460 



TABLE 482.— DISSIPATION OF ENERGY IN THE CYCLIC MAGNETIZATION 

 OF VARIOUS SUBSTANCES 



C. P. Steinmetz concludes from his experiments that the dissipation of energy due to 

 hysteresis in magnetic metals can be expressed by the formula e=zaB ue , where e is the 

 energy dissipated and a a constant. He also concludes that the dissipation is the same for 

 the same range of induction, no matter what the absolute value of the terminal inductions 

 may be. His experiments show this to be nearly true when the induction does not exceed 

 ± 15000 cgs units per cm 2 . It is possible that, if metallic induction only be taken, this may 

 be true up to saturation ; but it is not likely to be found to hold for total inductions much 

 above the saturation value of the metal. The law of variation of dissipation with induction 

 range in the cycle, stated in the above formula, is also subject to verification. 



The following table gives the values of the constant a as found by Steinmetz for a num- 

 ber of different specimens. The data are taken from his second paper. 



Kind of material Description of specimen 



Iron Norway iron 



" Wrought bar 



" Commercial ferrotype plate 



" Annealed " 



" Thin tin plate 



" Medium-thickness tin plate 



Steel Soft galvanized wire 



" Annealed cast steel 



" Soft annealed cast steel 



" Very soft annealed cast steel 



" Same as 8 tempered in cold water 



" Tool steel glass hard-tempered in water 



" " tempered in oil 



" " " annealed 



C Same as 12, 13, and 14, after having been subjected 

 < to an alternating m. m. f. of from 4000 to 6000 



[ampere turns for demagnetization 



Cast iron Gray cast iron 



" " containing {% aluminum 



" " " " " " . i% " 



f A square rod 6 cm 2 section and 6.5 cm long, from 



Magnetite <; the Tilly Foster mines, Brewsters, Putnam County, 



[New York, stated to be a very pure sample 



Nickel Soft wire 



<< /Annealed wire, calculated by Steinmetz froml 



\ Ewing's experiments J 



Hardened, also from Ewing's experiments 



£ Q k a i t fRod containing about 2% of iron, also calculated! 



\from Ewing's experiments by Steinmetz J 



Consisted of thin needle-like chips obtained by 

 milling grooves about 8 mm wide across a pile of 

 thin sheets clamped together. About 30% by vol- 

 Iron ilings <! ume °f t ^ ie specimen was iron. 



1st experiment, continuous cyclic variation of m. m.\ 



f. 180 cycles per second J 



2d experiment, 114 cycles per second 



.3d 79-91 cycles per second 



Nickel alloy Permalloy 



Hipernik 



Electrical sheet Silicon steel 4.5% Si 



Siljcon steel 4.5% Si 



Silicon steel 4.4% Si 



Silicon steel 3.5% Si 



Silicon steel 2.5% Si 



Silicon steel 1.0% Si 



Silicon steel 0.5% Si 



Low carbon sheet 



Cast steel annealed 



Cast iron annealed 



Value of 

 a 



.00227 

 .00326 

 .00548 

 .00458 

 .00286 

 .00425 

 .00349 

 .00848 

 .00457 

 .00318 

 .02792 

 .07476 

 .02670 

 .01899 

 .06130 

 .02700 

 .01445 

 .01300 

 .01365 

 .01459 



.02348 



.0122 

 .0156 

 .0385 

 .0120 



.0457 



.0396 



.0373 



.0001 



.00015 



.00046 



.00051 



.00056 



.00065 



.00081 



.00088 



.001 



.003 



.005 



.012 



SMITHSONIAN PHYSICAL TABLES 



