89 
1906-7.] Heusler’s Magnetic Alloy. 
and tested at the room temperature before proceeding to the next heating. 
So far the magnetic quality was little affected. The specimen was now 
baked at a temperature of 160° for three days. This produced a distinct 
improvement in quality (fig. 1, curve 2). The process of heating for short 
and long periods was continued step by step, and the magnetic quality 
showed gradual deterioration with a marked increase in hysteresis. Fig. 1, 
curve 3 shows the final state which was obtained after heating for two and a 
half days to 220° C. In the heating up to and including 160° a gas furnace 
Fig. 1. 
was employed, but for prolonged heating at higher temperatures an electric 
oven was constructed and found to give very steady temperatures. In all 
the experiments the temperature was measured with a platinum and 
platinum-iridium thermometer. The series of heatings proved that the 
time effect is very large, especially in regard to the increase in hysteresis, 
and it was decided to reserve its further investigation until a special 
furnace could be constructed for this purpose. 
Another ellipsoidal specimen was employed in an investigation of the 
permanent effects produced by bringing the alloy for a short time to a series 
of increasing temperatures and quenching thereat. But before this treat- 
ment was carried out the magnetic condition of the specimen was tested 
