is ever loaded with incense and perfumes, or where the palate is daily pampered with high-seasoned dishes and constant sweets. The nerves of smell and taste do not bear patiently a constant irritation, and the whole body suffers when a single nerve is continually jarred. Hence it is that water and air, which have to enter so often into the animal body, and to penetrate to its most delicate and most sensitive organs and tissues, are made so destitute of sensible properties that they can come and go to any part of the frame without being perceived. Noiselessly, as it were, they glide over the most touchy nerves; and so long as they are tolerably pure, they may make a thousand visits to the extremest parts of the body without producing the most momentary irritation or sense of pain. These negative properties, which are common both to air and water-though they are rarely thought of-are, nevertheless, most essential to our daily comfort.

In nature, however, water is never found perfectly pure; even that which descends in rain is contaminated by the impurities it washes out of the air, and that which rises in springs by the substances it meets with in the earth itself. The purest water known-that which flows from granite rocks contains from 1-20th of a grain of foreign matter to 4 or 5 grains in the gallon. The water which is supplied to the city of Edinburgh contains from 7 to 14 grains in the gallon. The water supplied to and used in London and its neighbourhood contains:

The most common substances in spring and river water are the carbonates and sulphates of lime, which impart to it its hardness. The softer the water the purer it is. The solvent power of water, however, always charges it with the more undesirable admixtures, as it has to pass through the neighbourhood of dwellings, and still more so of graveyards. The water of a well which is close to the old churchyard on the top of Highgatehill was found to contain as much as 100 grains of solid matter to the gallon, out of which 57.18 grains were nitrates produced where animal matters decay in porous soils.

Well-waters sometimes contain vegetable substances also of a peculiar kind, which render them unwholesome, even over large tracts of country. Waters of rivers and marshy places may be clarified from such by charcoal. In Paris they use alum; in the Landes, chips of oak; in India the traveller carries with him a supply of nuts of the strychnos potatorum for the same purpose. The muddy water of the Nile is purified by rubbing bitter almonds on the sides of the vessel. The Lord showed

Moses a tree by which the waters of Marah were made sweet. In all these the principle is the same: the albuminous matter is coagulated by a bitter astringent. Water also absorbs gases, and the presence of carbonic acid imparts to it a pleasant briskness. The presence of oxygen in water is essential to the life of fish.

We all know how every variety of soil, in every climate, supports its own vegetable tribes; but every one is not intimate with the influence of

artificial changes in the soil, upon the kind, the growth, and the character or appearance of the plants which spring up or are sown upon it. Drain a peaty soil and heaths disappear. Lime banishes sorrel, and guano the daisy. Some substances affect the colour of flowers: charcoal darkens the dahlia, the rose, the petunia, &c.; soda reddens hyacinths, soot turns yellow primroses pink; superphosphate of soda alters in various ways the hue or bloom of flowers. Still more important are the effects of protracted nursing in plants; all our grains are cultivated grasses, our carrot, in a state of nature, is a woody, spindly root, and our potato a bitter tubercle.

"It is with unconscious reference to these improved conditons that certain wild and useless plants attach themselves to and appear affectionately to linger in the footsteps of man. They follow him in his migrations from place to place-advance with him, like the creeping and sow thistles, as he hews his way through primeval forests-reappear constantly on his manure-heaps-spring up, like the common dock, about his stables and barns-occupy, like the common plantain, the road-sides and ditches he makes-or linger, like the nettle, over the unseen ruins of his dwelling, to mark where his abode has formerly been. Thus, with the European settler, European weeds in hundreds have spread over all Northern America, and are already recognised as familiar things, speaking to them of a far-off home, by the emigrants now landing in thousands on the shores of Australia and New Zealand. We cannot say that all these have followed the European. Many of them have only accompanied him, and, like himself, taken root in what has proved a favourable soil. But those which cling closest to his footsteps, which go only where he goes-which, like his cat or his dog, are in a sense domesticated-these attend upon him, because near his dwelling the appropriate chemical food is found, which best ministers to the wants of their growing parts."

The yeast with which we make our bread is a minute plant, which meets with a congenial food in syrups and juice of grapes. The results of its prolific vegetation is what is termed fermentation. It is from chemical changes within the plant that a number of peculiar substances, as medicines, perfumes, and things useful in the arts are produced. So also are the green of the leaf and the poison of the nettle. Vegetation adorns the landscape, purifies the atmosphere, supplies food, comforts, and luxuries, and ends by producing mould, or forming deposits of combustible matter. No one step of its progress and decay but is beneficently of use to man.

