the Conductivity of Solutions of Double Salts. 517 



content of double molecules, as the corresponding solutions of 

 double salt ; (3) the values of the conductivity of both, calcu- 

 lated on the assumption of the non-existence of double 

 molecules ; (4) the differences expressed as percentages 

 between the calculated and observed values for the double 

 salt solutions ; and (5) the differences, similarly expressed, 

 between the conductivities of the double salt solutions and 

 the equivalent mixtures. Concentrations are expressed in 

 terms of the gramme-equivalent per litre. The conductivities 

 are specific conductivities, and are expressed in terms of 10~ 8 

 times the conductivity of mercury at 0° C. 







Conductivity. 







Concen- 













tration, 

 double salt 

 solutions. 



±0uK 2 (SO 4 ) 2 . 



Observed. 





Differences per cent. 



Double salt 

 solutions. 



Equivalent 

 mixtures. 



Calculated. 













A. 



B. 



C. 



C-A. 



B-A. 



1-294 



504-1 





535-9 



4-6-38 





1-000 



4235 



425*7 



4470 



+5-54 



+6-52 



•909 



394-4 



396-3 



414-8 



+5-17 



4-0-48 



•7500 



340-1 



341-2 



3547 



+4-29 



+0-32 



•66(56 



310-5 



311-6 



322-4 



+3-83 



+0-35 



•5000 



246-3 



246-9 



254-9 



+3-49 



+0-24 



•4000 



2059 



206-4 



212-3 



4-311 



+0-24 



•3333 



176-7 



176-4 



1817 



+ 2-83 



-017 



•2222 



126-1 



1260 



128-1 



+ 1-59 



-0-07 



•1666 



99-21 



99-33 



99-85 



+065 



4-012 



•1000 



65-20 



65-31 



65-44 



4-0-37 



4-0-16 



•0909 



60-21 



60-29 



60-34 



4-0-22 



+0-13 



•0750 



50-96 



5102 



51-12 



+031 



4-0-11 



•06666 



46-26 



4620 



4613 



-0-20 



-0-08 



•05000 



35-89 



35-86 



35-79 



-0-28 



-0-08 



•04000 



29-40 



29-45 



29-43 



-hO-10 



4-0-17 



•03333 



25-18 



25-14 



2511 



-0-28 



-0-15 



•02222 



1759 



17-62 



17-64 



+0-34 



4-017 



•01666 



13-88 



13-86 



13-85 



-022 



-014 



•01000 



8-760 



8-770 



8-784 



4-0-27 



+011 



•00800 



7-180 





7-196 



4-0-22 





•00750 



6-776 



6-781 



6-797 



4-0-31 



+00*7 



•00600 



5-584 



5-574 



5-569 



-0-26 



-0-17 



•00500 



4-730 



4-724 



4-719 



-0-23 



-012 



It appears from the above table that for the solutions of 

 double salt the differences between observed and calculated 

 values, from a concentration of about 0*1 gramme-equivalent 

 per litre upwards, are beyond the limits of error of the obser- 

 vations, reaching at concentration unity the magnitude of 

 5*5 per cent., the conductivities being less than they would be 

 if no double molecules were present. It appears also that at 



