Table 472. 



375 



DISSIPATION OF ENERGY IN THE CYCLIC MAGNETIZATION OF VARIOUS 



SUBSTANCES. 



C. P. Steinmetz concludes from his experiments * that the dissipation of energy due t» 

 hysteresis in magnetic metals can be expressed by the formula e = aB^-'', where e is the energ 

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

 range of induction, no matter what the absolute value of the terminal inductions may be. Hi 

 experiments show this to be nearly true when the induction does not exceed -J- 15000 c. g. s 

 units per sq. cm. It is possible that, if metallic induction only be taken, this may be true up U 

 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. t 



Values of Constant a. 



The following table gives the values of the constant a as found by Steinmetz foi' 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 



Magnetite 

 Nickel 



n 

 it 



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 S 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 tiirns for demagnetization . . . . ; 



Gray cast iron 



" " " containing \ % 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 ) 



Ewing's experiments ) 



Hardened, also from Ewing's experiments 

 Rod containing about 2 % of iron, also calculated / 

 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 \ 



2d experiment, 114 cycles per second 

 3d " 79~9i cycles per second . 



.002 27 

 .00326 

 .00548 

 .00458 

 .00286 



.0457 

 .0396 

 •0373 



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

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



Smithsonian Tables. 



