224 
A SYSTEM OF 
on account that it is found in the Hungarian gold 
mines : Yet ftill we know no more of the confti- 
tuent parts of this femi-metal than the others, 
iiotwithftanding all that has been wrote on the 
fubje6t. Some fay that its earth is not vitrifiable, 
becaufe it is volatile, which is perfedlly contrary 
to experience : And if volatility is the charadterif- 
tic of a mercurial earth, the pipe clay from Co- 
logne ought to be of the fame nature. Perhaps it 
is better to fay that the calx of antimony is vola- 
tile, and is incapable of being reduced into a me- 
tallic ftate with phlogifton alone, but may be melt- 
ed into glafs ^ and fuch is its nature, though we 
do not know the reafon of it. 
SECT. CCXXXVIIL 
5, Arfenic, Arfenicum, This is 
a. In its metallic form nearly of the fame 
colour as lead, but brittle, and changes 
fooner its fhining colour in the air, firft to 
yellow, and afterwards to black. . 
It appears laminated in its fra6lures, or 
where broken. 
c. Is very volatile in the fire, burxns with a 
fmall fiame, and gives a very difagreeable 
fmell, like garlick. 
J. It is, by reafon of its volatility, very 
cult to be reduced, unlefs it is mixed with 
other metals : However, a regulus may 
be got from the white arfenic, if it is 
quickly melted with equal parrs of pot- 
allies and foap j but this regulus contains 
generally fome cobalt, mofc of the white 
arfenic being produced from the cobalt 
ores during their calcination. The white 
arfenic, mixed with a phlogifton, fablimes 
like- 
