1% LIMESTONE. 



a minute division of shelly bodies, now indurated 

 by time and superincumbent pressure, and become 

 a coarse-grained marble. Our limestone thus ap- 

 pearing not to be contaminated with any great por- 

 tion of magnesian earth, it may be used for all agri- 

 cultural purposes with advantage. Many detached 

 blocks of limestone are found about us, having 

 broken shelly remains, and the joints of the encri- 

 nite, greatly mutilated, embedded in them. Irre- 

 gularly wandering near the lime-ridge is a vein of 

 impure sandy soil, covering a coarse-grained siliceous 

 stone ; sand agglutinated, and coloured by oxide of 

 iron, resisting heat, and used in the construction of 

 our lime-kilns : the labourers call it " fire-stone.'' 



We occasionally, though sparingly, find, in a few 

 places on our downs, nodules of lead ore, which in- 

 duced persons in years past to seek for mineral 

 riches; but the trial being soon abandoned, the 

 result, I suppose, afforded no reasonable ground 

 for success. We likewise find thin veins of carbo- 

 nate of strontian, but make no use of it ; nor is it 

 noted by us different from common rubbish ; nor 

 do I know any purpose to which it is peculiarly 

 applicable, but in pyrotechnics. Spirit of wine, in 

 which nitrate of strontian has been mixed, will 

 burn with a beautiful bright red flame ; barytes, 

 which approaches near to strontia, affords a fine 

 green ; nitrates of both, compounded with other 

 matters, are used in theatrical representations. 



