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ence, were found to have an equal effect with lime, it wouldnever produce the mischief which has been experienced from o-verliming open soils. As its particles always lie compact, itwould correct and not inflame the fault of such soils. Clayearth should be submitted to torrefaction before it be dry, that thewater, swelling with the heat, may separate its parts, and pre-vent it ftom uniting in hard masses. There are some occasions onwhich a considerable store of this useful manure might be advan-tageously obtained. There are still, in different parts of Scot-land, fields which, having lain long neglected, have a thick co-vering of mosses, heath, and other wild herbage accumulated ontheir surface. Whatever objections there are to exposing to theaction of fire, the surface of cultivated land, bearing a sward ofesculent herbage, which yields to putrefaction, and quickly be-comes nourishment for a new race of plants, there can be noneto the consuming of the refractory herbage of such fields, whichresists putrefaction and does not yield support to a cultivatedcrop. A turf of no sparing thickness might be spared off suchfields, as the stiff growth on it would keep it at some distancefrom the damp ground, and facilitate the drying ; and, w-hen dry,the bulk and inflammability of the herbage would roast a largeportion of the earth, provided the sods were laid gradually roundthe fires, kept alw r ays in near contact with one another, and newones added as the heat increased, never allowing the flame tobreak much through. By the effect of this smothered burning,a proper consistence would be given to the soil, die refractoryherbage would be reduced to a soft cinder, which dissolves inwater, and greatly promotes vegetation ; and thus barren fields,which lie waste from the just apprehension that the expense ofculture and manure, necessary for the improvement of them,would exceed the profit, might produce a plentiful crop at a mo-derate expense. Grass seeds might be sown along with the firstcorn crop, which would be of some value for a few’ years, tillthe occupier could provide manure to augment its fertility.
Matter left on the soil by irrigation .—The earths thus left, be-ing brought together by the same means, must partake of thequality of water-formed soils. But, besides these earths, water,from the bowels of the earth, is frequently charged with muchcarbonic acid, which it quits when exposed to the air, and leavesamong the herbage : and water from the surface brings alongwith it the spoils of vegetables, &c. which it must drop as ittrickles along the meadow.
llejme of salt contains earth, of which nothing more need hesaid. With respect to its salts, these and others shall be consi-dered at the close of this branch.
Ashes ar.d soot, as possessing earth, may be properly enoughranked in this order; but as wood and peat certainly are, andcoal generally believed to be, vegetable substances, the articlesabetc-namsd Issuing from them, may be sa.d to be derived from