Dr. Draper on the Electro-motive PoVoer of Heat, 453 
The metals I have tried were in the form of wires. They 
w^ere in the state found in commerce, and therefore not pure; 
they were obtained in the shops of Philadelphia. 
Table I. 
Names of the pairs of Metals. 
Temperatures (Fahr.) 
32 F. 
122 F. 
212 F. 
662 F. X 
Copper and iron 
0 
93 
176 
2331 1 
Silver and palladium... 
0 
65 
147 
613 II 
Iron and palladium .... 
0 
112 
223 
631 1 '3 
122 f s 
Platina and copper 
0 
11 
26 
Iron and silver 
0 
89 
137 
244 1 -t 
Iron and platina 
0 
28 
56 
248J 1 
a 
In this table I have estimated the temperature of boiling 
mercury at 662° Fahr. The quantities of electricity evolved, 
as estimated by the torsion of a glass thread, are ranged in 
columns under their corresponding temperatures. Each series 
of numbers is the mean of four trials, the differences of which 
were often imperceptible, and hardly ever amounted to more 
than one degree. 
Now if this table be constructed, the temperatures being ran- 
ged along the axis of abscissas, and the quantities of electricity 
being represented by corresponding ordinates, we shall have 
results similar to those given in fig. 2, in which it is to be ob- 
served, that the curves given by the systems of silver and 
iron, copper and iron, and palladium and iron, are concave 
to the axis of abscissas ; but those given by platina and copper, 
silver and palladium, and platina and iron, are convex. 
Let us now apply the numbers obtained by these several 
pairs, for the calculation of temperatures, which will set their 
action in a more striking point of view. The following table 
contains such a calculation, on the supposition that for the 90 
degrees from 32° Fahr. to 122° Fahr., the increments of elec- 
tricity are proportional to the temperatures. 
Table II. 
Temperatures by the Mercurial Thermometer. 
32 F. 1 
122 F. 
Water boils. 
Mercury boils. 
!>, ^Copper and iron 
32 
122 
202 
257 
■S<g j Silver and palladium 
32 
122 
235 
880 
1 Iron and palladium .. 
32 
122 
211 
539 
S S'! Platina and copper... 
32 
122 
244 
1030 
S I Iron and silver 
32 
122 
170 
279 
H LIron and platina 
32 
122 
212 
829 
