in Aqueous Solution, and the Existence of Complex Ions. 359 



following potassium chloride, or K -7 is stable with a potential fall of 



a 



cd 



0'82 volt, whilst for the stability of the — S0 4 margin, a voltage of 



2*54 volts at least is necessary. 



The explanation of this is to be looked for, not in the fall of potential 

 in the measured solution, to which the above figures refer, but rather 

 to the change of potential fall on passing from the indicator solution 

 to the latter, and is probably connected in some manner with the 

 Nernst theory of liquid cells. 



Certain regularities in the influence of different salts on the melting 

 points of the jellies have been noted, and it seems that this influence 

 is more or less of an additive nature, depending on the nature of the 

 anion and of the cation. Amongst anions the SO4 ion has the least, 

 and the I and N0 3 ions the greatest, effect in lowering the melting 

 point. Amongst cations, the K ion has a much less influence than the 

 Li or Mg ions : these relations are as yet, however, only qualitative. 



The values for the transport number that have been obtained 

 show a remarkable agreement with Masson's figures, as measured in 

 gelatin, for potassium and sodium chlorides. On the other hand, for 

 lithium chloride and magnesium sulphate no such agreement exists. 

 For all the salts a comparison with Hittorf 's figures shows only an 

 approximate agreement, being about as good at that shown by a com- 

 parison of the figures for the same salt, as measured by different 

 investigators, by the indirect method of Hittorf. 



From a knowledge of the specific resistance of the measured solution 

 it is possible to calculate the potential fall in this part of the system, 

 and from this the absolute average velocity U = xu, where x = the 

 coefficient of ionisation, and u the absolute ionic velocity. A very 

 striking agreement holds between the sum of the velocities of anion 

 and cation and the sum as calculated from Kohlrausch's conductivity 

 figures. The velocities of a large number of ions at different concentra- 

 tions of different salts have been calculated, and the velocity of the 

 hydrogen and hydroxyl ions have been also measured, with the following 

 results : — 



OH in KOH, 0-5 N 

 „ NaOH, 0-2 N 



Hin HNO3, 0-2 N... 



The ratio of the current, as measured by the galvanometer, to that 

 calculated from the velocity of the margins in the manner indicated by 

 Masson, is found to be equal to unity only for a few salts of the type of 

 potassium chloride ; for other salts this ratio has a value in some cases 



VOL. LXVIII. 2 c 



Found. 



0-001435 

 0-00158 

 f 0-00282 -1 

 1 0-00272 J 



Calculated 

 0-00145 

 0-00152 



0-00280 



