ELECTROMOTIVE FORCES. 



759 



The following table has been calculated from Tait's experi- 

 ments,' 54 ' assuming that the electromotive force of the Grove's 

 element, which was taken as standard, is 1-95 volts. 



THERMOELECTRIC POWER IN MICROVOLTS. 



Referred to Lead. 



Substance. 



Cadmium 



Zinc 



Silver 



Gold 



Copper 



Alloy 



Tin ...... 



Aluminum . . . 

 Platinum hardened . 

 Magnesium . . . 

 Platinum malleable . 

 Alloy (qoPt+loIr) . 

 Steel ..... 

 Palladium .... 

 Iron ..... 

 Argentan .... 

 Nickel (-18 to 175) 



(250 to 300) 

 ,, above 340 . 



Fleeming Jenkinf deduced from Matthiesen's experiments the 

 thermoelectric powers of different bodies in respect of lead at the 

 temperature of 20: 



Bismuth, Pressed commercial 



Wire . . . . +97 



,, Pure pressed Wire . +89 



,, Crystal axial . . . +65 



,, ,, equatorial . +45 



Cobalt +22 



Argentan +1175 



Mercury +0*413 



Lead O'O 



Tin -o-i 



Copper, Commercial . . . -O'l 



Platinum -0*9 



Gold -1-2 



Pressed Antimony Wire . . -2*8 



Silver, Pure hard -3*0 



Zinc ,, pressed .... -3*7 

 Copper, Gal vanoplastic . . . -3 '8 

 Antimony, Commercial pressed 



Wire , -6-0 



Arsenic - 13-56 



Iron, Pianoforte Wire . . . - 17-5 



Antimony, Axial -22 '6 



,, Equatorial . . . -26*4 



Red Phosphorus 29*9 



Tellurium - 502*0 



Selenium .-807*0 



* TAIT. Phil. Tram. Roy. SVv. Edin., 1873, Vol. xxvn., p. 125. 

 t FLEEMING JENKIN. Electricity and Magnetism, p. 176. 1873. 



