792 Transactions. 
Holleman (2) found 1 part of carbonate in 80,040 of water—i.e., approxi- 
mately 0:0125 gram per litre. He quotes (Lc.) the following: Fresenius, 
1 part in 16,600 of water; and Bineau, 1 part in 50,000 of water. 
Kendall (3) found the value of 0-01433 gram per litre at 25° C. 
Gothe (4) found the solubility slightly variable, his final value being 
31-0 mg. per litre. This result appears anomalous, but may be explainec 
when the great effects of traces of carbon dioxide, taken up from the air 
or elsewhere, are considered. 
Seyler and Lloyd (5) determined the solubility product of calcium 
carbonate, obtaining : 
[Ca] [CO^,] = 71-9 x 107" at 25? C. ; 
they also obtained the equation 
T — . Ca" = 1:92 x 10-4 
1—2 
where z is the fraction of carbonate hydrolysed. By solving these equations, 
the value 14-6 x 10-5 grm. mols. per litre is obtained. This result agrees 
closely with that of Kendall. 
McCoy and Smith (6) calculated from the data of Kohlrausch (7) for 
the conductivity of saturated solutions of calcium carbonate a solubility 
of 12 mg. per litre. Their calculation allowed for hydrolysis to the extent 
of 66 per cent. "They themselves obtained the value 16-6 mg. per litre. 
They say no explanation of the discrepancy is forthcoming. ; 
An important matter in relation to all these determinations is the partial 
pressure of the carbon dioxide in contact with the solution. For each 
_ In the presence of salts of the alkalis the solubility of calcium carbonate | 
1s greatly altered, perhaps by formation of complex ions, thus reducing the 
Gothe (Lc.) states that the solubility is increased by chlorides, nitrates, 
and sulphates ; while a decrease occurs in the presence of alkali carbonates _ 
and salts of the alkaline earths. pe 
Rowe (l.c.) came to somewhat the same conclusions, and added, “as 
regards the alkalis, that calcium carbonate appears most soluble in the 
ammonium salt of any given acid, and in Solutions of the sulphate of any 
given base." He also found that there is apparently a discontinuity in the 
curve with аы of sodium chloride of strengths about M/500. (Private 
In this present case the apparent solubility of caleium carbonate, in the. 
calcite form, was determined in -free water, in presence of уатушё 
amounts of alkali salts; while the degree of hydrolysis was deduced from 
electromotive-force measurements. ^ С. 
SOLUBILITY MEASUREMENTS. 
_ These were carried out in Jena glass vessels fitted with mercury-seale 
stirrers and side tubes leading to a series of guard-bottles. This form ber 
adopted after two other types of solution-vessels had been used. A multiple 
тошо] regulator was used to maintain the temperature at 25-0° C.; W 
а spiral tube stirrer driven by a hot-air engine was employed to keep ' 
