498 Mr. Pickering on the Theory of Osmotic Pressure 



to that of a 2*5 per cent, solution (H 2 S0 4 to 200 H 2 ; this 

 was selected merely because at this percentage the dia- 

 gram attains the highest relative point) and plotting out the 

 deviations of the observed freezing-points from this line. 

 The accompanying figure illustrates the result. The deviation 



Deviation of the Freezing-points of weak solutions of Sulphuric Acid 

 from regularity. 



Deviation. 



0-02 



0-08 



I m/ 







\ 

 \ 



\ 

 \ 



a \ 

 \ 



- 



\ 



\ 

 \ 

 \ 

 \ 

 \ 

 \ 





\ 

 \ 

 1 



\ 



\ 

 \ 

 \ 



\ 

 \ 



Per cent. H.,SO J 



from straightness amounts to at least 20 times the mean 

 experimental error, and 28 per cent, of the total depression. 

 Even if we draw our straight line from a solution of 0*44 

 (•08 H 2 S0 4 to 100 H 2 0) per cent, strength— in which the 

 sulphuric acid would be as much expanded as it would when 

 a gas at ordinary pressures — the aberration, at 0*7 per cent., 

 amounts to 0°'008, or 20 per cent, of the total depression. 



The molecular depression calculated from these results, 

 together with others obtained with stronger solutions, are given 

 in the folio win g table: — 



