La Boite Verte's post Des illustrations de manuscrits d’alchimie has a good collection of Alchemist illustrations. These images, and those after the jump, are a sample of some of those images. Their esoteric nature makes them fascinating, with a hint of magic and the dark arts about them.
La Boite Verte is in French, but it is easy to find the links to their sources, which are in English. Also, there are many more -- and larger -- images at La Boite Verte.