"Could that photograph of Lincoln be showing the effects of Mercury poisoning?"
I would have to agree with that statement. It could be. I am going to have to dig back sometime to give you the site to support what I am saying. I know it was a "Cure all" in those days, but this particular Doctor did not believe it to be and strongly suggested to Mr. Lincoln that the continued use only made his depression and temper worse. As I recall he stopped using it about six months into his first term and his mood did indeed improve. More on this later when I dig it up.
Frank