THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE 



[FIFTH SERIES.] |' y MAY 15 1899 



0^ 



MA Y 1899. 



r 

 XXXIX. The Effects of Temperature and of Circular Mag- 

 netization on Longitudinally Magnetized Iron Wire. By 

 F. H. Pitcher, M.A.Sc, Demonstrator in Physics, McGill 

 University, Montreal* . 



Objects of the Investigation. 



IN commencing these experiments in October 1894, the 

 original intention was to investigate only the effect of 

 temperature on the magnetization of iron. With this object 

 the specimen was heated in a platinum tube, maintained at a 

 steady temperature by means of an electric current. The 

 temperature was inferred from the resistance of the platinum 

 tube, which was very uniformly heated and extended for some 

 distance beyond the ends of the iron wire. This proved to be 

 a very perfect method of heating, as the temperature could 

 be easily varied and accurately regulated and measured. The 

 current in the platinum tube was also without magnetic effect 

 on the specimen or the magnetometer, and the specimen was 

 necessarily at the same mean temperature as the enclosing 

 tube. A concentric brass tube formed the return lead. 



Unfortunately there was some difficulty at the outset in 

 procuring suitable platinum tubes, and the attempt to make 

 tubes in the laboratory by rolling up strips of platinum foil 

 did not prove entirely satisfactory owing to the inferior 

 quality of the foil. The tubes invariably cracked and became 

 useless before a complete series of observations had been 



* Communicated by Prof. H. L. Calleudar, M.A., F.R.S. 

 Phil. Mag. S. 5. Vol. 47. No. 288. May 1899. 2 G- 



