THEORY. 191 



The reason why I suppose a magnetic vibration 

 may be induced as well as a chemical or electric 

 motion, is obvious, since Morichini and Mrs. M. 

 Somerville have shown, by direct experiment, that 

 magnetism is induced in steel by exposure to the 

 most refrangible of the solar rays, precisely those 

 which induce phosphorescence. * Moreover, light 

 is engendered by magnetism in a curious experi- 

 ment made by Grove in 1845. A tube, filled with 

 the liquid in which magnetic oxide of iron has been 

 prepared, and terminated at each end by plates of 

 glass, is surrounded by a coil of coated wire. 

 " To a spectator, looking through this tube, a 

 flash of light is perceptible whenever the coil is 

 electrized ; and less light is transmitted when the 

 electrical current ceases, showing a symmetrical 

 arrangement of the minute particles of magnetic 

 oxide while under the magnetic influence/' (Cor- 

 relat. of Phys. Forces, p. 158.) Some remarkable 

 results were likewise arrived at by Sir W. Snow 

 Harris, as early as 1834, by vibrating magnets 

 in the sun, and published in the ' Edinburgh 

 Philosophical Transactions' for that year. 



A similar conception would apply to phospho- 

 rescence produced by heat, chemical action, elec- 

 tricity, etc. 



* These are also the rays which cause chlorine to combine 

 with, hydrogen, and which decompose many chemical com- 

 pounds. 



