AskEw.—Solubility and Hydrolysis of Calcium Carbonate. 795 
The apparatus was airtight, and the pressure of the carbon dioxide 
under these conditions may be considered about 3:7 x 1077 atmosphere. 
(Johnston and Williamson (8).) | 
Johnston and Williamson obtained а minimum concentration of calcium 
carbonate at this pressure, their value being 16 x 107° ртт. mols. per litre 
at 16° On either side of this value the concentration increased rapidly, 
thus again showing the great influence of the carbon dioxide. For this 
minimum concentration they found that the hydrolysis was about 54 per 
cent. Against this value is that of Seyler and Lloyd (5)—namely, 66-7 per 
cent. 
In discussing the electromotive-force experiments it was shown that 
theoretically, and in part practically, the concentration of the hydroxyl 
ion in the solution can be determined. 
Now, the ions present in the solution are 
H, Ca, HCO,’, OH’, and CO;', 
if the presence of the neutral salts be neglected. And between these ions 
the following relations exist :— 
T s BOO... ORE 
oe DOS FX TT 
Н: x OH’=1 х 107" 
Hx CO,” ,. ü 
HOO, — 415 x 107 
The last equation is due to Kendall (10 — 
Hence if y is the concentration of the caleium ion and c that of the 
hydrogen ion, then 
1x | * Cy (1 — 2) 
y=y(L—2) t Tax 415 0 
where x is the degree of hydrolysis of the carbonate. | 
This more fos neat relation takes the place of that deducible approxi- 
mately, viz., 
yx NO 
Behe Op 
y 
The following table contains some of the more reliable data :— 
i ; Per Cent. 
Salt. Se od olia 101°, | OH’ x 105. | йуу. 
| ee 
NaCl im M/400 1:98 41 2-44 ie 
NaCl ..| М/500 1:62 233 4-35 19 
NaCl ie M/1000 1-44 1:95 кр s 
NaNO,  ..| M/100 3-00 47 
| | 
to the extremely high resistance of the pure-water solutions, 
Owing 
i | btained. rrt 
ды = oe I RE calculations the degree of ionization of 
th bonate was taken as 0-9. : 
^ Prin Че je table the product [Ca] [cos] ung be anite 
Values are obtained ranging from 52 to Ho wem € 
as low as 26 x 10™, using Seyler and Lloyd's equation, [Ca T 
- = constant. 
