142 INOKGANIO AGENTS 



their water of crystallization. Soluble in 5.8 parts of water; 

 insoluble in alcohol ; slightly alkaline reaction. ^ 



X)ose.— Same as sodium sulphate^ D., 3i--ii- (4-8.), as 

 laxative. 



The phosphate resembles the sulphate, but is a milder 

 purgative and is wrongly thought to be an hepatic stimu- 

 lant. It is indicated in jaundice due to duodenitis, and as a 

 laxative for foals and calves. It is occasionally prescribed 

 in rickets as a source of phosphorus, but the calcium phos- 

 phate is more appropriate. 



SoDii SuLPHis. Sodium Sulphite. Na, SO, 7 H^O. 



(U. S. & B. P.) 

 Synonym. — Natrum 8uHai-iosum,sulfis sodicus (natricus), 

 sulphite of soda, E.; sulfite de soude, Fr.; schwefligsaures 

 natron, G. 



Derivation. —Satureite a solution of sodium carbonate or 

 hydrtite with sulphurous anhydride gas. Na, CO, + S02= 



Na, SO3 + CO,. 



Properlies. — Colorless, transparent, monoclinic prisms, 

 odorless, and having a cooling, saline, sulphurous taste. In 

 air the salt effloresces, and is slowly oxidized to sulphate. 

 Soluble in 4 parts of water ; sparingly soluble in alcohol ; 

 Neutral or feebly alkaline. 



i?ose.— H. & C, 3i. (30.); Sh. & Sw., 3 ss.-i. (2.-4); D., 

 gr.v.-xxx. (.3-2.). 



SoDii Bisulphite. Sodium Bisulphite. NaHSOa. (U. S. P.) 



Derivation. — Obtained from sodium carbonate or bicar- 

 bonate and sulphurous anhydride gas. 



■ Properties. — Opaque, prismatic crystals, or a granular 

 powder, exhaling an odor of sulphur dioxide and having a 

 disagreeable, sulphurous taste. Exposed to the air the salt 

 loses sulphur dioxide and is gradually oxidized to sulphate. 

 Soluble iu 4 parts of water and in 72 parts of alcohol ; reac- 

 tion acid. 



Dose. — Same as sodium sulphite. 



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