ON THE BOILING POINTS OF AQUEOUS SOLUTIONS OF ELECTROLYTES. 23 9 



the curves obtained thus would meet at infinite dilution and diverge with increase of 

 concentration. This result is in accordance with the conclusion of former observers. 



PART IV. 

 Concentrated Solutions. 



We come now to study solutions, reaching as high a concentration as 7 or 8 

 gramme equivalents per litre. 



In the following pages the results are given of calculations which have been made of 



the elevation constant over a wide range of concentration. 



The formula employed was — 



c m.W.AE 



(1+71- la)A'«> 



where C is the boiling-point elevation constant— 



m = molecular weight of salt added. 

 W = weight of solvent used in grammes. 



AE = increment of elevation of boiling point on addition of salt to a solution. 

 Aw = increment of salt added in grammes. 



a = ionization coefficient assumed equal to the ratio of equivalent conductivity 



at the concentration to that at infinite dilution. 

 n = the number of free ions into which a molecule dissociates. 



A boiling tube for 15 cubic centimetres of solvent was used, consequently con- 

 centrated solutions were quickly obtained. In consequence we have only a very few 

 observations for dilute solutions. It was impossible therefore as a rule to draw the 

 curves with grammes of salt added as ordinates, and elevation of boiling point as 

 abscissae, so accurately in the neighbourhood of the origin as when dilute solutions 

 were specially under consideration. In consequence a smaller degree of accuracy must 

 be expected in values obtained for the elevation constant for the dilute solutions than 

 when the latter were being dealt with specially. The error involved in determining 

 the increment of the elevation, although it creates a somewhat large percentage error 

 for the dilute solutions, is usually under one-hundredth of a degree, which for con- 

 centrated solutions where the elevation is from three to ten or more degrees would 

 only be one in from three to ten hundred, and consequently negligible, the more so 

 because at these concentrations it is not supposed the ionization coefficients are more 

 than rough approximations. It should be remembered, however, that the ionization 

 coefficients enter the calculations of values of the elevation constant in the form 



1+n — la. 



In the following tables "ionization coefficient" stands for i^ v /^ x , where Mv is the 

 equivalent conductivity at a dilution represented by v, where the latter is the 

 number of litres to the gramme equivalent, and m* the equivalent conductivity at 

 infinite dilution. 



