Creta or chalk is naturally discussed along with calcium or lime, of which it is the carbonate.

The various preparations of lime may be represented as follows, according to their source.

1. Creta

Creta. Chalk. CaCO3 (impure). Native. From Creta are made: a. Creta Prseparata.- Prepared Chalk. CaC03 (nearly pure).

Source. - Made from Chalk by elutriation and subsequent drying.

Characters. - A white amorphous powder, insoluble in water; incompatible with all acids and sulphates.

Impurities. - Alumina and oxide of iron.

Dose. - 10 to 60 gr.

Preparations.

α. Mistura Cretae. - Chalk Mixture. Prepared Chalk, Gum Acacia, Syrup, and Cinnamon Water. 1 in 32. Dose, 1 to 2 fl.oz.

.. Pulvis Cretae Aromaticus. - Aromatic Powder of Chalk. Prepared Chalk, Cinnamon, Nutmeg, Saffron, Cloves, Cardamoms, and Sugar. 1 in 4. Dose, 10 to 60 gr.

From Pulvis Cretae Aromaticus is made: i. Pulvis Cretae Aromaticus cum Opin - Aromatic Powder of Chalk and Opium. 39 parts of Aromatic Chalk Powder, mixed thoroughly with 1 part of Opium in powder. 1 of opium in 40. Dose, 10 to 40 gr.

γ. Hydrargyrum cum Creta. - Mercury with Chalk. Mercury, 1; Prepared Chalk, 2. Dose, 3 to 8 gr.

b. Calx. - Lime. CaO (with some impurities). Source. - Made by calcining Chalk. CaCO3 = CaO + CO2.

Characters. - Compact whitish masses.

From Calx is made: a. Calcis Hydras. - Slaked Lime. Hydrate of Lime. CaH1O2 (with some impurities).

Source. - Made by slaking Lime with distilled water. CaO + H1O = CaH1O2.

Characters. - A. white powder, strongly alkaline. Soluble in 900 parts of water. Incompatible with vegetable and mineral acids, alkaline and metallic salts, and tartar emetic.

Preparations.

i. Liquor Calcis. - Solution of Lime. Lime Water! Made by shaking up Slaked Lime in Distilled Water, and decanting after the excess has subsided. 1/2 gr. of lime in 1 fl.oz. Dose, 1/2 to 4 oz.

From Liquor Calcis is prepared:

Linimentum Calcis. - Liniment of Lime. Solution of Lime and Olive Oil, equal parts mixed.

Liquor Calcis is also used in preparing Lotio Hydrargyri Flava, Lotio Hydrargyri Nigra, and Argenti Oxidum.

ii. Liquor Calcis Saccharatus. - Saccha-rated Solution of Lime. Made by digesting Slaked Lime with Sugar and Water, and straining. 7.11 grains of lime in 1 fl. ounce. Dose, 15 to 60 min.

From Calcis Hydras are made: iii. Calx Chlorata. - Chlorinated Lime. "Chloride of Lime." CaCl2O2,CaCl2.

Source. - Made by passing Chlorine gas over Slaked Lime. 2CaH1O2+2Cl2=CaCl2O2, CaCl2 + 2H1O. Partially soluble in water, bleaches and disinfects.

Impurities. - Deficiency in chlorine; detected by volumetric test.

Characters. - A dull white powder, with a feeble odour of chlorine.

Preparations.

(1) Liquor Calcis Chloratae. - Solution of Chlorinated Lime. 1 pound to 1 gallon of Water; mixed, agitated, and strained. See Chlorum.

(2) Vapor Chlori. Inhalation of Chlorine. Chlorinated Lime, moistened with cold water, to disengage chlorine. See Chlorum.

Calx chlorata is also employed in preparation of Chloroform. See Chloroformum.

iv. Calcis Hypophosphis. - Hypophosphite of Lime. Ca2PH1O2.

Source. - Made by heating Slaked Lime and Water with Phosphorus, purifying the liquid, and crystallising. 3CaH1O2 + P8 + 6H1O = 3(Ca2PH1O2) + 2PH3.

Characters. - White pearly crystals, with a nauseous taste. Soluble in 6 parts of cold water; insoluble in spirit. Dose. - 5 to 10 gr.

Calcis Hypophosphis is used to make: (1) Sodas Hypophosphis. - See Soda.

c. Calcii Chloridum. - Chloride of Calcium. CaCl2.

Source. - Made by neutralising Hydrochloric Acid with Chalk, and evaporating to dryness. CaCO3 + 2HCl=CaCl2+CO2+H1O.

Characters. - White, very deliquescent masses; solubility, 1 in 2 of- water.

Impurities. - Carbonates, salts of alumina, and iron; Hypochlorites, detected by evolving Cl with HC1.

Dose. - 10 to 20 gr.

