ee 
in changing the dimensions of Iron and Steel bars. 87 
was first passed around it. On now breaking the circuit the 
rod retracts to the length it had before the current was passed 
for the second time. hat is, after the first magnetization and 
demagnetization of the rod, the successive elongations and re- 
tractions are equal. These conditions exist until four or five 
Continuing the experiments, the scale gradually yon over 
the entire 
Heat developed in the rod at the instant of ws demagnetization. 
The above described experiments show conclusively that the 
minute elongations which take place on breaking the cireuit 
in the experiments, the rod during this time does not elongate. 
If the current is sufficiently intense to heat directly the helix 
and rod, the above phenomena of heating on demagnetization 
nevertheless manifests itself and can readily be disentangled 
r on. 
These interesting results proving the development of heat on 
demagnetization, were obtained a year ago without any knowl- 
edge of the recent work of Jamin and Roger, and the measures 
made directly on the changes in length of the rods, tend to 
confirm the result arrived at by these experimenters.* Recent- 
ly Cazin (Compt. Rendus, t. xxv, p. 1265), has shown that ‘‘ the 
heat thus produced is proportional to the square of the intensity 
of the magnetism and to the polar distance :”’ and Moutier, 
they discovered this fact is not stated by Cazir. 
