97 
MINER A Y, 
with any other kind of earth, by which i: 
might be confidered as a variety of any 
other. That Which is here defcribed, is or 
a yellow colour, and is fold by druggiils, 
■who do not know where it is , found 
SECT. XC. 
_E, Common Clay, or Brick day, Argilla com- 
munis \ vulgaris Flaft.ica, 
This kind may be diftinguiflied from the 
other clays, by the following qualities. 
I. In the fire it acquires a red colour, more 
or lefs deep. 
It melts pretty eafily into a greenlili 
glafs. 
5.' It contains a fmall quantity of iron and 
of the vitriolic acid, by which the pre- 
ceding effedLs are produced. 
It is found, 
A. DiiFufible in water. 
I. Pure. 
a. Red clay, from Kinnekiille, in 
the province of Wehergottland. 
h. Flelli coloured, or pale red, i^. 
found on the plains between Wef- 
teras and Sala, in the province of 
Weilmanland. 
c. Grey, in the xorn- fields in the prc- 
.vi nee of Upland. 
^ I have got of this kind of tripoii from Scotland, which 
has .been lately idfiGovered there. But the rotten-ftonc, ih 
called, is another fort found in England, viz. in Derby fhu. . 
It is in common ufe here in England among workmen i.vv 
all forts of finer grinding and polifhing, and is alfo fornc- 
tipaes ufed by lapidaries for cutting of ftones, D. C. 
d. Blue 
IT 
