On different Sorts of Lime ufedin Agriculture. 233 
were found to confift of magnefia and calcareous earth, like the 
magnefian limeftone ; fo that it ought no doubt to be confider- 
ed as the fame Blecich of ftone, but j in a ftate of greater purity. 
The pieces of dolomite were from different ides ; one of them 
being found among the ruins of Rome, where it is thought 
to have come from Greece, as many ftatues of Grecian work 
manfhip are made of it, and no quarries of a fimilar kind are 
known in Italy ; the fecond was faid to have been thrown up 
by Mount Vefuvius; and the third was from Tona, one of 
the weftern iflands of Scotland. In many kinds of common 
marble, fmall particles and veins may be obferved, which are 
a long time in diffolving, Thefe, upon examination, I dif- 
covered to contain a confiderable proportion of magnefias 
but, as they were probably not guite free from the furround- 
ing marble, I did not afcertain the quantity precifely. 
The cryftallifed {truacture which may generally be obferved 
in the magnefian limeftone, feems to fhew that it has not 
been formed by the accidental union of the two earths, -but 
mutt have refulted from their chemical combination. The . 
dificulty of diffolving it, may alfo arife from the attraction 
of the different component parts to each other. The mortar 
formed from this kind of lime is as foluble in acids as com- 
mon marble; and the fubftances of which it confifts are eafily 
feparated. The magnefia may be taken from it by boiling it 
in muriated lime, and lime is precipitated by it from lime 
water; but neither of thefe effets can be produced by the 
fione before it is calcined. 
Magnefian limeftone is probably very abundant in various 
parts of England. It appears to extend for thirty or forty 
miles, from a little fouth-weft of Workfop in Nottingham. 
fhire, to near Ferry-bridge in Yorkfhire. About five or fix 
miles further north there is a quarry of it, near Sherburn; 
but whether this is a continuation from the ftratum near 
Ferry-bridge, I have not learnt. From fome fpecimens which 
were fent me, I find that the cathedral and walls of York are 
made of it, have not been able to learn whether there 
were any fhells in the limeftone of the tract of country be- 
fore-mentioned. In Mr. Marfhall’s account of the agricul- 
ture of the midland counties, he fpeaks of the lime made at 
Ercedon, near Derby, as deftruétive to vegetables, when ufed 
in 
