1904 - 5 .] Note on Boiling Points of Aqueous Solutions. 953 
quickly obtained, — so steady that, notwithstanding the delicacy of 
the thermometer used, no change of reading could be detected 
frequently for five or ten minutes, and sometimes for longer 
periods. 
In the experiments, the amount of solvent delivered by a fifty 
c.c. pipette was used. As the result of several experiments to 
determine the amount of vapour in the tube during an experi- 
ment, it was found to be ’41 grammes, and was allowed for. The 
distilled water used was redistilled to guard against impurities. 
The filling material, after each series of experiments, was 
thoroughly cleansed with boiling water and dried before being 
used again. The platinum foil, in addition, was heated in a 
Bunsen flame. 
Series of solutions were made from each salt by the addition of 
compressed pellets of salt successively to the solvent or solution 
during ebullition. The pellets were made at first by the aid of a 
steel press, but later by one with ivory fittings, to safeguard their 
purity, which was essential when deliquescent salts were the 
subject of research. 
The procedure adopted was to bring the solvent to a steady 
boiling temperature, which was noted. Then pellet after pellet of 
salt was added at intervals of from twenty to twenty-five minutes, 
the boiling temperature of the successive concentrations being 
noted. It was found essential to the success of an experiment to 
allow at least twenty minutes for the diffusion of the salt. 
Corresponding to the successive readings of the thermometer, a 
succession of readings of the barometer was taken, so that any 
change in atmospheric pressure might be allowed for. The 
barometer gave readings corresponding to four thousandths of 
a degree, but could be estimated to the equivalent of two 
thousandths. 
The salts used were supplied by Messrs Merck & Co. as 
specially pure, and were tested quantitatively and spectroscopically. 
In the calculation of results ionization coefficients were 
necessary at high temperature, as near the boiling point as 
possible. These were obtained from conductivity values as given 
by Kranhals * as follows. Kranhals gives the molecular conduc- 
* Zeit. fur phys. Chem . , 5 , 250 . 1890 . 
