V. MANURES RICH IN PHOSPHORIC ACID (seed-formers). Burnt bones, bone-black, refuse-charcoal, sugar-refuse from sugar-refiners.

Phosphorite, and a few other kinds of stone.

Bad (washed-out) guano.

Raw bones, bone-dust.

Good guano.

Animal substances of all kinds.

Oil-cakes, brewers'-grains.

Solid human and animal excrements.
Stable-manure.

Urine of carnivorous animals.

Wood-ashes, straw, leaves, &c.

VI. MANURES CONTAINING SULPHURIC ACID (partly direct manures, partly absorbents of manuring substances).

Gypsum, sulphuric acid.

Green vitriol, sulphur-coal.

Many kinds of brown-coal.

Ashes of pit-coal, peat, and brown-coal.

VII. MANURES RICH IN LIME.

Burnt lime, chalk, marl.

Gypsum, ashes of brown-coal and peat.
Building-rubbish, pond-mud, soap-boilers' ashes.

VIII. MANURES RICH IN SILICA.

Pit-coal ashes, as also ashes of all kinds.
Sand, straw, stable-manure, &c.

IX. MANURES THAT DISSOLVE THE CONSTITUENTS OF
THE SOIL.

Sulphuric acid, muriatic acid.

Lime, marl, humus, &c.

X. MANURES THAT AMELIORATE THE PHYSICAL CHARACTER

OF THE SOIL.

Lime, marl, loam, sand.

Pond-mud, vegetable-mould, turf, &c.

E

IV. EXCREMENTS AND URINE.

THERE are, indeed, many countries and tracts of land where the soil brings forth fruits, and frequently with exceeding abundance, without the application of manure by the hand of man. These are either regions where a scanty population does not demand from the farmer such high cultivation and exhaustion of his land, or which are so favoured by Nature that the natural coating of rich soil provides a supply of nutritive materials sufficient for many harvests. This supply, however, is not inexhaustible, as is seen in America, where lands of the most fertile character have been so exhausted by the continued cultivation, for nearly a century, of tobacco and sugar, that they also must now be manured, if they are to yield their usual produce. The northern countries of our globe do not belong to these favoured regions, and if we would here reap abundantly, we must manure abundantly.

The beneficial influence which animal and human refuse (excrements, urine, &c.) are capable of exerting upon vegetable growth, has made these otherwise worthless and loathsome substances the most natural and in most places the exclusive means of fertilizing our fields; hence it will be altogether in order if they are taken first into consideration.

How do the fæces of the different animals operate? To what crops are they the most profitably applied? What amount is yearly obtained from a horse, a cow, a sheep, or from a given quantity of provender? What is the worth of these different excrements when compared with each other? These and similar inquiries of extreme importance to the practical agriculturist have been already answered with the greatest fulness of detail in agricultural writings, but the answers unfortunately differ so widely from each other, as to impart little assistance to the farmer; since in most cases he will be in doubt which of these statements is best entitled. to belief. Accurate experiments are here greatly needed, in order to attain absolute certainty as to which of the figures given as the respective equivalents of the food. and manure, the quantity and quality of the latter, &c., rest merely on conjecture, and which are founded upon the re

sults of actual experience. If, however, such experiments are to lead to reliable results, the circumstances under which they were instituted must be also specified with the utmost exactness, and the constituents of the food and the fæces produced must be no less carefully ascertained. The path leading to this goal is laborious, and many years will probably expire before the principal questions are discussed in such a manner as to enable us to deduce sure rules for practical agriculture; but it is the only one that will conduct to perception of the truth.

That the excrements of our live stock are derived from the food which is given to these animals, every one is aware; as also that a large part of this provender disappears during its passage through the body of the animal, that, namely, which was appropriated to the nourishment and preservation of the animal, and, besides this, some devoted to its fattening (that is, to the formation of flesh and fat), or to the production of milk. Which, then, are the ingredients of the food that are converted into flesh and fat? which are removed by breathing and perspiration? and which, finally, are voided in the urine and excrements from the body? Is it not obvious that a clear insight into the nutritive processes, and a safe judgment upon the proportion of the food to the fæces, can only be attained when their individual constituents are known, and the alterations are learnt from them which the provender has undergone in the body of the animal? How will it be possible to form an accurate judgment respecting the differences of animal excrement and its effect upon the various cultivated plants, if the first elements essential to this judgment, the constituents of the plants, the manure, and the soil, are unknown? Questions of this character can be solved by chemistry alone; this science must constitute the basis, if the results ascertained by practical experience and experiments are to arrive at clearness, connection, and certainty. What has been already brought to light concerning these points by chemical investigations is in manifold respects still incomplete and defective; nevertheless we must be contented with what is incomplete, until something more perfect has been produced. What is now known will be communicated in the following sections.

1. ORIGIN OF ANIMAL FACES.

Here is a potato; of what does it consist, and what alterations must its constituent elements undergo when it is used as food? The potato has been subjected, countless times, to chemical examination, and its constituent parts are perfectly known. It has been found to contain :

Proximate Elements.

Starch, Vegetable Fibre,

Albumen.

Mineral Substances

(Ashes).

Ultimate Elements.

Carbon, Hydrogen, Oxygen,
Nitrogen.

Potash, Lime, Silica, Phos-
phoric Acid, &c.

Most of the other substances employed in foddering cattle, as well as the potato, have been already analysed, and the separate constituents of the bodies of the animals are likewise very accurately known. If now the composition of the food is compared with that of the animal body, we find, that, of the proximate constituents of plants, some have the greatest similarity to the blood and flesh, others to the fat, others, again, to the bones of animals. And hence we infer that these vegetable constituents are actually converted in the animal body into blood, flesh, fat, and bones.

Of the above-stated constituents of the potato,

The vegetable fibre and starch have great similarity and almost identical composition with the fat of animals; The albumen, with the blood and flesh;

The mineral substances, with the bones.

A very large portion, however, of the food given to an animal disappears, as is universally known, during its passage through the body; for the dried fæces and urine weigh conjointly but from one-third to one-half as much as the food in a similarly dry condition. To know which elements of the food pass off in this manner,—partly through the skin, as evaporation or perspiration, partly through the lungs and mouth, as breath,-must of course be extremely important in forming an opinion concerning the nutrient power of the aliment, and also concerning the strength of the manure that is produced from it. The following results have been furnished by those experiments which have been made, up to the present time in regard to these points:

As these figures show, the three substances first named are principally used up in breathing and perspiration ; the nitrogen is consumed by these processes in a far more trifling proportion, while the mineral ingredients even acquire in some cases an increase of quantity, which must, however, be attributed, always, simply to the dust adhering to the provender. In young growing animals a considerable dimi