing Table of daily Dietaries of well-fed Operatives is ty Playfair : — H 2 114 DIETARIES OF WELL-FED OPERATIVES, 1 ^ oi^t^OOr-lCMlOlO'^CMb- a a ^^cqo^iOGOiooi:^oooco s Ococqcococq^co^''?^'^ "T rt CDO^T-H^OO^IO^ o M3CO'^C:)CDCOt>.— lOiO O 'S ^r-HCM'^IOOOCOOOG^IOO erf O •\«S^^^.N.>.v »S^> Lo ioiocr>io^o-co 02 M r-Hr-H(Mr- 5- ^ o ="' § 2 ' 1^^ J_( V fll Sj ' - > 03 o li?ll|lllJ Ph eg Q^ eg H f^ W H H pq NITROGEN IN NITROGENOUS FOODS. 115 264. In all these cases the carbonaceous matters of the food are estimated as starch. It is of first import- ance now to remember that nitrogenous foods contain one-sixth of their weight of nitrogen, and that the relation of the nitrogenons to the carbonaceous consti- tuents of food should be about one to six. The admix- ture in the food of an adult should, then, be as nearly as possible one of nitrogenous to six of carbonaceous. Dr. Playfair gives the following Table of daily Diets according to work done. Daily Diets for Nitrogenous. Carbonaceous. Oz. Oz. Subsistence only 2*0 + 13-3 Quietude 2*5 + 14-5 Moderate exercise 4*2 + 23*2 Active labour 5"5 + 26'3 Hard work 6-5 -h 263 For mere subsistence, for rest, and for moderate exercise, say one of nitrogenous to six of carbonaceous ; for active exercise, one to five ; and for hard work, one of nitrogenous to four of carbonaceous. 265. In paragraph 108 two hundred grains of nitrogen have been mentioned as the least upon which a man at rest, doing but little active work, could subsist. This really means insufiicient diet. Three hundred grains of nitrogen would be a fair quantity for an adult man, and somewhat less for a woman. 266. According to the late Dr. Edward Smith, the following Table would express the relative propor- tions of food that should be taken at difierent meals. carton. Nitrogen. Carbona- Nitro-_ Grains. Grains. Ounces. Ounces. For Breakfast 1,500 ... 70 ... 6-62 ... 1-04 For Dinner 1,800 ... 90 ... 7-85 ... 1*34 For Supper 1,000 ... 40 ... 4-52 ... 0*59 Total in the Day ... 4,300 ... 200 ... 18-99 ... 2-97 116 ALCOHOL INJURIOUS TO THE YOUNG. It will be observed that the amounts given are barely sufficient to support adult life. 267. A strong healthy man consumes about two pounds weight of dry food per day. If the carbon- aceous matters be greatly in excess in a man's diet, not only is the growth of fat promoted, but the nutrition of the tissues is prevented. And if the nitrogenous be greatly in excess, then is blood too freely formed. 268. With reference to drinks at meals, it must be an exceptional case when the digestive organs of a growing person require a stimulus, and none such should be indulged, even in small quantities with fer- mented liquors, except under medical advice. The use of weak table beer might be allowed in places where the water was undrinkable ; but, except in such cases, })arents should have the strength of mind to exclude alcohol in every form from their children's diet. Inasmuch as the flow of the saliva during a meal is of the utmost importance in digestion, liquids should not be taken in sips, but at the close. Frequent draughts stop the flow of saliva, and are therefore injurious. 