474 



Tables 576-579 

 TABLE 576. — Magnetism and Temperature, Critical Temperature 



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

 In the formula M t/Mo = (i — at) the value of a may range from .0003 to .001 (see Tables 559-560). 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?). Diamagnetic 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: (1) 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, 26S, 1911. 



TABLE 577. — 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, igio; 37, 657, 1912). See the following table. 



References: (1) 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 578. — 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 Diamond, 200 to 1200° 



C Amorphous 



C Ceylon graphite 



Cu — 



Zn +300 to 700° 



Gd —179 to 30° 

 Ge —170 to qoo° 

 Zr 500 to 1200° 

 Cd 300 to 700° 



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 6oo° 



I —170 to 114 

 Hg —170 to — 30 



Tl — 



Pb —170 to 327 

 Bi —170 to 268° 



TABLE 579. — Temperature Effect on Susceptibility of Paramagnetic Elements 



No effect: 



Li — 



Na — r7o to 97 



Al 657 to noo° 



K 



Ca 



V 



-170 to rso° 

 -170 to 18° 

 -170 to 500° 



Cr 



Mn 

 Rb 



-170 to 500° 

 -170 to 250° 



Increase with rise in Temperature: 



—40 to 1100° 

 500 to IIOO° 



Cr 



Mo 



500 to IIOO° 

 — 170 to 1200° 



Ru +550 to 1200° 

 Rh 



Decrease with rise in Temperature: 



(O) — Ti -180 to -40° 



As —170 to 657° Mn 250 to 1015° 



Mg — (Fe) — 



Tables 578 and 579 are due to Honda and Owen; for reference, see preceding table. 



Smithsonian Tables. 



Ni 350 to Soo° 

 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 



