Quotation from: The Notebooks of Leonardo Da Vinci
Written by: Leonardo da Vinci
620.
You can make a fine ochre by the same method as you use to make
white.
621.
A FINE YELLOW.
Dissolve realgar with one part of orpiment, with aqua fortis.
WHITE.
Put the white into an earthen pot, and lay it no thicker than a
string, and let it stand in the sun undisturbed for 2 days; and in
the morning when the sun has dried off the night dews.