316 INFLAMMABLES. 



(t.) Sir H. Davy, substituting the pressure of the vapor of ether for 

 that of the gas itself, and causing the former, through the medium of 

 mercury in the bend of the tube, to press upon the latter in the other 

 leg, while cold was applied, succeeded in condensing the sulphurous 

 acid into a fluid.* 



4. PROPERTIES OF THE LIQJJIFIED GAS. 



(a.) Limpid, colorless, refractive power similar to that of water ; 

 when the tube was opened it evaporated rapidly, but without explo- 

 sion. 



(b.) Sp. gr. 1.45 bolls at 14 Fahr. and evaporates rapidly, but 

 without explosion, cooling the residuary fluid to 0, so that it re- 

 mains some time liquid under the pressure of the atmosphere. 



(c.) JY0 visible fumes, but a strong smell of sulphurous acid, 

 eventually leaving the tube dry. 



(d.) Ice dropped into the fluid, proved so much warmer, that the 

 ice made the fluid boil. 



(e.) Mercury is frozen by the cold produced by the evaporation 

 of sulphurous acid ; for this purpose the ball of a thermometer tube 

 is surrounded with cotton, and kept wet with the liquid. 



(jf.) By its aid, and that of a moderate pressure, several addition- 

 al gases have been liquified. f The cold was carried to 60, but 

 absolute alcohol and ether did not freeze. One part of the acid 

 in a watch glass, freezes, by the spontaneous evaporation of the 

 other. 



5. COMBINING WEIGHT. 



Sulphurous acid consists of 1 proportion of sulphur 16, -f-2 of oxy- 

 gen 16 = 32, which is therefore its equivalent number. 



6. POLARITY. Like other acids, it is electro negative, as it is 

 attracted to the positive pole in the galvanic arrangement. 



7. SULPHUROUS ACID IN VOLCANOS AND SOLFATERRAS. It is 

 constantly emitted wherever volcanic fires are active. This arises 

 from the combustion of sulphur, raised by the subterranean heat r 

 and burned by the air in its passage. Those who visit volcanic cra- 

 ters and solfaterras are constantly incommoded by this gas, and ^often 

 find it necessary to mount some elevation in order to escape from 

 suffocation. 



corked tight, and the vessel must be constantly surrounded by a freezing- mixture, 

 else the gas will escape, or the vessel explode. A few drops of the liquid sulphu- 

 rous acid thrown upon water, produces a crust of ice. 



If mercury, of the volume of a hazlenut, is moistened by a few drops of the acid, 

 and the apparatus placed under an exhausted receiver, the metal will freeze solid, 

 and a considerable mass may be thus frozen and preserved for a few minutes. It is 

 found that solid mercury is a much better conductor of electricity than the fluid 

 metal. In its pure liquid state, it was not decomposed by electricity, but if a little 

 water was added, sulphuretted hydrogen appeared at one pole, and oxygen at the 

 other. 



* See Faraday's Chemical Manip. p. 205. t Ann. Phil. N. S. Vol. VIII, p. 307, 



