WATER, in many respects, more closely resembles nutritive food than it does heat-giving food; that is to say, it more closely approaches, in its relation to the human system, the character of flesh than it does the character of starch or sugar; and for this reason, that it combines with the tissues of the body, and forms a necessary part of its structure.

I have made a calculation that a human body weighing 154 lbs. contains 111 lbs. of water. You see, then, how necessary water is. If you reduce the size of the man, you reduce the quantity of water; and you will find that water enters into the composition of all our food.

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Before speaking more particularly of water, I will call your attention, in the first place, to its composition; it is not my province to dwell on the elementary composition of food any further than it throws a light on its action. Water, then, is composed of two gases, one called oxygen, and another called hydrogen; and we can easily decompose water so as to demonstrate its composition. If you take a piece of potassium-which is a metal so malleable that you can cut it with a knife-and put it into water, it has such an affinity for the oxygen of the water, that, when combined with it, it inflames. putting it into water, the metal actually appears to take fire, and is converted into common potash. The hydrogen gas of the water is liberated, and it is this gas which burns during the decomposition of the water. This is a beautiful chemical experiment, and demonstrates the composition of water. But there are many other ways of doing this. If we take a little alcohol, or anything which contains hydrogen, and burn it in atmospheric air, under a glass vessel, we shall find that we produce water; so that we can easily by household experiments demonstrate the composition of water.

I now come to speak of water in relation to the life of plants and animals. Both animals and plants require it; and no animal, and no plant, exists without certain quantities of water. Sometimes it is so large in quantity that it constitutes the great

mass of the animal or plant. Thus, if we take some plants that grow in water, we find that they are formed of from 90 to 95 per cent. of water; and many of the little animals contained in water, if we take them and expose them to heat, so as to evaporate their water, almost entirely disappear. Even solid timber contains as much as 30 per cent. of water. Plants will not live without water: if we refrain from watering them, they die. The water passes in at their roots, and up their stems and into their leaves, and the sun dries them, and evaporates their moisture. The water taken up by plants contains their food, -carbonic acid gas and ammonia. These two substances pass into the plant with the water, and out of these things we have manufactured in the system of the plant all our vegetable food. Carbonic acid gas, ammonia, and water, then, are the food of plants. They contain the four elements-carbon, oxygen, hydrogen, and nitrogen; and of these the food of man principally

consists.

I told you just now that a human body weighing 154 lbs. contains 111 lbs. of water; but there are some animals in the lower scale which contain larger quantities than this. Thus Professor Owen tells us he took a jelly fish, and found it weighed 2 lbs., and when dried in the sun its solid parts weighed only 16 grains; so that you see there were 2 lbs. of water organised by 16 grains of solid matter. If we examine the tissues of animals, we shall find that they contain large quantities of water. This water, which is contained in animals, just the same as in plants, is constantly liable to evaporation. If you take a piece of blotting-paper, and roll it up, and put one end in water, you will find the water will be gradually drawn up, and get into the dry end, which you may cut into strips, so as to resemble the expanded leaves of a plant. In this way water finds its way to the leaves and flowers of plants, and the heat of the atmosphere causes the water to evaporate from the expanded surface of the plant, in the same way as in the blotting paper: the mass is constantly losing its moisture, and water must therefore be supplied.

Water is contained in our solid food, and we thus get it entirely independent of our supplying it in a liquid form. . . Now I will draw your attention to the great importance of understanding the fact that certain forms of solid food contain but very little water, and that other forms contain a great deal. Thus, for instance, those who live chiefly on potatoes, as the Irish peasantry, require but very little water in their ordinary diet. A very curious fact illustrative of this took place during the famine in Ireland in 1847. It was all at once discovered that Ireland, in the midst of her famine, was beginning to consume a larger quantity of what might be regarded as the

luxuries of diet, such as sugar, tea, coffee, chocolate, and the like. The explanation is this-When the potatoes became diseased, the peasantry ate corn, maize, Indian meal, and rice in their place, and therefore lost a quantity of water, to which they had been accustomed in their potatoes; and then it was they took tea and coffee, to which they had not been accustomed before; and there can be no doubt these were consumed in larger quantities for the purpose of supplying the necessary water to the system. . .

The quantity of water in a pound of potatoes is about twelve ounces, and this is not got rid of by cooking. Let us now look at the quantity in rice: instead of having twelve ounces, as in the potato, you have but two ounces and an eighth. There is barley, which contains but two ounces of water in sixteen of barley; and in beans there are but two ounces of water to the pound. With regard to the other cereal and leguminous foods, they have very much the same quantity of water. But there are the cabbage, the parsnip, the turnip, and the carrot, with larger quantities of water than the potato; thus accounting for the comparative inutility of carrots, cabbages, and potatoes, as compared with beans, peas, and other materials with which animals are fed. Then with regard to the beverages which we take, such as tea and coffee, we find that the greater portion is water. Even with regard to beer, taking table beerwhich, by the bye, is much the best for ordinary drinking-it contains not more than half an ounce of alcohol in a pint, and the rest is water; while the strong pale ales and stout contain two ounces of alcohol, the rest being water. Taking the French wines, very few of them contain more than two ounces of alcohol in a pint of twenty ounces. Even our ports and sherries, brandied as they are, contain as much as twelve or fourteen ounces of water in the pint.

