44 
A SYSTEM OP 
But the gypfum or plafter ftone, on the contrary^ 
m of very great confequence in building ; and its 
ftrata, which are very fparingly diftributed in the 
earthy are worth fearching for. If it is true5 that 
the flrata of the earth are fituated in a regular 
©rdef throughout the whole globe, as fome affert, 
concerning which they have formed fyflenis 
to themfelves, founded upon obfervations made 
only at fome few places, we might exped to have 
a eonfiderabk quantity of this ftone ; but there 
^fe innumerable experiments yet wanted, before 
this can be demonftrated. In the mean v/hile, it 
may be aflced, and with fome reafon, If the gyp- 
foffi is to be fearched for in any other places be- 
fides thofe ftrata where there is a pofitive proof 
of their being farmed 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, 
md afterwards fixed itfelf to a pure calcareous 
earth X ? 
The miners life crude limeftone to make the 
htarthi of their iron furnaces, and as fluxes in 
melting their ores. The folid and the fcaly lime- 
ftones are both employed to the former ufe •, but 
the fcaly (Seel, ix.) is the beft, and next to that 
the grained limeftone (Sedt. viii.). 
Thofe who intend to fearch for limeftone to 
make lime, and are afraid to miftake the white 
iron ore (Seeft. xxx.) for it, ought only to obferve, 
that the latter always decays in the open air into 
f This whole pafagrapli, efpecially 
©hieiite and uninuliigible. D. C. 
the latter lines, is very 
a black 
