Properties of some Liquid Metals. 409 



The current in the long heating section was adjusted before 

 each reading till the temperature of the fixed temperature 

 junction was at a certain point, slightly above the melting- 

 point of the tested metal. Readings were taken with the 

 temperature of the variable temperature junction both above 

 and below the melting temperature of the metal. With tin 

 and lead this latter was easy, but with bismuth, owing to 

 the crystallization effect before mentioned, the readings were 

 rather uncertain. Above the melting-point, however, they 

 were perfectly constant. 



The curves plotted from the results of the experiments by 

 this method are given in figs. 6, 7, and 8 respectively. 



In each of these curves we see that in a small variation of 

 temperature, about the melting-point, there is a considerable 

 change in the direction of the thermo-electric curve. The 

 effect is smallest with lead, with tin it is larger, and with 

 bismuth it is very remarkable ; that metal changing, during 

 melting, from an exceedingly active thermo-electric metal to 

 one very similar to lead in its thermo-electric properties. 

 With mercury also (fig. 4) we see that a great change takes 

 place at the melting-point. This indicates that there is a 

 difference between the Peltier effect for the solid and for the 

 melted metal. But the change in curvature is not sufficiently 

 marked for us to be able to say whether the specific heat of 

 electricity remains proportional to the absolute temperature. 

 To decide this point a direct determination of the Thomson 

 effect is needed. 



The worked-out observations from which the curves in 

 figs. 6, 7, and 8 were plotted are given below. 



Copper- Tin Element. (Fig. 6.) 



Temperature of constant temperature junction 239° C. 

 Temperature of 



variable temperature 



junction. 



255-8 



E.M.F. in 



volts XlO 5 . 



2-86 



276 



7-01 



286-1 



90 



306-1 



132 



323*2 



16-92 



353-7 



23-63 



251 



2-0 



272-2 



6-35 



3151 



15-45 



219-7 



-5-1 



200-1 



-11-15 



179-5 



-16-86 



