Dr. Draper on the Electro-motive Poller of Meat. 453 



The raetals I have tried were in the form of wires. They 

 were 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. >. 



Copper and iron 





 

 





 

 



93 



65 



112 



11 



89 



28 



176 



147 

 223 



26 

 137 



56 



233") 1 



613 a 



631 , =3 



122 ' s 

 244 1 -t 

 248J 1 



Silver and palladium... 

 Iron and palladium .... 



PJatina and copper 



Iron and silver 



Iron and platina 



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. 



122 F. 



Water boils. 



Mercury boils. 



>, j-Copper and iron 



%■-. Silver and palladium 

 = .j: Iron and palladium .. 

 a =■'' Platina and copper... 

 S*^ Iron and silver 



32 

 32 

 32 

 32 

 32 

 32 



122 

 122 



122 

 122 

 122 

 122 



202 

 235 



211 

 244 

 170 

 212 



257 



880 



539 



1030 



279 

 829 



H LIron and platina 



