According to Wikipedia, "A Tesla coil is a type of resonant transformer circuit invented by Nikola Tesla around 1891. It is used to produce high voltage, relatively high current, and high frequency alternating current electricity. Tesla experimented with a number of different configurations and they consist of two, or sometimes three, coupled resonant electric circuits. Tesla used these coils to conduct innovative experiments in electrical lighting, phosphorescence, x-ray generation, high frequency alternating current phenomena, electrotherapy, and the transmission of electrical energy without wires.... Tesla coil circuits were used commercially in sparkgap radio transmitters for wireless telegraphy until the 1920s, and in electrotherapy and pseudo medical devices such as violet ray." It is with these last two usages that we are going to concern ourselves.
Electrotherapy is any kind of medical therapy that used electrical or electromagnetic currents to treat various medical conditions. These conditions range from pain management to the treatment of neuromuscular dysfunction, improving the range of joint mobility, tissue repair, acute and chronic edema, peripheral blood flow, delivery of pharmacological agents, and urine and fecal incontinence. Studies to show the efficacy of these treatments are inconclusive at best with most reports of effectiveness being anecdotal. 
The Violet Ray machines came on the market in the early part of the 20th century and, like their cousins the notorious patent medicines, were promoted to cure virtually every manner of illness. These kits were sold to both home consumers and doctors. The main differences between the two types of kits being the number and types of attachments and probes that came with them.
According to The Museum of Quackery, "Tens of thousands of these devices were sold for home use between about 1915 and 1950 under brand names such as Masters, Elco and Renulife."  By the end of the 19th century, while the properties of electricity and electromagnetism had been theorized and in some cases proven, by the likes of Benjamin Franklin, James Clerk Maxwell, and Michael Faraday, their practical applications were new and novel and largely unproven. While Tesla himself advised physicians to experiment with the heating effects of radio waves, it fell to well meaning physicians, in the best cases, to the common charlatan, more often than not, to practice and promote the new field of electrotherapy.
The earliest record of the use of electrotherapy was in 1855 by Guillaume Duchenne, considered the developer of electrotherapy. His research was aimed at treating various muscular conditions. In the 1940's, the U.S. War Department studied the use of electrotherapy to retard and prevent muscular atrophy as well as to restore muscle mass and strength. 
The violet ray machines were touted as a cure for a variety of ills including poor circulation, nervous disorders, arthritis and rheumatism, hair and skin disorders, problems with digestion and elimination, female reproductive disorders, prostate disease, cataracts-even possession and schizophrenia, by none other than Edgar Cacey. It seemed that there was no disorder, no ill, that the violet ray machine couldn't cure. In fact, the literature that came with these devices often listed over 200 aliments that the device could supposedly treat.
The idea that these violet or ultra-violet rays could heal was not limited to the area of quack medicine. In a 1928 lecture delivered to the British Medical Association, E. Cumberbatch stated the following: "There is another important chemical change which the rays bring about. This is what is known as the " activation of cholesterol". This substance is present in all growing tissues and it plays an important part in metabolism. It cannot perform its function unless it is rendered active. Ultra-violet rays possess this activating power. In this way the curative action of the rays in rickets is explained." 
We now know that rickets is best treated by calcium, phosphorus or vitamin D.
In 1951, a libel suit was filed against the Master Electrical Company (nearly the last manufacturer of violet wand medical devices left in existence) for misbranding its devices as medical cures for various diseases. The court ordered that the devices be turned over to the Food and Drug Administration as contraband. 
The judgment read, in part:
NATURE OF CHARGE: Misbranding, Section 502 (a), certain statements in the circulars were false and misleading. The statements represented and suggested that the device would produce pleasing, invigorating, and corrective effects; that it would be effective as a general treatment by stimulating the circulation; that it would be effective for beauty, health, and strength; that it would be efficacious in the treatment of rheumatic pain in the shoulder, nervous disorders, rheumatism, lumbago, and neuritis; that it would produce a sedative or quieting effect and establish a normal equilibrium of the nervous system; that it would relieve painful sensations' that it would be efficacious for treatment of the eyes and ears; that it would be efficacious in the treatment of cystitis, strictures, gonorrhea, and prostate and vaginal troubles; that it would promote circulation; that it would aid beauty and health by gently stimulating the flow of blood; that it would be helpful in relieving pain and congestion and in restoring food health and vigor; that it would be helpful in removing facial blemishes and in promoting a clear, healthful complexion; and that it would aid in the removal of dandruff and assist in stopping falling hair. The device was not an effective treatment for the conditions stated and implied, and it was not capable of producing the effects claimed.
DISPOSITION: April 24, 1951. Default decree of condemnation. The court ordered that the devices be released to the Food and Drug Administration. (American Medical Association's Historical Health Fraud & Alternative Medicine Collection,
Even though these devices have been banned for use in medical treatment, as late as 2009 during the H1N1 flu pandemic scare, the unscrupulous were taking advantage of the fear to peddle a new product similar to the Violet Wand in Canada:
"H1N1 Destroying UV (ultra violet) Wand, which manufacturers said, "eliminates the H1N1 virus from surfaces using safe UV-C light."
An advertisement for the wand says it uses "the same technology trusted to sanitize hospital surfaces." If so, it's news to the University Health Network in Toronto, Ontario. A spokeswoman says none of the network's facilities (Toronto General, Toronto Western and Princess Margaret), nor the Toronto Medical Laboratories use UV light to sterilize surfaces." 
