54 ELECTROCHEMICAL INVESTIGATION OF LIQUID AMALGAMS 



always remain a mystery. Perhaps the compensating effects of rate of 

 solution and degree of saturation may have combined to give the results 

 he observed, or perhaps his potentials came not from copper at all, but 

 rather from some impurity. 



It would have been particularly interesting to have obtained good 

 results in the case of this amalgam, for the electrolytic solution pressure 

 of copper is of the same order of magnitude as that of mercury, and it 

 might be expected that a balanced action would be established between 

 the passage of mercury into the electrolyte and of copper into the amal- 

 gam. This idea, which has been followed up by Hulett and De Lury in 

 another way since the beginning of our work, was one of the secondary 

 objects of the present research. A balanced action, indeed, may be in 

 part the cause of the lack of constancy of the potentials observed, as one 

 would be led to expect from this cause a gradual fall in potential. It is 

 possible that if the electrolyte were wholly saturated with cuprous sul- 

 phate, satisfactory measurements might be obtained, and one of us hopes 

 to return to the problem in the future. 



IRON AMALGAM. 



J. P. Joule * seems to have been the first person to study iron amalgams. 

 He records that an amalgam containing i per cent of iron is fluid, and 3 

 per cent is semi-fluid. 



An amalgam containing I per cent of iron was therefore made, by elec- 

 trolysis. This amalgam on filtration through soft leather proved to be a 

 suspension. The amalgam was filtered twice more, and finally the mercury 

 in a weighed amount of the amalgam was evaporated, and the remaining 

 ferric oxide was weighed. The same process was repeated with a fresh 

 amalgam similarly prepared. In the first instance, 65.0 grams of amalgam 

 gave 0.0013 gram of Fe 2 O 4 ; solubility 0.00135 per cent. In the second, 

 143.0 grams gave 0.0027 grams of Fe 2 O 3 ; solubility 0.00133 per cent. 



Thus the solubility of iron in mercury can not greatly exceed I milli- 

 gram in loo grams. There is no proof that even this small trace might 

 not have percolated in the solid state through the leather. As the solu- 

 bility is so small, the investigation of the potential of iron amalgams was 

 not pursued further. 



43 Journ. Chem. Soc., 16, 378 (1863). 



