422 MM. F. Kohlrausch and 0. Grotrian on the Electric 



If we now consider, secondly, the dependence of the conducting^ 

 power on the amount of salt or acid contained } the only thing 

 common to all the substances investigated appears to be the 

 constancy of the variation. The annexed figure exhibits this 

 better than the numbers in the Table. It has for abscissae the 

 percentage contents, and for ordioates the conducting-powers at 

 18°. LiCl, so far as it was investigated, very nearly coincides 

 with NaCl, and is therefore not delineated. 



Both the absolute quantities of the conducting-powers and the 

 laws according to which they depend on the content vary to a 

 degree which is surprising in bodies which stand chemically 

 so near one another. CaCl 2 has a maximum (at 24 per cent.), 

 and so has MgCl 2 (at 20 per cent.). NaCl seems to go towards 

 one ; but it is questionable whether it reaches it before satura- 

 tion (25'5 per cent.). The curve for SrCl 2 is moderately curved ; 

 those for BaCl 2 and NH 4 CI are less so ; with KC1 the conducting - 

 power at 18° is almost exactly proportional to the salt-content. 

 Indeed, from the Table for 0° it is seen that at this temperature 

 the conducting-power of the KC1 solution increases somewhat 

 faster than the percentage strength, which has not, till now, been 

 observed in any liquid. 



As the above-mentioned minimum of the temperature-coeffi- 

 cient (see p. 421) and the maximum of conducting-power belong 

 to the same liquids, the two properties appear to have an inti- 

 mate connexion. 



In general BaCl 2 is the worst conductor; by far the best is 

 NH 4 C1, which in a 25-per-cent. solution conducts about half as 

 well as the best-conducting acids known, and, at all events, is 

 the best among all known salts. It is to be presumed, since the 

 solubility of NH 4 CI increases considerably with the temperature, 

 that a solution saturated at 100° conducts at least as well as the 

 best-conducting acid at the same temperature. Accordingly by 



