108 Prof. W. Ostwald's Electrochemical Researches. 



about 90 for all these acids, at a dilution of 512 litres ; in 

 more dilute solutions the conductivities are slightly dimi- 

 nished, owing to the impurities in the distilled water (Journ. 

 fur prakt. Chemie, [2] xxxi. p. 440). Whether the molecular 

 conductivities of all acids reach a maximum equal to about 90 

 in very dilute solutions cannot be determined by direct expe- 

 riments, because even with dilutions to 542 and 1024 litres 

 the impurities present in the purest distilled water begin to 

 exert an influence which cannot be accurately measured. An 

 answer may, however, be given to this question if it is found 

 possible to draw conclusions as to the behaviour of acids in 

 more dilute solutions from their observed behaviour in less 

 dilute solutions. 



The observed values of the molecular conductivities of 

 several acids are given in the following table. B = butyric, 

 A = acetic, F = formic, M = monochloracetic, D = dichlor- 

 acetic, H = hypophosphorous, I = iodic, acid ; v = dilution, 

 in litres. 



V. 



B. 



A. 



R 



M. 



D. 



H. 



I. 



2 



0-394 



0-520 



1-758 



4-994 



25-72 



30-89 



42-57 



4 



0-604 



0-755 



2-465 



6-984 



34-32 



37-91 



50-56 



8 



0-876 



1-078 



2-431 



9-531 



43-00 



45-81 



590 



16 



1-278 



1-514 



4-796 



12-86 



52-17 



54-13 



66-3 



32 



1-810 



2-123 



6-634 



17-29 



60-25 



62-10 



72-3 



64 



2-560 



2-943 



9-180 



22-85 



67-40 



69-06 



76-9 



128 



3-594 



4-084 



12-59 



29-61 



72-45 



74-05 



80-2 



256 



5-036 



5-642 



16-98 



37-81 



76-24 



77-84 



81-8 



512 



7-015 



7-753 



22-43 



46-75 



79-76 



79-92 



83-0 



1024 



9-740 



10-47 



29-02 



55-64 



80-52 



81-00 



831 



2048 



13-37 



14-44 



35-83 



63-48 



80-87 



81-39 



82-9 



4096 



18-03 



19-35 





68-69 



79-74 



80-48 



81-8 



The molecular conductivity increases in every case, but in 

 a very varying degree, with increasing dilution. The increase 

 is greater, for a given increase of dilution, the smaller the 

 conductivity of the acid ; it is also greater for weak than for 

 strong acids, and greater for small than for large dilutions. 

 The value of the increase in molecular conductivity for each 

 dilution follows a special course : in the case of weak acids it 

 increases as dilution increases ; the increase attains a maxi- 

 mum value, equal to 8*9, in the case of monochloracetic acid 

 for a dilution of 512 litres (mol. conduc. at 256 litres = 37*8, 

 and at 512 litres = 46*7, diff. = 8*9) ; the same value is 

 attained for dichloracetic acid for the dilution from 8 to 16 

 litres (mol. c. = 43 and 52*1) ; approximately the same value 

 is attained for hypophosphorous acid for the dilution from 8 



