Shimizu 3 indicate that Steinmetz's formula holds for nickel and annealed cobalt up to B =3000, for cast cobalt and tungsten steel up to B =8000, and for Swedish iron up to B =18,000, the range being in all cases extended at the temperature of liquid air.
The hysteresis-loss in Swedish iron was decreased for inductions below about 9000 and increased for higher inductions; in tungsten-steel, nickel and cobalt the hysteresis-loss was always increased by cooling.
These high values render hardened tungsten-steel particularly suitable for the manufacture of permanent magnets.
In its improved form this meter consists of a single horseshoe permanent magnet formed of tungsten-steel having a strong and constant field.