Bread is truly the staff of life; the Hindoo who lives on rice, the negro who lives on the plantain, and the Irishman who lives exclusively on the potato, are all described as being more or less pot-bellied. This peculiarity is to be ascribed in part to the necessity of eating a large bulk of food, in order to be able to extract from it a sufficient amount of necessary sustenance. The onion, like the cheese of the English labourer, from the large proportion of gluten it contains, helps to sustain strength, and adds-beyond what its bulk would suggest-to the amount of nourishment.

As the nutritive properties of vegetables depend upon the presence of three different constituents-gluten, starch, and fat-so the most wholesome are those in which these constituents are best adjusted, the least

wholesome those in which one or two predominate to the exclusion of others. When the proportion of any one of these ingredients is too small, chemistry indicates, and experience suggests, that an additional quantity of the deficient substance should be added in the progress of cooking, or preparatory to eating.

"Thus we consume butter with our bread, and mix it with our pastry, because wheaten flour is deficient in natural fat; or we eat cheese or onions with the bread, to add to the proportion of gluten it naturally contains. So we eat something more nutritive along with our rice or potatoes-we add fat to our cabbage-we enrich our salad with vegetable oil-eat our cauliflowers with melted butter-and beat up potatoes and cabbage together into a nutritious kol-cannon.

"In all natural varieties of vegetable food which are generally suitable for eating without cooking, a large per-centage of water is present. In preparing food in our kitchens we imitate this natural condition. Even in converting our wheaten flour into bread, we, as one important result aimed at, mix or unite it with a large proportion of

water.

"All the kinds of food by which the lives of masses of men are sustained being thus constituted, it is obvious that those vegetable substances which consist of one only of the constituents of wheaten bread, cannot be expected to prove permanently nutritious; and experience has proved this to be the case. The oils or fats alone do not sustain life, neither does starch or sugar alone. With both of these classes of substances, as we have seen, a certain proportion of gluten is associated in all our grains, fruits, and nutritive roots.

"Hence arrowroot, which is only a variety of starch, cannot give strength without an admixture of gluten in some form or other. To condemn a prisoner to be fed on arrowroot alone, would be to put him to certain death by a lingering, torturing starvation. The same is true, to a less extent, of tapioca, and of most varieties of sago, all of which consist of starch, with only a small and variable admixture of gluten. Even gluten, when given alone to dogs, has not kept them alive beyond a few weeks; so that no vegetable production, it may be said, and no kind of artificially prepared food, will support life, in which starch and gluten at least are not united. If they contain at the same time a certain proportion of fat, they will admit of more easy digestion, and of a more ready application in the stomach to the purposes of nutrition; and if they are either naturally permeated with a large quantity of water, or are transfused with it by artificial means, they will undergo a more complete and easy dissolution in the alimentary canal, and will produce the greatest possible effect in ministering to the wants of animal life."

But if the nutritive properties of vegetables depend upon the adjustment of their various constituents, still more so is this the case when we add meat, in the due adjustment of the fat, starch, or sugar, and gluten and fibrine. Many persons will not allow drink during dinner-time; but Mr. Johnston not only lays it down that a mixed food is most wholesome, but that food, if not naturally liquid, should be intimately mixed with a large quantity of liquid before it is introduced into the stomach. Old cheese acts as a digester after dinner, by inducing fermentation. It acts after the same manner as sour leaven does when mixed with sweet dough.

be

Cheese mould, and the digestive quality which accompanies it, may propagated by inoculation, that is to say, by removing a bit of a new cheese from the interior and putting a bit of the old in its place.

Artificial drinks agree in being all prepared from, or by means of, substances of vegetable origin. The love of warm infusions of herbs prevails universally. The custom, therefore, must meet some universal want of our poor human nature. Tea exhilarates and yet soothes, stilling the vascular system: coffee exalts nervous life, and both lessen the waste of the system. The cocoas being prepared from oily seeds are more properly soups or gruels than infusions. All, however, diminish the quantity of carbonic acid given off from the lime, and that also of urea, phosphoric acid, and common salt in the urine. Teas and coffees have come more and more into use as the intellectual activity which distinguishes the leading nations of modern times has developed itself.

