﻿i 9 i6] BOVIE- SCHUMANN RAYS 3 



important features of the public baths of the Greeks and the 

 Romans. 



In the beginning of the nineteenth century Vallet (33) reported 

 a complete cure of a case of dropsy by exposing the patient to sun- 

 light one hour each day for 14 days, and Lobel (24) cured a case 

 of amaurosis by focusing sunlight upon the diseased eye. Lobel 

 thought that the beneficial effects of the exposure were due, not 

 only to the physical action of the heat and the light, but also to the 

 chemical action of the sunlight. 



In 1858 Charcot (9) reported the experiences of two chemists 

 who were using an electric arc for vitrifying certain materials. The 

 electric current was obtained from a Bunsen pile of 20 elements. 

 The experiment lasted one and one-half hours. The experimenters 

 were 50 cm. from the arc, and experienced no change in temperature, 

 but their eyes pained them so severely the following evening and 

 night that they were unable to sleep. The next day they had a 

 painful erythema of the skin. Charcot cites other cases of electric 

 light burn caused by an arc from a battery of 600 Bunsen elements. 

 He concluded that the erythema was due to the chemical action of 

 the light, and not due to the heat. 



The first impetus to a critical study of the destructive action of 

 light came when the germ theory of disease had been thoroughly 

 established and scientists had recognized the importance of dis- 

 covering efficient methods of disinfection. In 1877 Downes and 

 Blunt (io) reported the results of their experiments on the effect 

 of light upon bacteria and other organisms. They undertook an 

 investigation to determine whether or not light has a deleterious 

 effect upon bacteria. They exposed culture media contained in 

 glass tubes to sunlight. They showed that light is inimical to and, 

 under certain conditions, may wholly prevent the development of 

 organisms which are prone to appear in culture media. The action 

 is more energetic upon bacteria than upon mycelial fungi. The 

 fitness of the substratum for growing bacteria is not impaired by 

 insolation. By using colored screens they showed that the blue end 

 of the spectrum is more active than the red end. In a second 

 paper (11) they showed that light will kill organisms which are in 

 distilled water, and organisms which are air-dried. They tried to 



