on the Conducting Power of Mercury, 



459 



powers of the various metals in their solid states in conjunction 

 with that of fluid mercury. 



As it is important to know which of these opinions is right, I 

 have calculated the conducting powers of the foreign metals from 

 all the tests in the given Tables, and set their means in column B 

 of the following 



Table of Conducting Powers of Metals in Amalgam. 







Conducting powers. 



Table. 













B (calculated). 



Matthiessen. 



I . . 



Bismuth 



37-25 



7-91 



II . . 



Lead . . 



61-31 



52-64 



Ill . . 



Tin . . . 



75-16 



78-51 



IV . . 



Zinc . . 



92-99 



18406 



V . . 



Gold . . 



109-89 



494-68 



VI . . 



Silver . 



61-46 



633-33 



The comparisons are made with the gold- silver alloy of Dr. 

 Matthiessen, the conducting power of which, at 0° C, is taken 

 at 100. 



The opinion of Dr. Siemens with regard to the conducting 

 powers of dissolved metals is therefore corroborated qualitatively 

 by these tests of the amalgams of gold, silver, tin, and zinc, the 

 conductibilities of which are all less in a melted than in a solid 

 state, but opposed by those of lead. The results of the tests 

 of bismuth-amalgam is also qualitatively corroborative of Dr. 

 Siemens's opinion, as the conductibility of melted bismuth is 

 greater than that of mercury at the same temperature. 



Dr. Siemens gave the calculated conductibility of fluid silver 

 at 15° C. (the temperature of the amalgams he tested) from 

 three different experiments, respectively 8*8, 9*3, and 7*8, com- 

 pared with the conductibility of mercury as unit. These num- 

 bers do not differ so materially from 5 '64, the value given in 

 col. B reduced to the same standard, when we consider that the 

 conducting power of solid silver, according to Dr. Matthiessen, 

 is no less than 58*05, and according to Dr. Siemens 64*38. 



The results of Dr. Siemens' s calculations of the conducting 

 power of fluid zinc at about 20° C, from three measurements 

 with zinc-amalgams given in the same paper, are 11*2, 12*7, and 

 11*2 respectively. Corresponding results from my calculation 

 of Drs. Matthiessen and Vogt's experiments (col. B), reduced to 

 the same standard, is 8*5, while the conductibility of solid zinc 

 is 16-9. 



It is evident, therefore, that in no case are we entitled to take 

 the conductibility of metals in their solid states into our calcu- 

 lations of fluid amalgam resistances. 



