ed, their being kept in stables that are too close and filthy, and are not sufficiently aired. The mildew, producing the disease, is that which dries and burns the grass and leaves. It falls usually in the morning, particularly after a thunder-storm, Its poisonous quality, (which does not continue above twenty-four hours) never operates, but when it has been swallowed immediately after its falling. The disorder it occasions attacks the stomach, is accompanied with pimples on the tongue, with loss of appetite, with the desiccation of the aliments in the stomach, with a cough and a difficulty of respiration. As a preservative, the author prescribes purging in spring and in winter. The medicine he advises is composed of thirty grains of sulphur of antimony, and sixty grains of resin of jalap. He is against vomiting, and every thing that is of a heating

for the next day. As the liver was large and oily, though without any particular bad taste, the captain and the two Mr. Forsters only tasted it. About three o'clock in the morning, Mr. Forster, awaking, found himself extremely giddy, and his hands and feet entirely, as it were, benumbed. He got up, and was scarcely able to stand; and Captain Cook and the younger Mr. Forster, upon being awakened, found themselves in the same situation. The symptoms were somewhat alarming. Their limbs were benumbed, and without sensation, so that they could not distinguish between light and heavy bodies; the blood had left their cheeks, their lips became livid, and a great degree of languor and oppression had taken place. Emetics were administered to them by the surgeon, Mr. Patton, and afterwards sudorifics. These medicines gave them great relief, and in a few days they were all restored to health, without any bad consequences remaining. Some dogs which had seized upon the remains of the liver were taken extremely ill, and a pig which had eaten the entrails of the

in those lands which have been under the plough for some years, it is found in proportion to the quantity of putrid dung that had been laid upon them, making an allowance for the crops they have sustained. To set this matter in a clear light, let us attend to the effects of manures of an oily nature, and we shall soon be satisfied that oil, however modified, is one of the chief things concerned in vegetation. Rape-dust, when laid upon land, is a speedy and certain manure, though an expensive one, and will generally answer best on a limestone land, or where the soil has been moderately limed. This species of manure is much esteemed by the farmer. It contains the food of plants ready prepared; but as it is not capable of loosening the soil by any fermentation, the lands upon which it is laid ought to be in excellent tilth. At present; that useful article of husbandry is much diminished in goodness, owing to the improved methods of extracting the oil from the rape. Heat and pressure are employed in a double degree.-Farmers that live in the neighbourhood of large towns use abundance of soot. It is an oily manure, but different from the former, containing alkaline salt in its own nature, calculated as well for opening the soil, as for rendering the oily parts miscible with water. It is observed that pigeons dung is a rich and hasty manure. These animals feed chiefly upon grains and oily seeds; it must therefore be expected that their dung should contain a large proportion of oil. The dung of stable kept horses is also a strong manure, and should not be used until it has undergone the putrid ferment, in

order to mix and assimilate its oily, watery, and saline parts. Beans, oats, and hay, contain much oil. The dung of horses, that are kept upon green herbage, is of a weaker kind, containing much less oil. Swines dung is of a saponacious and oily nature, and perhaps is the richest of the animal manures. When made into a compost, and applied with judgment, it is excellent for arable lands. The dung of ruminant animals, as cows and sheep, is preferable to that of horses at grass, owing to the quantity of animal juices mixed with their food in chewing. And here I beg leave to remark in general, that the fatter the animal, cæteris paribus, the richer the dung. Human ordure is full of oil and a volatile alkaline salt. By itself, it is too strong a manure for any land; it should therefore be made into a compost before it is used. The dung of carnivorous animals is plentifully stored with oil. Animals that feed upon seeds and grains come next, and after them follow those which subsist upon grass only. To suit these different manures to their proper soils, requires the greatest judgment of the farmer, as what may be proper for one soil, may be highly detrimental to another.

In order to strengthen my argument in favour of oil being the principal food of plants, I must beg leave to observe, that all vegetables, whose seeds are of an oily nature, are found to be remarkable impoverishers of the soil, as hemp rape, and flax; for which reason, the best manures for lands worn out by these crops, are such as have a good deal of oil in their composi tion; but then they must be laid on with lime, chalk, marl, or

soap

soap-ashes, so as to render the oily particles miscible with water. The book of nature may be displayed, to shew that oily particles constitute the nourishment of plants in their embryo state; and, by a fair inference, we may suppose that something of the same nature is continued to them as they advance in growth. The oily seeds, as rape, hemp, line, and turnip, consist of two lobes, which, when spread upon the surface, form the seminal leaves. In them the whole oil of the seed is contained. The moisture of the atmosphere penetrates the cuticle of the leaves, and mixing with the oil constitutes an emulsion for the nourishment of the plant. The sweetness of this balmy fluid invites the fly, against which no sufficient remedy has, as yet, been discovered. The oleaginous liquor being consumed, the seminal leaves decay, having performed the office of a mother to her tender infant. To persons unacquainted with the analogy between plants and animals, this reflection will appear strange. Nothing, however, is more demonstrable. The leguminous and farinaceous plants keep their placentia, or seminal leaves, within the earth; in which situation they supply the tender germ with oily nutriment, until its roots are grown sufficiently strong to penetrate the soil.

