Salmon, William: Polygraphice; Or, The Art of Drawing, Engraving, Etching, Limning, Painting, Washing, Varnishing, Colouring and Dying: In Three Books ... (London, 1672)

Os Glass and Vretiotis Stones* iyi
and Brass twice Calcined, of each one
pound, mix and melt them, (Hiring them
well with an Iron Rod.
XVIII. An Artisicial Saphyre.
To melted Crystal put a little Zapho*
rd (two Drachms to a pound of Cry-
stal) then stir it continually srom top to
bottom with an Iron hook, till itis well
mixed, keep it in the surnace three days
and it is done: yet when it is well co-
loured 3 unless it be presently removed
from the sire it will lose its tincture a-
gain.
XIX. To make white Enamel*
Take Calx os Lead two ounces. Calx
os Tin sour ounces, make it into a body
with Crystal I1 ounces,role it into round
balls, 8c fet it on a gentle sire sor a night,
stirring it about with an Iron rod, till it
is melted, and it is done.
X X. The general preparations and pro*
portions of Mineral Colours.
Plates os Copper muft be made red Hot,
and then quenched in cold water 5 os
which sive or six grains mixed with Cry-
stal and Sal Tartan os each hals an
ounce,