NEW YORK 



BOTANICAL 



UAKUtJil 



THE EFFECT OF PRESSURE ON THE THERMAL 

 CONDUCTIVITY OF ISIETALS. 



By p. W. Bridgman. 



Received Oct. 7, 1921. Presented Oct. 19, 1921. 



TABLE OF CONTENTS. 



Page. 



Introduction 77 



Description of Apparatus and Method 78 



Experimental Procedure 98 



Detailed Data 100 



Lead 100 Silver 110 



Tin 103 Nickel 110 



Cadmium 106 Platinum 113 



Zinc 107 Bismuth 114 



Iron 107 Antimony 116 



Copper 109 Petroleum Ether 119 



General Comment on Lussana's Results 122 



Discussion 123 



Summary 126 



IXTRODUCTION. 



It is known that there is an intimate connection between the 

 electrical and thermal conductivities of metals. This connection 

 finds expression in the constant value of the Wiedemann-Franz ratio 

 for different metals; the meaning of this is supposed to be that the 

 largest part of the heat transfer in metals is accomplished by the same 

 electrons which transfer the electricity in current conduction. I have 

 already measured the effect of pressure on the electrical resistance of a 

 large number of metals, and have drawn certain conclusions from the 

 results as to the mechanism of electrical conduction.^ It seemed that 

 it would be no less interesting to measure the effect of pressure on 

 thermal conductivity. This paper contains the results of measure- 

 ments of the effect of pressures to 12000 kg/cm^ on the thermal con- 

 ductivity of lead, tin, cadmium, zinc, iron, copper, silver, nickel, 

 platinum, bismuth, and antimony at 30° C. 



At the time that I undertook these measurements this was an en- 

 tirely untouched field; not even the sign to be expected for the effect 

 was known. Since starting this work, measurements have been 

 published by Lussana ^ on the effect of pressures to 3000 atmospheres 



