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been handed down to us from the Romans, to whom it wasknown. But though it has been known from remote times as asubstance adapted to awaken fertility, the use of it long conti-nued to be partial and sparing. It is only since the middle ofthe last century that its beneficial effects have been generallyrecognized and duly appreciated. Lime is found in Scotland chiefly in the state of limestone and marble, lying either incontinuous layers in the bowels of the earth, sometimes too deepto be brought up at a moderate expense, or heaped in immenseblocks on the mountains. It is scarcely ever found pure, beingmixed with a greater or less quantity of clay, sand, iron, &c.sometimes to the extent of 30 parts in 100. It is held in a hardmass by combination with carbonic acid and water. By the ex-periments of the illustrious Dr Black, 100 parts of crude lime,exclusive of all extraneous mixtures, consist of 11 parts of wa-ter of composition, 34 parts of carbonic acid, * and 55 parts oflime. It is well known that this substance is reduced to powderby calcination in a strong heat. When water is afterwards thrownupon it, heat is engendered, and it crumbles into dust. In thisstate it is called quick lime, and dissolves in a large proportionof water ; and, with the aid of water, consumes and decomposesall animal and vegetable substances. When wetted and exposedto the air, it quickly attracts from the atmosphere its naturalproportion of carbonic acid, and forms into hard masses. It isthen called effete lime, is quite insoluble, and does not seem toaffect dry substances.
Husbandmen have applied lime to tlie soil in both these states.Where nature has not furnished it at hand, it has been broughtfrom a great distance both by sea and land, even the length of30 miles of land carriage, f The quantities applied by differentindividuals, and in different districts, are various. The least, ofwhich there is any account, is 100 Winchester bushels in pow-der, and the greatest 500, per acre, and different quantities be-tween these. But it is an universal rule that cohesive soils re-quire a greater quantity than those which are open and friable.It is sometimes spread on pasture grounds, or on clover stubble;but the most generally approved application is on ground fallow-ed, or such as has been ploughed for the reception of the seed,to be immediately harrowed, and mixed with the soil. Somerecommend covering it in the soil before it have lost its causti-city ; others contend that it should lie exposed on the surfaceto attract fertilizing principles from the atmosphere ; and others
* An aeriform body or species of gas, formed by the combination of carbon withoxygon. It exists in tlie atmosphere in all regions, and on the highest elevationsas well as. the lowest valleys, though it is one-third heavier than common air.
f Roxburghshire Report.