Powder gall nuts and let this stand 8 days in the white wine; and in
the same way dissolve vitriol in water, and let the water stand and
settle very clear, and the wine likewise, each by itself, and strain
them well; and when you dilute the white wine with the water the
wine will become red.
647.
Put marcasite into aqua fortis and if it turns green, know that it
has copper in it. Take it out with saltpetre and soft soap.
648.
A white horse may have the spots removed with the Spanish haematite
or with aqua fortis or with ... Removes the black hair on a white
horse with the singeing iron. Force him to the ground.
649.