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XXVII. Preliminary Notice on the Electric Conducting Power of 

 the Alkaline Metals. By A. Matthiessen, Ph.D."^ 



OF the physical properties of the metals of the alkalies and 

 alkaline earths very little is at present known ; and having 

 some of them at my disposal, I thought it would be interesting 

 to study some of their most important properties. I have com- 

 menced, under the direction of Professor Kirchhoff, in the Hei- 

 delberg Physical Laboratory, with the electric conducting power 

 of the alkaline metals, and have found that of potassium at ordi- 

 nary temperature, compared with that of silver at 0° = 100, to be— - 



201 

 Of sodium . . . 36*6 

 Of lithium . . . 18-7 



The manner in which the wires were pressed and the method 

 of observation I shall describe as soon as I have determined their 

 conducting power at different temperatures, as well as that of 

 the metals of the alkaline earths. 



An interesting fact is the rapid diminishing of the conducting 

 power at the point of fusion. With potassium it diminishes 

 gradually between the temperatures 50° to 57° C. ; whereas with 

 sodium, suddenly at about 96°, as the following data show : — 



That of sodium is at — 



75° C. . . 24-44 



85° C. . . 23-41 



95° C. . . 22-42 



97° C. . . 16-23 



110° C. . . 15-36 



120° C. . . 14-17 



Compared with silver at 0°=100. 



This difference in the behaviour of these metals may be ex- 

 plained by the observation lately made by Regnault, in his paper 

 " On the Specific Heat of Simple Bodies " {Ann. de Chim. et de 

 Phys. vol. xlvi. p. 257), wherein he states that potassium does 

 not pass directly from the liquid to the solid state, like sodium, 

 but becomes first semi-fluid and then gradually solid, which fact 

 is plainly shown by comparing the conducting power of the two 

 metals at their fusing -points. 



* Communicated by the Author. 



