that animals fed entirely upon proximate organic principles not containing nitrogen, invariably sink under such diet, and if its use be prolonged, they will ultimately die, with all the symptoms which are attendant upon death from total starvation.

Although nitrogen is abundantly present in the atmosphere, the chemist discovers that it is never withdrawn from thence or elaborated into the animal body, and that it is always indirectly derived from the organic food taken as sustenance.

Blest with health and strength, happy indeed is the man that "goeth forth unto his work and to his labour until the evening," and can thus obtain a moderate share of both varieties of necessary food, that will enable him to keep aloof from those who would fain persuade him that "raw vegetables and pure water are conducive to health and longevity;" or who, during his poverty, would penuriously dole out a minimum of animal food, for the miserable support of the frail earthly tenement of his immortal soul, which at length escaping from temporal wrong and oppression, seeks for everlasting mercy and repose in the bosom of its God.

The chemical phenomena attendant upon the nutrition of the human body by a proper supply of food, are but little known, and vain is the attempt to bring ordinary laboratory processes forward in aid of such recondite functions of vitality.

The human body, whilst endowed with vitality, exerts an action upon every variety of food that defies imitation by the utmost stretch of chemical skill; but

it is discovered that food undergoes a remarkable change-after mastication and mixture with the secretions of the salivary glands, and transposition by deglutition into the stomach.

A secretion of the stomach called " gastric juice," exerts a powerful solvent agency upon the food, and during digestion reduces it to a semifluid white matter called "chyme."

The gastric juice is a most energetic solvent of every kind of food, which of a necessity must be matter deprived of life; but it has no action upon the stomach in which it is secreted through the mysterious agency of vitality; and that vitality is the sole cause of the suspension of the solvent power of the gastric juice, becomes evident after death, for then the stomach, like food, is often found to be corroded and dissolved.

Chemical analysis of the gastric juice does not materially enlighten experimenters regarding its solvent powers, but it contains a peculiar acid, termed the hydrochloric, probably derived from common salt, naturally contained in the generality of food and drink, or added to it as a condiment. The small quantity of hydrochloric acid, and of other acids and peculiar principles supposed to exist, are insufficient to account for its power upon food, and it must be referred to the recondite agency of vitality.

"Chyme," the first product of digestion, may be considered as intermediate with the original food and arterial blood; from the stomach, this chyme proceeds into the small intestines, and meets with another ex

traordinary secretion termed “bile," which mingles with it, and very probably confers some alkaline matter; a chemical change is likewise sustained by the chyme, in consequence of its contact with the bile, for it separates into two portions, one of which passes into the large intestines, and is ultimately voided as excrementitious; the other a milk-white fluid termed " chyle," which is rapidly absorbed by a peculiar set of vessels termed the "lacteals," and by them transmitted to the thoracic duct, and from it to the venous system.

Upon entering the venous system, the whiteness of chyle is succeeded by a dark purple colour, referrible, as it would appear, to the absorption of a superabundance of Carbon, which would prove hurtful if retained in the system.

The Creator has ordained that this purple or venous blood is to be received by the right cavity of the heart, which wondrous organ, by regular pulsations, transmits it to the lungs, where, extremely diffused by their peculiar membranous structure, it is exposed to the influence of the air, and the changes immediately ensue, as already mentioned at page 60.

The blood, thus deprived of its excess of carbon, returns to the left cavity of the heart, as red arterial, or perfect blood, containing a peculiar colouring principle, termed "hæmatosyn," and the two other proximate principles already mentioned as fibrin and albumen; a small proportion of saline matters; and it is endowed with the power of circulating throughout the system, for the secretion of new parts, and for the removal of

such as have performed their functions. Whilst circulating throughout the system, the blood is a homogenous fluid, but upon removal it spontaneously separates into a solid and a fluid portion, the former containing the colouring principle, and fibrin, the latter, the albumen.

The human mind has always a tendency to seek into incomprehensible matters; but incessant and laborious as have been the researches regarding the physical cause of the functions of digestion, nutrition, respiration, and animal heat, very little of real importance has been discovered beyond the above statement, "though a wise man think to know it, yet shall he be not able to find it."

Of all the varied productions of Autumn, the corn harvest is of the utmost importance to mankind, and therefore a few general observations upon the chemical nature of the proximate principles contained in wheat, and to which the nutritive property of good bread may be referred, will claim our attention at this period of our inquiry.

66

In harvest work," the utmost care is taken that the sheaves of corn are perfectly dried by the combined influence of the sun and air, before they are carted from the fields, and housed in barns or stacked in rickyards; care is likewise taken to cleanse them as much as possible from tares, thistles, and other succulent plants, which are ordained to accompany the growth of wheat; because, like hay, all varieties of corn, even when pure, will heat if stacked whilst damp, and with

even greater facility, if contaminated by succulent weeds; whereas if dry, there is no danger of its becoming heated and musty, and unfit for food.

The methods of thrashing, winnowing, and grinding the grains of wheat into flour, are too well known to require comment; but if we turn our attention to the flour, we shall discover a few facts that are not so generally known.

Knead a portion of flour with water into the size and shape of a dumpling; then hold it beneath a slender stream of water, and continue to knead; at first the water will flow away perfectly milk-white, and this may be received in a pail, and set aside; then the water will gradually become less and less white, until at length it flows unchanged, and leaves upon the hands a grey, tough, elastic substance, very much like bird-lime; it is called Gluten; it is a proximate principle, which existed in the flour, and is educed by this first or simple analysis.

Gluten, when submitted to ultimate analysis, by an experienced chemist, yields the ultimate elements, Carbon, Hydrogen, Oxygen, and Nitrogen, as at page 21; and on account of containing the last-named element in considerable abundance, and therefore being nearly identical with the Fibrin and Albumen of the animal body, Gluten is frequently called a vegetoanimal principle, for it gives to articles of diet in which it exists, a nutritive power nearly equal to that of animal food.

Wheat-flour contains more gluten than that of any