"Besides the mere brickwork and marble, so to speak, by which the human body is built up and sustained, there are rarer forms of matter upon which the life of the body and the comfort of animal existence most essentially depend. This truth is not unworthy the consideration of those to whom the arrangement of the dietaries of our prisons, and other public institutions, has been entrusted. So many ounces of gluten, and so many of starch and fat, are assigned by these food-providers as an ample allowance for every-day use. From these dietaries, except for the infirm and the invalid, tea and coffee are for the most part excluded. And in this they follow the counsel of those who have hitherto been regarded as chief authorities on the chemistry of nutrition. But it is worthy of trial whether the lessening of the general bodily waste, which would follow the consumption of a daily allowance of coffee, would not cause a saving of gluten and starch equal to the cost of the coffee;-and should this not prove the case, whether the increased comfort and happiness of the inmates, and the greater consequent facility of management, would not make up for the difference, if any. The inquiry is an interesting one in physiological economics, and it is not undeserving of the serious attention of those benevolent minds which, in so many parts of our islands, have found in the prisons and houses of correction their most favourite fields of exertion.

"I might add, as a stimulus to such experiments, the evident craving for some such indulgence as a kind of natural necessity, which is manifested in the almost universal practice among every people not absolutely savage, of preparing and drinking beverages of this sort. If there be in the human constitution this innocent craving, it cannot be misplaced humanity to minister to it, even in the case of the depraved and convicted. Where reformation is aimed at, the moral sense will be found most accessible where the mind is maintained in most healthy activity, and where the general comfort of the whole system is most effectually promoted."

In common life the sweets we extract are a constant accompaniment of the beverages we infuse. The chemist is familiar with many substances which are sweet to the taste and yet not available to the usages of life. Sugar of lead is a well-known poison, which derives its name from the sweetness of its taste. Silver, in certain of its compounds, is equally A mineral earth called glucina produces many compounds which have a sugary taste.

-sweet.

The number of vegetable substances which can be transformed into sugar by means of sulphuric acid is very great. Starch-sugar is extensively used for sweetening purposes, and for the manufacture of spirituous liquors in the north of Europe. Paper, raw cotton and flax, cotton and linen rags, sea-weeds, woody fibre, and even sawdust, may be by similar means converted into sugar. A distinct kind of sugar, called sorbine, has been obtained from the elderberry.

Neither mechanical nor chemical means have been applied to the sugar manufacture of our West India colonies as they have been in Europe and elsewhere. The same skill which now extracts seven per cent. of refined sugar from the more difficult beet, might easily extract ten or twelve from the sugar-cane.

"The means by which this better result is to be attained are, the use of improved crushing rollers, by which 70 and even 75 per cent. of juice can be forced from the canes-of better modes of clarifying, which chemical research has recently discovered-of charcoal filters before boiling, which render skimming unnecessary-of steam and vacuum boilers, by which burning is prevented, and rapid concentration effected-of centrifugal drainers to dry the sugar speedily and save the molasses-and of coal or wood as fuel where the crushed cane is insufficient for the purpose. By the use of such improvements, planters in Java, in Cuba, and, I believe, here and there in our own colonies, are now extracting and sending to market 10 to 12 per cent. of raw sugar from the 100lb. of canes! Why should our own enterprising West India proprietors spend their time in vain regrets and longings for the past, instead of earnestly availing themselves of those scientific means of bettering themselves which are waiting to be employed, and which are ready to develop themselves to meet every new emergency? It is not the readier or cheaper supply of labour which gives the Dutch planter of Java, or the Spanish planter of Cuba, 10 per cent. of marketable sugar, but better machinery, and more refined chemical applications. And these are surely as much within the reach of British subjects as of any other people on the face of the earth."

The liquors we ferment are all directly produced either from the natural sugars which we extract from plants, or from the sugars which we prepare by art. The chica, or maize-beer of South America, is prepared by moistening the corn, drying it in the sun, and then mashing in warm water.

"In the valleys of the Sierra, however, the most highly-prized chica is made in a somewhat different manner. All the members of the family, including such strangers as choose to assist in the operation, seat themselves on the floor in a circle, in the centre of which is a large calabash, surrounded by a heap of dried maize (malt). Each person takes up a handful of the grain and thoroughly chews it. This is deposited in the calabash, and another handful is immediately subjected to the same process, the jaws of the company being kept continually busy until the whole heap of corn is reduced to a mass of pulp. This, with some minor ingredients, is mashed in hot water, and the liquid poured into jars, where it is left to ferment. In a short time it is ready for use. Occasionally, however, the jars are buried in the ground, and allowed to remain there until the liquor acquires, from age, a considerable strength and powerfully intoxicating qualities.