Recipe for aqua fortis and for casting a copper figure
A chemical recipe, with a square gridded into 49 small squares above
Below a small square ruled into a seven-by-seven grid of forty-nine squares, a pen note gives a recipe for aqua fortis compounded from Roman vitriol, saltpetre, cinnabar and verdigris, then a method for dissolving copper. The copper is evaporated to a paste, daubed onto a figure, cleaned with a brush and dried, then fired between two 'earths' so the metal fuses, or else amalgamated with quicksilver. The passage is a practical metal-working and casting memorandum. Mirror-script writing fills the top and bottom of the leaf.
On this page
Square divided into 49 small squares
At the centre of the leaf a square is ruled into a seven-by-seven grid of forty-nine small squares, the kind of proportional grid used for scaling or subdividing a figure. The caption pairs it with a circle.
Aqua fortis and dissolving copper
The recipe compounds aqua fortis from parts of Roman vitriol, saltpetre, cinnabar and verdigris, and uses it to dissolve copper. The dissolved metal is then evaporated until it thickens like paste and mustard.
Fixing the copper onto a figure
The copper paste is daubed onto the figure, brushed clean and dried, then buried with vent-holes and given a great fire so that the copper unites between the two earths of the mould. Alternatively the copper is kneaded together with quicksilver.