I can’t find any reference to brown gold in “Henley’s”. Maybe I am
I do have one reference to brown gold . On page 37 0f "Working
in precious metals " ( 1933) by Ernest Smith. It has been
reprinted several times-- at one time several years ago it was
available at B&N on closeout. I found a closeout copy in the UK
but it was the last one.
a more or less quote:
This is not an alloy but a result of nitric acid depleting a high
silver content gold alloy leaving a spongy mass of gold that is the
brown gold of commerce. The mass is dried but not heated enough to
change the physical appearance.
The only thing I find on lead in gold is in Brepohl’ “Theory and
practice of goldsmithing” page 53 :
“Fractions of a percent of lead are sufficiently damaging to form
the brittle compound Au2Pb which is deposited at grain boundaries.
The alloy melts at a low 418C and is too brittle too be worked
either hot or cold.” A photo micrograph is shown on page 54.
The book “Precious metals Science and technology” A reasonably
current and very complete monograph translated from Japanese
shows gold 75, silver 5, palladium 20 as a white 18 karat gold.
This book also shows no brown gold or any lead containing gold