36 



On the Electric Conducting Power of Mercury. 



same amalgam twice in different tubes of different lengths and 

 diameters, the same amount of filtration should occur in both 

 cases. The great concordance in most of the values obtained 

 with amalgams of the same composition proves, we think, con- 

 clusively that no such error was made in our experiments : this 

 also proves that the amount of the metal oxidized during the 

 process of heating the amalgams was so small that it has no 

 influence on the values obtained. For, looking at the values 

 deduced for the conducting power of tin from the tin amalgams, 

 published in a former paper* (I.), and on comparing them, as 

 shown in Table IV. with those deduced from the amalgams in 

 our paper (II.), we find them almost identical. 



I 



Tab] 



• 



^eIV. 



I. 



Volumes per cent, of 



Deduced conducting 



Volumes per cent, of 



Deduced conducting 



tin. 



power of tin. 



tin. 



power of tin. 



00186 



107-6 



00186 



1150 



00372 



94-1 



00465 



873 



00930 



87-1 



00930 



83-4 



0-186 



80-2 



0-186 



81-6 



0-372 



78-8 



0-371 



81-3 



0-926 



77-2 



0-922 



78-0 



1-84 



62-6 



1-83 



591 



3-66 



49-4 



3-59 



50-1 



719 



430 



6-93 



43-5 





75-5 





75-5 



With regard to the remarks respecting the analysis of the 

 contents of the tube, we would only state that such analyses 

 would be exceedingly difficult ; and it appears to us very doubtful 

 whether they could be made with nearly so great accuracy as the 

 weighing out of the two pure metals and alloying them together. 



It is also very doubtful whether, in Dr. Siemens ; s experiments 

 with the silver amalgams, he did not have in different parts of 

 his tube amalgams of different composition ; for they were forced 

 into it by means of a small pressure-pump. We must not over- 

 look one fact of importance, viz. that Mr. Sabine has not taken 

 into consideration whether the alloys partially solidify on cooling 

 or not, but deduces the values for the conducting powers of the 

 metals in a " liquid state " from all the observations. 



In conclusion, Mr. Sabine remarks (page 459) that we ought 

 not to have taken into our calculations of the conducting powers 

 of the amalgams the conducting powers of the metals in their 

 solid state with that of fluid mercury. The calculated conduct- 



* Phil. Mag. September 1861. 



