Guglielmo Gratarolo

Guglielmo Gratarolo or Grataroli or Guilelmus Gratarolus (16 May 1516, Bergamo – 16 April 1568, Basel) was an Italian doctor and alchemist.

A Calvinist, Gratarolo sought refuge in Graubünden, Strasbourg, and finally settled in Basel in 1552.

There, he taught medicine and edited a number works, particularly alchemical ones, notable among them the 1561 collection Verae alchemiae artisque metallicae published by the printer Henricus Petrus, and reprinted in 1572.

Verae alchemiae artisque metallica relied heavily on the earlier printed alchemical collection De Alchemia and was in turn heavily relied upon for the Theatrum Chemicum.

Gratorolo omitted only the Tabula Smaragdina and Ortulanus' commentary on it from volume 1; these had been published separately a year earlier in 1560, although falsely attributed to Johannes de Garlandia.