A SYSTEM OF 
SECT. CCXXXL 
Observations on Zink. 
It does not feem jull to conclude from old coins 
.and other antiquities, that it is evidently proved 
;that the making of brafs was known in the moft 
.antient times, and that it was their jEs Corinthia- 
ireralifed with fulphur. The fulphur, neverthelefs, exifts in 
the diiFerent kinds of bJende, equally as in the zink ore ; and 
ijiis remarkable difference in their appearance muft be account- 
ed for from another principle than the quantity of the zink 
which they contain ^ b.ecaule the yellow and white blendes are 
often found richer than the zink ores^, but the zink ores are how- 
ever more eafy to melt, and confequently more profitable. Per^ 
Itaps it is becaufe the blende does not contain afufficient quan- 
tity of the phlogifloa of the fulphur, to prevent the calcina- 
tion of the zink. 
It is no matter whether a calcined blende is called calamine 
©r not, provided it has fuch properties that it may be employ- 
ed to the fame purpofes. and with the fame advantage as that 
calamine which nature has freed from its fulphur by its wea- 
thering or decaying. This may be done with foms kinds of 
blende, and Mr. Von Swab has given evident and excellent 
proofs of it in Sweden | infomuch that it would demonftrate 
a want of experience to infill that fulphur cannot be expelled 
hy calcination, without deftroying the zink itfelf, and that 
Itowers of zink may be produced from zink ores in a calcining 
hear, without addition of any phlogifton, 
Mr. Jufti however avers, that he has found an ore of this 
quality, which in his Mineralogy he calls Ztnkfpat ; but there 
is great i'„afon to doubt if it really contains any zink, until it 
Is proved whether the author added any phlogifton during the 
calcination, or reduced the zink out of it ; becaufe, although the 
powers of zink may not always be perfeftly well calcined, yet 
there is no inflance of a natural zink ore being difeovered, 
which by itfelf yields thofe flowers during the calcination : And 
It requires, befides, a flrongheat to produce thefe flowers from 
pesfe£l calx or glafs of this femi-metal, either natural or ar- 
ti&cial, though mixed with a phlogillon ; for it could not have 
jbeen a native zink, fince it refembied a fpar, and fuch a one 
very likely k- not to be found in nature. 
cum 
