ON ELECTROLISIS IN ITS PHYSICAL AND CHEMICAL BEARINGS. 347 



Here it is evident that the conductlTity alters only uniformly -with temperature, 

 for had this been other-vvise great variations in the neighbourhood of 24° should 

 have been noticeable, for the internal Iriction increases about that temperature from 

 a moderate value to an infinitely great one. But no sign of such a sudden variation 

 can be deduced from the above figures. The calculated values of the coefficient of 

 temperatui-e are, 



for gelatine solutions 



Gelatine alone Sodium chloride 



0-0281 0-0244 



and for aqueous solutions 



0-0238 



Zinc sulphate 

 0-0243 



00234 



Copper acetate 

 0-0248 



0-0213 



Those for gelatine solutions are generally some-what higher than for the 

 corresponding aqueous solutions, but the difierence is unimportant. If it be 

 assumed that the coefficients of temperature for internal friction and conductivity 

 are the same with aqueous solutions, it cannot be so with gelatine solutions, because 

 for these the temperature-coefficient of internal friction must be infinity, while the 

 conductivity-coefficient never exceeds 03. If the conductivity of pure aqueous 

 solutions at 17-8°, which are very mobile, be compared with that of gelatine solu- 

 tions of 4-2 per cent, containing the same amount of salts, which are solid at 24°, 

 the following table results : — 



The gelatine solution has accordingly about 17 per cent, less conductivity than 

 the con-esponding aqueous solution. The found difierence of 17 per cent, is not of 

 the magnitude which might be expected if internal friction had really the effect 

 usually attributed to it. 



Let us now examine the reasons for assuming parallelism between internal 

 friction and conductivity. In most cases the molecular conductivity in aqueous 

 solutions decrease.s with increase of concentration, and similarly with the fluidity. 

 These relations hold with few exceptions for aqueous solutions, and it is therefore 

 pot remarkable that the fluidity and the molecular conductivity of aqueous 

 solutions should vary at about the same rate. But it does not follow that tliey are 

 interdependent or to be ascribed to the same cause. If very dilute solutions be 

 employed the fluidity remains nearly constant, but the molecular conductivity of 

 salts increases considerably with dilution, as I have shown in my former work, and 

 my results have been confirmed bj' Kohlrausch.' 



There cannot therefore be a complete parallelism between fluidity and conduc- 

 tivity in aqueous solutions. For very dilute solutions our present views of the 

 nature of electrolysis lead us to conclude that the variation in conductivity is 

 dependent on chemical change, such as the breaking down of complex molecules, 

 the union of molecules of salt with molecules of water, and so on. And the 

 difiference between dilute and concentrated solutions is merely a relative one. We 

 cannot draw any definite line between bodies in dilute and in concentrated 

 solution. Thus strong acids in concentrated solution pass through precisely the 

 same phases as weak acids in dilute solution. There is the same relation between 

 alkali salts on the one hand and mercury salts on the other. The conclusion fol- 

 lows therefore that the molecular conductivity depends chiefly on chemical rela- 

 tions. And there appears no reason to connect internal friction with molecular 

 changes of a chemical nature. 



A similar relation holds between the temperature-coefficient for fluidity and 

 the conductivity. These are for dilute solutions approximately comparable, and it 



Gottinger Nachrickten, February 25, 1885. 



