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

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For casting

Chalk most recently drawn from the quarry is good for lead. But do not wet nor crush it, make it fine only by grinding or grating it and passing it through a sieve. The same applies to pumice, which one must not crush with water nor corrupt its nature. Lead must be mixed with little tin, just to give it some strength, and two parts of lead for one of tin or more.