ELECTROCHEMICAL INVESTIGATION OF LIQUID AMALGAMS 



The temperature-coefficient functions 



ATT 



AT 



7T, 



of these cells, calculated in 



the usual way from the figures given in table n, are as follows: 



Cell Pi-P2 0.00437 



P2-P3 o . 003805 



P3-P4 0.00381 



Cell Qi-Q2 0.00376 



Q2-Q3 0.003677 



The first value is much higher even than that for zinc. Here again as 

 usual, the figures rapidly approach the limiting value 0.00366 as the 

 dilution proceeds, although the coefficient for cell Pi-P2 containing the 

 most concentrated amalgams is 16 per cent in excess of this figure. 



The theoretical significance of these results will be considered later, in 

 connection with all the other results. The possibility that the high tem- 

 perature coefficient of the most concentrated amalgam cell might be due 

 to the crystallization of the most concentrated amalgam at the lower 

 temperature was considered, and w r as experimentally investigated in an 

 exactly similar manner to that used in the case of the zinc amalgams. 

 An amalgam containing 1.03 per cent of lead was placed in an H cell and 

 one side was in one case diluted and in the other concentrated, and in 

 both cases a permanent potential, in the direction indicated by theory, 

 was obtained, the measurements of course being made at o C. Control 

 experiments, using a saturated amalgam with excess of lead, showed no 

 potential on adding either mercury or lead to one side of the cell. 



These results seem to show clearly that the most concentrated amalgam 

 used, i. e., 1.02 per cent, is less than saturated at o. 



At this point the potentiometer was recalibrated, but no change as great 

 as o.oi ohm was found in any of the resistance, and hence, as before, cor- 

 rections w r ere unnecessary. 



COPPER AMALGAM. 



Seeking all the light available upon this type of cell, the investigators 

 next turned to the metal copper. Copper amalgams have been examined 

 in this connection by Meyer and by Spencer. Meyer made an amalgam, 

 by electrolysis, intended to contain 0.217 per cent of copper. This amal- 

 gam he dried by filter-paper and standing in a desiccator, and then diluted 

 portions of it. Table 12 gives his results, the concentration being ex- 



TABLE 12. Potentials of Copper Amalgams measured by Meyer. 



