An 18th-century investigation into mesmerism shows us how to think about 21st-century therapeutic magnets

In an uncritical August 11, 1997, World News Tonight report on “biomagnetic therapy,” a physical therapist explained that “magnets are another form of electric energy that we now think has a powerful effect on bodies.” A fellow selling $89 magnets proclaimed: “All humans are magnetic. Every cell has a positive and negative side to it.”

On the positive side, these magnets are so weak that they cause no harm. On the negative side, these magnets do have the remarkable power of attracting the pocketbooks of gullible Americans to the tune of about $300 million a year. They range in scale from coin-size patches to king-size mattresses, and their curative powers are said to be nearly limitless, based on the premise that magnetic fields increase blood circulation and enrich oxygen supplies because of the iron present in the blood.

This is fantastic flapdoodle and a financial flimflam. Iron atoms in a magnet are crammed together in a solid state about one atom apart from one another. In your blood only four iron atoms are allocated to each hemoglobin molecule, and they are separated by distances too great to form a magnet. This is easily tested by pricking your finger and placing a drop of your blood next to a magnet.

What about claims that magnets attenuate pain? In a 1997 Baylor College of Medicine double-blind study of 50 patients (in which 29 got real magnets and 21 got sham ones), 76 percent in the experimental group but just 19 percent in the control group reported a reduction in pain. Unfortunately, this study included only one 45-minute treatment, did not try other pain reduction modalities, did not record the length of the pain reduction and has never been replicated.

Scientists studying magnetic therapy would do well to read the 1784 “Report of the Commissioners Charged by the King to Examine Animal Magnetism” (reprinted in an English translation in Skeptic, Vol. 4, No. 3). The report was instituted by French king Louis XVI and conducted by Benjamin Franklin and Antoine Lavoisier to experimentally test the claims of German physician Franz Anton Mesmer, discoverer of “animal magnetism.” Mesmer reasoned that just as an invisible force of magnetism draws iron shavings to a lodestone, so does an invisible force of animal magnetism flow through living beings.

The experimenters began by trying to magnetize themselves, to no effect. To test the null hypothesis that magnetism was all in the mind, Franklin and Lavoisier deceived some subjects into thinking that they were receiving the experimental treatment with animal magnetism when they really were not, while others did receive the treatment and were told that they had not. The results were clear: the effects were from the power of suggestion alone.

In another experiment (there were 16 altogether), Franklin had Mesmer’s representative, Charles d’Eslon, magnetize a tree in his garden: “When a tree has been touched following principles & methods of magnetism, anyone who stops beside it ought to feel the effect of this agent to some degree; there are some who even lose consciousness or feel convulsions.” The subject walked around the garden hugging trees until he collapsed in a fit in front of the fourth tree; it was the fifth one that was “magnetized.”

One woman could sense “magnetized” water. Lavoisier filled several cups with water, only one of which was supposedly magnetized. After touching an unmagnetized cup she “fell completely into a crisis,” upon which Lavoisier gave her the “magnetized” one, which “she drank quietly and said she felt relieved.”

The commission concluded that “nothing proves the existence of Animal-magnetism fluid; that this fluid with no existence is therefore without utility; that the violent effects observed at the group treatment belong to touching, to the imagination set in action & to this involuntary imitation that brings us in spite of ourselves to repeat that which strikes our senses.” In other words, the effect is mental, not magnetic.

Modern skeptics should take a lesson from this historical masterpiece, which employed the control of intervening variables and the testing of specific claims, without resorting to unnecessary hypothesizing about what was behind the “power.”

A sad fact is that true believers remain unaffected by contradictory evidence, today as well as in the 18th century.