INFLAMMABLES. 315 



.00 If tw o measures of sulphurous acid gas and one of oxygen be 

 mingled in a jar, standing over mercury, and a little water be added, 

 sulphuric acid will be formed ; the same result is obtained by passing 

 the mixed gases through a red hot tube, or causing the electric spark 

 to pass through them. 



(k.) Becomes liquid by great cold ; or by moderate cold, 31, 

 if aided by pressure. 



(/.) Decomposed when passed over ignited charcoal, or with hy- 

 drogen, through a red hot tube ; water and sulphur are the products 



(m.) Liquid sulphurous acid does not give up its gas by freezing, 

 and becomes so heavy as to sink in water. 



(n.) Boiling expels the gas, although the water remains acid, from 

 the formation of sulphuric acid. 



(o.) Exposed to the air, the liquid acid becomes slowly sulphuric 

 acid, absorbing oxygen gas from the air ; its smell is like that of the gas. 



(p.) Decomposed, by potassium* heated in it ; products, probably 

 potassa and sulphuret of potassium ; also, at ignition, by hydrogen, 

 forming water and leaving sulphur ; and by carbon, producing carbo- 

 nic acid and carbonic oxide, and liberating sulphur. 



(q.) Sulphurous acid attracts oxygen powerfully ; it converts the 

 peroxide into the protoxide of iron ; the same with manganese, and it 

 precipitates gold, platinum, and mercury in the metallic state, be- 

 cause their affinity for oxygen is feeble ; it becomes itself, in the 

 mean time, sulphuric acid, by acquiring one proportion of oxygen. 



(r.) Condensation of sulphurous acid gas. Mr. Faraday,f by 

 confining, in a bent glass tube, both sulphuric acid and mercury, and 

 applying heat, caused the sulphurous acid gas which they produced 

 by their reaction, to pass into the other end of the tube, cooled by a 

 freezing mixture, and thus obtained the sulphurous acid in a liquid 

 state. The pressure was about two atmospheres. 



(s.) Mr. Bussy\ also obtained the liquid anhydrous acid, from 

 the above named materials, by passing the dried gas into a vessel 

 cooled by ice or snow, then through a tube containing melted muri- 

 ate of.lime, and finally into a matrass surrounded by a mixture of 

 ice 2 parts and common salt 1 ; in this, the gas is condensed into a 

 liquid, at the common atmospheric pressure.^ 



* It is decomposed in the same manner by sodium. 



t Phil. Trans. 1823, p. 190. 



i Ann. Phil. Vol. VIII, p. 307, N. S. 



& M. A. de la Rive (Bib. Univ. Mars, 1829, and Am. Jour. Vol. XVII, p. 166,) 

 directs that a second tube, filled with muriate of lime, should pass from the second 

 to a third vessel cooled like the others, and from this a tube may proceed to the mer- 

 curial cistern. The junctures must be luted tight. The gas having been disenga- 

 ged during 8 or 10 hours, white crystals, (hydrates) are found in the vessel No. 1 ; 

 they resemble the hydrate of chlorine ; they are said to remain solid at 4 or 5 (centi- 

 grade ) and in Nos. 2 and 3, is the liquid sulphurous acid, which must be immediately 



