ON THE THERMAL AND ELECTRICAL CONDUCTIVITY 



OF SOFT IRON. 



By Edwin H. Hall. 



Received May 9, 1900. Presented July 17, 1900. 



Trirc general method used in the investigation of which this paper is 

 to give an account is set forth with much detail in two articles already 

 published.* Certain more or less important changes of apparatus or 

 procedure will be described and discussed later; but the main results 

 will first be given. 



The metal studied was Taylor (Yorkshire) wrought iron, recommended 

 to me by an engineer friend of much experience as the softest wrought 

 iron to be found in the Boston market. Chemical analysis showed the 

 following composition : — 



Iron 99.93 % 



Carbon 0.059 



The density was about 7.785 at 0° C. 



The values which I find for the thermal conductivity, k, of this* iron 

 are 



at 0.1528 28°. 2 C. 



" 0.1514 58°.3 C. 



if the specific heat of water at each of these temperatures is called 1. 

 This would give for the temperature coefficient 0.0003, very nearly. 



If the values of k are revised in accordance with the values proposed 

 by Winkelmann f for the specific heat of water at the given tempera- 

 tures, they become 



at 0.1513 28°.2 C. 



" 0.1511 58°.3 C. 



* Thermal Conductivity of Mild Steel, by E. II. Hall, These Proceedings, XXXI. 

 271, 1896 ; On the Thermal Conductivity of Cast Iron, by E. II. Hall and C. H. 

 Ay res, XXXIV. 283, 1899. 



t Part 2 of Vol. II. p. 340. 



