This advertising flyer is promoting J. C. Boyd's Miniature Galvanic Battery, which supposedly worked by "galvanic action" due to the "union of metals." Whereas in a common battery the effect is facilitated by an acid, Boyd's device needed only "the natural humidity of the skin" to cause a beneficial flow of electricity. This was sufficient to cure nearly any disease by producing a "proper proportion of electricity" in the blood - or so "Professor" Boyd claimed. The device sold for fifty cents and sparked (so to speak) a number of testimonials from customers.
J. C. Boyd
Digital image copyright 2014 Images in this collection are not to be used for any commercial purposes without the expressed written permission of the Center for Inquiry and Dr. Joe Nickell. Patrons of this digital museum are free to utilize materials from the museum for non-commercial and educational purposes.