or little cups of porcelain, or even in metallic dishes. If these last
are sufficiently large, they do not melt, because, metals being good
conductors of heat, the caloric spreads rapidly through the whole mass,
so that none of its parts are very much heated.
In the Memoirs of the Academy for 1782, p. 476. and for 1783, p. 573.
the series of experiments I have made with this apparatus may be seen at
large. The following are some of the principal results.
1. Rock cristal, or pure silicious earth, is infusible, but becomes
capable of being softened or fused when mixed with other substances.
2. Lime, magnesia, and barytes, are infusible, either when alone, or
when combined together; but, especially lime, they assist the fusion of
every other body.
3. Argill, or pure base of alum, is completely fusible _per se_ into a
very hard opake vitreous substance, which scratches glass like the
precious stones.
4. All the compound earths and stones are readily fused into a brownish
glass.
5. All the saline substances, even fixed alkali, are volatilized in a
few seconds.
6. Gold, silver, and probably platina, are slowly volatilized without
any particular phenomenon.
7. All other metallic substances, except mercury, become oxydated,
though placed upon charcoal, and burn with different coloured flames,
and at last dissipate altogether.
8. The metallic oxyds likewise all burn with flames. This seems to form
a distinctive character for these substances, and even leads me to
believe, as was suspected by Bergman, that barytes is a metallic oxyd,
though we have not hitherto been able to obtain the metal in its pure or
reguline state.
9. Some of the precious stones, as rubies, are capable of being softened
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