232 Mr Barlow, On the Osmotic Pressure of Aqueous Solutions. 



The level was thus steady for more than a week, and the 

 osmotic pressure was at the greatest 27 mm. at 13° C. ; again 

 below the theoretical value. The pressure in the previous experi- 

 ment was 27'5 mm. at 11°'5 C. 



The experiments with cell XIII where sugar solution was 

 used, and where the cell had been used so long with dilute solu- 

 tions and had several soakings in water, show that all pressures set 

 up were below the theoretical value. Hence it is most likely that 

 the excess of pressure registered by cell XIV was due to traces of 

 alcohol which had not been got rid of in the time allowed for 

 washing, and was not due to inversion of the sugar. 



(1) Cell e. '0012 N solution of potassium sulphate. Theo- 

 retical pressure = 20 mm. at 0° C. Previous history of cell. The 

 last experiment for which this cell had been used was one with a 

 4'6 9 /o solution of cane-sugar to get some values for the rate of rise 

 of pressure. The cell had nearly got up the theoretical value 

 when it was opened, and was still rising. After this it was wash- 

 ing for six days (Jan. 25 to Feb. 1, 1904). On Monday, Feb. 1, it 

 was filled with the above K 2 S0 4 solution, closed and standing till 

 Tuesday ; it was then emptied and refilled for the experiment. 





Gauge 



levels 



Tempera- 





Time, etc. 







ture 







narrow- 

 limb 



wide-limb 



(degrees C.) 







I open, 









Tuesday, Feb. 2 



-< closed 

 ( 274 



267-6 



— 





Wednesday, Feb. 3 



277 



266-7 



10 





Saturday 



282-2 



265-2 



10 





Monday 



289-2 



264-8 



10-2 





Wednesday, Feb. 10 ... 



291 



264-2 



10 





To ensure greater purity 









_ 



of contents, cell refilled ; 











and pressure added 











Friday, Feb. 12 



288 



265 



— 





Saturday 



292-6 



264-4 



10 





Monday 



294 



264 



10 





Wednesday 



295 



264 



9 



^Maximum 



J pressure 



Saturday 



295 



264 



10 



Tuesday 



292 



— 



— 





The maximum readings of the gauge give a difference of level 

 equal to 31 mm. at 10° C. From this has to be deducted the 

 difference of levels when opened to give the excess of internal 



