178 On the Electric Conducting Power of Mercury. 



with very minute quantities of another metal, with the exception 

 of zinc, has a greater conducting power ; but when alloyed with 

 larger quantities, has a lower conducting power than the mean 

 of the conducting powers of their relative values. 



That zinc behaves differently from other metals when alloyed 

 with mercury is what might have been expected; for zinc will 

 only alloy with mercury to a small extent, just as it does with 

 lead and bismuth* ; for when zinc is melted with either lead, 

 bismuth, or mercury, they separate, after having been well 

 mixed together by stirring, immediately into two layers, — the 

 upper one being zinc alloyed with small quantities of the other 

 metal, and the lower one being the other metal alloyed with 

 small quantities of zinc. 



Does mercury stand alone in its behaviour when alloyed with 

 traces of other metals? Is it the only one whose conducting 

 power increases with traces of foreign metals to such an extent 

 that it is greater than the calculated one, or is this a property 

 of all metals in a liquid state ? The following experiments prove 

 that in all probability mercury is the only metal that behaves in 

 this manner. 



I. Tin was melted in tubes, as above described, in a bath of 

 Rose's metal. The tubes were about 150 millims. long. The 

 metal was first fused in the one arm of the tube, this lying at first 

 somewhat inclined in the bath to prevent the metal from flowing 

 in the thermometer-tube; when fused, it was sucked up the 

 length of tube, and heated copper wires placed in it. It was 

 found that the copper wires might be removed and replaced 

 without materially affecting the conducting power. The alloys 

 were made by first filling the tubes with tin and determining its 

 resistance, and then adding traces of other metals (from 0*125 to 

 4 per cent.) to it in the tube. The tube after each addition was 

 slightly inclined several times, to allow the alloy to flow from 

 the one arm to the other, care being taken, as with the 

 amalgams, not to allow the thermometer-tube to become empty. 

 We only give the qualitative results obtained, as we do not 

 possess any means of measuring high temperatures with accu- 

 racy, as well as owing to the great difficulty in obtaining constant 

 values for the conducting powers of the melted metals and their 

 alloys. The qualitative results will, however, answer the ques- 

 tion we proposed. 



I. Tin, when fused, loses in conducting power with an increase 

 of temperature, but at the point of solidification increases 

 rapidly, as already observed by Siemensf, and just in the same 

 way as potassium and sodium J; and when solid, if allowed 

 * Proceedings of the Royal Society, vol. xi. p. 430. 

 t Poggendorff's Annalen, vol. cxiii. p. 91. 

 % Phil. Mag. February 1857. 



