44 



ELECTROCHEMICAL INVESTIGATION OF LIQUID AMALGAMS 



In order to make these results as definite as possible, it was decided to 

 carry out two sets of experiments simultaneously, the two cells containing 

 the same amalgams. To effect this, the usual method of diluting a 

 " parent " amalgam in the cell was, of course, impracticable, and four 

 separate amalgams had to be made and sealed in the pipettes. The con- 

 centration of these amalgams was known to within about 0.5 per cent 

 a degree of accuracy, which, although not sufficient to admit of the theo- 

 retical potentials being calculated with the utmost precision, was ample 

 for finding the temperature coefficients with great exactness. 



The cells were filled as in table 7. 



TABLE 7. 



The cells were then put into the o bath, and their potentials measured 

 at two intervals of about an hour, the cell being shaken between. The 

 greatest change in potential during this treatment was 0.000004 volt. Cell 

 N was then put in the 30 bath, and each pair of amalgams was put in 

 opposite to the similar pair in cell M at o, and hence a direct measure- 

 ment of the temperature change was obtained. Cell M was then put in 

 the 30 bath, and the potential of both cell M and cell N determined at 

 30 ; finally, N was once more packed in ice, but after two readings had 

 been taken, the familiar irregularities at o became too great for further 

 accurate work. 



A slight mischance prevented the complete fulfilment of the program, 

 but although this mischance complicated affairs, it did not interfere with 

 the significance of the results for the present purpose. Probably because 

 of insufficient mixing in the bulb before the stem was filled, the amalgam 

 in cup M2 was found to be slightly less concentrated than in N2. This 

 prevented the direct comparison of these two cups, but did not affect the 

 results from each separately. The concentrations of the amalgams in these 

 two cups, as given above, were calculated from their potentials in con- 

 nection with the others, by the method given at the very end of this paper. 

 All the other cups were perfectly comparable, as was shown by the precise 

 equality of each pair, both at o and at 30. 



All the figures in table 8, except the last two columns, represent the 

 actual readings of the potentiometer. The last two columns are obtained 

 by difference from the appropriate preceding columns. 



