44 A- SYSTEM OF 



But the gypfum or plafter ftone, on the contrary, 

 h of very great confequence in building \ and its 

 ftrata, which are very fparingly distributed in the 

 earth, are worth fearching for. If it is true, that 

 the ftrata of the earth are fituated in a regular 

 order throughout the whole globe, as fome aftert, 

 and concerning which they have formed fyftems 

 to themfelves, founded upon obfervations made 

 only at fome few places, we might expect to have 

 a confiderable quantity of this ftone j but there 

 are innumerable experiments yet wanted, before 

 this can be demonftrated. In the mean while, it 

 may be afked, and with fome reafon, If the gyp- 

 fum is to be fearched for in any other places be- 

 fides thofe ftrata where there is a pofitive proof 

 of their being formed in the middle age, by 

 means of water carrying their particles with it, 

 and depofiting them as a fediment there, and 

 where alfo the vitriolic acid has been prefent ? 

 Likewife, If thefe ftrata ought before to have 

 been fet on fire, whereby the vitriolic acid has 

 been feparated from the inflammable fubftance, 

 and afterwards fixed itfelf to a pure calcareous 

 earth J i 



The miners life crude limeftone to make the 

 hearths of their iron furnaces, and as fluxes in 

 melting their ores. The folid and the fcaly lime- 

 (tones are both employed to the former ufe ; but 

 the fcaly (Seel, ix.) is the beft, and next to that 

 the grained limeftone (Scd:. viii.). 



Thofe who intend to fearch for limeftone to 

 make lime, and are afraid to miftake the white 

 iron ore (Seel:, xxx.) for it, ought only to obferve, 

 that the latter always decays in the open air into 



| This whole paragraph, efpecially the latter lines, is very 

 fcbicure and unintelligible. D. C. 



a black 



