The alchemists of the fifteenth century were firmly convinced that the Golden Fleece was a treatise on the transmutation of metals, written on sheepskin.

Some of the alchemists in their writings seem disposed to attribute the ill success of their efforts at transmutation to the presence of some taint of these pieces in the silver upon which they were experimenting.

The Dutch physician, Van Helmont, lived in the latter part of the sixteenth and the beginning of the seventeenth centuryin the transition period between alchemy and chemistryand was rather more alchemist than chemist.