I9II.] 



AGGREGATES OF ELECTRONS. 



349 



between the two phenomena is. 

 columns of figures are shown. 



In the accompanying table two 



Material. 



Copper, commercial 



Copper (T) pure 



Copper (2) pure 



Silver, pure 



Gold (I) 



Gold ( 2) pure 



Nickel 



Zinc ( i) 



Zinc (2) pure 



Cadmium, pure 



Lead, pure 



Tin. pure 



Aluminium 



Platinum (i) 



Platinum (2 ) pure 



Palladium 



I ron ( I ) 



Iron (2) 



Steel 



Bismuth 



Constantan (6oCu, 40Ni) ... 

 Manganin (84CU, 4Ni, i2Mn) . 



Ratio: Thermal Conductivity, 

 Electrical Conductivity. 



at 18° C. 



6.76 X 

 6.6s X 



6.71 X 

 6.86 X 

 7.27 X 

 7-09 X 

 6.99 X 

 7-05 X 



6.72 X 

 7.06 X 



7.15 X 



7-35 X 

 6.36 X 



7.76 X 



7-53 X 



7.54 X 



8.02 X 

 8.38 X 

 9-03 X 

 9.64 X 

 11.06 X 



9.14 X 



at 18° C. 



at 18° C. 



at 18° C. 



at 18° C. 



at 18° C. 



at 18" C. 



at 18° C. 



at 18° C. 



at 18° C. 



at 18° C. 



at 18° C. 



at 18° C. 



at 18° C. 



at 18° C. 



at 18° C. 



at 18° C. 



at 18° C. 



o'" at 18° C. 



o^" at 18° C. 



0'" at 18° C. 



o"' at 18" C. 



Temperature 



Coefficient of 



this Ratio, 



Per Cent. 



They represent the results of measurements by Jaeger and Dies- 

 selhorst of the electric and thermal conductivities of a large number 

 of metals and alloys. The first column of figures gives the ratio of 

 the thermal to the electrical conductivitv for each of these substances 

 and the second gives the percentage change of this ratio when the 

 temperature is increased one degree. It will at once be noticed that 

 the numbers in each column are almost equal, particularly if we 

 keep to the pure metals. Thus for every pure metal the electrical 

 conductivity bears to the thermal conductivit}- a proportion which is 

 almost independent of the metal : and the ratio of the thermal con- 

 ductivity to the electrical conductivity increases by almost the same 

 amount for one degree rise of temperature for each metal. The 

 coefficient of increase of this ratio with increase of temperature is 

 also very nearly equal to the coefficient of increase of the volume of all 

 gases with temperature, when the pressure is maintained constant. 



