Fig. 280. Plan of the apparatus for showing the circular polarization of oil of turpentine.
This image is from 2. Oleum Terebinthinae, E. D.—Oil of Turpentine in Pereira's Elements of Materia Medica and Therapeutics, 1854.
A herbal distance course
Henriette's herbal is one of the oldest and largest herbal medicine sites on the net. It's been online since 1995, and is run by Henriette Kress, a herbalist in Helsinki, Finland.