THE PHENOMENA OF ELECTROSTATICS. 241 



that is to say, the velocity of the particles is equal to the ratio 

 of the electric field intensity e in abvolts per centimeter to the 

 magnetic field intensity h in gausses, on the condition that the 

 combined action of the fields produces no deflection of the mov- 

 ing particles. 



"Electrochemical equivalent" of a- and /3- particles. Ac- 

 cording to the dissociation theory of electrolysis each atom of 

 hydrogen, for example, in a dilute solution of sulphuric acid is 

 isolated and carries a definite amount of charge, and the ratio 

 (mjq) of the mass m of a hydrogen atom (ion) to the charge 

 q upon it is equal to the electrochemical equivalent of hydrogen, 

 or, in other words, to the number of grams of hydrogen which 

 are liberated during the passage of one coulomb of electric charge 

 through an electrolytic cell containing dilute sulphuric acid. The 

 ratio (m/<?) of the mass of a gas ion to the charge upon the ion 

 is called the "electrochemical equivalent" of the gas ion. This 

 ratio is determined by equation (iii) or (iv) when the electric or 

 magnetic deflection of the particle has been observed and when 

 the velocity of the particle is known. The value so determined 

 is given in grams per abcoulomb and it is equal to 5.36 x IO"" 8 

 grams per abcoulomb for the /3-particles (electrons), from which 

 it follows that the particles have a mass ^-^ as great as the mass 

 of a hydrogen atom if the charge q is the same in both cases.* 



* In regard to the equality of charge on mono-valent ions in electrolytes and on gas 

 ions, see Oliver Lodge's Electrons, pages 77~9> where a simple account is given of 

 the work which has been done by J. J. Thomson in the determination of the value of 

 q (or m). 



