( 57 ) 



We repeat once more: tliis expression holds from .v:=0 to x = 

 near 1, wlien the following conditions are satisfied : 



a. the solution is an ideal hinanj mixture of ?/c>rma/ components; 



b. the solution is practically incoDipressible. 



Then (2) represents the additional pressure on the solution, in order 

 to repel the penetrating water (the so-called ''osmotic" pressure). 



As however in all the experiments made up to now loater was 

 the solvent, hence an anomalous substance, (2) must not be applied to 

 solutions in water without reservation. It is, however, easy to show 

 that the influence of the association does not play a part before 

 the term with x^ (just as the influence of the two components inter 

 se), so that in the above experiments, whej-e .i'" may undoubtedly 

 be neglected (cf. § 1), formula (2) may certainly be used. 



Let us, liowever, first reduce it to a form more practical for use. 



4. Let us write (2) for this purpose : 



RT ^ , RT 



JT^^ (., + 7^ ,,^ ^ _ .) ^ __ .,. (1 _^ i _,)^ ^ _ _ (2«) 



which is more than sufticient for solutions up to 1-normal. Let us further 

 assume that c Gr. mol. are dissolved in 1000 Gr. H^O (called by 

 Morse and Frazer "weight-normal solutions"), then : 



c c 



when we put V34 <^ = c' (34 = 55,6 : 1,65 is the number of Gr. mol. 

 H,0 in 1000 Gr. at 18° C; cf. § J). 

 We find then : 



RT c' , 



1 + 0' V '14- c'/ 



or when we restrict ourselves to terms of the second degree with 

 respect to c' : 



RT RT c 



., = _,(i_V,,) = _-(>-v„.). 



In this 7^=3:82,13 (c.c.M., Atm.), and i', = 1001,4 : 34 cM' at 



RT 

 18°. For we therefore find at 18° C. : 



RT _ 82,13 X 291,04 _ 

 34;r - l^^4: - ^^'^^' 



hence 



.Ti8° = 23.87 c (1 — 0,015 0) Atm . ... . (26) 



We see from the calculation, as w^e already observed above, that 