The manufacturer also makes the following claims for their device:
*Kills resistant Staphylococcus aureus
*Kills mold and dust mites
*Destroys the DNA of viruses and microbes effectively sterilizing them and keeping them from reproducing
This is a very familiar pattern of untested, unproven claims that have been made for quack products throughout our modern history and which, sadly, still flourish. While the devices mentioned about are not actual violet ray machines, they are similar in that they use a similar technology to promote unsubstantiated claims.
The real flourishing of the alt-med uses of the Violet Ray are on the Internet. In the course of researching this article, I discovered so many sites making so many different claims that it would be impossible to give even a partial list here without overwhelming the reader with a plethora of quackery. However, I have chosen one site to use as an example of the kind of magical thinking that is common to them all. The site is Beautiful On Raw. Here they describe how they believe the Violet Ray machine can enhance your health:
"You'll find that the current produces an agreeable tingling on your skin's surface as it increases oxygenation in the form of Ozone (O3) in the blood.O3 ozone is so reactive chemically that it constantly wants to become stable O2 oxygen by giving up O1. Chemists know this reactive form of oxygen as "singlet oxygen". These singlet oxygen molecules are created in a gush of O1 releases. These O1s are negatively charged. They are hungry to catch something positively charged. Toxins and pathological bacteria are all positively charged. Because of the active oxygen's negative charge, it combines with the filth in the body, oxidizing it, then to be flushed out in the bloodstream.
All the wastes the body excretes - whether through urination, bowel movements, sweating, spitting, skin particles that are sloughed off the body's outer surface - are composed mainly of four basic elements - hydrogen, carbon, nitrogen and sulfur. If combined with oxygen, natural oxidation processes will turn these into H2O, CO2, NO2 and SO2. These are, respectively, just the chemical names for water, gaseous carbon dioxide, the toxic gas nitrogen dioxide, and the acidic gas sulphur dioxide. In this way additional toxins leave the body. Applying the Violet Ray stimulates this vital "detoxification" process."
They mention that pathological bacteria is positively charged when in fact, studies going back over a century show that, "Bechhold (1904) was the first to record the fact that bacterial cells carry a negative charge. Cernovodeanu and Henri (1906) studied a larger series of bacteria and reported that all species, except B. dysenteriae (Flexner), carried a negative charge." 
They are also the usual alt-med buzz words such as "vital" and "detoxification" that so many practitioners of woo constantly use. The idea that our bodies need to be detoxified has been proven wrong by study after study, so just on that alone the whole premise of their argument for the use of ozone is suspect. The fact that the vast majority of bacteria have negative charges, not positive ones only seals the deal. Also, while oxidization can, in fact, help kill cells, oxidization is caused as the result of chemical reactions caused by other compounds like those found in chlorine bleach, not by direct application of ozone molecules.
These days, the violet ray machine has been replaced by Violet Wand machines, which are more specialized toward their use in sex play. The web site, voletwand.org, explains how to use these products for sexual stimulation:
"...the wand only creates sensation when there is a gap between the wand attachment and the body. Plugging any of the attachments into the violet wand nozzle and grasping them firmly will result in no sensation. The second thing to remember is the bigger the surface area of the attachment, the less the sensation is felt since it is spread over a wider area. With these two principles in mind, a good attachment to start with is the large globe. Its big size makes it the softest item in the violet wand kit. Start with the violet wand turned down to very low intensity and bring the globe into direct contact with the skin. No sensation will be felt. Slowly move the globe away from the body. You will notice as the distance increases, the sensation felt increases as well, until the distance becomes too far and the arc is broken. The large globe is a great warm up item since almost anyone can take it.”
There are other sites as well as groups on sites such as yahoo.com dedicated to using these devices in sexual play. Using this device is a way to direct and control that tingly sensation that you sometimes get from static electricity to various erogenous zones on the body, such as the nipples or genitals. By increasing the voltage you can increase the sensation from a tingle to sharper spikes that can become painful, which, obviously, some people enjoy.
The Violet Ray Machine is one more alt-med treatment that has been proven to be worthless. Unfortunately, even though it has been banned by the FDA, that hasn't stopped the practitioners of woo from championing its supposed virtues. While these devices cannot be sold as medical treatment devices, there is nothing to stop them from being sold as antiques. You can find dozens of these machines available to purchase on sites like ebay.com at any given time.
In fact, Beautiful On Raw, which we saw earlier, touts the supposed health benefits of the Violet Ray machine, actually sells one on its site, but cleverly uses the following disclaimer to protect its self from legal problems:
"Even though in the past physicians used this device for every imaginable health problem, today the FDA approved its use only for various skin and scalp conditions, such as reducing wrinkles, eliminating acne, fighting gray hair, eradicating dandruff, and treating baldness. The Violet Ray is a holistic device that will complement your healthy lifestyle and will provide invaluable assistance in revealing your Rawsome beauty.".
Jay Walker currently works in the IT field but is pursuing a career as a skeptical writer. He has been published in AIM Magazine and various local newspapers. He is also the author of the Freethinking For Dummies blog at http://freethinkingfordummies.
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 The Violet Wand, Museum of Quakery, 11 2010.
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 E. Cumberbatch. Observations on ultra-violet ray therapy, 1928.
 S.E. Gardner, R.A. Frantz, and F.L. Schmidt. effect of electrical stimulation on chronic wound healing:a meta-analysis. Wound Repair and Regeneration, 7(6):495–503, 1999.
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