On the Conductivity of Mercury and Amalgams. 541 



was twenty grammes. The fused alloys were cast in a form and 

 very thin, to avoid internal cavities from crystallization. Three 

 separate determinations were made of their specific gravity, which, to- 

 gether with the mean result, are given in Tables. In every case the 

 alloy was recast at least three times before the first determination, and 

 once again before each succeeding one. The distilled water used 

 in the weighing was first boiled and allowed to cool in vacuo, and 

 the alloys were suspended in it by a fine platinum wire, except the 

 soft amalgams, which were weighed in a tube similarly suspended. 

 In calculating the specific gravities, the weight of water displaced 

 was corrected for the temperature, the unit in all cases being distilled 

 water at 0° C. All the weighings were reduced to a vacuum, and 

 a correction was made for the platinum wire which dipped in the 

 water. 



The numerical results are stated in three Tables, of which the first 

 gives the specific gravities of the pure metals employed, and the 

 temperature in Centigrade degrees ; the second gives the same of 

 the alloys ; and the third exhibits the mean specific gravities found, 

 and the specific gravities as calculated, — 1, from the volume of the 

 metals forming the alloy ; 2, from their equivalent ; and 3, from 

 their weight. 



From the last Table it appears that the alloys of antimony are 

 greater in volume than the aggregate of the constituent inetals, while 

 those of bismuth, silver, and gold are less. The following alloys ex- 

 pand greatly on cooling, viz. all those of bismuth-antimony, bismuth- 

 gold, and bismuth-silver, which were experimented on ; those of 

 bismuth-tin, from Bi^ Sn to Bi.^ Sn, the rest of the series very slightly ; 

 and bismuth-lead, viz. Big Pb and Bi^ Pb (Bi^ Pb slightly), the rest 

 apparently not at all. Of the bismuth-cadmium scries. Big Cd and 

 Bi Cdj expand very slightly, the rest not at all. The zinc-alloys are 

 all so very crystalline that no results of value were obtained re- 

 specting them. 



"On the Conductivity of Mercury ar\d Amalgams." By F. Grace 

 Calvert, Esq., and R. Johnson, Esq. 



The object of the researches described in this paper, was to carry 

 out with reference to amalgams the investigations relative to alloys 

 contained in a former paper. In comparing the results of theory 

 and experiment in the manner followed in the former paper, the 

 conducting power of mercury itself was a constant, which it was 

 essential to know. The figure given in the former paper was 

 mercury = 677, on the scale silver=1000. On adopting in the first 

 instance this value of the conducting power of mercury, the results 

 obtained with alloys, which consisted mainly of mercury, appeared 

 very anomalous ; it seemed as if a very small per-centage of even the 

 best conducting metals reduced immensely the conducting power of 

 mercury. But it was suggested to the authors, that the a|)parcntly 

 high conducting power of mercury obtained by their method, was 

 proljal)ly due to the transference of heat by convection ; that the 

 real conducting power of mercury for heat was low, like its conduct- 



