MAGNETISATION ON THE THERMOELECTRIC QUALITY OF IRON. 381 
unloading to loading), or when the process of loading or unloading is resumed after the 
metal has been subjected to vibrations while supporting a load of any assigned value. 
[September 17, 1886. The influence of magnetisation on the thermoelectric quality 
of iron forms the subject of a chapter in Messrs. Bar us and Strouhal’s compre¬ 
hensive memoir “ On the Physical Characteristics of the Iron Carburets.”* Their 
experiments, like those of the writer, confirm Thomson’s observation that longitudinal 
magnetisation makes iron thermoelectrically negative (in the sense used in this paper). 
Their absolute measurements of the effect are of the same order of magnitude as those 
in the examples cited above. Messrs. Barus and Strouhal have investigated with 
much fulness the thermoelectric effects of tempering, in the case of steel, and have 
pointed out that these are far greater than the effects of magnetisation. It may be 
added that they are also far greater than the effects which result from hardening by 
mechanical strain. Iron hardened by stretching is thermoelectrically positive to soft 
iron : glass-hardened steel is also thermoelectrically positive to soft steel, but to a 
much greater degree.—J. A. E.] 
* Bulletin of tlie U. S. Geological Survey, No. 14, 1885. 
