90 MATERIA MEDICA. 



and Bij bicarbonate of soda in one paper, and 35 grs. tartaric acid 

 in another paper; each paper to be dissolved in a separate tumbler, 

 and the two mixed, when effervescence occurs from the escape of 

 carbonic acid, and the patient swallows a mixture of Rochelle salts 

 and tartrate of soda. 



Phosphate of Soda. — (Sod^ Phosphas, U. S.) 

 Prepared by the action of sulphuric acid on bone earth, which 

 consists of carbonate and phosphate of lime ; sulphate of lime is 

 thrown down, and superphosphate of lime remains in solution ; this 

 is now to be decomposed by carbonate of soda. Occurs in large 

 rhombic transparent crystals ; very efflorescent ; contain more than 

 60 per cent, of water of crystallization ; taste resembles that of 

 common salt ; soluble in water ; — dose, 3j to 3ij. Particularly ap- 

 plicable to case of children ; but not much used on account of its 

 expense. 



Magnesia. 



Sometimes called calcined magnesia^ and magnesia usta. Pro- 

 cured by exposing the carbonate to a red heat. A very light white 

 powder; its degree of levity, however, depends upon its amount of 

 trituration, its density being increased by that process ; almost inso- 

 luble in water. 



Efects. — A mild and useful cathartic, particularly when there is 

 acidity in the primoe vise. Its cathartic operation is somewhat un- 

 certain, depending upon the presence of an acid : it sometimes accu- 

 mulates in the bowels. It is also used in sick headaches, and in 

 nephritic complaints ; also, in bowel complaints, combined with rhu- 

 barb. Dose 3j, — best given rubbed up in syrup. 



Carbonate of Magnesia. — (Magnesi.e Carbonas, U. S.) 



Prepared by decomposing any soluble salt of magnesia by an 

 alkaline carbonate. Occurs in white cakes, extremely light and 

 porous ; insoluble in pure water ; somewhat soluble in carbonic acid 

 water. 



Effects. — A gentle laxative, but dependent for its operation on the 

 acid found in the stomach and bowels; apt to occasion flatulence 

 from the escape of the carbonic acid. Dose, 3j to 3ij. 



Sulphur. 



Used in medicine in the form o^ flowers of sulphur, or common 

 sublimed sulphur washed in water. Odour and taste slight ; insolu- 

 ble in water, and nearly so in alcohol ; soluble in oils. 



Effects. — A mild laxative, but slow in its operation, sometimes 

 griping ; it has a decided tendency to the skin, and is thought to act 

 on the broH<6hial mucous membrane. It is used in constipation at- 



