THE 
LONDON, EDINBURGH, and DUBLIN 
PHILOSOPHICAL MAGAZINE 
AND 
JOURNAL OF SCIENCE. 
[SIXTH SERIES.] 
FEBRUARY 1908. 
XVII. On certain Phenomena exhibited by Small Particles on 
a Nernst Glower. By 0. E. Mendenhall and L. R. 
Ingersoll *. 
IN the course o£ some recent work on the determination 
of high temperature melting-points (see Phys. Review, 
July 1907), the present writers noted several rather curious 
phenomena attending the heating of minute particles of 
various metals placed upon the surface of a Nernst glower — 
whose temperature could be controlled with a suitable rheostat 
— and examined with a microscope of low power. These 
phenomena seemed sufficiently novel and interesting to merit 
separate study, and the results of our observations are con- 
tained in the present paper. 
Phenomena of Undercooling of Molten Globules. 
The first phenomena are associated with an undercooling of 
molten globules which is so great as to be in itself worth noting. 
If a small particle of, say, platinum be placed on the glower, 
melted into a globule about 1/10 mm. or 1/20 mm. in diameter, 
and then allowed to cool either slowly or rapidly, it will not 
solidify at the melting temperature, but will remain very 
evidently fluid until a temperature is reached from 50° to 
300° lower than the melting-point, when solidification will 
suddenly occur, accompanied by a quick " flash " or brighten- 
ing of the drop. Upon reheating there is no flash and the 
drop melts at its proper melting temperature. The same 
* Communicated by the Authors. 
Phil. Mag. S. 6. Vol. 15. No. 86. Feb. 1908. Q 
