

Foreign Metals on the Electric Conducting Power of Mercury. 33 



The values given in columns 3 and 4 agree together as well as 

 * can be expected when we consider that we have assumed that the 

 conducting power of mercury takes part in that of its amalgams 

 in the ratio of the volumes of mercury employed, and that we have 

 merely taken the mean of the values deduced from the experi- 

 ments, whereas it is obvious, from Table I., that, if the hypo- 

 thesis from which we started be correct, the conducting power of 

 a metal deduced from the conducting power of the alloy is no 

 constant value, but varies with the amount of metal added. 



With the solid alloys* (those which may be looked upon as a 

 solution of the one metal in the other) we find sometimes, — for 

 instance, with the lead-tin and cadmium-zinc alloys, — that the 

 conducting powers of the components take part in that of the 

 alloy in the ratio of their relative volumes. Sometimes, however, 

 we may assume that the conducting power of one component re- 

 mains unaltered whilst the other changes — for instance, lead-silver 

 and tin-silver alloys; and lastly, there are cases where the conduct- 

 ing powers of both metals are altered when forming an alloy — for 

 instance, gold-copper, gold-silver, and, in all probability, the 

 amalgams. 



The above-mentioned facts seem to indicate that the con- 

 ducting powers of the component metals of an alloy follow the 

 same laws whether the resulting alloy be a solid or a liquid 

 one, and that Dr. Siemens's hypothesis, from which we started, 

 viz. "that the conducting power of a fluid metallic mixture is in 

 proportion to the conducting power of the two metals in their fluid 

 state at the same temperature" [I. II.«], "and" (as he continues 

 in his paper already quoted) " that the reason of the great de- 

 crement in the conducting power of solid alloys is only to be looked 

 for in the process of solidification" [11.6,111. & IV.], is not sup- 

 ported by any facts. 



It is our intention to discuss these points more fully in our 

 paper " On the Influence of Temperature on the Electric Power 

 of Alloys," which will be shortly ready for publication ; for we 

 think we shall now be able, with the help of some new data 

 we are gaining, to calculate from former experiments the parts 

 which the conducting powers of metals take in that of their 

 alloys. We are already able to deduce in a great many cases 

 from the determination of the conducting powers of two metal 

 alloys at 0° and 100°, the percentage amount of the metals com- 

 posing them. 



Mr. Sabine remarks, p. 459, "Dr. Siemens gave the calcu- 

 lated conductibility of fluid silver from three experiments, 8*8, 9*3, 

 and 7*8, taking mercury as unit. These numbers do not differ 



* Assuming that the conducting power of an alloy is equal to that of 

 parallel wires of the components forming it. 



Phil Mag. S. 4. Vol. 24. No. 158. July 1862. D 



