9 
$5 sine or antimony, this reduction requires somewhat of 
a different apparatus from the fixed metals, to which chief- 
ly the present observations apply. It has been a constant 
custom with chemists in almost all cases (till of late years) 
to add to the ore in reduction, not only a due quantity of 
Carbonaceous matter, but also to mix it with a large pro- 
portion (seldom less than thrice its weight) of some alka- 
line or easily verifiable matter to serve as a flux to pro- 
mote the fusion of all the heterogeneous contents of the 
ore, and to afford a thin flowing medium, through which 
the globules of reduced metal can readily fall by their su- 
perior gravity* and at last be collected in a single mass or 
button at the bottom of the crucible* 
In all the common processes of reduction, therefore*' 
which are usually given, the additions to the ore are of 
two kinds* the purpose of which should be well distin- 
guished, namely, the carbonaceous matter* which is es- 
sential to the disoxygenation of the metallic oxyd, and the 
saline or fusible flux, the use of which is often highly con- 
venient and even necessary, but also often needless or 
even detrimental. The invariable fault of saline fluxes 
as generally applied, is, that they always dissolve a portion 
#f the metallic oxyd before it has time to pass to the me- 
tallic state, and retain it permanently* thus robbing the 
metallic button of a part of what otherwise would unite 
with it 2 and hence it almost invariably happens that com- 
mon assays made in the dry way with saline fluxed re- 
turn a less proportion of metal than the ore really con- 
tains . Nor is this loss trifling in many instances, since 
the accurate Klaproth found a difference of 9 per cento 
between the yield of copper from a certain ore assayed in 
the dry way, and the same ore treated in a different man- 
ner, in the moist way. As a proof of the solution of a 
part of the metallic oxyd in the saline flux, it may be ad- 
ded that the scoria, or flux after melting, is always found 
deeply coloured with that precise tint which would be 
W 
