fluid conductors when transmitting the electric current. 179 
of the mercury is radiated in all direction s from the point of 
contact to the circumference of the globule, and that the 
whole of the hydrogen is given off at the other end of the 
wire where it touches the liquid. A little consideration will 
suffice, however, to show that both these effects are merely 
modifications of one and the same, It is not to, or from the 
wire as such, that the superficial particles radiate ; they 
merely follow the direction of the predominant electric cur- 
rents in their passage through the liquid. It is in fact the 
case of the source of positive electricity, being the mercury 
itself, instead of its being conveyed to it from a pile at a 
distance. 
27. Having thus distinctly traced the alteration in the me- 
chanical effect by contact with the negative pole, to the amal- 
gamation of the mercury with sodium, the knowledge of this 
fact led me to investigate more minutely the effects of diffe- 
rent metals in their contact and amalgamation with mercury ; 
and the results I have encountered in the course of these en- 
quiries, appear to me so remarkable, that I cannot forbear 
annexing them, especially as they afford an explanation of 
almost every anomaly which perplexed me in the com- 
mencement of the investigation. In order to render the effects 
less liable to objection, as well as more distinct and striking, 
I now used solutions of potash or soda, pretty highly impreg- 
nated with the caustic alkali, for the conducting liquid. This 
has the advantages at once of high conducting power, and 
of producing no currents whatever in pure mercury, neither 
pole being placed in contact. Of course, whatever motions 
arise on the introduction of an extraneous metal must be due 
entirely to the presence of that metal, and the mercury may 
