Quotation from: The Notebooks of Leonardo Da Vinci
Written by: Leonardo da Vinci
646.
TO DILUTE WHITE WINE AND MAKE IT PURPLE.
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.