74 Messrs. J. W. Swan and J. Bhodin. Absolute [May 24, 



The absolute specific resistance in C.G.S. units was calculated from 

 the above numbers as follows. The resistance in ohms of the 

 measured wire -at any temperature is found by using Equation 

 No. 2 : 



From the definition of the B, and that of specific resistance in 

 C.G.S. units, formula 5 is deduced: 



(5.) . = X.^10 9 , 



where r = radius of the wire in centimetres. 



Z = length 



If the value of X as given in Equation No. 2 is substituted in 

 Equation No. 5, the following is obtained : 



(6.) a = < 



In the previous table if G x is read as in the last column, the follow- 

 ing will be the values for the various elements of Equation No. 6 : 



R B = 8000 B.A. units for all observations. 



B x = 2000 



S = 17-3 



B = 1 ohm. 



G K = 1240. Scale divisions for all observations. 



r At 15 C. But, according to Mat- 



2r = 0'05151 cm. J thiessen, no correction is made 

 I = 250* for the variation of these con- 



*- stants. 



In Equation No. 6 everything is constant except a and G x , and the 

 equation results in the following, when the numerical values as above 

 are substituted for the general expressions : 



(7.) a = 1-6906 



log 1-6906 = 0-2280258. 



The specific resistance in C.G.S. units of the hard-drawn rocking 

 tank A deposit at any temperature can therefore be calculated by 

 making use of the values given in the above table. In order to find 

 the specific resistance at C. it is necessary to calculate the tempera- 

 ture coefficient (A^) from the above observations. The method of 



