water to render it more liquid, provide some gold in a shell, which
must be detached in order to reduce it to a powder, when this is
done moisten it with the gum solution, and stir the whole with a
small hair brush, or your finger, then leave it for a night that
the gold may be better dissolved. If the composition becomes dry
during the night, dilute it with more gum water in which a little
saffron has been infused, but take care that the gold solution be
sufficiently liquid to flow freely in a pen; when the writing is
dry polish it with a dry tooth.


46. WHITE INK FOR WRITING ON BLACK PAPER

Having carefully washed some egg shells remove the internal skin and
grind them on a piece of porphyry, then put the powder in a small
vessel of pure water, and when it has settled at the bottom, draw
off the water and dry the powder in the sun. This powder must be
preserved in a bottle; when you want to use it put a small quantity
of gum ammoniac into distilled vinegar, and leave it to dissolve
during the night, next morning the solution will appear exceedingly
white, and if you then strain it through a piece of linen cloth, and
add to it the powder of egg shells in sufficient quantity, you will
obtain a very white ink.


47. SECRET INK FOR YOUNG LADIES AND GENTS

Take a drachm of clean rain water, put into it, in a clean vial, 10
or 12 drops of pure, clean sulphuric acid, and it is ready for use;
write with this using a clean quill pen on letter paper, and when