Tesla’s experiments with his Tesla coil coincided with a time when physicians were exploring the use of electrical devices to treat various ailments. In fact, Tesla went as far as publishing a paper on “High Frequency Oscillators for Electro-Therapeutic and Other Purposes” that showed his coil treatment was beneficial for human tissues.

But it didn’t stop there. Tesla’s disruptive coil design was soon co-opted by many manufacturers who used it as a power source for glass electrodes containing noble gases. This resulted in the popular “violet ray device,” which gained its name due to the brilliant purple glow that emanated from the argon gas vacuum tubes wired in series to these coils.

These glass tubes were constructed under low vacuum and filled with different noble gases that became excited by the electrical output, causing them to glow in different colors depending on the gas used. Neon gas, for example, glowed red.

What’s more interesting, these electrified noble gases, when pulsed, could be ionized or excited, causing electrons to move from lower energy states to higher ones. When the electrons cycled back to the lower state, they emitted light and photons, including spectral emissions within the ultraviolet (UV) and infrared (IR) ranges.

Many people believed that these devices could improve or even cure a wide variety of conditions and illnesses.