Prof. W. Ostwald's Electrochemical Researches. 109 



to 16 litres (mol. c. = 45'8 and 54 # 1), and for iodic acid for 

 the dilution from 4 to 8 litres (mol. c. = 50*5 and 59). As 

 dilution increases in these cases, the increase in molecular 

 conductivity for each dilution begins to decrease ; for the 

 strong acids the increase of conductivity is very small. It 

 appears as if the maximum increase in molecular conductivity 

 occurs where the conductivity is equal to 45 — that is, is equal 

 to half the maximum limit, 90. The relations between dilu- 

 tion and molecular conductivity are more definite in the 

 various series of acids. The mol. c. of formic acid is 1*76 for 

 the dilution 2 litres ; almost the same value (1*81) is reached 

 by butyric acid for the dilution 32 litres. The following 

 table exhibits the numbers for these two acids : — 



Formic Acid. 



Dilution, 



in litres. 



Butyric Acid. 



1-76 



2 



32 



1-81 



2-47 



4 



64 



2-56 



3-43 



8 



128 



3-59 



4-80 



16 



256 



5-04 



633 



32 



512 



7-02 



918 



64 



1024 



9-74 



12-6 



128 



2048 



13-4 



170 



256 



4096 



18-0 



22-4 



512 



8192 



23-8 



290 



1024 



16384 



31-5 



The numbers run parallel to each other ; those for butyric 

 acid are about 5 per cent, greater than those for formic acid. 

 Aqueous solutions of formic and butyric acids exhibit there- 

 fore about equal molecular conductivities when the latter is 

 sixteen times more dilute than the former. If the data for 

 the other acids are examined, it is apparent that the dilutions 

 at which the molecular conductivities of the monobasic acids 

 exhibit equal values always bear a constant relation to each other. 

 This fundamental fact is exhibited by the following table, 

 wherein equal molecular conductivities are placed in the same 

 horizontal lines. The different series exhibit a closely corre- 

 sponding course. The dilution is expressed by means of the 

 exponent p, which is defined by the relation, dilution = 2 p . 

 If the values of p and the molecular conductivities are regarded 

 as coordinates of a curve, then the lines for the individual 

 acids all form parts of one and the same curve which is 

 common to all the acids. The point of origin for each acid 

 must be specially chosen on the axis of the dilution-exponents p; 

 in other words, a special constant must be given for the value 

 of p for each acid. 



