32 ELECTROCHEMICAL INVESTIGATION OF LIQUID AMALGAMS 



Take for example 62-63. Here ' =3.4104, and its natural logarithm 



c n 



is 1.2268. Hence the first member of the equation becomes 



8316x1,2268 =a 

 1x96,530 



and the second member becomes 



0.032408 0.029303 

 2- ^o_o =0.0001035 



30.0 



Here the agreement is not so good ; but, on the other hand, it might be 

 worse. Another thallium amalgam cell, Ai-A3, taken at random, shows 

 essentially the same relation, the terms being as follows : 



8.316x1.3808 =aoooi700 52.920-47.903 =0.000,670 - 



96,530 30.0 



In the case of indium, a somewhat less percentage accuracy in fulfilling 

 the requirements of the Cady equation is shown. For the cell Ei-E2 the 

 terms are these: 



8.316x1.6082 15.78614.455 



2- =0.0000461 -2-*- n =O.OOOO444 



3X96,530 30.0 



With tin, about the same order of agreement is to be found. For 

 example, in the cell, Ji-j2, the first member of equation (4) becomes 



8.3i6x 1.2365 

 ^- .. J =0.0000532 

 2 X 96,580 



and the second member becomes 



15.156-13.612 =0.0000515 



a difference of about 3 per cent, or about like that found in the case of 

 indium. 



One conclusion drawn from these partial agreements is the same as 

 that drawn from the case of cadmium studied by Richards and Forbes, 

 namely, that the equation of Cady does not contain an exact representation 

 of all the influences producing electromotive force. On the other hand, 

 the new results strongly reinforce the hope expressed in the earlier paper 

 that this equation, although not wholly exact, is really a step in the right 

 direction. For it is inconceivable that all these cells, possessing very 

 different temperature coefficients, one as much as 13 per cent different 

 from the requirement of the gas law, should all come within 3 per cent 

 of the fulfilment of equation (4), if the equation were without meaning. 



Expressed in other words, the meaning of the results and mathematical 

 considerations just detailed may be stated as follows : The reason for the 

 deviation of the actual electromotive forces of amalgam cells from the 

 values calculated from the concentrations is found to be primarily in the 

 free energy of the change of chemical affinity involved in the dilution of 



