458 Mr. R. Sabine on the Influence of Traces of Foreign Metals 



carefully through the above paper, and have arrived at the 

 results which follow. 



"When, from the formula given by Dr. Siemens in his paper 

 " Ueber Widerstandsmaasse und die Abhangigkeit des Leitungs- 

 widerstandes der Metalle von der Warme*/' 



wsm 



we develope the value of the conducting power of the amalgam, 

 substitute volumes instead of weights divided by specific 

 gravities, and set C = the specific conducting power of mercury 

 instead of unity, we get the simple formula 



A =*m +c ( l -m)> 



in which A is the conducting power of the amalgam, and B that 

 of the dissolved metal. 



With this formula (based on the supposition that the con- 

 ducting power of an amalgam is equal to the sum of the con- 

 ducting powers of two parallel wires of the metals composing 

 it) it would seem that Drs. Matthiessen and Vogt have also 

 reckoned the numbers given in their columns headed " conduct- 

 ing power calculated ; " for, in so far as the first four Tables go, 

 the results agree perfectly with the formula. In the remaining 

 two Tables, however, Drs. Matthiessen and Vogt, for no assigned 

 cause, forsake the formula by which their former results were 

 calculated, and give us, in the u conducting powers calculated " 

 of gold and of silver amalgams, only a tenth part of the value of 

 the first member in the equation making up the value of A. 



As the amount of this error (probably due to setting false 

 indices before the mantissse of their logarithms) is very con- 

 siderable, I give in four instances the corrected numbers. 



Amalgams. 



V. 



Conducting power. 



Error 

 per 

 cent. 



Observed. 



Calculated. 



Re-calculated. 



Silver-mercury . 

 Gold-mercury . . 





0-129 

 1-280 

 0007 

 0-700 



10-984 

 11-566 

 10-913 

 11-571 



10-978 

 11-581 

 10-913 

 11180 



11-715 



18-878 

 10-944 

 14-296 



6-3 

 38-6 



03 

 21-8 



In his paper above referred to, Dr. Siemens expresses his 

 opinion that the conducting power of a fluid metallic mixture is 

 in proportion to the conducting powers of the two metals in 

 their fluid state at the same temperature. 



Drs. Matthiessen and Vogt have taken into their calculations 

 of the conducting powers of their amalgams the conducting 

 * Poggendorff's Annalen, vol. cxiii. p. 91. 



