Prepared Chalk. Carbonate of Lime, CaO,C2, nearly pure. Chalk reduced to a very fine powder, and elutriated. Lime 56, Carbonic Acid 44, in 100 parts.

Calcis Carbonas PrAecipitata. Precipitated Carbonate of Lime. Precipitated Chalk. CaO.CO2. Prepared by precipitating a solution of Chloride of Calcium with Carbonate of Soda, collecting and drying at 212°.

Med. Prop. and Action. Antacid, absorbent, and astringent. If continued for any length of time, an occasional aperient is advisable, as it is apt to accumulate in the bowels, and form intestinal concretions. Like Liquor Calcis, it appears to have the effect of diminishing the secretion of the mucous membrane of the intestines, besides correcting any existing acidity. Hence it is termed an astringent. The medical properties and action of Precipitated Chalk are similar to those of Prepared Chalk, but the latter should be used in preparing Chalk Mixture, as Precipitated Chalk from its crystalline property is said to occasion irritation of the bowels (Squire**). Externally it is applied in fine powder to ulcers and excoriations.

Offic. Prep. Of Creta PrAeparata: -

1. Hydrargyrum Cum Creta (See Art

Hydrargyrum cum Creta).

2. Mistura Creta; (Prepared Chalk Oz

1/4; Powdered Gum Arabic oz. 1/4; Syrup fl. oz. ss.; Cinnamon Water fl. oz. viiss.). Dose, fl. oz. j. - fl. oz. ij.

3. Pulvis CretAe Aromaticus (Aromatic Powder [see Cinnamon] lbs. iij.; Prepared Chalk lb. j.). Similar to the Confectio Aromatica of the Lond. Pharm. Dose, gr. xxx. - gr. lx.

4. Pulvis Cretae Aromaticus Cum Opio (Aromatic Powder Of Chalk Oz

ix. 3/4; Powdered Opium oz. 1/4); gr. xl contains gr. j. of Opium. The dose depends on the amount of Opium it is wished to administer. (This powder is intended to supersede the Pulvis Crete Comp. cum Opio of the Pharm. Lond., which contained Prepared Chalk, Cinnamon, Tormentilla, Gum Acacia, Long Pepper, and Opium - the last in the proportion of gr.j. in xl. of the powder.)

* On Phlegmasia Dolens, Lond. 1862.

Dict. Pract. Med., vol. i. p. 767.

On the Properties of Creasote, op. cit.

§ Lancet, Dec. 8, 1855.

II Med Times andGaz., Jan. 7,1860. ¶ Dublin Journ., vol. xi p. 237. ** Companion to Brit. Pharm., p. 69.

Dose of Creta Prasparata and of Calcis Carbonas PrAecipitata, gr. xx. - gr. lx.

Incompatible*. Acids; Acidulous Salts.

1004. Therapeutic Uses

In Diarrhoea, arising from acidity of the prim vice, and in some other forms of the disease, the Chalk Mixture (ut supra) proves of the greatest benefit. It may be advantageously combined with Aromatic Powder, Catechu, and Opium, as the circumstances of the case may require. In children and infants, the Pulvis CretAe Aromaticus should be preferred Its operation in these cases can hardly be attributed solely to its antacid property, as other antacids fail to produce the same astringent effects.

1005. To Diseases of the Skin, Excoriations, Burns, and Ulcers, when accompanied by an acrid irritating discharge, Chalk finely powdered, and sprinkled over the surface, is highly useful, absorbing the discharge, and thus preventing the disease extending. An emollient poultice should be placed over the whole surface.

1006. In Chronic Bronchitis, in the advanced stages, particularly when colliquative sweats and Diarrha are present, Dr. Copland * observes that the Mistura CretAe is often very serviceable. He states that he has derived the most essential benefit from the following mixture; even where the bowels were regular, he found it by no means productive of costiveness: -1004 Therapeutic Uses 77 Mist. CretAe fiss., Vin. Ipecac. f5iss.,Tinct. Opii f3j. (velTinct. Camph. Co. f3vj.), Syrup. Tolut. f3iij., M. cap. coch. amp. ij. ter quaterve in die. A similar formula proved very effectual in the hands of Dr. Hastings.