1904-5.] Note on Boiling Points of Aqueous Solutions. 965 
Prom the expression for C given above, page 956, we have 
C.w.(l +n - la) 
m= W(E-OP) ' 
To illustrate this application of the method, I calculated the 
values of m for the bromide, chloride, and nitrate of potassium, 
and for sodium nitrate. The first series , as given above, in each 
was taken. 
In the calculations the theoretical value of C, i.e. 520, was 
used. The values of m for potassium bromide were 121, 123, 120, 
118, 118, 116, 115, 114 : the mean value being 118T, the 
recognised value 1 18*7. For potassium chloride the molecular 
values were 73, 73*3, 76, 76, 76, 76, 76, 74, 74, 74 : 
their mean value is 74*83, the recognised value 74*59. For 
potassium nitrate the values were 101, 104, 102, 99*4, 100, 
103, 103, 101 ; mean value, 101*2; recognised value, 101*17. 
For sodium nitrate the values were 86, 87, 87, 86, 85, 82, 80, 
83, the arithmetic mean being 84*4, and the recognised value 
85*08. 
Had my object been the determination of molecular weights, 
greater care would have been taken when drawing the curves. 
The molecular weight calculations I have made indicate how 
accurately my method might be employed in such observations. 
Up to the present the boiling-point method has only been 
applied roughly to determine molecular weights, and generally* 
with considerable divergence of value. This divergence would 
frequently have been much greater had not one error helped to 
counterbalance another. An inaccurate determination, usually too 
low, of the boiling point of the solvent when water was used, 
resulting in too high elevation of the boiling temperature of the 
solution, was largely overcome by the assumption of total ioniza- 
tion when the latter was only from seventy to ninety per cent. 
The variation is accentuated when molecular weights obtained by 
* Ber. Der. Chem., 31, 471. 1898. 
Practical Methods for determining Molecular Weights , by ... . Biltz, 
translated by Jones and King, p. 189. 1899. 
Zeitschrift fur Anorg. Chemie, 17, pp. 435 and 450. 1898. 
Sakurai, Journal of the Chemical Society , 61, 987. 
Walker and Lumsden, Journal of the Chemical Society, 73, 509. 1898. 
