Johann Friedrich Schweitzer (1625-1709), known as Helvetius, was a Dutch-German physician. In 1667, he published The Golden Calf,
whose strapline was How the intire Substance of Lead, was in one Moment Transmuted in Gold-Obrizon, with an exceeding small particle of the true Philosophick Stone
. The whole book is available online
Helvetius was most famous as one of the few alchemists who supposedly achieved the transmutation of lead into gold in front of witnesses.