SCIENTIFIC WRITINGS. 407 



heat are only distinguished from one another by the 

 greater number of vibrations of the former, and be- 

 cause the radiating power in general seems to decrease 

 with the number of vibrations. At any rate the power 

 of radiating light appertaining to dust-free pure gases 

 is so exceedingly small, that the luminosity of flame 

 must be specifically different from the luminosity of 

 the gases heated by the process of combustion. Apart 

 from the luminosity of the solid particles separated by 

 combustion or suspended as impurities in the gas, the 

 luminosity of flame can only be an electrical process, 

 which is connected with the chemically shifted position 

 of the molecules of the burnt gases. The light of flame 

 would according to that be just as much electric light 

 as the light of the ozone tube or of the Geissler tube. 

 The interesting controversy, in which my deceased 

 brother William became involved with the astronomers 

 through his work "On the conservation of the solar 

 energy"', led me also to the sun and occasioned my 

 paper "On the admissibility of the assumption of an 

 electrical solar potential and its importance for the ex- 

 planation of terrestrial phenomena". As the known 

 ways of producing electrical phenomena always depend 

 on a separation of positive and negative electricity, we 

 must assume that this holds good for the sun also, that 

 therefore an electrical solar potential can only exist, if 

 the one electricity is carried away from the sun. The 

 theory set up by my brother, that solar matter is 

 flung off and diffused in the universe in consequence of 

 the sun's rotation, makes therefore the supposition of a 



