William H. Mumler
n.d.
Mary Todd Lincoln with the spirit of Abraham Lincoln

Carte de visite, type of photograph unclear
College of Psychic Studies
Accessed from the Internet.
 
I'm indebted to Beverly Wilgus for locating this example (Facebook, "Victorian images" group, 4 October 2015)
 
This portrait has an unusually high contrast and this may have been done when Hudson copied the Mumler photograph. Clarification on the format is requested.
 
LL/61607