Now, the action of water in our food is very important. There would be no carrying of food into the system but for the agency of water. It dissolves everything that we take; and nothing that we take as food can become nutriment that is not dissolved in water. It would not do to test that by taking things and putting them into water, and seeing whether they dissolve, and rejecting them as food according to that circumstance; because food undergoes a considerable change in the stomach. It undergoes a change, to begin with, in our mouth. One of the great objects of that change is to render things soluble which had been before insoluble in water. Starch, which cannot dissolve in water out of the stomach, is dissolved in water directly it gets into the mouth, for the starch is changed by the saliva into sugar, and that which would lie unchanged in water for months, is so changed by the saliva of the mouth and the gastric juice of the stomach, that it is speedily dissolved. Then,

where we are taking considerable quantities of dry food, it becomes absolutely necessary that we should add a certain quantity of water, so that this dry food should become dissolved. Such things as oats, barley, wheat, rice, maize, and other articles of diet containing little water, must have water added, in order that their starch, fat, and gluten may be dissolved and enter into the system.

Having indicated the necessity of water, let me call your attention to the sources of water as drunk ordinarily for the purposes of diet. People are generally very indifferent about water; and perhaps it arises from the fact that boiling it before we make tea or beer makes us independent of the impurities of water in its natural condition. At the same time, I do not think it wise to be dependent for the water needed by the system on beverages containing a variety of foreign ingredients; and for this reason that the water gets its soluble powers interfered with by having things in solution. Thus a pint of beer will not dissolve so much of the starch or digested meat as water. So with regard to the food which is digesting; it is sometimes better that we should pour upon it cold pure water than hot water containing a variety of substances in solution. I am not advocating the giving up of tea, coffee, beer, or wine, but the necessity of taking a portion of the water we daily consume as pure as it can be had.

Now, there are many sources of water. The first great source is the ocean, which collects all the water from the earth; and this water contains so large a quantity of salt, that none of us can drink it. The shining sun, however, bears down upon the ocean's surface, and its heating rays penetrating the water, combine, as it were, with it, and raise it up. The atmosphere, like a sponge, absorbs the vaporous water, carrying it from the equator to the Arctic and the Antarctic regions; thus distributing it north and south. It then condenses in the form of rain and of snow, when, sinking into the earth and pouring down its mountain sides, it forms springs and rivulets, entering the ocean again in the form of rivers; and now man catches it in tubs or cisterns, in its progress in the rivers, or digs down into the earth, and catches is as it passes along beneath his feet. Thus we have rain water, river water, and spring or well water.

I need not dwell on sea water; but it is a very interesting fact to know, that by a process invented by my ingenious friend Dr. Normandy, sea water may be distilled and rendered perfectly pure and fit for human use.

With regard to rain water, there is no doubt that it is one of the purest waters that we have, arising from the fact that it is the first condensed water after it has passed from the ocean into the atmosphere; but its use is liable to the objection that, where

it runs down the sides of houses into cisterns, it passes through an atmosphere frequently contaminated with sulphurous acid and ammonia, and the unconsumed carbon of chimneys, of which we have so constantly unpleasant reminders in large towns. Still, where rain water can be collected in the open country, there is no doubt that it is the purest form of water. It is, however, on spring and river water that we are more dependent; and to the spring and well waters I would more especially call your

attention.

water.

There are two kinds of well waters, or spring waters, which are consumed in London, as well as most other parts of the world; and those are the surface-well waters, and the deepwell waters. In London we dig down deep into the chalk, and get water from below the London clay; this is deep-well London is, in fact, situated in a basin of chalk. Above the chalk is a deposit, varying in thickness, branching off to the side of the basin, as you see, of London clay above this clay is a layer of gravel. Now, the water, passing through or under this gravel, gradually accumulates on the clay, so that if you dig 20 or 25 feet in any of the gravelly districts of London, you get plenty of water—this is called surface-well water: but, if you want to get pure water, you must dig deeper than the clay; you must go through the clay down to the chalk. Wells dug down to the chalk are called Artesian wells. I shall have to speak of these waters again when I speak of the constituents of water; but I may just say here, that persons suppose it is a matter of indifference whether they obtain their water from surface-wells or from deep-wells. This, however, is not the fact; for, although surface-well water is frequently clearer, cooler, and more sparkling than deep-well water, it is always liable to suspicion.

The sparkling of these waters arises from the carbonic acid gas they contain; and in nine cases out of ten that carbonic acid is derived from the decomposition of animal and vegetable matters. Their cooling taste is no less indicative of their impure origin, as it arises from the formation of salts, which could only occur from the decomposition of organic matter.

The situation of these wells, especially in London, explains the origin of these impure matters. The water that supplies the surface-wells of London is derived from the rain which falls upon the surface of the land, and which percolates through the gravel, and accumulates upon the clay. Now, this gravel contains all the soakage of London filth; through it run all the drains and sewers of London, and its whole surface is riddled with innumerable cesspools. Here is the source of the organic matter of surface-well waters, and also the cause of their coolness, their sparkling, and their popularity. In most small towns there is a public pump, and, when this is near the