269. The atmosphere of rooms in which we take our meals should be'^''ke|)t scrupulously clean. Flies and other nuisances, in summer especially, abound where cleanliness is not the first law. Nothing takes away so much from the pleasure of a social meal as a close room, and nothing is much more calculated to promote indigestion. Dustbins, and other similar con- trivances for shortening life, should be as far as possible removed from our dwelling-rooms : in fact, everything that affords breeding-places of animal life. 270. And so also from within. If we would, humanly speaking, preserve our bodies in health, we must keep them in subjection. ** A godly, righteous and sober life," as the good old Church Service has CONCLUSION OF THE WHOLE MATTER, 117 it, is greatly promotive of health, and lias much to do with that happy condition of unconsciousness as to the existence of the body which is the very perfection of our animal life. " Send portions unto them for whom nothing is prepared," and " be given to hospitality," are direc- tions in no-wise to be disregarded. Certainly they are a great encouragement to cheerfulness, which is also an aid to proper nutrition. Above all things, let us praise Him who '^ knoweth our frame, and remem- bereth that we are but dust." The carbon and the nitrogen are simply instruments in His hands. When He withholds, neither does the nitrogen repair, nor the carbon and hydrogen heat. "The eyes of all wait upon Thee, and Thou privest them their meat in due season. Thou openest Thine hand, and satisfiest the desire of every living thing." THE END. INDEX. Acid, acetic, 39, 43, 46. , butyric, 35. , caffeic, 81. , carbonic, 14, 43. , citric, 48. , cream of tartar, 39. , hydrochloric, 70. , lactic, 72, 43. , malic, 48. , oxalic, 48. • , , antidote to, 48. , oleic, 35. , phosphoric, 74. , palmitic, 35. , sulphurous, 72. , stearic, 35. salts, 39. , tannic, 49. , tartaric, 47. , vegetable, 49. Albumen, 37, 52, 50, 55, 58, 65, 70, 72. , oxydized, 64. Alcohol, 37, 46, 71. , absolute, 40. , quantity in wine, 39, 44. Ales, bottled, 43. Ammonia, 51. Appetite, defective, 41. , guide to quantity of food, 113. Apples, 87. Arabin, 25. Ardent spirits, 43. Arrack, 44. Arrowroot, 22. Ash, 75. Barley, 58. Bathing, 8. Beans, 95, 96. Beaumont, Dr., 110, 111. Beef.tea, 65. , Liebig's, 70. Beer, 41. Bees, 113 Beetroot, 94, 105. Blood fibrin, 64. Boilers, 11. Bones, 66, 69, 70. , composition of, 66. Bordeaux, 39. Brandy, 44. Bread, 58, 63, 103. , amount of water in, 60. , Dr. Dauglish's process, 61, 62. — , making, 59, 60. , pure white, 61. Brimstone, 72. Brocoli, 92. Burgundy, 39. 120 INDEX. Butcher's meat, 64, Butter, 56. Butyrin, 33. Cabbages, 94. Caffein, 83, 84. Calcium bicarbonate, 11. Calcium phosphate, 69. Calves' feet, 101. Caramel, 28. Carbon, 17, 31, 51, 71. in bread, 62. Carbonic acid from lungs, 18. Carnivorous, 107. Carpenter, Dr., 43. Carrots, 94. Casein, 56, 58, 72, 74. Cassava, 23. Cauliflower, 92. Cellular tissue, 24. Cellulose, 24. , composition of, 24. Charcoal, 17. Cheese cream, 33. , Cheshire, 57. Cherries, 88. Chocolate, 72, 84. Cider, 41. Cisterns, 13. Clark, F.R.S., F. Le Gros, 110. Close day, 8. Cocoa, 72, 84. , butter, 72, 84. Cod, 98. Coffee, 81. , mocha, 82. , roasting, 82. , sugar in, 82. Cow's milk, 57. Cream, 33. Cucumbers, 95. Currants, 48, 88. Damsons, 88. Dextrine, 24, 60, 61, 69. Dextrose, 29, 69. Diastase, 42. Diet, mixed, necessary to health, 108, 112. Digester, Papin's, 16, 66, 68. Digestion of food, 57. Drinks of breakfast-table, 77. at meals, 116. Ducks, 100. Dustbins, 73, 116. Eau de Cologne, 40. Eggs,'50to58. — — , composition