506 



TABLE 516.— VERDET'S CONSTANT FOR SOME GASES 



Du Bois shows that in the case of substances like iron, nickel, and cobalt which have a 

 variable magnetic susceptibility the expression in Verdet's equation, which is constant for 

 substances of constant susceptibility, requires to be divided by the susceptibility to obtain 

 a constant. For this expression he proposes the name "Kundt's constant." These experi- 

 ments of Kundt and Du Bois show that it is not the difference of magnetic potential be- 

 tween the two ends of the medium, but the product of the length of the medium and the 

 induction per unit area, which controls the amount of rotation of the beam. 



Some data on the Verdet constant of gases by Ingersol (*) and by de Mallemann (t) 

 for wavelength 5780A, pressure 760 mmHg, and at temperature 0°C: 



Verdet Verdet Verdet 



constant constant constant 



in min Substance in min Substance in min 



6.29 X 10-* Helium* 51 X 10"° Methane t 17.4X10" 



6.26 Oxygen* 5.55 Ethylene t .... 34.4 



6.21 Oxygen t 5.69 Ethylene* .... 34.6 



6.30 Argon t 9.36 Carbon dioxide * 9.25 



Substance 

 Hydrogen t 

 Hydrogen * 

 Deuterium * 

 Nitrogen * , 



The de Mallemann values are from numerous papers in Comptes Rendus, 1929 to date 

 (See in particular R. de Mallemann, F. Suhner, and J. Grange, C. R., vol. 232, p. 1094, 

 1915. See also P. Gabiano Ann. d. Physique, vol. 10, p. 68, 1933.). The Ingersoll values 

 are from an ONR preliminary report (October 1952). The probable error of the de Malle- 

 mann and the Ingersoll values is of the order of 1 percent. The dispersion of the rotation 

 for most gases, except oxygen, is roughly as the inverse square of the wavelength. 



Substance Pressure 



Atmospheric air Atmospheric 



Carbon dioxide 



Carbon disulfide 74 cmHg 



Ethylene Atmospheric 



Nitrogen " 



Nitrous oxide " 



Oxygen 



Sulfur dioxide 



246 cmHg 



Temp. 

 Ordinary 



70° C 

 Ordinary 



20° C 



Verdet's 

 constant 

 in min 



6.83 X 10- 



13.00 " 



23.49 " 



34.48 " 



6.92 



16.90 " 



6.28 " 



31.39 " 



38.40 " 



TABLE 517.— VERDET'S AND KUNDT'S CONSTANTS FOR SOME MATERIALS 



The following short table is quoted from Du Bois's paper. The quantities are stated in 

 cgs measure, circular measure (radians) being used in the expression of "Verdet's con- 

 stant" and "Kundt's constant." 



Magnetic 



Name of substance susceptibility 



Cobalt — 



Nickel — 



Iron — 



Oxygen: 1 atm +.0126 X 10" 



Sulfur dioxide — .0751 " 



Water —.0694 



Nitric acid —.0633 



Alcohol —.0566 



Ether —.0541 



Arsenic chloride —.0876 " 



Carbon disulfide — .0716 " 



Faraday's glass —.0982 " 



Verdet's constant 



Number 



.000179 X 10- 5 



.302 



.377 



.356 



.330 



.315 

 1.222 

 1.222 

 1.738 



SMITHSONIAN PHYSICAL TABLES 



