ON THE BOILING POINTS OF AQUEOUS SOLUTIONS OF ELECTROLYTES. 203 



error, while those based upon the observed elevation of the boiling point of a stronger 



solution above that of a weaker solution will be independent of the possibly large 



error which may affect the determination of the boiling point of water. 



Accordingly, in computing the values of the elevation constant, I have used the 



following expression — 



c= m.W.AE 



where m, W, n and a are as before, and AE is the increment in boiling-point 

 elevation corresponding to the addition of Aw grammes of salt to a solution. 



AE 



The ratio . was found as follows : — 

 Aw 



Let OW and OE be axes of weight of salt added and 



elevation of boiling temperature respectively. Let LK, 



the curve for any series of observations, found as seen above 



to be for dilute solutions approximately a straight line, 



be produced to meet the axis in P. Through any near 



points Q and R on this curve draw parallels to the axes. 



AE^QS_PT_E -OP 

 Aw~RS~TR~ w ' 



Hence C = 



E-OP/ wW 



\ +11 - la 



Elevation of Boiling Point. 



Fig. 5. 



PAET II. 

 (l) The Boiling-Point Elevation Constant. 



We now come to the determination of the boiling-point elevation constant for which 

 observations on dilute solutions only have been used. 



In the computations given below, I have used the formula given above. 



The conductivity values used in the calculations are my own (see Part III.), except 

 those for KN0 3 , for which Krannhals' values have been used. 



From these tables it will be seen that the values of the elevation constant obtained 

 for the various salts lie about 520, some being greater, some less. 



The value obtained, 519*6, is the mean of the means for the several series of observa- 

 tions the results of which are given below. I have given several other series of 

 determinations in Proc. Roy. Soc. Edin., 25, 960, 1905. From the first series of each 

 salt there given the mean of the mean values for the several series is 519'5. 



The experimental value of the elevation constant, as I have obtained it, is con- 

 sequently very approximately the theoretical value. 



[Tables. 



