4 8 



ELECTROCHEMICAL INVESTIGATION OF LIQUID AMALGAMS 



A series of density experiments of lead amalgams was carried out at 

 20, and is recorded in table 10, but the necessary correction is insignifi- 

 cant in this case, because the density of lead is so nearly that of mercury. 

 The densities were determined by the use of an ordinary Ostwald pyc- 

 nometer ; the only unusual precaution taken was to displace the air in the 

 pycnometer by carbon dioxide. On this account very little oxidation took 

 place when the amalgams were drawn into the tube. 



These results are plotted in fig. 10. The imaginary density, supposing 

 no contraction to have happened, is given by the dotted line. For a i per 

 cent amalgam this is 13.524 instead of the actually observed value 13.536. 

 Thus as a matter of fact a slight contraction occurs on amalgamation. 



13.52 



13.53 



13.54 



13.55 



0.2 0.4- 0.6 0.8 



Fig. 10. Densities of Lead Amalgams at 20. 



1.0 percent 



Densities are plotted as ordinates, per cents by weight of lead in amalgams as abscissae. 

 The dotted line indicates the imaginary theoretical values. 



The electrical measurement of similar amalgams was now undertaken. 

 The most concentrated amalgam of lead used for the purpose contained, 

 as before, 1.02 per cent of this metal by weight. Some of this was placed 

 in the cup labeled Pi. Into cups P2. P3, and ?4 were placed respectively 

 12.684, ! 2-603, an d 10.946 grams of this amalgam, diluted with 19.358, 

 58.96, and 108.86 grams of mercury respectively. The second series 

 began about where this left off, with a freshly prepared amalgam contain- 

 ing 0.0994 per cent of lead. Cup Qi contained this alone, while cup Q2 

 contained 14.308 grams of it diluted with 74.628 grams of mercury. The 

 least concentrated amalgam of all, that contained in Q3, was made by 

 diluting 8.429 grams of material like that in Qi with 115.72 grams of 

 mercury. The electrical measurement with these two series of cells is 

 given in table II. 



