Table 31 7. 



295 



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=^aB^-^, 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 c. g. s. 

 units per sq. cm. 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 satura- 

 tion 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.f 



Values of Constant a. 



The following table gives the values of the constant a as found by Steinmetz for a number of different specimens. 

 The data are taken from his second paper. 



Number of 

 specimen. 



Kind of material. 



Description of specimen. 



Value of 



3 

 4 

 5 

 6 



7 

 8 



9 

 10 

 II 

 12 



13 

 14 

 15 

 16 



17 

 18 



19 

 20 



22 

 23 

 24 

 25 



26 



Iron 



Steel 



Cast iron 

 it i< 



Magnetite 



Nickel 

 « 



Cobalt 

 Iron filings 



Norway iron ........ 



Wrought bar ........ 



Commercial ferrotype plate 



Annealed " " 



Thin tin plate 



Medium thickness tin plate 



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 ....... 



( 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 . . . . ) 



Gray cast iron 



" " " containing J % aluminium 

 " " " " i% " . . 



( A square rod 6 sq. cms. section and 6.5 cms. long, ) 

 < from the Tilly Foster mines, Brewsters, Putnam > 

 ( County, New York, stated to be a very pure sample ) 



Soft wire 



( Annealed wire, calculated by Steinmetz from 

 I Swing's experiments 



Hardened, also from Ewing's experiments 

 ( Rod containing about 2 % of iron, also calculated ) 

 j from Ewing's experiments by Steinmetz . . ) 



' 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- 

 ume of the specimen was iron. 



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



f. I So cycles per second j 



2d experiment, 114 cycles per second 

 [ 3d " 79-91 cycles per second . . . 



.00227 

 .00326 

 .00548 

 .00458 

 .00286 

 .00425 

 .00349 



.00457 

 .00318 

 .02792 

 .07476 

 .02670 

 .01899 

 .06130 

 .02700 

 .01445 

 .01300 

 .01365 

 .01459 



.02348 



.0122 

 .0156 

 .0385 

 .0120 



•0457 

 .0396 

 •0373 



* " Trans. Am. Inst. Elect. Enp." January and September, 1892. 

 t See T. Gray, " Proc. Roy. Soc." vol. Ivi. 



Smithsonian Tables. 



