3 22 -Attempt to make a Thermometer 
of Chinefe porcelain does not perfectly vitrify by any fire I 
could produce; but began to foften about 120°, and at 156° 
became fo foft as to fink down, and apply itfelf clofe upon a 
very irregular fur face underneath. The true ftone Nankeen, 
by this ftrong heat, does not foften in the leaf; ; nor does it 
even acquire a porcelain texture, the unglazed parts continuing 
m fuch a date as to imbibe water and flick to the tongue. The 
Drefden porcelain is more refractory than the common Chinefe, 
out not equally fo with the ftone Nankeen. The cream- 
coloured or Queen’s ware bears the fame heat as the Drefden, 
and the body is as little affeCted by this intenfe degree of fire. 
Mr. pott fays, that to melt a mixture of chalk and clay in 
certain proportions, which proportions appear from his tables 
to be equal parts, is “ among the mafter-pieces of art.” This 
mixture melts into a perfect glafs at 123° degrees of this ther- 
mometer. 
I he whole of Mr. pott’s or any other experiments may, 
by lepeating and accompanying them with thefe thermometric 
pieces, have their refpeCtive degrees of heat afcertained, and 
thereby be rendered more intelligible, and ufeful, to the reader, 
the experimenter, and the working artift. 
I flatter myfelf that a field is thus opened for a new kind of 
■: hcrmometncal inquiries ; and that we fha.ll obtain clearer ideas 
with legard to the differences of the degrees of ftrong fire, and 
rheir correfponding effe&s upon natural and artificial bodies ; 
thofe degrees being now rendered accurately meafurable, and 
comparable with each other, equally with the lower degrees of 
heat which are the province of the common mercurial thermo- 
meter. 
APPENDIX. 
