Making and Knowing
A minimal edition of BnF Ms Fr 640 in English Translation

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Sand from pulverised rock salt and sand from a minium finely ground on marble

After they have been dryly ground and beaten in the mortar, they are ground finely on the marble. I mixed the same quantity of each material, and in order to mix them better, I ground them on the porphyry again, and then filtered this through a double sieve or the sleeve of a shirt. Then, I put them on sheets of paper and stored it on marble in a cellar. In one night, they were both moist enough [that there there was no need] to dampen them further because rock salt, like all other salts, dissolves in dampness. I molded with this very neatly because both should be quite fine. They need to be moist enough so it can be removed easily.