372 



TABLES 45^-462. 



MAGNETISM AND TEMPERATURE. 

 TABLE 459. Magnetism and Temperature, Critical Temperature. 



The magnetic moment of a magnet diminishes with increasing temperature. Different specimens vary widely. 

 In the formula Mt/Mo = (i at) the value of a may range from .0003 to .001 (see Tables 457-458). The effect on the 

 permeability with weak fields may at first be an increase. There is a critical temperature (Curie point) above which 

 the permeability is very small (paramagnetic?). Diamagnetk susceptibility does not change with the temperature. 

 Paramagnetic susceptibility decreases with increase in temperature. This and the succeeding two tables are taken 

 from Dushman. " Theories of Magnetism," General Electric Review, 1916. 



References: (i) P. Curie; (2) see Williams, Electron Theory of Magnetism, quoted from Weiss; (3) du Bois, 

 Tr. Far. Soc. 8, 211, 1912; (4) Hilpert, Tr. Far. Soc. 8, 207, 1912; (5) Gumaer; (6) Stifler, Phys. Rev. 33, 268, 1911. 



TABLE 460. Temperature Variation for Paramagnetic Substances. 



The relation deduced by Curie that x ~ C/T, where C is a constant and T the absolute temperature, holds for some 

 paramagnetic substances over the ranges given in the following table. Many paramagnetic substances do not obey the 

 law (Honda and Owen, Ann. d. Phys. 32, 1027, 1910; 37, 657, 1912). See the following table. 



References: (i) P. Curie, London Electrician, 66, 500, 1912; see also Du Bois, Rap. du Cong. 2, 460, 1900; (2) Per- 

 rier, Onnes, Tables annuelles, 3, 288, 1914; (3) Oosterhuis, Onnes, I.e. 2, 389, 1913. 



TABLE 461. Temperature Effect on Susceptibility of Diamagnetic Elements. 



No effect: 



B Cryst. 400 to 1200 

 C Diamond, +170 to 200 

 C "Sugar" carbon 

 Si Cryst. 



P white 

 S Cryst.; ppt. 

 Zn 170 to 300 

 As 



Se 



Br 170 to 18 



Zr Cryst. 170 to 500 



Cd 170 to 300 



Increase with rise in Temperature: 



Be 



B Cryst. +170 to 400 



Decrease with rise in Temperature: 



C Amorphous Gd 1791030 



C Ceylon graphite Ge 170 to ooo 



Cu Zr 500 to 1200 



Zn +300 to 700 Cd 300 to 700 



C Diamond, 200 to 1200 

 Ag - 



In 170 to 150 

 Sb +50 to +631 

 Te 



I +114 tO +200 



Sb 170 to 50 

 Cs and Au 

 Hg 39 to +350 

 Pb 327 to 600 



I 170 to 114 

 Hg 170 to 30* 



Tl 



Pb 170 to 327 

 Bi 170 to 268* 



TABLE 462. Temperature Effects on Susceptibility of Paramagnetic Elements. 



No effect: 



Li 



Na 170 to 97 



Al 657 to 1100 



K i 70 to 150 

 Ca 170 to 18 

 V 170 to 500 



Increase with rise in Temperature: 



Ti 40 to 1100 Cr 500 to 1100 



V 500 to 1100 Mo 170 to 1200 



Decrease with rise in Temperature: 



(O) Ti -iSoto -40 



As -i 70 to 657 

 Mg 



Mn 250 to 1015 

 (Fe) 



Cr 170 to 500 

 Mn 170 to 250 

 Rb 



Ru +550 to 1200 

 Rh 



Ni 350 to 800 

 Co above 1150 

 Cb 170 to 400 



W 

 Os 



Ba 170 to 18 

 Ir and Th 



Pd and Ta 



Pt and U 



Rare earth metals 



Tables 461 and 462 are due to Honda and Owen; for reference, see preceding table. 

 SMITHSONIAN TABLES. 



