D. Sears—Magnetism of Soft Iron. 21 
The increased effect is less marked in steel than in iron, 
The following table shows the effect of rapid reversals of the 
current. 
TABLE VI 
é 0” D 
160 180 190 
160 180 190 
160 185 189 
160 180 190 
_ It will be seen that the effects in this case are much less than 
in the case of soft iron. The current was passed through differ- 
the large size of the bar and the instantaneous duration of the 
current. : 
The conclusions from the foregoing experiments appear to 
be as follows: 
- Lhe passage of an electric current through an iron or steel 
bar produces a molecular change in it, which is apparent both 
at the closing and breaking of the circuit. 
2. The rapid change of direction of a current through iron or 
steel bars produces a molecular disturbance which is greater 
than that imparted by a current sent in one direction alone. 
3. Magnetization of the iron or steel bar is sufficient to 
restore it to the normal magnetic state which is imparted by 
the magnetizing helix. 
4 The molecular action increases with the strength of the 
electric current. 
No. X.—Magnetism of Soft Iron; by DAVID Sears. 
Jamin’s experiments showed that the magnetization was ome 
a 
est when two north or two south poles were op nD 
least when a north and south pole were directed toward each 
other. T results seem to him to require a modification in 
