DUFAY'S EXPERIMENTS. 481 



of his own suggestion, but because Gray had said that 

 among electrified bodies physically alike, those which are 

 red, orange, or yellow, attract very much more strongly 

 than those which are blue, green or purple. Dufay saw 

 in this not merely a possible cause of error in his future 

 researches, but a suggestion that there might be a relation 

 between electricity and light, if the former had a capacity 

 for color selection. For both reasons, he proceeds. 



His initial experiments seem to confirm Gray decisively. 

 Of nine suspended ribbons (black, white and the rainbow 

 colors), the rubbed glass tube attracts the black first and 

 the red last. White gauze and black gauze intercept the 

 electric virtue, while gauzes of the rainbow hues, the red 

 especially, allow it to pass. Dufay presses on to the 

 broader question, fully believing that he is on the track of 

 a startling discovery. 



If color alone exercises the effect, it can make no differ- 

 ence, he argues, whether the hue be natural or artificial: 

 whether it appear on the rose-leaf or on a painting. So 

 he tries the flowers and the signs fail. The scarlet gera- 

 nium responds to the attracting glass as readily as does the 

 purple pansy the green leaves as quickly as the white 

 petals of the lily. Perhaps there is something in the inher- 

 ent quality of these vegetable substances which interferes. 

 Clearly the crucial test requires pure color, and that is only 

 in the rainbow. 



He directs a sunbeam through a prism, and spreads it 

 out into its gorgeous spectrum, and distributes therein 

 white ribbons, so that the sun paints one red, another 

 orange, another yellow, and so on through nature's color 

 box. But the ribbons act like the flowers. No one of 

 them responds to the electric pull any more than does an- 

 other. The notion that electric attraction could tear the 

 sunbeam to pieces, and change it from white to red by 

 drawing out the blue rays, was only a delusion. 



Then Dufay went back to his colored ribbons and wet 

 them and their differences vanished. He heated his 



