Nature of Solution. 



99 



the contraction on dilution in the case of salts whose solubility 

 increases greatly with the temperature, while it scarcely 

 affects those salts whose solubility remains nearly constant. 



Table V. 



Salt. 



t°. 



Spec. grav. 



Spec. grav. 

 after dilution. 



Mean spec, 

 grav. 



C. 



Solubility. 



NaOl .... 



■•{ 



O 



20 



1-02257 



1-01147 



1-01128 



17+ 



10-99 mol. 



40 



1-02182 



1-01103 



1-0109 



13 



11+ „ 



KOI 



{ 



! 



20 



1-02569 



1-01301 



101284 



17 



8+ „ 



40 



1-02516 



1-01272 



1-01258 



14 



9+ „ 



NaN0 3 . 



-{ 



20 



1-03161 



1-01596 



1-0158 



15+ 



10+ „ 



40 



1-02998 



101509 



101499 



10 



18+ „ 



KN0 3 .... 



-{ 



20 



1-03352 



1-01692 



1-01676 



16 



5+ „ 



40 



1-03232 



1-01619 



1-01616 



3 



10+ „ 



KOIO3 . 



"I 



20 



104131 



1-02088 



1-02065 



23 



1+ „ 



40 



1-04014 



1-02024 



1-02007 



17 



(2-?) „ 







Solubility 



x molecules in 100 H 2 0. 



Again, the determinations of the coefficient of expansion of 

 salt-solutions lend additional support to this view of their con- 

 stitution. Gerlach* and Kremersf have, with others, done a 

 large amount of work in this direction; and the result appears 

 to be that, for weak solutions of salts, the coefficient of expan- 

 sion is in most cases greater than that of water for the whole 

 range of temperature from 4° to 100° C. ; and this is also the 

 case with strong solutions up to a certain temperature, which 

 varies with the salt and with the degree of concentration, but 

 is lower the more concentrated the solution. These pheno- 

 mena may, I think, be satisfactorily explained as follows, 

 according to the statement on page 93. We have three factors 

 to consider in a solution : — 



The attraction of water for water . = a, 



That of water for salt =?/, 



That of salt for salt = 0. 



Now, in a solution the effect of heat on x and y will be to 

 produce expansion, and on z to produce contraction ; for if z 

 be weakened y is increased. If z be very small, as in a weak 

 solution, it will scarcely affect y; and the result will be that, 

 in addition to the expansion of water, there is the expansion 

 due to the effect of heat on y. If, however, z be very large, 

 as in a strong solution, y is correspondingly smaller in pro- 

 portion ; and a weakening of z is accompanied by a large 



* Spec. Geivicht der Salzlosungen, Part III. 

 t PoggendorfF's Annalen, vol. c. &c. 



