This section is from the book "Materia Medica Pharmacy, Pharmacology And Therapeutics", by W. Hale White. Also available from Amazon: Materia Medica Pharmacy, Pharmacology And Therapeutics..
A colorless liquid of the characteristic odor of burning Sulphur, and of a very acid, sulphurous taste. Sp. gr., not less than 1.035.
Sulphuric acid, and mineral matters.
Dose, 1/2 to 2 fl. dr.; 2. to 8. c.c.
Sulphurous acid is strongly deoxidizing, and as it takes up oxygen so easily from organic bodies, it readily decomposes them, becoming itself converted into sulphuric acid, and hence is irritant, but not violently so, for the amount of sulphuric acid in proportion to the water is slight. It is a disinfectant and deodorant; for in virtue of its property of absorbing oxygen, it destroys micro-organisms and arrests fermentation. When applied to the skin it is a parasiticide.
It is believed to act as a disinfectant in the stomach and intestine, but it is very doubtful whether enough of it to have any appreciable action in this direction can be safely taken.
Sulphurous acid is chiefly used as an antiseptic, disinfectant, and deodorant. Sulphur dioxide is employed as a disinfectant for a sick-room after a patient with an infectious disease has been in it. The chimneys and windows should be stopped up. A quarter to half a pound 120. to 240. gm. or more of flowers of sulphur or better, one or two sulphur candles, now to be found in pharmacies, are placed in an earthenware vessel and lighted; the door is shut, and the cracks around it pasted over. The room should be left untouched for six hours. Generally not enough sulphur is burned for this method to be efficacious. Sulphurous acid 1 to 4 in water is locally applied to cure ringworm. Foul sores may be washed with it.
Sulphurous acid is sometimes given internally with the object of preventing abnormal fermentation in the stomach and intestines in certain varieties of dyspepsia, but there is no clinical proof that it can do this, and it should be remembered that it is possible it may do harm by impeding the action of the normal ferments.