the earlieft times, being then reckoned among* tfe' 
metals, when even they were named after the 
planers, the number ot both being thought equal. 
The opinion, which has a long time prevailed, 
that the quickfiiver is a neceffary ingredient, andl 
conftituent part in all metals, is not fo generally- 
received nov/ as heretofore *, fmee thofe procelTes, 
which have been advanced as proofs of it, and 
which have, however, but feldom been repeated,. 
do by no means fucceed, at leaft not in all places j . 
it is rather fuppofed, that by the mercurial earth 
the ancients have underftood am earth, which may,, 
by addition of phlogifton, be reduced in the fire 
to a metallic ftate , and this appears to be fo much 
the more reafonable, as the quickfiiver only attracts 
the metals in their fubflances, and not in their 
burnt calces. 
SECT, eexxr. 
2. Bifmuth, Tinglafs, Vifmiitum^ 
Marcafita officinalis. It is 
a. Of a whitifh yellow colour. 
h. Of a laminated texture, foft under the 
hammer, and neverthelefs very brittle. 
c. Its fpecific gravity to v/ater is, as 9,700 : r 
1000. 
d. It is very fufible, calcines and fcorifies like 
lead, if not rather eafier, and therefore 
it wmrks on the cuppel. It is pretty vola- 
tile in the fire. 
e. Its glafs or flag becomes yellowifii brown,. 
and has the quality of retaining fome part 
of the gold, if that metal has been melted, 
calcined, and vitrified with it. 
/. It may be mixed with the other metals, 
cept cobalt and zink, making them white 
and brittle. g. It 
