Quotation from: The Notebooks of Leonardo Da Vinci

Written by: Leonardo da Vinci

TO COMBINE LEAD WITH OTHER METAL.

If you wish for economy in combining lead with the metal in order to
lessen the amount of tin which is necessary in the metal, first
alloy the lead with the tin and then add the molten copper.

How TO MELT [METAL] IN A FURNACE.

The furnace should be between four well founded pillars.