272 Tables 277, 278. 



CONDUCTIVITY OF ELECTROLYTIC SOLUTIONS. 



This subject has occupied the attention of a considerable number of eminent workers in 

 molecular physics, and a few results are here tabulated. It has seemed better to confine the 

 examples to the work of one experimenter, and the tables are quoted from a paper by F. Kohl- 

 rausch,* who has been one of the most reliable and successful workers in this field. 



The study of electrolytic conductivity, especially in the case of very dilute solutions, has fur- 

 nished material for generalizations, which may to some extent help in the formation of a sound 

 theory of the mechanism of such conduction. If the solutions are made such that per unit 

 volume of the solvent medium there are contained amounts of the salt proportional to its electro- 

 chemical equivalent, some simple relations become apparent. The solutions used by Kohlrausch 

 were therefore made by taking numbers of grammes of the pure salts proportional to their elec- 

 trochemical equivalent, and using a litre of water as the standard quantity of the solvent. Tak- 

 ing the electrochemical equivalent number as the chemical equivalent or atomic weight divided 

 by the valence, and using this number of grammes to the litre of water, we get what is called 

 the normal or gramme molecule per litre solution. In the table, m is used to represent the 

 number of gramme molecules to the litre of water in the solution for which the conductivities 

 are tabulated. The conductivities were obtained by measuring the resistance of a cell filled with 

 the solution by means of a Wheatstone bridge alternating current and telephone arrangement. 

 The results are for i8° C, and relative to mercury at o° C, the cell having been standardized by 

 filling with mercury and measuring the resistance. They are supposed to be accurate to within 

 one per cent of the true value. 



The tabular numbers were obtained from the measurements in the following manner : — 



Let A',8 = conductivity of the solution at i8° C. relative to mercury at o° C. 



A'J", = conductivity of the solvent water at iS° C. relative to mercury at o° C. 

 i Then K^^ — JC^g = k^^ = conductivity of the electrolyte in the solution measured. 



-iS. = fi = conductivity of the electrolyte in the solution per molecule, or the " specific 

 tn 



molecular conductivity." 



TABLE 277.— Value of ku lor a lew Electrolytes. 



This short table illustrates the apparent law that the conductivity in very dilute solutions is proportional to the 



amount of salt dissolved. 



TABLE 278.— Electro-Chemical Eanlvalents and Normal Solntlona. 



The following table of the electro-chemical equivalent numbers and the densities of approximately normal solutions 

 of the salts quoted in Table 271 may be convenient. Tliey represent grammes per cubic centimetre of the solution 

 at the temperature given. 



Smitnsonian Tables. 



• " Wied. Ann." vol. 26, pp. 161-226. 



