fluid conductors when transmitting the electric current. 195 
contact of a metal capable of amalgamating, even for an in- 
stant, communicates its peculiar properties, almost in the mo- 
ment of contact, to the whole mass. The experiments in Art. 
33, abundantly prove this ; and it may be readily shown also 
by the following. Let a quantity of mercury be placed in a 
vessel of muriatic acid ; no action takes place ; but if touched 
with a zinc wire it presently becomes covered with bubbles, 
copiously disengaged from every part of the surface. 
60. In the circumstances of M. Serrulas’s experiments, it is 
therefore obvious that his mercury must have been always 
sensibly impregnated with potassium and the supernatant 
liquid, a solution of potash ; and that it was so, is proved by 
the effects of the electric current, which agree precisely with 
those I have stated, as being always produced in such cir- 
cumstances (Articles 18, 28 ;) but the cause assigned to these 
effects by Mr. S. viz. the electro- positive energy of the pellicle , 
is proved not to be the real one by the simple fact, that the 
violence of the motion is always proportional to the cleanli- 
ness of the surface, and is greatest when there is no pellicle at 
all ; besides which, the pellicle here consisted of metallic bis- 
muth, a substance incapable of producing any such effect as 
shown in Art. 38. 
61. The gyration of the fragments is produced as follows : 
a strong Voltaic excitement takes place at the point of contact 
of two metals so different as mercury and potassium. The 
mercury becomes strongly positive, and the floating frag- 
ments negative. The circuit is completed by the alkaline 
liquid ; and the mercury, being alloyed with a portion of po- 
tassium, and being itself the positive pole of the combination, 
we have here the case of Art. 21 ; and the result, as stated 
