276 Upon Caloric as a Canse of Galvanic Currenis. | 
negative current by an accumulation of caloric. ‘This metal, there- 
fore, like antimony, governs its combinations according to the ele- 
mentary electricity peculiar to itself, and which always exhibits the 
positive current moving in opposition to the caloric. 
The other metals are intermediate, in their power, between these 
two; and, we find one or other of the foregoing laws prevailing ac- 
cording to the nature of the combinations. 
_ Arsenic is, most decidedly, a regulating metal, and its influence 
is in accordance with the elementary condition, as Jaid down in the 
. There it is stated that an increase of heat enables this metal 
to transmit to the galvanometer a positive current, and when associ- 
ated, it is found to act most powerfully whenever it is colder than the 
other metals, previous to contact. Indeed there is little or no effect 
if the caloric is made to proceed from the arsenic, except’in the ca- 
ses of bismuth, nickel and mercury. In every instance the positive 
current passes through the arsenic, when the caloric does so, but the 
polarity is inverted when the hot metal is made to touch cold antimo- 
ny. There is abundant evidence of a tendency towards the same 
inversion, when cold platinum, copper, silver, lead, tin, iron or zine 
is employed, because, under these circumstances, there is no current 
rendered manifest, and, accordingly, we may conclude that arsenic, 
like antimony, governs its combinations, excepting where bismuth, 
nickel or mercury enters as an element, by the law that calorie and 
the positive current move together. 
Mercury. The exact relation between unequally hehisd portions 
of this metal was not determined, owing to its fluidity, but a suffi- 
ciently close approximation may be obtained by amalgamating a 
piece of Jead until it becomes able to sustain a drop of mercury— 
another portion of the fluid metal is then to be heated in a vessel, 
over a spirit lamp, and after having connected both portions of the 
mercury with the galvanometer, the suspended drop is to be brought 
into contact with that which is heated. It will thus be perceived 
that the portion which receives the caloric, transmits the negative 
current. In its combinations with other metals, the mercury usual- 
ly receives caloric, and when by previous heating, it is made to give 
it out, upon contact, its power is obviously diminished. In two or 
three cases the polarity even becomes inverted. 'Thus, cold mer- 
cury is negative, as to the current, with hot zinc, but positive when 
the zinc receives the caloric. ‘Tin and silver seem to furnish similat 
