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226 AlECUANICAL DENTISTRY AND METALLURGY. ;
ished, is the brightest of the metals. It is very malle-
able and ductile. It exceeds gold in tenacity or co-
hesion, but is inferior to platinum in this respect. Fine
silver is unaffected by moisture or pure atmospheric air,
but is readily tarnished with a film of brown sulphuret by
exposure to sulphuretted hydrogen. The sulphuret of
silver thus formed may be easily removed by rubbing the
metal with a solution of chameleon mineral, prepared by
calcining equal parts of black or peroxid of manganese and
niter. Unlike gold and platinum, it is readily soluble in
nitric acid, this and sulphuric acid being tJie only simple
ones that dissolve it.
Fusing Point.—Silver fuses at an extreme red heat, gen-
erally estimated at 1873° F. It becomes very brilliant
when heated ; boils and vaporizes above its fusing point
and when cooled slowly its surface presents a crystalline
appearance.
Alloys of Silver.—Silver combines readily with most
metals, forming compounds of variable degrees of mallea-
bility, ductility, density, etc.
Tin, zinc, antimony, lead, bismuth, and arsenic render
it brittle. A very minute quantity of tin is fatal to the
ductility of silver. Silver does not easily combine with
iron, although the two metals may be united by fusion.
Gold, copper, platinum, iridium, steel, manganese, and
mercury also form alloys with silver.
Refining Alloys of Silver.—The following accounts of
the manner of obtaining pure, or nearly pure, silver from
alloys of that metal by the dry, and wet, or humid, methods
are given by Professor Essig in his treatise on " Dental
Metallurgy :"
—
Dry Method. " The dry method, or assaying process,
consists in forming an alloy of the silver with lead, and is
especially applicable to ores and the sweepings of the den-
226 AlECUANICAL DENTISTRY AND METALLURGY. ;
ished, is the brightest of the metals. It is very malle-
able and ductile. It exceeds gold in tenacity or co-
hesion, but is inferior to platinum in this respect. Fine
silver is unaffected by moisture or pure atmospheric air,
but is readily tarnished with a film of brown sulphuret by
exposure to sulphuretted hydrogen. The sulphuret of
silver thus formed may be easily removed by rubbing the
metal with a solution of chameleon mineral, prepared by
calcining equal parts of black or peroxid of manganese and
niter. Unlike gold and platinum, it is readily soluble in
nitric acid, this and sulphuric acid being tJie only simple
ones that dissolve it.
Fusing Point.—Silver fuses at an extreme red heat, gen-
erally estimated at 1873° F. It becomes very brilliant
when heated ; boils and vaporizes above its fusing point
and when cooled slowly its surface presents a crystalline
appearance.
Alloys of Silver.—Silver combines readily with most
metals, forming compounds of variable degrees of mallea-
bility, ductility, density, etc.
Tin, zinc, antimony, lead, bismuth, and arsenic render
it brittle. A very minute quantity of tin is fatal to the
ductility of silver. Silver does not easily combine with
iron, although the two metals may be united by fusion.
Gold, copper, platinum, iridium, steel, manganese, and
mercury also form alloys with silver.
Refining Alloys of Silver.—The following accounts of
the manner of obtaining pure, or nearly pure, silver from
alloys of that metal by the dry, and wet, or humid, methods
are given by Professor Essig in his treatise on " Dental
Metallurgy :"
—
Dry Method. " The dry method, or assaying process,
consists in forming an alloy of the silver with lead, and is
especially applicable to ores and the sweepings of the den-
