14^ INORGANIC AGENTS 



Mistura Cretce. Chalk Mixture. (U. S. P.) 

 Compound chalk powder, 200; cinnamon water, 400; water to make 

 1000. 



Dose.— D., liAi. (30.-60.). 



Trochisci Cretce. Troches of Chalk. (U. S. P.) 

 Contain .25gm., or gr.iv., each. 

 Dose. — D., same as prepared chalk. 



Calch Carbonas PHiECiPiTATUS. Precipitated Calcium Car- 

 bonate. CaCOs. (U. S. P.) 



Synonym. — Calcis carbonas praecipitata, B. P.; pre- 

 cipitated carbonate of lime, creta prsecipitata, carbonas cal- 

 cicus praecipitatus, E.; calcaria carbonica praecipitata, P. G.; 

 carbonate de chaux precipite, craie precipitee, Fr.; prse- 

 cipitirten kohlensauren kalk, G. 



Derivation. — Obtained by precipitation of calcium chlo- 

 ride with sodium carbonate. 



CaCl^ -h Na,Co3 = CaC03 + 2 NaCl. Dry the precipi- 

 tate. 



Properties. — A fine, white powder, without odor or taste, 

 and permanent in the air. Nearly insoluble in water; insol- 

 uble in alcohol. The solubility is increased by presence of 

 carbon dioxide. Permanent in air. 



Dose.—R., 5i.-ii. (30.-60.); C, 5 ii.-iv. (60.-120.); Sh. k 

 Sw., 3ii.-iv. (8,-15.); D., gr.x.-3i. (.6-4.). 



Calcium Carbonate. 



Action External. — Dessicant and slightly astringent 

 powder ; also protective. 



Action Internal. — Alimentary Canal. — Calcium carbonate 

 is the slowest acting antacid, because of its comparative 

 insolubility, and is of value when it can exert its long- 

 continued influence throughout the digestive tract. It 

 resembles bismuth in mechanically coating or protecting 

 inflamed or irritable surfaces. It is not so astringent nor 

 antiseptic as the bismuth salts, and these are generally 