of, 53. Endives, 105. Fat, 31 to 36. as diet, 35. , compounds of, 34, 71. , general character of, 32. , heating of, 33. , heat-producing agent, 71. , influence of cooking on, 31. , production of, 19. , value of, in food, 71. , vegetable, 33, 34. Fermentation, process of, 36. Fibrin, 50, 59, 63, 65, 70, 72. , animal, 63. in blood, 63. , varieties of, 63. , vegetable, 7, 63. Fish, 98, 99. , broiling, 99. , frying, 99. , nitrogen in, 99. Flour, 59. Food, carbonaceous class of, 26, 32, 71, 107. Food, digestibility of, 110, 111. INDEX. 121 Food, influence of, 7. , influence of different kinds of, 112. , iron in, 7Q. , nitrogenous, 32, 50, 75, 107. , nitrogenous foods contain one-sixth part nitrogen, 115. , plastic, 50, 72, 107. , proportion in, 75. , quantity of, 113. , respiratory, 32,50,71, 107. , value of fat in, 71. Force, 37. Fruits, a vaiiety of drink, 86 90. , acids in, 90. , nitrogenous matter in, 90. , salts in, 90. , sugar in, 90. Garlic, 106. Geese, 100. Gelatin, 67, 72, 101. and bones, 66 to 70. solvent of phosphates, 68. , vehicle for food, 68. Gin, 44. Glucose, 37. Glue, 66. Glutin, 51, 59, 72. Glycerin, 34. Gooseberries, 88. Gi-apes, 88. Gum, 21, 24. Health, maintenance of, 112. Heat, production of, 18. , keeping up, 19. Herbivorous, 107. Herring, 99. Hock, 39. Hollands, 44. Horseradish, 104. Hydi-ogen, 14, 16, 31, 51, 70, 71. , oxide of, 14, 16. , phosphide of, 73. , sulphide of, 72. Inosin, 69. Iron, oxide of, 76. in food, 76. in wine, 39. Isinglass, 66. Jelly, 67. Johnson, Dr., 81. Kettles, 11. Kreatin, 68, 69. Lactose, 30, 56. Laevulose, 30. Lamb, 101. Lard, 33. Leaven, 61. Legumen, 50. Leguminous, 92. Lentils, 50, 95, 96. Lettuce, 105. LiEBiG, Dr., 45, 65, 69, 70, 76, 81, 97. Lime, carbonate of, 11. , salts of, 11. Liquors, fermented, 36 to 45. Macaroni, 57, 62. Mackerel, 98. Malt, 41. Malting, process of, 42. Manihot utilissimu, 23. Maranta, 22. Meat, extract of, 55. , for boiling, 65. , juice of, 54, 65, , lean, 32. Milk, 50—58. , human, 57. 122 INDEX. Milk, skim, 86. Molecule, 38. Moselle, 39. Mucilage, 25. Mulberries, 89. Muscle sugar, 69. Muscular fibre, 63. tissue, 63. Mustard, 106. Nitrogen, 50, 51. in beef, 101. in bread, 62. in herring, 99. in mutton, 101. in vegetables, 70. Table, 74. Nutrition, insufficient, 112. Oatmeal, 50, 62. Oats, 58. Oils, 32. , volatile, 80. Olein, 32. Omnivorous, 107. Onions, 94. Ovalbumen, 54. Oxide of iron, 76. Oxygen, 31, 51, 71. Oyster sauce, 98. Palmitin, 33. Papin's digester, 16, 66, 68. Parsnips, 94. Pears, 87. Pease, 95, 96. Pectin, 25. Pelargonic ether, 39. Pepper, 104. Perry, 41. Phosphorus, 50, 53, 58, 72. Physiology; 108, 109. Pilchards, 99. Plastic, 60, 72. Playpaie, Dr. Lyon, 113, 115. Pork, 101, 102. Port, 45. Potassium, 70. Potatoes, 20, 92, 93. Poultry, 100. Proof spirit, 40, 44. Rabbits, 100. Radishes, 105. Raisins, 89. Raspberries, 89. Rice, 21, 68. Rum, 44. Rye, 68. Sago, 23. Salads, 105. Saliva, 116. Salmon, 98. Salt, 70. meat, 70. Salts, 69. Sauerkraut, 72. Sausages, 103. Semola, 62. Sherry, 45. Skim-milk, 86. Skin, 7. Smith, Dr. Edward, 101, 102. Soda, 53, 75, 76. Sodium, 76. chloride, 70, 75, 76. Soles, 98. Spinach, 92. Spirits, 43. Sprats, 99. Starch, 16, 25, 59, 71. , composition of, 21, 22. granules, 20. , percentage of, 21. Steam, 16. Stomach, 108, 111. Strawberries, 89. INDEX. 