1891.] 



On Electrical Evaporation. 



101 



from the liquid to the gaseous state will differ widely in each 

 case. 



It was interesting to try a parallel experiment with metals, to find 

 their comparative volatility under the same conditions of temperature, 

 pressure, and electrical influence. It was necessary to fix upon one 

 metal as a standard of comparison, and for this purpose I selected 

 gold, its electrical volatility being great, and it being easy to prepare 

 in a pure state. 



Fia. 12. 



TO MOTOR 



An apparatus was made as in fig. 12. It is practically a vacuum 

 tube with four negative poles at one end and one positive pole at the 

 other. By a revolving commutator I was able to make electrical 

 connection with each of the four negative poles in succession for 

 exactly the same length of time (about six seconds) ; by this means 



