590 CV RUS ES LOLMVAWN 
K 
CS Ks 4 
1 1K 3 ( ) 
Now the dissolved undissociated part of the salt dissociates into 
its ions 
< ab e 
(Co) os, (5) 
1 
but substituting from (4) 
ab —K,K,=K. (6) 
This K is called the constant of solubility, or the ion product. 
This is the law governing precipitation of electrolytes, and under 
it there are three cases. 
(a) ad> K. 
(b) Zo 
(c) ad< K. 
(a) If ad is greater than K the action goes A + B 
and again C, >C, therefore we have precipitation. 
(b) If a= K, we have equilibrium, and neither precipitation 
nor solution takes place. 
(c) If aé is less than K the action goes 
Ce >A+ BandC a Ga 
that is solution takes place. 
Now, if we mix solutions of two or more salts, besides the 
undissociated salts which were present in the separate solutions 
in equilibrium with their respective dissociated ions, we will 
have in the mixture also the salts that can be formed by the 
union of the positive ion of each salt with the negative ion of 
each of the other salts. From the foregoing the following 
= C 
1? 
propositions are derived : 
Proposition 1.—Mixed solutions of two or more salts will 
contain all the salts that can be made by the combination of 
the ions of the original salts together with the free ions. 
Proposition 2,—Ogf all these salts that one will be precipitated 
first whose product of ionic concentration first exceeds its con- 
stant of solubility or ion product. 
If a salt be added to a mixture of salts in solution, there is 
added not only the salt itself but its ions also. If one of the 
