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XT. Bakerian Lecture.— The Effects of Temperature and Pressure on the 
Thermal Conductivities of Solids.—Part II* The Effects of Low 
Temperatures on the Thermal and Electrical Conductivities of Certain 
Approximately Pure Metals and Alloys. 
By Charles H. Lees, D.Sc ., F.R.S., Professor of Physics in the East London 
College , University of London. 
Received November 8,—Read in Abstract December 12, 1907,—Received in Revised 
Form, with Additions, March 24, and Read as Bakerian Lecture, March 26, 1908. 
[Plates 30-31.] 
During the last fifty years a considerable amount of attention has been bestowed on 
the question of the variations of the thermal and electrical conductivities of metals with 
the temperature, but the results obtained by different observers, especially of thermal 
conductivities, differed so widely from each other that the answer to the thermal 
part of the question long remained doubtful, f In recent years, however, there has 
been an accumulation of evidence in favour of a slight decrease of thermal con- 
ductivity with increase of temperature from 0° C. to 100° C. in the case of most of 
the metals. The experiments of Lorenz, | and more especially the careful work of 
Jager and Diesselhorst,§ have contributed greatly to this result. In both these cases 
the experiments were limited to the range of temperature between 0° C. and 100° C., 
and it Seemed advisable, in view of the importance of both questions in the electronic 
theories of conduction of heat and electricity in metals, to extend the range over 
which the theories could be tested, particularly in the direction of low temperatures, 
where the experiments of Dewar and Fleming || had already furnished information as 
to the electrical conductivities. The present paper contains an account of the 
measurements of the thermal and electrical conductivities carried out for this purpose, 
* Part I., “The Effect of Temperature on the Thermal Conductivities of some Electrical Insulators,” 
appeared in the ‘Philosophical Transactions,’ A, vol. 204, pp. 433-466 (1905). 
t A good account of the subject will be found in Graetz’s article in the new edition (1906) of 
Winkelmann’s ‘ Handbuch cler Physik,’ Band III. 
\ L. Lorenz, ‘Ann. der Physik,’ 13, p. 422 (1881). 
§ W. Jager and H. Diesselhorst, ‘Abh. d. Phys.-Techn. Reichsanstalt,’ 3, p. 269 (1900). 
|| J. Dewar and J. A. Fleming, ‘Phil. Mag.,’ 36, p. 271 (1893). 
vol. ccviii.—a 437. 
29.7.08 
