SULPHUROUS ACID 259 



If steam can be introduced into the apartment, together 

 with sulphur fumes, the effect is vastly more efficient. The 

 sulphur and alcohol may be placed in an iron or earthen- 

 ware vessel, floating in a tub of water to avoid danger of 

 fire. The sulphur not infrequently fails to burn freely, and 

 combustion is secured more certainly by placing flowers of 

 sulphur with alcohol in an iron vessel which should rest 

 upon a stand in a large iron pot. A lighted alcohol lamp is 

 then put under the smaller iron vessel, containing the sul- 

 phur, and the lamp is ignited. The lamp insures complete 

 combustion of the sulphur and the outer iron pot prevents 

 the surrounding premises from catching fire. 



Sulphurous anhydride has been employed for its local 

 antiseptic and stimulant action, in inflammatory diseases of 

 the upper air passages in horses. For this purpose it is 

 burned in such quantities that the vapor is capable of being 

 inspired because largely diluted with air. With such dilu- 

 tion the antiseptic action is lost, and there is danger of 

 producing considerable irritation, and the procedure is of 

 doubtful value. The same treatment has been pursued in 

 verminous bronchitis of lambs and calves, caused by the 

 Strongylus filaria and S. micrurus. Local treatment, with 

 tracheal injection, is more efficient. 



AciDUM SULPHUEOSUM. Sulphurous Acid. HjSOs- 

 (U. S. & B. P.) 



Synonym.— A.oide 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 = 4 SO, + 2 CO, + 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. 



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