124 Conductivities and Viscosities in Pure and in Mixed Solvents. 



(3) In the case of trichloracetic acid, with increase in dilution from 

 



20 to 300 liters approaches -\l > and beyond 300 liters a relation 



JJ.V \ V 



obtains which can be expressed approximately by the dilution law. 

 The fact that the values of for solutions more concentrated than 



M* 



300 liters are not in keeping with the dilution law, was confirmed in a 

 later investigation 1 by Wildermann using an independent method. An 

 explanation of this anomalous condition was offered in a previous 

 paper, 2 and will not be discussed here. 



(4) It had been pointed out by Ostwald, that in aqueous solutions 

 the degree of dissociation of the same dilution of trichloracetic, dichlor- 

 acetic, monochloracetic, and acetic acids showed a decrease in the 

 order named. A like succession was observed by Wildermann for the 

 same acids in alcohol. 



In summing up, Wildermann says that it is possible to apply the 

 Kohlrausch method to the determination of the conductivity of strong 

 organic and inorganic acids in alcoholic solution, but that reliable 

 results could not be obtained for such weak acids as acetic, monochlor- 

 acetic, and succinic. However, even in the cases where the method is 

 best applicable, much time and patience on the part of the experimenter 

 are required to obtain results that are at all reliable. 



Because of the difficulty which he experienced in applying the Kohl- 

 rausch method to the study of the conductivity of weakly dissociated 

 organic acids in absolute alcohol as a solvent, Wildermann employed 

 another method 1 for the investigation of these acids. This consists 

 in the use of a direct current of high voltage (140 to 150 volts) . Polari- 

 zation can be neglected, and since the external resistances are large, the 

 measurement of conductivity resolves itself into the measurement of the 

 strength of the current. This is done comparatively by means of a 

 reflecting galvanometer, the solutions being contained in capillary tubes 

 of varying lengths and diameters. The same conclusions were reached 

 as before, except that the galvanometer method was found susceptible 

 of more general application than that of Kohlrausch. 



This method has been found open to objection by Malmstrom, 3 who 

 prefers a method described by Nernst, 4 whenever small conductivities 

 are to be measured. 



In 1902 Hantzsch and Voegelen 5 found the conductivity method 

 capable of distinguishing between a true acid and a so-called "pseudo 

 acid" which in aqueous solution partly breaks down into the constituent 

 ions of the true acid. The application of the method in this instance 

 depends upon the different behavior of the molecular conductivities of 



eit. phys. Chem., 14, 247 (1894). *Ibid., 14, 622 (1894). 



2 Ber. d.deutsch.chem.Gesell.,26, 1782(1893). 6 Ber. d. deutsch. chem. Gesell., 35, 1001 (1902). 

 3 Zeit, phys. Chem., 22, 331 (1897). 



