MAGNESIA 155 



nesium), or a light, white powder (light magnesium), without 

 odor, and having a slightly earthy taste ; permanent in the 

 air ; almost insoluble in water, to which, however, it imparts 

 a slightly alkaline reaction ; insoluble in alcohol. 



Dose. — Foals and calves, 3 i--ii- (4.-8.); D., gr.v.- 3 i. 

 (.3-4). 



Magnesia. Magnesia. MgO. (U. S. P.) 



Synonym. — Magnesia levis, light magnesia, B.P.; calcined 

 magnesia, magnesia calcinata, E.; magnesia usta, P. G.; 

 magnesie, magnesie calcinee, Fr.; gebrannte magnesia, G. 



Derivation. — Heat magnesium carbonate. 4 (MgCOj). 

 Mg(OH), + 5 H,0 = 5 MgO + 6 H,0 + 4 CO,. Water 

 and carbon dioxide are driven off and magnesia (MgO) is left. 



Properties. — A white, very light, very fine powder, with- 

 out odor, and having an earthy, but not a saline taste. On 

 exposure to the air it absorbs moisture and carbon dioxide ; 

 almost insoluble in water ; insoluble in alcohol. 



Dose. — Foals and calves, 3 i.-ii. (4-8.); D., gr.v.- 3 L 

 (.3-4.). 



Magnesia Ponderosa. Heavy Magnesia. MgO. (U. S. P.) 



Derivation. — Made from light magnesia by trituration 

 with alcohol, drying and pulverizing. 



Properties. — A white, dense, very fine powder. Only 

 differs in tests from light magnesia in that it does not readily 

 unite with water to form a gelatinous hydrate. 



Dose. — Foals and calves, 3 i.-ii. (4.-8.); D., gr.v.- 3 i. 

 (.3-4.). 



ACTION OF MAGNESIUM CARBONATES AND OXIDES. 



Internal. — Alimentary Canal. — These salts are antacid 

 and neutralize abnormal acidity, due to fermentation, 

 when exhibited after a meal. The carbonate also exerts 

 a sedative action in liberating carbon dioxide in the 

 stomach, and both the carbonate and oxide unite with the 



