166 B 



arker— 



-Thermoelectromotive Forces of 



Potassium, 



etc. 











Table 



II. 













Sodium-Platinum 







Mercury 



-Platinum 





E 



T 



84-24 



N 

 4 



D 





E 

 50 



T 

 84-42 



N 

 6 



D 





170 



o 

 0-54 



1-0 



o 

 2-35 



0-9 



160 



79-29 



4 



0-60 



1-1 



40 



58-56 



5 



1-24 



0-6 



150 



73-60 



5 



0-62 



1-2 



30 



39-31 



2 



0-25 



o-i 



140 



68-14 



4 



0-52 



1-0 



20 



21-69 



2 



013 



o-i 



130 



63-46 



3 



0-36 



0-7 



10 



10-64 



3 



0-29 



0-3 



120 



5829 



3 



0-34 



0-6 













110 



52*79 



5 



0-72 



1-4 













• 100 



47-58 



4 



0-77 



1-5 













90 



41-51 



2 



0-33 



0-7 













80 



37-32 



2 



0-04 



0-1 













TO 



32-16 



1 



--- 



--- 













30 



12-64 



2 



0-40 



0-8 













noticed that, as expressed in microvolts, the highest values for 

 each of the three couples are not widely different. 



The successive observations of a given series were fre- 

 quently and even prevailingly much more concordant than 

 those of different series. A similar observation was recorded 

 by "W. H. Steele in his well known paper,* who says that 

 " One is led to the suspicion that the thermoelectric constants 

 are not really constants, but that they vary in a given speci- 

 men in a manner which, if not arbitrary, yet arises from 

 changes in condition which are inappreciable." While not 

 perceiving in just what sense a natural phenomenon can be 

 regarded as "arbitrary," I can otherwise fully appreciate the 

 comment quoted, since I have myself failed to trace such vari- 

 ation to its causes with any certainty. 



The curves are virtually self-explanatory ; in addition to 

 those obtained by direct experiment, the curves deduced from 

 them for potassium-mercury and sodium-mercury are indicated. 



I hope to find opportunity at some future time to make fur- 

 ther measurements with a potentiometer system better adapted 

 to the measurement of such small electromotive forces, and 

 with metals of whose purity I shall have more assurance. The 

 foregoing values are therefore presented as preliminary approx- 

 imations rather than as final results. It is also highly desirable 

 to extend the temperature range in both directions. 



My thanks are due Prof. A. "W. Goodspeed, both for sug- 

 gesting the domain of investigation, and for placing the 

 resources of his laboratory most freely at my disposal ; and I 

 should be most remiss if I failed to acknowledge my indebted- 

 ness to Dr. R. H. Hough for his constant advice and aid, par- 

 ticularly in the construction of the special apparatus required. 

 University of Pennsylvania, Philadelphia. 



*Phil. Mag., Feb. 1894. 



