come very much blackened and burnt, the resulting charcoal is not useless, as might be supposed; for upon throwing it into a portion of water unfitted for beverage by long keeping, the charcoal will deprive it of all offensive odour and taste, and render it palatable, yet the theory of this fact is not understood.

By the long-continued action of diluted sulphuric acid upon starch, the chemist can further derange the natural proportions of its elements, and produce Sugar, a proximate principle likewise consisting of Carbon, Hydrogen, and Oxygen, as shown at page 21.

A small proportion of Sugar exists in wheaten flour, and likewise another principle called Albumen; but these require a very considerable amount of chemical knowledge for their eduction, and the details of the process would encroach too much upon the prescribed limits of this examination; reference, however, must be made to the fact, that wheat flour, in addition to its organic principles, gluten, starch, sugar, and albumen, contains notable traces of the inorganic compounds, called phosphate of lime and phosphate of magnesia ; and it is a most remarkable fact, that these inorganic substances are transferred from wheaten and other food in which they exist, into the constitution of the bones of man, and of the higher order of animals.

The extreme utility of manuring wheat-lands with recent "bone-dust," consists in the fact, that the organic, or tough matter of the bone called Albumen, is extremely prone to putrefy, and thus render soluble the phosphates of lime and magnesia with which it is

associated; these are accordingly rendered into a state suitable for absorption by the rootlets of the growing grain, and are chiefly transferred to the ear, whilst the silica and potash are arrested, to form the glistening straw, as mentioned at page 145.

Bones, when calcined or burnt, have all their really organic matters, such as albumen, fat, and oil, destroyed and dissipated, and nothing but their inorganic phosphates remains; such "bone-ash," although invaluable to the chemist as a source of phosphorus, is not so to the agriculturist, because it is insoluble, and not easily or perfectly received by the rootlets of plants, and therefore it requires solution, or rather decomposition, by the agency of diluted sulphuric acid, before it is added to the soil.

Bone-ash is the source from whence the chemist elicits all his supplies of phosphorus,-about twenty thousand pounds weight per annum,-for the manufacture of "Lucifer matches;" he generally effects the decomposition of the bone-ash by submitting it to the action of charcoal and sand at a red heat; these agents deprive the phosphoric acid of oxygen, and elicit phosphorus, as the "red lead" deprived hydrochloric acid of hydrogen, and elicited chlorine, at page 232.

Another most important office of the organic matter of bone, and of animal and vegetable manures in which nitrogen exists as an ultimate element, is to supply this extraordinary form of matter to growing plants; hence it is found that wheat, grown upon soils chiefly manured with nitrogenous matters, contains

a relatively large proportion of gluten; and the same remark is applicable to the growth of other vegetables, for it does not appear that any of them have the power of secreting nitrogen directly from the air; it enters their living structure indirectly from the decomposition of dead organic matter, and when the season of maturity is attained, such vegetables become the food of animals; nitrogen enters into the composition of their flesh, and this, conjoined with the use of vegetables as food, aided by proper culinary operations, then enters into the constitution of the human body; at least so it is presumed, according to the observations and experiments of the ablest physiologists and chemists.

The use of quick-lime as a manure is on account of its causticity, soon rendering dead organic matters soluble, and fit for the nutrition of growing vegetables; and having performed this office, it gradually absorbs carbonic acid from the atmosphere, reverts to the state of neutral carbonate of lime, and then sustains the office of absorbing the water of the shower, or the aqueous vapour of the air, by capillary attraction, and thus preserves a reservoir of nutriment for the plants that it supports.

The offal of the stable and fold-yard is invaluable as manure, because it returns to the soil a very large proportion of the proximate and ultimate elements, that were taken from it by the growth of the hay and corn-crops; it returns them in a state fitted for affording vegetation the support that it demands; these facts

regarding manures are not of such recent date as some persons imagine; they are to be found in the works of the chemist who first devoted his unrivalled talents to agriculture upwards of thirty years ago, and to whom the agriculturist is deeply indebted for the rational principles upon which he now successfully conducts his labours.

Very few vegetables are destitute of Gum; it contributes to their nutritive powers, and when pure, is wholly soluble in cold or hot water, forming a mucilage; it frequently exudes spontaneously from the stems and barks of trees, as from the plum, cherry, apricot, and almond; but the substance most popularly known as gum, is the produce of the "acacia vera," a plant that is very abundant in Morocco.

As gum exists in vegetables, it appears to have some nutritive properties, and it is said that during the gum harvest the Arabs subsist principally upon it; and moreover, that a large caravan of Abyssinians would have starved, had they not fortunately discovered among their merchandize a large stock of gum, upon which one thousand persons subsisted for two months.

The sweet and luscious taste of fruits may be chiefly, if not exclusively, referred to the presence of the proximate principle well known as Sugar, and it is possessed of considerable nutritive powers; it is soluble in hot and cold water, forming a syrup, which, if concentrated, will yield four and six sided prismatic crystals as seen in sugar-candy, and thus materially

differs in its physical state from gluten, starch, and gum, which are uncrystallizable.

The composition of all the proximate principles that have been considered, including sugar, will be evident upon reference to page 21; the source of the enormous supplies of sugar, is well known to be the

sugar cane," or "arundo saccharifera," and therefore demands no detailed mention here; the annual consumption of sugar furnished from this plant, and the vast amount of carbon that it contains, are shown at page 82.

Sulphuric acid has a strong attraction for water, and in combining with it as at page 234, a great elevation of temperature results; but the chemist discovers that the acid has no attraction for carbon; now analysis teaches him, that all the proximate principles of which mention has been made, consist of the elements of water, viz., oxygen and hydrogen combined with carbon.

He therefore reasons as follows,-if sulphuric acid be presented to such proximate principles of vegetables, say to sugar for example, it might probably combine suddenly with the oxygen and hydrogen or water, and liberate or educe the carbon; he tries the experiment and discovers the truth of his supposition.

Place a quarter of an ounce of powdered sugar in a small gallipot and add sufficient sulphuric acid to moisten it perfectly, stirring the two substances together with a piece of stick; this will appear as if charred, and it really is so, by the sulphuric acid decomposing it first