ELECTRICITY. 



51 



(71) TABLE OF THERMO-ELECTRIC VALUES IN MICROVOLTS 

 REFERRED TO LEAD AS ZERO. [THE LOWER LIMIT OF TEMPERA- 

 TURE IS - 18 C., THE UPPER LIMIT IS 416 C., EXCEPT FOR 

 CADMIUM 258, ZINC 373 C., GERMAN SILVER 175. A GROVE'S 

 CELL is ASSUMED TO HAVE THE ELECTROMOTIVE FORCE 1*97 

 VOLTS.] 



- -024$ 



- -015$ 



- -0102$ 



- -0095$ 



- -0055$ 



- -0039$ 

 + '0359$ 

 + 0512$ 



- -241$ 

 + -0512$ 



(72) THERMO-ELECTRIC PILES. 



A bismuth-copper element with one junction at C. and the 

 other at 100 C. gives an E.M.F. of 005476 volt. 



20 elements of Noe's form (German silver and an alloy of zinc and 

 antimony) joined up in series have a resistance of 0*5 B.A. unit, and 

 an E.M.F of 1' 25 volt. 



6000 Clamond's elements (iron and an alloy of bismuth and 

 antimony) heated by a coke fire, with a resistance of 15*5 B.A. 

 \inits, give an E.M.F. of 109 volts. 



