sod MINES, METALS, AND GEMS. 
a half ago ; and this bed had been Avrought fof 
a century, when, in the same neighbourhood, 
stratum was fallen in evith, separated 
UA'-ef.’;, 
inferior 
former by a bed of indurated clay. This p*',« 
was ascertained to possess a very great degree 
and freedom from earthy admixture ; on 'poit’'!; 
and from die local advantages of Northwich for f. 
the fossil salt is worked in the vicinity of that 
It occurs in two great strata or beds, lying neai'l) 
tally, and separated, the superincumbent pf.sy 
jaceut stralnm, by several layers of indurated 
r-enns smne. T'liese intervening beds nosse^s *' i,;.!'' 
ceons stone. I'hese intervening beds possess • 
tion a very uniform thickness of from tliiriy t‘’ j 
feet, and are irregularly penetrated by veins oi 
to believe that the beds iP 
o* .iPi 
,.hcD 
Nordiwich, are perfectly distinct from any o 
t district, and form what are termed by t" J 
There is every reason 
at 
salt 
incumlint bodies or masses of mineral. 
These enormous masses stretch a mile 
at 
longitudinal direfction from north-east to soutl’^^ fjgl’', 
their transverse extent. 
as measured by a bn® 
jt exceed A 
:rs of a mile. " 
area, the brine which is met with is of a veiX ucQ 
" .. *■ . P » 
gles from tlie former, does not exceed 
what more than three quarters of a mile. .^e^. 
inferior quality, and at a short distance disapp®j^^y ti' 
The thickness of the upper bed varies frornJ'J’^-.fl, 
. .., i^v 
feet ; and a general estimate made from na 
that its upper surface, which Is ninety feet hen , 
LliclL ILD jy . , . 
the earth, is at least thirty-six feet beneath 
u'“ i 
mark of the sea at Liverpool— a fact not - 
determining the nature of the formation ot tit^, 
■ ..heftn ,, 
The thickness of the lower bed has not n'‘) 
certained ; but the workings are usually 
depth of from sixty to seventy-five feet, an 
down for the space of fifteen or eighteen iK j f, 
forms the purest portion of the bed. In 
a shaft has been sunk to a level of pf 
lower, without passing through the . ^gd n* ‘.iJi'' 
There is thus an ascertained thickness of ihi® -» ^ 
oy 
hundred and twenty feet, and without any . 
that it may not extend to a considerably gt®.^ Ir 
Although two distinct beds only of fn2?n 
