130 MATERIA MEDIC A AND THERAPEUTICS. 



Source. SodaB Biboras, by the action of sulphuric acid. 



Characters. In white glittering plates, odourless, with a 

 slightly bitter taste. A weak acid. Solubility, 1 in 26 of cold 

 water, 1 in 3 of hot water ; freely in glycerine ; less freely 

 in spirit. 



Dose. 5 to 30 gr. 



Preparations. 



1. "Boracic Lint." Lint steeped in a boiling satu- 

 rated solution, and dried. Contains nearly half its weight 

 of the acid. 



2. Various Ointments and Lotions. 



ACTION AND USES. 



Externally, boracic acid destroys low organisms, a solution of 

 1 in 133 arresting the activity of bacteria, and it is thus an anti- 

 septic, disinfectant, and deodorant. On the tissues it produces 

 little or no irritation, and is thus peculiarly adapted for use as 

 a surgical dressing. The lint is now extensively employed in 

 the antiseptic system; and lotions, warm fomentations made 

 from a boiling saturated solution, and ointments with paraffin 

 and vaseline, have almost replaced for the time other applica- 

 tions to wounds and ulcers. As its action does not extend 

 beyond the surface to which it is applied, boric acid is never 

 used for dressing cavities. It relieves itching, in the form of a 

 powder, ointment, or glycerine. It is a test for Rheum (q.v.) . 



Internally, boric acid is a gastro-intestinal irritant in large 



Acidum Sulphur o sum. Sulphurous Acid. Sul- 

 phurous acid gas, S0 2 , dissolved in water, and constituting 9 -2 

 per cent, by weight of the solution (rarely contains more than 

 6 per cent.). 



Source. Made by heating sulphuric acid with charcoal, 

 and dissolving the gas in water. 4H 2 S0 4 -f C 2 = 4S0 2 + 2CO 2 

 -f 4H 2 0. 



Characters. A colourless liquid, with a pungent sulphurous 

 odour. 



Impurities. Sulphuric acid; mineral matters; excess of 

 water, detected by volumetric starch and iodine test. 



Dose.^to 1 fl.dr. 



Non-officinal Preparations containing Sulphurous ^Acid. 

 Sodse Sulphis. Sulphite of Soda. Na 2 S0 3 ,7H 2 0. 

 Source. Made by saturating a solution of carbonate of 

 soda with sulphurous acid gas. 



