178 Proceedings of Royal Society of Edinburgh. [sess. 
entitled “ Gedanken liber eine vielleiclit vorhandene Moglichkeit, 
Molekulargewichte der Metalle nach zwei neuen Methoden zu 
bestimmen.” The same subject was also attacked independently 
by G. Meyer ( Zeits . f. physikal. Chem ., vii. 477), who con- 
structed concentration cells of zinc, cadmium, lead, tin, copper, 
and sodium amalgams. Knowing the concentrations of the solu- 
tions of the metals in mercury (p and pf he was able (on the 
assumption, which has been confirmed by an independent investi- 
gation, that the metals dissolve in mercury in the atomic state) to 
calculate the electromotive force of the cells with the help of the 
above formula. Kot only was the agreement between the found 
and calculated values of the electromotive force of the cells good, 
but the variation with temperature corresponded with the theory. 
If the hydrogen occluded by palladium is simply dissolved or 
amalgamated with the palladium it ought to be possible to con- 
struct a hydrogen concentration cell, composed of palladium con- 
taining a small quantity of hydrogen, an electrolyte containing 
hydrogen ions (i.e., an acid), palladium containing a large quantity 
of hydrogen, and if the calculated electromotive force of such a cell 
agreed with the experimental value, then we would have pretty 
conclusive evidence that the phenomenon of occlusion was simply 
one of solid solution. 
Up to the present all attempts to work concentration cells with 
different alloys, other than liquid alloys or amalgams, have proved 
a total failure. The reason of this is not far to seek. It may be 
due to the non-homogeneity of the alloy from the very beginning ; 
or, assuming that we could start with a perfectly homogeneous 
alloy, the moment it is dipped in the electrolyte there will be 
either a deposition on the surface of the electrode of the consti- 
tuent metal which forms the electrolyte, or one of the metals 
composing the alloy will be dissolved out of the surface of the 
electrode, leaving the other exposed, so that we would practically 
get the electromotive force of the exposed metal. In the case of 
solid alloys diffusion is so slow as to be nearly negligible, whereas, 
in the case of liquid alloys or amalgams, it can take place with 
greater ease. It was hoped that in hydrogenised palladium diffu- 
sion throughout the mass would take place with as great ease as in 
liquid amalgams, and that the above source of difficulty would not 
