an the fields,

ADDITIONAL NOTES. 593

Of alluvial limeftone, like Ketton limeftone, which they do not burn for fale, over the bed of the calcareous limeftone, which they get from beneath the former, and calcine for fale.‘It is probable, that the fuperior bed may contain magnefña, which hâs rendered it not fo ufeful in agriculture.|

It is more probable, that alluvial limeftone has acquired its mixture of magnefia from the fea-water; as magnefia in its uncalcined ftate will precipitate lime from water, as obferved by Dr. Alfton; who thence propoles to render water pure and potable, which has been long kept at fea free from putridity by having lime mixed with it, by precipitating the lime by the addition of mild magnefa; which is a fubject now perhaps worthy the attention of the court of admiralty, fnce magnefian limeftone appears to be fo plentifully diffufed over the earth. See Dr. Black’s Exper. on Magnefa in the Eflay Philof. and Literary, Edinb.

The lime from Breedon is magnefan,£hat from Ticknal(which is fold) 1 calcareous lime I believe; and fome farmers in the vicinity of Derbÿ affert, that two loads of Breedon lime will go as far, that is will apparently do as much fervice to their land as three loads of Ticknal lime. Breedon lime, I am alfo informed, is préferred in ar- chiteëture, and is faid to go further in making mortar; which I fup- pofe means, that it requires more fand to be mixed with it. Mr. Marfhall in his account of the agriculture of the Midland eounties fpeaks of lime made at Breedon near Derby as deftruétive to vegeta- bles when ufed in large quantities. And in Nottinghamfhire it is af- ferted, that the lime from Critch in Derbyfhire is fo mild, that thiftles and grafs fpring up through the edges of large heaps of it, when laid Dr. Fenwick of Newcañftle obferves, that the farmers in that country divide lime into hot and mild; which Mr. Tennant

__believes to mean magnefian and calcareous lime.

By experiments which were made by Mr.Tennant by fowing feeds

TC A À Axe of colewort on various mixtures of calcined magnefña with foil, and 4 G of