123 Sucrose, 28. Suet, 62. Sugars, 25, 71. , burnt, 28. , cane, 26. , grape, 29. Sulphur, 53, 58, 92. Summer drink, 81. Syntonin, 63. Table of albumen, 55, 64. of daily dietaries, 114. of digestibility, 110, 111. of fats, 34. of fruits, 90. of nitrogens, 74 of sugars, 31. of water in foods, 9. Tables, 9, 21, 24, 31, 34, 53, 55, 57, 64, 66, 71, 79, 90, 110, 111, 114. Tannin, 39, 67. Tapioca, 23. Taste, 68. Tea, 77. , adulterations of, 79. , cold, 81. Teetotalism, 43. Thein, 81. Theobromin, 84. Tinctures, 40. Toast-and -water, 13, 61. Tripe, 56. Tri-sodium phospbate, 70. Turnip, 92, 94. Varnish, 40. Veal, 101. Vegetable acids, 46, 49. fibrin, 63. Vegetables, 33, 70, 91, 97. , dressing of, 72. , refuse, 72. , salt in cooking, 75. Vermicelli, 62. Vessels, bright, 78. Vinegar, 46, 104. Vitellin, 53. Volatile oil, 80. Washing, 8. Water as article of food, 7. , amount of, 8. , boiling, 15. , carbonic acid in, 10. , composition of, 14. , crust from, 11. , drinking, 10, 11. , hard, 10, , in meat, 64. , purity of, 10. , soft, 10. , toast-and-, 13, 61. Wheat, 58. Whey, 56. Whisky, 44. White of egg, 53. Wines, 38, 39, 41, 45. Wort, 42. Yeast, 42. Yolk of egg, 53. THE END. WYMAN AND SONS, PRINTERS, GREAT QUEEN STREET, LONDON, W.C. Sndet^i for ''§xomoixnQ € ^rtstiattlatiotol^bgc . Fcap. 8vo., 128 pp., limp cloth, Is. MANUALS^OP HEALTH. ON PERSONAL CARE OF "HEALTH. By the late E. A. PAEKES, M.D., F.K.S. The following Volumes are in P^'eparation. FOOD. By ALBERT J. BERN AYS, Professor of Chemistry at St. Thomas's Hospital. HEALTH AND OCCUPATION. By B. W. KIOHARDSON, Esq., F.E.S., M.D. WATER, AIR, AND DISINFECTANTS. By W. NOEL HAETLEY, Esq., King's CoUege. Fcap. 8vo,, containing 128 pp., with Illustrations, limp cloth, Is. MANUALS OF ELEMENTARY SCIENCE. PHYSIOLOGY. By F. LE GROS CLARKE, F.R.S. St. Thomas's Hospital. GEOLOGY. By the Rev. T. G. BONNEY, M.A., F.Gr.S., Fellow and Tutor of St. John's College, Cambridge. CHEMISTRY. By ALBERT J. BERNAYS, Professor of Chemistry, St. Thomas's Hospital. ASTRONOMY. By W. H. CHRISTIE, M.A., Trinity College, Cambridge ; the Eojal Observatory, Greenwich. BOTANY. By ROBERT BENTLEY,, Professor of Botany in King's College, London. ZOOLOGY. By ALFRED NliWTON, M.A., F.R.S., Professor of Zoology and Comparative Anatomy in the University of Cambridge. The following Volumes are in Preparation. MINERALOGY. By T. HEATHCOTE G . WYNDHAM, M.A., Merton College, Oxford. MATTER AND MOTION. By J. CLERK MAX- WELL, M.A., Trinity College, Cambridge, University Professor of Experimental Physics. CRYSTALLOGRAPHY.— By the Rev. H. P. GURNEY, M.A., Fellow of Clare College, Cambridge. THE WORK OF THE SPECTROSCOPE. By R. A. PEOCTOE, Esq. 77f Geeat Queew Street, Lincoln's-Init-Fields 4, EoTAL Exchange ; 48, Piccabilly ; AND By all booksellebs. PUBLICATIONS Bmi^ isx |wMting €|nstia« fnatoleljgf. Jklcs^ of these Works may be had m ornamental bindings, with gilt edgesy at a small extra cJiarge, Trice. «. d Adventures of Marshall Vavasour, Midshipman. With three full-page illustrations on toned paper. Cro\\n 8vo cloth boards i 6 Africa Unveiled. By the Rev. H. Rowley. With Map, and eight full- page illustrations on toned paper. CxQWDiZwo cloth boards 5 o Australia's Heroes ; Being a shght Sketch of the most prominent amongst the band of gallant men who devoted their lives and energies to the cause of Science, and the development of the fifth Continent. By C. H. Eden, Esq., Author of the *' Fortunes of the Fletchers," *• Home of the Wolverene and Beaver," &c. With Map. Crown Svo... cloth boards 5 o Brave Dame Mary ; or, The Siege of Corfe Castle. With three full-page illustrations on toned paper. Cro w 11 8vo cloth boards 2 o Ca.stle Cornet; or. The Island's Troubles in the Troublous Times. A Story of the Channel Islands. By Louisa Hawtrev. With four full-page illustrations on toned paper. Crow n 8vo cloth boards 2 o Ch.arlie Tyrrell, and other Tales illustrative of the Jjord's Frayer. By C. E. BowEN, Author of "New Stories on Old Subjects." Tliree full-page illustrations on toned paper. Crown 8vo cloth boards i 6 Chi»a, the Land and the People of. A short Account of the Geography, History, Religion, Social Life, Arts, Industries, and Government of China and its People. By J. Thomson, Esq., F.R.G.S., Author of " Illustrations of China and its People," &c. With Map, and twelve full-page illustrations on toned paper. Crown 8vo cloth boards 5 o Effie and her Ayah j or, The Faithful Monkey and his little "White Mistress. On toned paper, with four full-page illustrations. Royal i6mo , cloth boards z 6 \i. II. 76.] [i^cap. Svo. PUBLICATIONS OF THE SOCICTY «. 4, Pan : a Village Tale. With two full-page illustrations on toned paper. Crown 8vo clothboards i 6 First Bector of Burgstead, The. A Tale of the Saxon Church. By the Rev. E. L. CUTTS, B.A., Author of "Some Chief Truths of Reli- gion," "St. Cedd's Cross," &c. With three full-page illustrations on toned paper. Fcap. 8vo clothboards i 6 Tor Faith and Fatherland. By M. Bramston, Author of " Rosamond Ferrars," &c. With three full-page illustrations on toned paper. Crown 8vo cloth boards 2 6 Fortunes of the Fletchers, The: a Story of Life in Canada and Australia. By C. H. Eden, Esq. With three full-page illustrations on toned paper. Crown 8vo cloth boards 2 6 Gather up the Fragments. Two illustrations on toned paper. Fcap. Bvo cloth boards i 6 Heroes of the Arctic and their Adventures. By Frederick Whymper, Esq., Author of "Travels in Alaska." With Map, eight full-page illustrations and numerous small woodcuts. Crown Bvo clothboards 5 o Heroes of the North; or, Stories from Norwegian Chronicle. By F. Scarlett Potter, Esq. With three full-page illustrations on toned paper. Crown 8vo . . . cloth boards 2 6 His Heart's Desire. With three full-page illustrations on toned paper. Crown 8vo cloth boards i 6 Home of the "Wolverene and Beaver, The; or. Fur- hunting in the "Wilds of Canada. By C. H. Eden, Esq., Author of "Australia's Heroes," &c. With three full-page illustrations on toned paper. Crown 8vo cloth boards 2 6 In and Out of London; or. The Half-Holidays of a Town Clerk. By the Rev. W. J. LOFTIE, B.A., Author of "A Century of Bibles," «S:c. With four full-page illustrations and numerous small engravings. Post 8vo clothboards 2 6 In the Marsh. By Miss B. C. Curteis. With tliree full-page illus- trations on toned paper. Cro\vn 8vo cloth boards 2 6 King's Namesake, The. A Tale of Carisbrooke Castle. By CATHERINE MARr Phillimore. With four full-page illustrations on toned paper. Crown 8vo clothboards 2 o FOR PROMOTING CHRISTIAN KNOWLEDGE. Price. «. d. Klatsassan, and other Keminiscences of Missionary liite in British Columbia. By the Rev. R. C. Lundin Brown, M.A. With Map, and three iHustrations on toned paper. Post 8vo clotA boards 3 o Ling Bank Cottage : a Tale for "Working Girls. With two full-page illustrations on toned paper. Crown 8vo cloth boards 2 o Lofty Aims and Lowly Efforts : a Tale of Christian Ministry. With three full-page illustrations on toned paper. Crown 8vo cloth boards 3 o London Sparrows. By the Author of "Ruth Lee," &c. With three full- page illustrations on toned paper. Qio^xiZso clothboards i 6 Marchfield : a Story of Commercial Morality. By the Author of "In and Out of London," &c. With three full-page illustrations on toned paper. Crov/n Svo cloth boards 2 6 Mary : a Tale of Humble Life. With three full-page illustrations on toned paper. Crown Svo cloth boxrds 2 o Meg's Primroses, and other Stories. By H. M. Chester. On toned paper, with four full- page illustrations. Royal i6mo cloth boards 2 o Message, The, and other Stories. With three full-page illustrations on toned paper. Crown Svo cloth boards 2 o Michael Penguyne ; or, Fisher Life on the Cornish Coast. By W. H. G. Kingston, Esq. With three full-page illustrations on toned paper. Crown Svo ... cloth boards i 6 New Stories on Old Subjects. By C. E. Bo WEN, Author of "Stories on My Duty towards God and My Neighbour," &c. With four full- page illustrations on toned paper. Cvo^n Svo dashboards 3 o Panelled House, The : a Chronicle of Two Sisters* Lives. By M. Bramston. With three illustrations on toned paper. Crown Svo cloth boards 3 6 Parables of Life. By Author of "Earth's Many Voices." Royal i6mo, on toned paper, with seven illustrations, cloth brds, gilt edges 2 o Postmaster of Prenzlau, The, and other Tales. From the German. With two page woodcuts, on toned paper. Crown Svo cloth boards i G PUBLICATIONS OF THE SOCIETY. »- d* Silent Jim: a Cornish Story. By James F. Cobb, Esq., Author of "A Tale- of Two Brothers," &c. With four full-page illustrations on toned paper. Crown 8vo clotk boards 3 6 Stories of Success, as illustrated by the Lives of Humble Men who have made themselves Great. By J. F. Cobb, Esq. , Author of "Silent Jim." With four illustrations on toned paper. Ciown^wo ... cloih boards 3 o The Children of Seeligsberg: a Tale of the Lake of Lucerne. By the Author of " Madeleine's Forgiveness," " The Cathedral Organist." i8mo cloth boards i 6 Village Beech- Tree, The ; or. Work and Trust. With four full-page illustrations on toned paper. Crown 8vo cloth boards 2 6 ^Vreath of Mallow, The, and other Stories more or lees true. By Mrs. Jerome Mercier. With three page wood- cuts, on toned paper. Crown 8 vo cloth boards 2 o New Series of 3s. 6d. Books. Post Bvo, with Coloured Frontispiece and Title, Four Full-page Woodcuts, and numerous small Engravings. A Cruise on the Bosphorus, and in the Marmora and .^gean Seas. By the Rev. G. Fyler Townsend, M.A., Author of "The Sea Kings," " Siege of Colchester," &c. Away on the Moorland : a Highland Tale. By A. C. Chambers, Author of " Robin the Bold," &c. Julian's Droam. A Storv of A.D. 362. By the Rev. Gerald S. DAVIes, Author of " Gaudentius,"&c. Hosamond Ferrars. By M. Bramston, Author of " The Panelled House," &c. The Settlers : a Tale of Virginia. By W. H. G. Kingston, Esq.. Author of " The Two Ship- mates," *' Michael Penguyne," &c. Two Campaigns : a Tale of Old Alsace. By A. H. Engelbach, Esq., Author of " Lionel's Revenge," &c. 77, Great Queen Street, Lincoln's-Inn Fields ; 4, Royal Exchange ; 48, Piccadilly ; AND B^JLUU^OOKSELLERS. VA 02(36 XI^-"".?. ^rfUo