12 



A. W. Witkowski on the 



The thermo-electric current was measured by means of a 

 Despretz galvanometer, resistance about 145 ohms, the sensi- 

 tiveness of which was very constant and relatively considerable 

 — 163,500,000 scale-divisions per ampere ; this number has 

 been tested frequently, also by means of a thermo-electric 

 couple, at temperatures 0° and + 100°. 



The calibration of the couple was performed as follows : — 

 One of the solderings being placed in melting ice, the other 



Fisr. 3. 



r^ 



was heated or cooled, together with the bulb of the hydrogen 

 thermometer s to different temperatures : •&= +100°, +19°' 6, 



-79°'0, -104°'0, -182°-5. Let us denote by E* the 



electromotive forces observed (products of galvanometer de- 

 flexions and total resistance), and write 



