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

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That which has become rusty by itself, having been doused with water, salt, and either vinegar or urine, and then well—dried and reddened by heating, is deep red when crushed on porphyry and is of the color of bol de levant, almost like minium. But that which is doused with urine and dried acquires a deeper color and almost like crushed aes ustum or like vermillion. But the first one, finely crushed, acquires a bright red color like cinnabar when placed in spirits. And the one and the other, when prepared as said above, finely ground and made very hot, produce a red smoke like an acid vapor if, being thus hot and fine, one throws vinegar, urine or spirits on top. The urine makes a lot of color and the spirits as well.

Figure Figure