326 SULPHUR. 



receiving its vapour in a bottle artificially cooled, which can 

 afterwards be closed by a glass stopper. It condenses in solid 

 fibres, like asbestos, which are tenacious and may be moulded 

 by the fingers like wax. Its density at 68 is 1.97. At 77 it 

 is liquid, and a little above that temperature it enters into ebul- 

 lition, affording a colourless vapour, which produces dense 

 white fumes on mixing with air, by condensing the moisture in 

 it. The dry acid does not redden litmus, an effect, which re- 

 quires the presence of moisture. It combines with sulphur, and 

 produces compounds which are of a brown, green and blue 

 colour, and with one tenth of its weight of iodine forms a com- 

 pound of a fine green colour, which assumes the crystalline 

 form. Heated in the acid vapour, caustic lime or barytes in- 

 flames and burns for a few seconds ; the vapour is absorbed, and 

 sulphate of lime or barytes formed. The anhydrous acid has 

 a great affinity for water, and when dropped into that liquid, 

 occasions a burst of vapour, from the heat evolved. The den- 

 sity of its vapour was found to be 3000 by Mitscherlich, but it 

 is probably 2762, and formed of 3 volumes of oxygen and l-3rd 

 of a volume of sulphur vapour, condensed into 2 volumes, 

 which constitute its combining measure. This vapour is 

 resolved by a strong red heat into sulphurous acid and 

 oxygen. 



When the Nordhausen acid is retained below 32, well formed 

 crystals appear in it, which Mitscherlich finds to be a compound 

 of two equivalents of acid, and one of water, or 2SO 3 -f HO.* 

 This compound is resolved by heat into the anhydrous acid, 

 which sublimes, and the first hydrate, or oil of vitriol. 



The most concentrated oil of vitriol of the leaden chambers 

 (HO -f SO 3 ) is a dense, colourless fluid, of an oily consistence 

 which boils at 620, and freezes at 29, yielding often regular 

 six sided prisms of a tabular form. It has a specific gravity 

 at 60 of 1.847 or a little higher, but never exceeding 1.850. 

 It is a most powerful acid, supplanting all others from their 

 combinations, with a few exceptions, and when undiluted is 

 highly corrosive. It chars and destroys most organic sub- 

 stances. It has a strong sour taste, and reddens litmus even 

 though greatly diluted. Sulphur is soluble to a small extent in 

 the concentrated acid, and communicates a blue, green or brown 



* Eleraens cle Chimie, par E. Mitscherlicli, t. 2, p. 57. 



