308 VIII. ACIDS.— Sulphuric. 



2. Distil several successive charges of red sulphate of iron into 

 a small quantity of distilled water. 



Anhydrous sulphiric acid. Icy oil of vitriol, Oleum vitrioli gla- 

 dale. From calcined copperas, as the German oil, not putting on 

 a receiver until the white vapours come out very copiously, and 

 putting no water or phlegm into it. Bernhard from 6 cwt. of cop- 

 peras obtained 50lb. 



2. By distilling Nordhausen oil of vitriol in luted vessels; the 

 icy oil sublimes into the neck of the retort, while the hydrated 

 acid passes over in a liquid form. 



3. By distilling calcined copperas a number of times into the 

 same portion of English oil of vitriol ; white, transparent crystals, 

 smoking very much ; melts at QQ deg. Fahr. and crystallizes at 

 77 deg. ; contains no water. 



Acidum sulphuriciim depuratum, P. Belg. German oil of vitriol 

 boiled in a bolt head on a sand bath, until it admits no watery 

 vapours, and becomes pale. 



Acidum sulpliuricum puruih, P. Belg. German oil of vitriol 

 21b. ; distil in a very large retort in a sand bath into an unluted 

 receiver, by a heat not exceeding that of boiling water, as long as 

 large drops of water form in the neck ; then augment the heat even 

 to boiling, and when oily streaks appear and the vessels are filled 

 with the white vapours of sulphuric acid, apply another receiver 

 previously warmed, and distil, at the rate of 4 drops in a minute, 

 to dryness. 



Oil of sulphur by the hell. Oleum sulphuris per campanam. Burn 

 sulphur in a moist place and during moist weather under a glass, 

 bell, or some similar vessel, previously moistened on the inside 

 with the steam of water ; collect what drops from the bell in a 

 glass plate, and distil it until white vapours begin to appear, the 

 oil of sulphur remains in the retort. The purest sulphuric acid ; 

 but it was esteemed good workmanship to obtain 5 oz. from each 

 bell in i:34 hours. 



Common oil of vitriol. Sulphuric acid, Oleum vitrioli Ajiylicum, 

 Acidum sulpliuricum Anglicum. Mix sulphur 1001b. with salt- 

 petre 100 or l^Olb., burn it by degrees upon a plate of hot iron, 

 conduct the vapour into a chamber of 5000 or 10,000 cubic feet 

 capacity, formed of sheet lead, having at the bottom a layer of two 

 or three inches of weak sulphuric acid. A small hole, about two 

 inches above the level of the burning sulphur, must be left to 

 allow a draught of air to enter the chamber, and a chimney at the 

 further end to let it pass off. Inject occasionally a shower of 

 water, and draw off every morning the acid that was made during 

 the preceding day, leaving the original depth on the floor of the 



