SULPHUROUS ACID 213 



AcrDUM SULPHUROSUM. Sulpliurous Acid. H2SO3. 

 (U. S. k B. p.) 



Synonym. — Acide sulfureux, Fr.; schwefelige saure, G. 



Derivation. — Charcoal, 20, and sulphuric acid, 80, are 

 heated together and the sulphurous anhydride evolved is 

 passed into water. 4 H, SO, + 2 C = 4 SO^ 4- 2 CO, -f 4 

 H,0. 4 SO, + 4 H,0 = 4 H.SO,. 



Properties.— A colorless liquid of the characteristic odor 

 of burning sulphur, and of a very acid, sulphurous taste. It 

 should contain not less than 6.4 per cent., by weight, of sul- 

 phurous anhydride, and not more than 93.6 per cent, of water. 



i>ose.— H. & C, §i.-ii. (30.-60.); Sh. & Sw., 3i.-ii. (4.-8.); 

 D., 3ss..ii. (2.-8.). 



Actions and Uses. — Sulphurous acid decomposes organic 

 matter, abstracts oxygen, and is transformed intb sulphuric 

 acid. The amount of sulphuric acid formed from the medi- 

 cinal solution is not sufficient to interfere with its action in 

 or upon the body. Sulphurous acid is a deodorant, deoxi- 

 dizer, parasiticide and disinfectant externally. Solutions 

 (1-4) are used as local stimulant and antiseptic applications 

 to wounds, ulcers, or sores with foul discharges, and to kill 

 the fungus growths producing ringworm. 



Sulphurous acid is employed as an antiseptic in indi- 

 gestion,' associated with flatulence, and has the same effect 

 and value as the sulphites and hyposulphites which are 

 used for the same purposes. 



PoTASSA SuLPHURATA. Sulphurated Potassa. (U.S. & B.P.) 



Synonym. — Potassii sulphuretum, potassii sulphidum^ 

 liver of sulphur., E.; foie de soufre, Fr.; kalischwefel- 

 leber, G. 



Derivation. — Powdered and dried potassium carbonate, 

 200, is mixed with sublimed sulphur, and heated in a cru- 

 cible. Potassa sulphurata is a mixture of potassium hypo- 

 sulphite and sulphide. 3 K^C O3 -h 8 S = KAO3 -f- 2 K.S, 

 + 3 CO,. 



