388 PROPERTIES OF ELECTRICALLY CONDUCTING SYSTEMS 



tionships which otherwise are not apparent. 7 The atomic conductance 

 of potassium and of silver is of the order of 6 X 10 6 and that of mercury 

 at ordinary temperatures, which is a relatively poor conductor, 1.5 X 10 5 . 

 Compared with these values, the equivalent conductance of fused salts 

 is in the neighborhood of 50 and that of electrolytes at low concentra- 

 tions 100. In a few instances, the equivalent conductance of electrolytes 

 is considerably higher, as, for example, in aqueous solutions at high tem- 

 peratures, where it approaches a value of 1000, and in solutions of the 

 alkali metals in liquid ammonia at low concentrations. The above values 

 relate to the conductance of metals at ordinary temperatures. If a simi- 

 lar comparison were made at lower temperatures, the relative conduct- 

 ingf power of the metals would be found to be enormously greater. The 

 conductance of metals at very low temperatures will be discussed in 

 the next section. 



The conductance of elementary metals in the liquid state is, in gen- 

 eral, lower than in the solid state. The process of fusion is accompanied 

 by a discontinuous change in the conductance values. In the following 

 table are given the ratios of the specific conductances \i s /^ of metals 

 in the solid and liquid states, together with the ratio of their specific 

 volumes Vi/v s . 



TABLE CLIV. 



CHANGE OF THE SPECIFIC CONDUCTANCE OF ELEMENTARY METALS 



ON MELTING. 



Specific 

 Conductance 

 Melting at the 



Metal Point Melting Point H s /ty v l/ v s 



Lithium. 177.8 2.6 X 10 4 2.51 



Sodium 97.6 9.5 X 10 4 1.34 1.024 



Potassium 62.5 7.7 X 10 4 1.39 1.024 



Caesium. 26.4 2.54 X 10 4 1.65 1.027 



Zinc... 419. 2.7X10 4 2.0 >1 



Cadmium 321. 2.9 X 10 4 1.96 1.047 



Mercury 38.8 1.10 X 10 4 4.1 1.036 



Thallium.. 301. 1.35 X 10 4 2.0 



Tin 232. 2.1 X 10 4 2.2 1.028 



Lead 327. 1.06 X 10 4 1.95 1.034 



Antimony 629.5 0.88 X 10 4 0.70 



Bismuth 269. 0.78 X 10 4 0.46 0.967 



7 Richarz, Zfschr. }. anorp. Chew. 50, 356 (1908) ; Benedicks, JaJirb. f. Ro4, IS, 351 



