312 Thermo-Electricity and Electro-Magnetism. 
by taking two pieces of bismuth and antimony in the fingers and sim- 
ply touching them ; 50°, 30° and 20° may also readily be obtained 
by the contact of bismuth with the other metals under like circum- 
stances. Examining some of my former results with this instrument, » 
I immediately discovered that I had assigned wrong places to anti- 
mony, arsenic and gold. The two former must be included with 
bismuth and other positive metals, while the gold falls in with the 
negative ones. 
Although the elementary conditions of the metals appear to be suf- 
ficiently constant, some very singular results follow, when dissimilar 
portions of metallic matter come into contact. Ihave shown that of- 
tentimes the voltaic currents are reversed, by reversing the direction 
of the caloric ; and subsequent research has furnished new and inter- 
esting particulars. With my present multiplier, 1 find that antimony 
and arsenic are capable of giving off both currents from contiguous 
portions of the surface, when heated and touched by other metals. 
These opposite electrical states seem to be connected with crystalli- 
zation or irregularity of surface, I cannot say which, and they disap- 
pear, at temperatures varying for each metal brought into contact. 
Thus, upon heating a bar of antimony and touching it, from time to 
time, as it cooled, by the other metals, I found the opposite currents 
to disappear, with silver at a temperature near 280° F'.—with gold, 
near 90°—with lead at 82°—whereas, with bismuth, these opposing 
currents might be traced even at the mean temperature. It is a most 
singular fact that they may be drawn off by the galvanometer wires, 
from portions of the antimony not more than } of an inch apart. 
They are constant, as to position, while they last. 
The next law, as it seems to me, is one of still greater interest. 
In all the metallic combinations which I have yet examined, I have 
observed that “ the voltaic currents produced by the contact of dis- 
similar metals, are the reverse of those occasioned by, the friction of 
the same metals.” Some combinations, as lead and tin, will scarce- 
ly produce currents under any circumstances, and bismuth and anti- 
mony are most effectual, but the law may be observed even between 
particles of the same metal, as bismuth. 
The two following tables are regarded as denoting with sufficient 
accuracy, some of the:thermo-electric relations. 
1st. When particles of the same metal, unequally heated, are 
brought into contact. 
