102 A SYSTEM OF 
The ufe of clays, in common life, is more e^^- 
tenfive than I have been able to inform myfeif 
of^ for which reafon I will only mention fome 
particulars relating to it. 
The porcelane clay is employed to make veF 
fels which have that quality already mentioned 
(Se£t. Ixxviii,), I make no doubt but it enters into 
the compofition for making the fine porcelane 
ware at fome places at lealt veflels are prepared 
from it of the fame goodnefs in every refpefl: : 
and there are likewife fome varieties of this clay, 
which become quite white in the fire, a quality 
which is efteemed the moft valuable in the fine 
China ware. 
The indurated porcelane clay cannot be eafily 
lieated without cracking, and is therefore of no 
great fervice, if hardened in the fire alone, and in 
its natural ilate : though this circumflance is of 
lefs inconveniency, than when it has original 
cracks, or is mixed with heterogeneous fubflances. 
The fteatites is found purer and more folid in 
China than in any place in Europe. The natural 
faults of the European ones may, hov/ever, be 
altered by adding fome fat fubftance to it, when it 
is to be burnt ; by which means it becomes black 
or brown ; and this method is faid to be ufed at 
Bareith. The coarfe porcelane-like earth, which 
goes by the name of French cla)\ is ufed at the 
giafs-houfes, flee! furnaces, and other works of 
the fame nature, for the fame reafons it is the 
^ The deatites here meant is the fubftance of which the 
Chinefe joftes or figures commonly chilled rice figures are 
made : it is? according to my method, of the clafs of Talcs, 
and of the genus of Nephritics, D. C. 
principal 
