Upon Caloric as a Cause of Galvanic Currents. 273 
These results, satisfactorily prove, that the metals are capable of 
assuming either state of electricity, according to the direction which 
the caloric takes, and it will be seen that the effect of association be- 
tween dissimilar metals, is dependent upon these elementary forces. 
The order, above given, can be accurately represented only by a 
measurement of the deviations from the magnetic meridian, as indi- 
cated by the galvanometer needle; this, however, I have not been 
able, hitherto, to execute with the requisite degree of precision, and 
all, therefore, thatis here aimed at, is the representation of the gene- 
ral electrical states of the different metals, under the same conditions 
of heat. . 
It is obvious, although there are exceptions which will be noticed 
presently, that the electricity, thus generated by caloric, corres- 
ponds with the chemical habitudes of some of the metals. ‘Thus an 
increase of heat makes Jead, zinc, iron, &c. transmit a negative cur- 
rent, and these metals may, therefore be regarded as becoming more 
positive by the operation, the result of which is an increased affinity 
for electro-negative elements, such as oxygen, so as to render them 
not only easy of oxidation, but difficult of reduction, when exposed 
‘ tomere heat: whereas platinum and silver by becoming more 
tive, at high temperatures, must exhibit a facility of reduction, and 
other properties the opposite of the former metals. Modifications of 
this law, arising from volatility, fusibility, &c. must always occur, but 
still the conclusion will be an important one, if it can be shown, by 
any experimental process, that bodies possess a susceptibility for both 
electrical states, depending upon the amount of free caloric within 
them, and not wholly upon the contact of dissimilar matter. 
The galvanometer, however, indicates formidable exceptions to 
this rule, which must not be passed over. - Antimony, for instance, 
stands first among those metals whose particles, by an increase of 
heat, transmit a positive current, and it may, therefore, be regarded 
as becoming more negative by the process.—Yet antimony is easily 
oxidated when heated. The volatility of this metal will, in a great 
degree account for this result, since it becomes covered with crystals 
of the oxide at a temperature much below that necessary to make 
it obscurely red hot; but the well known attraction which cold anti- 
mony, in powder, bn for chlorine, another electro-negative element, 
does not admit of so favorable an adjustment. 
The position of gold, moreover, does not indicate its: chemical 
habitude, since it occurs among the metals which are made positive 
Vou. XXV.—No. 2. 35 
