552 Variation of Thermal Conductivity of Metals. 



The electrical conductivity of bismuth and antimony 

 shows an abnormal change during melting — that is, the 

 conductivity increases by melting. It is therefore very 

 interesting to see whether the thermal conductivity of these 

 metals, unlike other metals, increases during melting. 

 From fig. 6 we see that the thermal conductivity of bis- 

 muth at first slightly decreases and then increases : during 

 melting the conductivity considerably increases in the same 

 way as the electric conductivity does. The conductivity of 

 liquid bismuth slightly decreases along with the rise of tem- 

 perature. In the case of antimony the variation of the 

 conductivity is similar to that of the conductivity for bis- 

 muth, but there is some difference in the quantitative 

 respect. In the case of these metals Lorenz's law holds 

 o-ood onlv below 100°, as seen from fio-. 6. 



Sui 



•*/■ 



The results of the present investigation may be sum- 

 marized as follows : — 



1. The thermal conductivity of tin, lead, zinc, and 

 aluminium decreases with the rise of temperature up to 

 their melting-point. 



2. The thermal conductivity of these metals decreases 

 abruptly during melting. 



3. The thermal conductivity of bismuth and antimony 

 rslightly decreases at first, and then increases a little. 



4. During melting the conductivity of bismuth con- 

 siderably increases, and that of antimony seems to increase 

 only slightly. 



5. The thermal conductivity of all liquid metals here 

 investigated decreases but slightly with the rise of tem- 

 perature. 



6. The above changes of thermal conductivity are similar 

 to those of electric conductivity for the same metals. 



In conclusion, I wish to express my hearty thanks to 

 Prof. K. Honda, under whose direction the present experi- 

 ment was carried out. 



