MAGNETIZATION AND MAGNETIC CHANGE OF LENGTH. 39 



netizing coil was provided with a water-jacketed arrangement, 

 and a coil for the compensation of the vertical component of 

 earth field. 



The temperature of the ovoid was measured with a platinum 

 rhodium-platinum junction. One of the junctions was placed 

 in contact with the specimen at a point a quarter of the distance 

 from the upper end of the ovoid, the rest being well insulated 

 with asbestos paper. The interspace between the lead wire and 

 the wall of the porcelain tube was tightly filled with asbestos 

 fibres, and thus protected as much as possible from the convection 

 current. The other junction was arranged as in the second ex- 

 periment. The thermoelectric current was measured with a d'AK- 

 SONVAL galvanometer from Keiser and Schmidt, the reading of 

 which was corrected by the authors with a mercury thermometer 

 containing nitrogen below 5oO°C, and by Professor Nagaoka 

 and Mr. S. Kusakabe with the melting point of sodium chloride. 

 A low resistance galvanometer was, at the same time, employed 

 to measure the temperatures lower than 200°C. A simple con- 

 nection permitted us to pass the thermoelectric current through 

 the d'AESONVAL or the low resistance galvanometer, as the case 

 might be. 



The experiment was conducted in the following order. The 

 adjustments of the magnetometer and the coils, as described in 

 the first experiment, were effected ; the heating coil with the 

 specimen was then placed in the right position. The magnetiza- 

 tion at the temperature of the room was first determined ; then a 

 current from a dynamo was passed through the heating coil, till 

 the temperature of the specimen became constant. The direct 

 effect due to the current in the heating coil was tested by break- 

 ino; or reversinsf the current. The small deflection of the mag- 



