162 DB. B. D. STEELE, DE. D. McINTOSH AND DE. E. H. AECHIBALD 



compelled to use, in the calculation of *V", the total concentration instead of that of 

 the unassociated substance. 



It is also possible that more than one type of electrolytic compound is formed in a 

 given solution, as, for example, the compounds ABCD and (AB) 2 CD ; in which 

 case the total conductivity will be the sum of the conductivities due to the ionisation 

 of each of these compounds. In such a case as this extremely complicated curves 

 might result. Moreover, we cannot strictly apply the equation to the concentrated 

 solutions, since for these the active mass (b) of the solvent is no longer constant. 



The fact that the curves, as a whole, are so analogous to those for a simple 

 electrolyte in aqueous solution appears to indicate that, as a general rule, the main 

 effect is due to the ionisation of a single substance. 



The equation :V" = aK' should also be applicable to abnormal solutions in other 

 solvents. This is the case for the solutions investigated by PLOTNIKOFF (' Zeit. Phys. 

 ('hem.,' 1904, 48, p. 224), who found very abnormal variations of /u, for antimony 

 tribromide and phosphorus pentabromide in bromine. The experimental figures for 

 antimony tribromide lead to the following values for V and /cV" : 



The molecular conductivity of phosphorus pentabromide in bromine varies so 

 irregularly as to suggest that some disturbing effect is at work rendering the figures 

 valueless. 



Another solvent in which p. increases with concentration is amylamine (KAHLEN- 

 BERG and HUHOFF, ' Jour. Phys. Chem.,' 1903, 7, p. 254), and the equation has been 

 applied to the measurements of conductivity for cadmium iodide, ferric chloride 

 and silver nitrate dissolved in this solvent. The results of the calculations when 

 n = 2, 3 and 4 are given in Table III. It will be noticed that maxima are shown in 

 each case. 



Passing on now to the consideration of the molecular weight determinations which 

 are recorded in Part II., we find that some of these afford confirmation of our 

 hypothesis, inasmuch as ether and acetone in dilute solutions possess a greater 

 molecular weight than the theoretical. 



