1888.] Mr A. Campbell on Thermoelectric Properties of Tin, 125 
4. The Change in the Thermoelectric Properties of Tin 
at its Melting Point. By Albert Campbell, B.A. 
As in all the thermoelectric diagrams hitherto published the 
lines of the metals stop short at the melting points, it seemed 
interesting to the writer to trace the change in the thermoelectric 
properties of a metal as the temperature is raised to, and beyond, its 
melting point. The fusible metals containing bismuth or antimony 
were rejected, because their large expansion at the point of solidifica- 
tion rendered them very unmanageable ; ordinary block tin was 
accordingly chosen. 
The tin was contained in a thin glass tube (about haK a metre 
long), one end of which was bent up at right angles to the remainder. 
This bent end, which was almost filled by the tin, was packed (ver- 
tically) in asbestos within two small copper cylinders, the longer 
part of the tube projecting from a hole in the side. At the point of 
emergence it was well protected from the hot copper by a thick 
wrapping of asbestos. Into the tin in the vertical part of the tube 
dipped the end (already tinned) of a thin iron strip. The other 
ends of this strip and of the tin in the glass tube were soldered to 
