Upon Caloric as a Cause of Galvanic Currents. 271 
modes of investigation for both, has not only been productive of false 
general views, but has seriously retarded the developement of the 
laws which characterise galvanism. Volta’s very ingenious attempts 
to show that metals give rise to electricity by contact, are of .this 
character, inasmuch as they lead to the conclusion that the activity 
of the pile is dependant upon ordinary electricity ; whereas no such 
result will be obtained, if we view these electricities in other res- 
pects. It seems to be no small perversion, to use the gold leaf elec- 
trometer for the analysis of a battery, composed of two metallic plates, 
when it is well known that this instrument, even with the assistance 
of doublers, is incapable of indicating the galvanic currents of a bat- 
tery composed of several hundred plates. Yet such was the instru- 
ment in common use, until Oersted pointed out the value of the 
magnetic needle. Even now, that we possess this highly appropri- 
ate and delicate indicator, we incline strongly to confound ordinary 
electricity with galvanism, notwithstanding that the former, in its most 
concentrated condition, has no marked influence upon the galvanom- 
eter. Whatever may be our inclination to generalize, these simple 
instruments can alone sustain the opposition, since each one is ex- 
cessively delicate towards its appropriate fluid, and absolutely good 
for nothing, for the other. Very many circumstances might be men- 
tioned, in order to prove that common and voltaic electricities should 
be considered, in our investigations, as essentially different ; and the 
late discoveries with the magnet seem to point strongly to some ulte- 
rior and elementary condition, which must certainly, ere long, give 
us more correct views, and, most probably, mark the distinction, here 
noticed, more closely. 
To this limitation I shall confine myself, at all ous, and wherever 
the term electricity may appear in my remarks, it must be under- 
stood to refer to galvanism, unless the contrary be stated. The ex- 
periments were made with a galvanometer consisting of about one 
hundred coils, and constructed like the multiplier. 
The simplest view of the relation, existing between caloric and 
galvanism, is presented by thermo-electric combinations: I shall, 
therefore, proceed first, to this portion of the subject and reserve my 
remarks upon hydro-electricity, or that produced by metals and chem- 
ical solutions for a subsequent communication. 
Thermo-electricity_We are indebted chiefly, to the investigations 
of Cumming, Becquerel and Nobili, for most of the particulars 
which relate to the electric powers of combined metals, when exposed 
to heat, and it appears clear from their results, that the currents 
