"Does any one know when the term spelter changed meaning from zinc to
brass?"
I have never before heard of anything but zinc being called spelter. My
dictionary still defines spelter as being "zinc, especially impure zinc". In
the past it usually contained lead and iron and sometimes cadmium and tin.
It is possible that brass was called spelter before zinc was. My earliest
reference is an 1835 cyclopedia. Agricola was translated in 1912.
The coppersmiths in the 17-18th century must have used brass as a hard
solder. Zinc was an expensive imported metal before the middle of the 18th
century.
Brass was made by the cementation process before that and continued to be
made that way because zinc remained too expensive at least until the
"English" process was superseded in the 19th century.
In my cyclopedia the composition of solder for copper is given as 8 parts of
copper to one of zinc, or 3 parts of copper to one of zinc. Percy (1861)
says it should contain at least 66% copper but this probably means that it
often didn't. Bloxam (1882) says that zinc was added to brass to make
brazing solder, and silver as well for fine work. Hiorns (1888) says 2 parts
of brass to one of zinc for brass solder. Some brazing solder in the 20th
century contained 50% zinc (Gowland 1921). I do not have an analysis of
modern brazing rod.
Peter Hutchison
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