It is usual to talk of the salts of the earth; but chemistry has not been able to discover any salts in land which has not been manured, though oil may be readily obtained from every soil, the very sandy ones excepted. Marl, though a Marl, though a rich manure, has no salts. It is thought to contain a small portion

of oleaginous matter, and an abə sorbent earth, of a nature similar to limestone, with a large quantity of clay intermixed. Lime mixed with clay comes nearest to the nature of marl of any factitious body that we know of, and may be used as such, where it can be had without much expence. By increasing the quantity of clay, it will make an excellent compost for a light sandy soil; but to make the ground fertile, woollen rags, rotten dung, or any oily manure, should be incorporated with it some time before it is laid on. It is a received opinion, that lime enriches the land it is laid upon, by means of supplying a salt fit for the nourishment of plants; but by all the experiments that have been made upon lime, it is found to contain no kind of salt. Its operation therefore should be considered in a different light; by the fermentation that it induces, the earth is opened and divided, and, by its absorbent and alkaline quality, it unites the oily and watery parts of the soil. It also seems to have the property of collecting the acid of the air, which it readily forms into a neutral salt, of great use in vegetation. From viewing lime in this light, it is probable that it tends to rob the soil of its oily particles, and in time will render it barren, unless we take care to support it with rotten dung, or other manures of an oily nature. As light sandy soils contain but a small portion of oleaginous particles, we should be extremely cautious not to overdo them with lime; unless we can at the same time assist them liberally with rotten dung, woollen rags, shavings of horn, and other manures of an animal kind. Its great excellence,

excellence, however, upon a sandy soil, is by mechanically binding the loose particles, and thereby preventing the liquid parts of the manure from escaping out of the reach of the radical fibres of the plants. Upon clay the effect of lime is different; for by means of the gentle fermentation that it produces, the unsubdued soil is opened and divided; the manures laid on readily come into contact with every part of it; and the fibres of the plants have full liberty to spread themselves. It is generally said, that lime answers better upon sand than clay. This observation will undoubtedly hold good as long as the farmer continues to lime his clay lands in a scanty manner. Let him treble the quantity, and he will then be convinced that lime is better for clay than sand. It may be justly answered, that the profits will not admit of the expence. I agree. But then it must be understood that it is the application, and not the nature of the lime, that should be called in question Clay, well limed, will fall in water, and ferment with acids. Its very nature is changed. Under such agree able circumstances, the air, rains, and dews are freely admitted, and the soil is enabled to retain the nourishment that each of them brings. In consequence of a fermentation raised in the soil, the fixed air is set at liberty, which, in a wonderful manner, promotes vegetation. It is the nature of lime to attract oils and dissolve vegetable bodies. Upon these principles we may account for the wonderful effects of lime in the improvement of black moor - land, Moor-earth consists of dissolved, and half-dissolved, vegetable sub VOL. XX.

stances. It is full of oil. Lime assimilates the one and dissolves the other. Such lands, not originally worth four-pence per acre, may be made, by paring, burning, and liming, to produce plentiful crops of turnips, which may be followed with oats, barley, or grass-seeds, according to the inclination of the owner. These observations, however, are rather foreign to the present argument, to which I shall now return.

To the universal principle, oil, we must add another of great efficacy, though very little understood; I mean the nitrous acid of the air. That the air does contain the rudiments of nitre, is demonstrable from the manner of making saltpetre in the different parts of the world. The air contains no such salt as perfect nitre; it is a factitious salt, and is made by the nitrous acid falling upon a proper matrix. The makers of nitre form that matrix of the rubbish of old houses, fat earth, and any fixed alkaline salt. The universal acid, as it is called, is attracted by these materials, and forms true nitre, which is rendered pure by means of crystallization, and in that form it is brought to us. In very hos countries the natural earth forms a matrix for nitre, which makes the operation very short. It is observed that nitre is most plentifully formed in winter, when the wind is northerly: hence we may understand the true reason why farm ers and nurserymen lay up their lands in high ridges during the winter months. The good effects of that operation are wholly attributed to the mechanical action of the frost upon the ground. Light soils, as well as the tough ones, H

may