417 
electrical and chemical changes. 
powers to the poles of the battery, the virtual change may be 
regarded as taking place in the two extremities of these 
zones nearest the neutral point ; so that by a series of decom- 
positions and recompositions, the alkaline matters and hydro- 
gen separate at one side, and oxygen, pure or in union, at 
the other. 
In this way, the two electricities may be regarded as the 
transporters of the ponderable matters, which assume their 
own peculiar characters at the moment they arrive at the 
point of rest. I shall detail an experiment which I made 
under a different form some years ago, and which may assist 
the imagination in the conception of this singular and mys- 
terious mode of action. A flat glass basin, 10 inches in dia- 
meter, was filled with water containing -^^ndth part of its 
weight of sulphate of potassa, in the bottom of which 30 or 
40 separate globules of mercury, containing from 10 to 100 
grains each, were placed without any regard to order ; two 
wires of platinum from a battery of 1000 double plates, 
weakly charged, were made to connect the extremities of the 
water (passing to the bottom of the basin.) As soon as the 
electrical communication was made, the globules of mercury 
in or near the current became instantly agitated ; their nega- 
tive poles became elongated, and approached either the posi- 
tive pole of the battery, or the positive pole of the contiguous 
globules of mercury, and streams of oxide flowed with great 
rapidity from the positive toward the negative pole. No 
hydrogen appeared at the negative poles of the globules of 
mercury ; but after the action had continued a few minutes, 
and was then suspended, there was an appearance of some 
