224 



G. HAKKEK. 



ducted from the boiling solution to the metal surrounding 

 it, and so to the metal cylinder separating the inner column 

 of vapour from the outer. 



However, the presence of water running continuously 

 from the condenser ensured that the bottom portion of the 

 jacket contained saturated water vapour at a temperature 

 certainly not higher than 100°. The presence of even a 

 trace of water on the walls of the inner column always 

 prevented the thermometer A from rising above the tem- 

 perature of the vapour of the pure solvent. In the early 

 stages of the boiling of the solution the thermometer A 

 usually remained quite stationary for ten minutes or more, 

 at the temperature of the vapour of the pure solvent, 

 although the solution was boiling vigorously all the time. 

 It would then rise showing that all trace of water had 

 disappeared from the walls of the centre column. It is, 

 therefore, certain that the presence of water in the lower 

 portion of the jacket effectually prevented conduction of 

 heat from the solution through the metal walls of the 

 jacket. The thermometers used were corrected in the 

 hypsometer in the usual way by boiling distilled water. 

 The results of a typical experiment follow. The solution 



Time. 



Thermometer A. 

 ° C. 



Thermometer B. 



°C. 



Remarks. 



10*35 





. ., 



Started. 



10'39 





... 



Solution boiled. 



10-43 



99'9 



... 





10*48 



99*9 



99-0 





10*50 



101*0 



99*2 





11-0 



104*5 



100*4 





11*6 



105-5 



100*4 





11*14 



105*3 



101-0 





11*20 



106*0 



103*2 





11-26 



106*0 



103*8 





