High-frequency ('violet ray') apparatus, cased, by Uvral, England.

Powered by mains electricity supply, this set was used to apply high frequency electrical sparks to the body using the glass vacuum electrodes. Known as violet ray treatment, the purple, red, or blue electric sparks were believed to relieve aches and pains in the muscles, internal organs and the nerves (rheumatism) by massaging the surface of the skin with the electrode. The glass comb shaped electrode was used to stimulate hair growth on the scalp as a cure for baldness. The circular shaped electrode was used to massage the surface of the skin where there was a pain, such as the throat or ankle. It could also be used for other medical complaints.

This was a highly popular home treatment in the first half of the twentieth century and violet ray sets regularly turn up in the attics of elderly people. Although the electrodes certainly produced a tingling sensation on the skin, these sets were of dubious medical worth. This set was made by a company called Urval.