Sources of Calcium-salts. - The chief source is the carbonate found native as chalk or limestone.

General Test of Calcium-salts. - The addition of ammonium oxalate to calcium salts causes a white precipitate of calcium oxalate, which is very sparingly soluble in water. It is soluble in hydrochloric, but insoluble in acetic acid.

1 Hermann, Lehrbuch d. experimmtel. Toxicologic, p. 191.

2 Brunton and Cash, Centralblatt fur d. med. Wissenschaften, 1884, p. 545.

3 Lisfranc, quoted by Lewin, Nebenwirkungen d. Arsneimittel, p. 74.

General Preparation Of Salts Of Calcium

Is prepared



Creta prasparata, B. and U.S.P.

Chalk .

The process of elutriation, which consists in stirring with water, pouring off the liquid containing fine particles in suspension, and allowing them to subside.

Calx (quicklime), B. and U.S.P.

Chalk or limestone .

Calcining; CaCO3 = CaO + CO2.

Calcii hydras (slaked lime), B.P.

Quicklime . .

Slaking with water.

Calcii chloridum, B. and U.S.P.

Limestone or chalk (Carbonate) .

Neutralising with hydrochloric acid; CaCO3 + 2HC1 = CaCl2 + H2O + CO2.

Calcii carbonas pne-cipitata, B. and U.S.P.

Calcium chloride .

Precipitating with excess of carbonate of sodium; CaCl2 + Na2CO3 = CaCO3 + 2NaCl.

Calx chlorata (chlorinated lime), B. and U.S.P.

Slaked lime . .

Exposing lime to chlorine gas until saturated: thus is formed chlorinated lime, consisting of a mixture of calcium chloride and calcium hypochlorite.

Calcii hypophosphis, B. and U.S.P.

Lime and phosphorus

Heating together with water; removing excess of lime by CO2, and evaporating.

Calcii phosphas, B. and U.S.P.

Bone ash . .

Dissolving in diluted hydrochloric acid, precipitating with ammonia, and drying.

General Impurities. - The chief impurities are aluminium and magnesium.

Tests. - These are usually detected by converting the calcium-salt into chloride by hydrochloric acid, and evaporating to dryness so as to drive off all excess of acid. The residue is re-dissolved in water and the tests applied to the solution. On the addition of saccharated solution of lime, aluminium and magnesium will be precipitated. The B.P. states that only a very scanty precipitate should occur, showing that only traces of magnesium and aluminium are present. The test used in the U.S.P. to detect aluminium is water of ammonia; and to detect magnesium, water of ammonia and phosphate of sodium. These reagents should not give more than a faint turbidity with dilute solutions of calcium salts.

B.P. Marmor Album. White Marble. CaCO3. Hard white crystalline native carbonate of calcium, in masses. Used in producing carbonic acid gas.

B.P. Creta. Chalk. CaCO3. Native friable carbonate of calcium. Used in producing carbonic acid gas.

Preparation. Creta Praeparata.