8W FOOD. 



Class I. Alimentary Substances. 



Group A. Aqueous, containing water as a principal ingredient. Exam- 

 ples : Tea, coffee, beer, wine. 



Group B. Carbonaceous, containing carbon as a distinguishing 

 ingredient, 



1. Saccharine. Examples : Sugar, starch, cellulose. 



2. Oleaginous. Examples : Oil, butter, fat. 



Group C. Nitrogenous, containing nitrogen as a distinguishing feature. 



1. Vegetable. Examples : Flour, oatmeal, maize. 



2. Animal. Examples : Butcher's meat, cheese. 



Group D. Inorganic. 



1. From organic sources. Examples : Potash in fresh vegetables, 



phosphate of lime in flour and flesh. 



2. From the mineral kingdom. Example : Common salt. 



Class II. Medicinal Substances. 



Group A. A cids. Examples : Citric acid in oranges, tartaric acid in 

 grapes, oxalic acids in rhubarb-leaves. 



Group B. Volatile Oils. Examples : Mustard, pepper, nutmeg, 

 cloves. 



Group C. Alkaloids. Examples : Theine in tea and coffee, theobro- 

 miue in chocolate. 



We shall here make a few general remarks on the nature of the 

 substances in the groups indicated, referring for special information 

 on the plants and animals yielding food to the various articles devoted 

 to these subjects throughout the ' English Cyclopaedia.' 



Under the head of WATEHS, MINERAL, will be found an account of 

 Water and the substances it usually holds in solution. In taking it 

 as an article of diet, the following general remarks should be borne 

 in mind : 



First, It may be taken in too large quantities to be carried off by 

 the other emunctories, and then it remains in the system to impoverish 

 the blood, and to reduce the amount of solid matter that is necessary 

 for the performance of the functions of the tissues of the body. This 

 is one of the results that take place from what is called the ' water 

 cure.' Unless persons have sufficient vigour to take the exercise neces- 

 sary to throw off by the skin the water that is taken into the stomach, 

 serious ill effects must necessarily arise. The good that is effected by 

 thin system of the treatment of disease must be attributed more to 

 the exercise it renders necessary than to the unnatural quantities of 

 water taken into the system. 



Secondly, Water may not be taken in sufficient quantities to carry 

 on the healthy functions of the system. If the food is taken too dry, 

 it is only imperfectly digested, and many important constituents, 

 such as the salts, are not taken into the body in sufficient quantity. 

 A deficient quantity of water in the blood will also prevent the 

 healthy process of nutrition, and wasting and degeneration of the solid 

 parts of the body will occur. It would be difficult, perhaps, to lay 

 down any law with regard to the quantity of water individuals should 

 take, and perhaps it is safer to rely on the instincts of the body, 

 which seem to point out how much we ought to take by the feeling of 

 satiety that comes on after enough has been taken. We may however 

 get at something like an approximation of the proportion of solids and 

 fluids required by the system in food, by examining the composition 

 of milk, in which we find the proportion of water to solid parts is as 

 870 to 130 in 1000 parts, or about as seven to one. 



Thirdly, The good effects of water may be destroyed by the sub- 

 stances with which it is taken. Although the stomach has the power 

 of separating water from the food in which it exists, it yet often 

 happens that the fluid articles of diet are injurious. Water itself 

 may contain so large a quantity of saline matters, or of organic 

 matters in a state of decomposition, as to cause serious disease. The 

 taking habitually water in the form of fermented liquors, as beer and 

 wine, as also the admixture of distilled spirits, may cause irritation 

 and congestion of the mucous membranes, and derangement of the 

 nervous system. 



We now proceed to speak of the Carbonaceous Group. This class 

 of substances is sometimes called Respiratory and Combustible. They 

 are called respiratory because it is through the function of respiration 

 tht they become useful in the system. They are called combustible 

 because it is through the process of combustion that their effects upon 

 the system are developed. This class of foods does not, in fact, con- 

 tribute directly to the nutrition of the body, but they are consumed 

 in maintaining the animal heat. The temperature of the human body 

 is always a fixed one ; and if we place a thermometer upon the tongue, 

 or under the arm, or in any other unexposed part of the body, we 

 hall find that it stands at the point in the index of Fahrenheit's 

 thermometer marked 98. [HEAT, ANIMAL.] This heat the human 

 body maintains equally at the poles and under the tropics. No 

 external temperature alters it, and we have thus conclusive evidence 

 that it is produced from within. The cause of this heat is the com- 

 bustion of the carbon and hydrogen contained in the carbonaceous 

 group of foods. Starch, sugar, and oil are conveyed from the stomach 

 into the blood, and whilst in the blood they are brought in contact 

 with oxygen ga, which is taken in during respiration, and the conse- 



FOOD. 



83 r 



quence of this contact is the union of the carbon and the hydrogen 

 with the oxygeu, the formation of carbonic acid gas and water, and 

 the giving out of heat. 