Calcii Chloridum is used to make: a. Calcis Carbonas Prsecipitata. - Precipitated carbonate of lime. CaCO3.

Source. - Made by mixing boiling solutions of Chloride of Calcium and Carbonate of Soda, and washing the precipitate. CaCl2+Na2CO3=CaCO3 + 2NaCl.

Characters. - A white crystalline powder, insoluble in water. Dose, 10 to 60 gr.

Calcis Carbonas Precipitata is contained in Tro-I chisci Bismuthi (4 gr. in each).

2. Calcis Phosplias

Calcis Phosplias. Phosphate of lime. Ca32PO4.

Source. - Made by (1) dissolving Bone-ash in Hydrochloric acid; and (2) adding Solution of Ammonia, and washing and drying the precipitate. (1) Ca32PO4 + 4HC1 = CaH42PO4 + 2CaCl2; (2) CaH42PO4 + 2CaCl2, + 4NH4HO = Ca32PO4 + 4NH4C1 + 4H1O.

Characters. - A light white amorphous powder, insoluble in water.

Dose. - 10 to 20 gr.

Calcis Phosphas is contained in:

Pulvis Antimonialis (2 parts in 3). See Antimonium. |

Action And Uses. 1. Immediate Local Action And Uses

Externally. - Lime in the form of the hydrate is caustic, like the alkalies, but its action is more localised, so that it may be combined with fused potash to form a convenient caustic, potassa cum calce, Vienna paste, for ordinary use. Dusted on the skin as chalk, or applied in lime-water, it is astringent and desiccative (drying), and is used to promote the healing of burns, eczema, and ulcers. The linimentum calcis is a valuable application to burns.

Internally. - The local effect of lime is antacid, like the alkalies and magnesia, combined with an astringency peculiar to itself. In the mouth, chalk is used as an antacid and physical dentifrice. Admitted into the stomach and intestines, as lime-water or the carbonate, lime unites with the free acids of the contents, and acts upon the structures of the gastric wall. It is accordingly useful in acid dyspepsia, with heartburn, given after food, e.g. as the bismuth lozenge. Lime-water prevents the gastric juice from curdling milk in large lumps, and is extensively given to artificially-reared infants, the liquor calcis saccharatus being an excellent form when dilution of the food is injurious. Its power of combination with acids also makes lime a valuable antidote for poisoning by the mineral acids, oxalic acid, and chloride of zinc, and one which is always available in the form of wall-plaster; it must be freely given. The action of lime on the glands of the stomach appears to be depressant, and it is, therefore, not suited for administration before meals. Lime-water is, indeed, a general gastric sedative of some value, arresting some kinds of vomiting, especially in the acid dyspepsia of infants, and in pregnancy.

But little of the alkaline effect of lime or chalk can remain in the bowels beyond what has been exerted on the chyme. The astringent action of these familiar drugs in diarrhoea may be in part due to their antacid property, in part to an obscure sedative effect on the intestinal glands (?and vessels), which diminishes the excretion of water into the bowel. The lime salts can be traced along the whole length of the canal, and most of their bulk is finally expelled unabsorbed. Lime and chalk thus come to be two of our most valuable astringents in diarrhoea, either alone or with aromatics, opium, or vegetable astringents, as in the officinal preparations.

Lime-water is also employed locally as an enema for killing the thread-worm, and as a vaginal injection in leucorrhcea.

2. Action On The Blood

Lime enters the circulation in very small quantities only, and appears in the serum as the phosphate. It probably increases the alkalinity somewhat, but no special use is made of it for this purpose.

3. Specific Action And Uses

The important part played by lime as a constituent of bone has suggested its use as a specific remedy in rickets, fractures, and other lesions of these structures; and the phosphates and lime-water are extensively used for the two former conditions. The phosphate and the chloride have been recommended in scrofulous diseases of glands and phthisis, to promote absorption, or possibly to induce caloification; and apparently with some reason. None of the calcareous mineral waters, however, are of much service in this respect.

4. Remote Local Action And Uses

The greater part of lime or its salts being expelled by the bowel, little remains to be excreted by the kidney, so that their diuretic and alkaline effects are not marked. Their most useful form for influencing the urine is Bath or Wildungen water.

5. Action And Uses Of The Different Salts Of Lime

Creta in its various forms and combinations - Liquor Calcis and Liquor Calcis Saccharatus - possesses the general effects and uses of lime. Calcii Chloridum is a gastric sedative, but is also a specific in scrofulous enlargement of glands; and is used in ng. Calcis Phosphas is a specific in bone diseases and scrofula. Calx Chlorata and its derivates are media for supplying chlorine, and used accordingly. Calcis Hypophosphis is employed as a specific in tuberculosis and other wasting diseases. In the remaining preparations the action of the lime or chalk is comparatively insignificant, as, e.g., in the three preparations of mercury, of which they are ingredients, and in antimonial powder.