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

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To whiten enilanroc

Some believe the ceruse—color crust that is on top to be natural. Others say that it is a lost secret of ancient lapidaries. Others say that it is enamel that has been reheated. And, from this crust, one can form multiple ciphers, letters, circles and other bizarre motifs. As to the means, I proceeded thus: I once wanted to add a layer of arsenic ground on marble. However, I did the experiment without it, and I put the above mentioned thing, enilanroc, in a small iron casket on the fire of my goldsmith’s forge with three or four small half—burnt coals and blew on it only with my mouth. However, the thing caught fire and became all white, not only on its surface but also inside. And then I let it cool on its own near the fire, since otherwise, exposing it suddenly to cold air, it would have cracked. While it was all white, I passed it through my lead wheel and I found it to be as hard as it was before. And after scraping off a little of the white, I found it to be of a clear fleshy tone. Finally, I polished it and observed that it took quite a beautiful polish luster and that it could compare with a quite beautiful agate for the purpose of engraving it with some beautiful face and applying it to a table of

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agate of various colors. But because this overall whiteness did not correspond with the white crust on the surface that I was seeking, leaving the rest of the thing its natural color, I made a hole in a brick, precisely the same size as the object, and put it inside. Then I heated two glassmaker’s soldering irons until they became red hot and, when they were red hot, I applied them one after the other onto the surface of the object until I got the white crust I was looking for, on which I made the drawing that I wanted, revealing the red background, with a diamond point, and I polished it with hog bristles and tripoli. I don’t know if it would be better to reheat it under hot ashes, and if it would be good to encase it in alabaster, which is quite cold, as I did in the brick.