42 ELECTROCHEMICAL INVESTIGATION OF LIQUID AMALGAMS 



These results confirm wholly the work of Richards and Forbes, carried 

 out at 23, showing that cells of zinc amalgams give a much lower electro- 

 motive force than that required by the concentration law. The quantita- 

 tive agreement of the two series of results is shown in the accompanying 

 diagram (fig. 9), where the points surrounded by single circles are the 

 points found by the earlier work, and those surrounded by double circles 

 the present data. This curve is drawn on the same scale as that used in 

 the other similar curves in this monograph. 



The cells were measured also at 15 and o. In no case did the poten- 

 tial between cups I and 2 exceed o.oooooi volt. At 30 the other measure- 

 ments also were sufficiently concordant and convincing. At o the more 

 dilute amalgams gave less consistent results, and evidently were not so 



log 2 Iog4 Iog8 log 16 log3Z log 64- lo)28 log 256 

 Fig. 9. The Deviations of the Electromotive Force of Zinc Amalgams. 



r> 'p _ 



Deviations from the expression ir = - - i n -1 are plotted in millivolts as ordinates, 



2/< C 2 



the logarithms of the concentration ratios as abscissae. The most concen- 

 trated amalgam contained 0.9 per cent by weight of zinc and 99.1 per cent 

 by weight of mercury. A horizontal line on the diagram would indicate 

 complete fulfilment of the concentration law. This curve is almost if not 

 quite independent of temperature, at least between o and 30. Single circles 

 depict points found by Richards and Forbes; double circles depict points 

 found by the present investigation. 



trustworthy. As the technique and accordingly the consistency of the 

 results were both greatly improved later, these early measurements need 

 not be given in detail. It is enough to say that there was undoubted 

 evidence of the truth of the prediction of Richards and Forbes that the 

 temperature coefficient is greater than 0.00366, demanded by the gas law. 

 Moreover, it was clear that the value approached more and more nearly 

 that required by the gas law as the dilution became greater. 



