340 EEPOET— 1886. 



Kation Anion 



Copper. Chloric Acid. 



Mas'nesiiim. Acetic Acid. 



Zinc. 

 Sodium. 

 Litliium. 



. , . ' According to 31. Lenz, the hntion alone would influence the conductivit'f 

 in dilute solution, a statement which M. Kohlrausch refuses to accept. 



' 4. ' With hicreasinrf concentration the molecular conductivity always diminishes^ 

 and to a very unequal deg-ree for different salts. In order to e.x:hibit this yariatiou 

 conveniently to the eye, M. Kolilrausch constructed curves, taking as abscissEe the 

 values of m^, and as ordinates the molecular conductivities. These different curves 

 present markedly diff'erent courses, hut I observe that they all approach more or less- 

 to a common ordinate for to =0.' This peculiarity is especially well marked in the 

 case of the normal salts if Ave reject the portion of the curve, often a little inflected, 

 beyond to = 0'006; i.e., if we produce as near as can be judged {de sentiment) the 

 sensibly rectilinear portion which precedes this. 



' 5. For the salts of the monobasic acid.i the molecular conductivity in dilute- 

 solution is rejn-esentecl app'oximately by the formula 



Zr/m = A — B»i», 



expressing that this conductivity differs from a constant value A by a term inversely- 

 proportional to the mean distance of the molecules of the salt. My latest 

 researches ^ have led me to an analogous result. 



'The limiting value of the conductivity of sulphuric, hydrochloric, and nitric 

 acids is sensibly three times that of neutral normal salts, as I had previously pointed 

 out. Sulphuric acid, moreover, exhibits peculiarities which would alone require a 

 monograph. 



' Coming to the interpretation of the capital fact of the increase in the mole- 

 cular conductivity of all salts in dilute solutions, M. Kohlrausch thinks that it 

 must ' be attributed to a special conductivity acquired by the water xvhen it contains 

 other substances in solution, but which is too small to be evident in strong solutions. 

 Very small quantities of foreign matter may communicate to the water that state 

 of dissociation which Olausius looks upon as the origin of the migration of the 

 ions under the influence of electric forces, aiid hence a considerable portion of the 

 current might be diverted throuyh the mass of the water, which would itself then 

 share in the electrolysis. This hypothesis, to which M. Kohlrausch declines to 

 give greater precision, may be interpreted as a denial of the very principle which 

 he applies to the calculation of molecular conductivity, as in order to obtain this he 

 had already subtracted from the gross conductivity that part which belongs to the 

 distilled water, more or less impure, and therefore already possessing the special con- 

 ductivity with 7vhich he deals ; unless this be capable of changing with the nature- 

 and proportion of the salt in solution, which implies the formation of hydrates, and 

 that the conductivity of a solution is not equal to the sum of the separate conduc- 

 tivities of the salt and the solvent, the calculated numbers on which the discussion 

 hinges would in that case lose all definite meaning.' 



' [I should imagine an examination of the curves is all that is needed to refute this- 

 criticism : compare the curves for KNO3, iBaNO^, NaNOj.— E. F. J. L.] 



2 Comptes liendvs de VAcadhnie des Sciences, t. cii. p. 1375. 



^ [Kohlrausch gives another possible interpretation of the rapid diminution of the 

 conductivity of salts of polyvalent radicles as concentration increases, viz. — that in 

 extremely dilute solutions the more complete dissociation tends to assimilate such 

 compounds in behaviour to those of monovalent radicles: 'ein anderer Aggregations- 

 zustaud, etwa eine grossere Dissociation in ausserster Verdiinuung, welche die: 

 mehrwerthigen ahnlicher macht.' — E. F. J. L.] 



