HALL. — ELECTRIC CONDUCTION AND THERMOELECTRIC ACTION. 101 



TABLE Y. 



For 0° C. 



The method by which the numbers of column 5 are found may be 

 shown by an example. We have for aluminium 



(1) Coef. of cubical expansion = 70 X 10 -6 . 



(2) " " compressibility = 133 X 10" 8 . 



.'.No. of atm. (cm 2 kg) to keep v const, during 1° heating 



= 70 -T- 1.33 = 52.5. 

 f3) Compression coef. of resistivity = 43 X 10~ 7 . 

 .". Decrease ( — dw/w) of resistivity caused by 52.5 atm. 

 = 43 X 10- 7 X 52.5 = 226 X 10- 6 . 



(4) Temp. coef. (p const.) of resistivity = 40 X 10~ 4 . 



(5) Temp. coef. (v const.) of resistivity 



= 40 X 10- 4 — 226 X 10- 6 = 37.7 X 10- 4 . 



From the data given by Barus 27 the following statement for liquid 

 mercury is derived: 



27 Bulletin of the U. S. Geol. Survey, No. 92, 74 (1892). 



