O14 On different Sorts of Lime ufed in Agriculture. 
in large quantities. I therefore procured fome pieces of it, 
and they were difcovered to contain nearly the fame propor- 
tion of magnefia as that before defcribed. In this quarry the 
fione is frequently cryftallifed in a rhomboidal form; and 
petrified fhells, not calcareous, but fimilar in compofition te 
the ftone itfelf, are fometimes, but very rarely, found in it. 
This fubftance feems to be common in Northumberland. In 
the third yolume of the Annals of Agriculture, Dr. Fenwick, 
of Newcaftle, obferves, that the farmers of that country di- 
vide limes into hot and mild. The former of thefe is no 
doubt magnefian, as it has fimilar effects on the foil; and _ 
he remarks, that it is not fo eafily diffolyed in acids as the 
latter. At Matlock, in Derbyfhire, the two kinds are con- 
tiguous to each other; the rocks on the fide of the river 
where the houfes are built being magnefian, and on the other 
calcareous, The magnefian rock appears alfo to be incum- 
bent upon a calcareous ftratum; for, in defcending a cave 
formed in this rock, a diftiné&t vein of common limeftone 
say be obferved, which contains no magnefia. The latter 
firatum is very full of fhells; but, though there are fome alfo 
in the magnefian rock, yet they are very rare, In the fol- 
lowing tables, containing the analyfis of various fpecimens, 
fome other places are mentioned where this fubftance is 
found, but of which I received no further information. 
After 1t was known that the magnefian marble and lime-. 
flone confifted of the two earths, their proportion was at- 
tempted to be difcovered, by trying how much gypfum and 
Epfom falt could be obtained, by means of yitriolic acid, 
from a certain weight of each fpecimen. When the fuper- 
fluous vitriolic acid had been evaporated by heat, the Epfom 
falt was feparated from the gypfum by water. The refult of 
thefe trials is exprefled in the following table :— 
Dry Gypfum. Dry Epfom Salt. 
5 grains of limeftone from Breedon gave 3.9 3-15 
eerpetiinsnein Matlock - 3.95 2.9 
eomenie Workfop - 3.8 re 
a York - 3.8 LM 
3.grains of calcareous {par, and 1 grain} . 
of calcined magnefia, gave rm a 3:9 7 
6 As 