The human body is preserved at the same temperature by the 

 regulating action of the skin. When large quantities of heat are 

 generated in the body, by exercise or other causes, then the extra 

 heat is carried off by the perspiration from the skin ; but when the 

 body is exposed to a low temperature, and its heat is rapidly con- 

 ducted away by surrounding cold, the heat is maintained by increased 

 supplies of food belonging to the carbonaceous group. The animal 

 beat of the lower animals varies according to the circumstances of the 

 creature. Those performing great muscular exertions, and living iu 

 cold climates, have a higher temperature than man; whilst those 

 which are not active in their habits, and live in hot climates, have a 

 temperature lower than that of man. 



The substances belonging to this group which enter into the food 

 of man are cellulose, starch, sugar, and oil. 



Cellulose forming the external membrane of the cells of all plants 

 is found in all food derived from the vegetable kingdom. It has a 

 composition almost identical with starch, but differs in being insoluble 

 and indiffusible in water. There can be little doubt however that it 



:y are iudigestil , 

 of food as carrots, turnips, radishes, uncooked vegetables, &c., not 

 being readily digested. Cellulose is converted into starch by the 

 addition of sulphuric acid, and it is not improbable that some change 

 of this sort may take place when it is taken into the stomach. It is 

 however seldom taken by human beings alone, although recom- 

 mended by no less an authority than Benjamin Franklin, who 

 showed by example that saw-dust puddings might be used as an 

 article of diet. 



Starch enters very largely into the diet of man, and of the lower 

 animals. It is distinguished from cellulose by its ready diffusibility 

 in water. [SECRETIONS, VEGETABLE.] On this account it appears to 

 be much more readily absorbed from the stomach or converted into 

 the forms in which food is taken up into the system. Its property of 

 uniting with water and forming with it at a high temperature a 

 gelatinous mass, explains the change which takes place iu boiling the 

 flour of the grains in which it is contained. 



Starch is found in some plants in greater quantities than in others ; 

 it is however very generally found in perennial roots and rootstocks, 

 in the stems and in the see'ds of plants. There are few or no vege- 

 tables or parts of plants that are eaten that do not contain starch. It 

 is found in turnips, carrots, potatoes, cabbages, parsnips, beans, peas, 

 wheat, barley, oats, and the rest of the Cei-ealia; in chestnuts, walnuts, 

 hazel-nuts, and all other seeds ; in the apple, the pear, the plum, and 

 cherry, and all other fruits. In many of these things however it is 

 not the distinguishing alimentary ingredient, but it is often separated, 

 and is used pure as an article of diet. The substances in which it 

 occurs pure are arrow-root, sago, and tapioca. 



What is sold under the name of arrow-root in the shops, is a form 

 of starch procured from the rootstocks of various species of plants 

 belonging to the family Marantacece. There are three kinds of arrow- 

 root known in the shops, the West Indian and the East Indian 

 arrow-roots, and Tous les Mois. [MAUANTA.] 



Although there is much difference iu the price of arrow-root, its 

 composition is always the same. Even the substances used to 

 adulterate arrow-root, as potato and sago starch, are of the same 

 composition ; and though the appearance and flavour of the arrow- 

 root may be impaired, its ultimate dietetical action is the same. 



Although arrow-root, sago, tapioca, and potato starch, are all 

 composed of the same constituent, their flavour is very different ; 

 hence the preference given to arrow-root as an article of diet. This 

 flavour depends on some peculiar principle which is produced in the 

 plant from which the starch is obtained, and by very careful preparing 

 can be entirely got rid of. Arrow-root is used for making cakes, 

 puddings, and a thick gelatinous fluid in great request in the sick room. 

 It is a property of starch to combine with water at a temperature of 

 180, and form a gelantinous compound. This property of starch 

 renders it very useful in cookery, and seems to increase the digesti- 

 bility of the starch itself. 



Arrow-root is frequently regarded as nutritious ; but it will be 

 seen that it is not nutritious in the proper sense of that word. Those 

 foods can alone be called nutritious that contribute to the building 

 up of the fabric of the body by adding those materials to the tissues 

 which are being constantly removed by the wear of the body. Now 

 starch does not perform this function, and is entirely consumed in 

 the body in maintaining its animal heat. Arrow-root however and 

 the other forms of starch, are frequently mixed with nutritious 

 matters, such as milk and bread; and in this way the food into which 

 they enter becomes nutritious. 



Another form of starch is Sago. It is starch obtained from the 

 inside of the trunks of palms, and other trees. Many plants yield 

 starch in their stems, which, on being prepared, is called sago by 

 Europeans. The sago which is sold in the shops of England is princi- 

 pally imported from the islands of the Indian Archipelago, and is the- 

 produce of a palm called the true Sago-Palm, or Sayui Itei'is. There 



