Direction of Thermo-electric Currents. 



511 



The following table contains their results at 18° C. for 

 each of the metals tested. Where they give more than 

 one result that one has been used to which they attach 

 most weight. The unit of heat is the watt second ; electrical 

 conductivity is expressed in reciprocal ohms per centimetre 

 cube : — 



Metal. 



Conductivities, 



Thermo 

 powers in 



-electric 

 micro-volts 



thermal 

 electrical. 



electrical 

 thermal. 



per degree ; 

 with respect to 



copper A. 



lead. 



Aluminium 



Copper 



•636 X10" 5 



•665 



•672 



•686 

 •699 

 •706 

 •709 

 •715 

 •735 

 •753 

 •754 

 •838 

 •964 



1-57 XlO 5 



1-50 



149 



1-46 



1-43 



1-42 



1-41 



1-40 



1-36 



1-33 



1-326 



1-19 



1-04 



+3-2 

 -0-3 

 -01 







+22-3 



-06 





 + 29 

 +2-6 

 +61 



-0-3 

 +32 

 + 30 

 +2-9 

 -19-4 

 +35 

 +2-9 

 

 +0-3 



— a-2 



Zinc 



Silver 



Nickel 



Cadmium 



Gold 



Lead 



Tin 



Platinum .... 



Palladium 



-4-11-5 -86 



Iron 



Bismuth 



-8-4 

 +733 



+ 11-3 

 -704 



The numbers in the second and fourth columns are those 

 given by Jager and Diesselhorst, the third column contains the 

 reciprocals of those in the second, the fourth gives the thermo- 

 electric powers of the metals with respect to one of the copper 

 bars, the fifth has been calculated from the fourth and gives 

 the thermo-electric powers with respect to lead. The signs 

 have been reversed to comply with the convention which 

 makes the thermo-electric power of a metal positive if the 

 current flows from lead to the metal through the hot junction, 

 i. e. if the current flows from hot to cold through the metal. 



If the laws stated by M. Thomas are true the numbers in 

 the third and fifth columns of the table should increase and 

 decrease together. It is seen that as the numbers in the third 

 column decrease those in the fifth change irregularly in 

 magnitude and are sometimes positive, sometimes negative. 

 They afford therefore no confirmation of the laws, but on the 

 contrary disprove them. 



The following diagram, in which each metal is represented 

 by a point, with abscissa the quotient of the electrical by the 

 thermal conductivity and ordinate the thermo-electric power 



