TABLE 272. 



LIMITING VALUES OF u. 



This table shows limiting values of yu. = . ID* for infinite dilution for neutral salts, calculated from Table 271. 



If the quantities in Table 271 be represented by curves, it appears that the values of the 

 specific molecular conductivities tend toward a limiting value as the solution is made 

 more and more dilute. Although these values are of the same order of magnitude, they 

 are not equal, but depend on the nature of both the ions forming the electrolyte. 



When the numbers in Table 272 are multiplied by Hittorf's constant, or o.ooon, quan- 

 tities ranging between 0.14 ando.io are obtained which represent the velocities in milli- 

 metres per second of the ions when the electromotive force gradient is one volt per 

 millimetre. 



Specific molecular conductivities in general become less as the concentration is in- 

 creased, which may be due to mutual interference. The decrease is not the same for 

 different salts, but becomes much more rapid in salts of high valence. 



Salts having acid or alkaline reactions show marked differences. They have small 

 specific molecular conductivity in very dilute solutions, but as the concentration is in- 

 creased the conductivity rises, reaches a maximum and again falls off. Kohlrausch does 

 not believe that this can be explained by impurities. HsPO 4 in dilute solution seems to 

 approach a monobasic acid, while H 2 SO 4 shows two maxima, and like H 3 PO 4 approaches 

 in very weak solution to a monobasic acid. 



Kohlrausch concludes that the law of independent migration of the ions in media like 

 water is sustained. 



TABLE 273. 



TEMPERATURE COEFFICIENT. 



The temperature coefficient in general diminishes with dilution, and for very dilute solutions appears to approach a 

 common value. The following table gives the temperature coefficient for solutions containing o.oi gramme mole- 

 cule of the salt. 



SMITHSONIAN TABLES. 



26l 



