306 



B. O. Peirce — Thermo-electric Properties, etc. 



Of annealed manganine wire I had considerable quantities 

 of nine different specimens and these were of six different sizes, 

 22, 26, 28, 30, 33, and 36. Of this wire Mr. C. J. Shanahan 

 and I made a very large number of thermo-electric junctions, 

 sometimes opposing one specimen of manganine wire to 

 another and sometimes to copper. Experiments with these 

 junctions showed that one specimen (no. 22) differed rather 

 widely from the others, which were thermo-electrically pretty 

 close together, and that the thermo-electric position of the 

 abnormal wire was in no way changed by heating it repeatedly 

 red hot and cooling it suddenly. 



Table IV gives the results of numerous experiments upon 

 thermo-electric junctions made of annealed manganine and cop- 

 per. The numbers in the first column of electromotive forces 

 were obtained with the no. 22 wire just mentioned : the num- 

 bers in the last column are the averages of corresponding num- 

 bers in a table where each of the other eight specimens of wire 

 had a column for itself. There were slight persistent differences 

 between these last mentioned wires but there was no apparent 

 relation between the size of a wire and its thermo-electric posi- 

 tion. It will be noticed that the electromotive force of no one 

 of the manganine-copper combinations experimented on was 

 greater than about one-seventh that of the weakest of the pla- 

 tinoid-copper combinations under similar circumstances. 







Table IV. 









Electromotive 



Forces of 



Temperatures of 



Copper vs. Manganine 



Copper vs. Ordinary 



the Junctions. 



Wire no. 22. 



Annealed Manganine 



0° and 



10° 



24-0 



17-3 



0° and 



20° 



48-0 



34-7 



0° and 



30° 



72-5 



52-3 



0° and 



40° 



97-4 



70-1 



0° and 



50° 



123-0 



88-0 



0° and 



60° 



149-0 



106-0 



0° and 



70° 



175-0 



124-4 



0° and 



80° 



202-0 



143-0 



0° and 



90° 



229-0 



161-4 



0° and 100° 



257-0 



180-0 



Jefferson Physical Laboratory, Cambridge, Aug. 1894. 



