134 INORGANIC AGENTS 



SoDii Phospkas. Sodium Phosphate. Na^HPO, + ISiH^O. 



(U. S. & B. P.) 



Synonym. — Phosphas sodicus (natricus), sal mirabile 

 perlatum, phosphate of soda, E.; natrum phosphoricum, 

 P. G.; phosphate de soude, Fr.; phosphorsaures natrum, G. 



Derivation, — Digest bone ash with sulphuric acid. 

 Ca, 2P0, + 2 H, SO, = Ca H, 2 PO, (acid calcium phos- 

 phate) + 2 Oa SO4. Filter and add sodium carbonate to 

 filtrate. 



Ca H, 2 Po, + Na, Co, = Na, H PO, 4- H,0 + Co, + 

 Ca HPO4. Evaporate, and sodium phosphate crystallizes 

 out. 



Properties. — Large, colorless, monoclinic prisms, odor- 

 less, and having a cooling, saline taste. The crystals 

 effloresce in the dry air and gradually lose 5 molecules of 

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

 insoluble in alcohol ; slightly alkaline reaction. 



Dose. — Same as sodium sulphate ; D., 3 i.-ii. (4.-8.), as 

 laxative and chologogue cathartic. 



The phosphate resembles the sulphate, but is a milder 

 purgative and more efficient hepatic stimulant. It is indi- 

 cated in jaundice, and as a laxative for foals and calves. It 

 is occasionally prescribed in rickets as a source of phos- 

 phorus, but the calcium phosphate is more appropriate. 



Soon SuLPHis. Sodium Sulphite. Na, S03 7 H^O. 



(U. S. & B. P.) 



Synonym. — Natrum sulfuriosum, sulfis sodicus (natricus), 

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

 natron, G. 



Derivation. — Saturate a solution of sodium carbonate or 

 hydrate with sulphurous anhydride gas. Naj CO, -|- Soj = 

 Na, S03 4- Co,. 



Properties. — Colorless, transparent, monoclinic prisms, 

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

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



