308 INFLAMMABLES. 



4. MODERN PROCESS.* 



(a.) Carried on in chambers, lined throughout, with sheet lead ; 

 usual size, 20 feet long, and 12 wide or 40 to 60 by 16 or 18; 

 in one case, in England, 120 by 40, and 20 high contents 96000 

 cubic feet. 



(b.) Sulphur, 7, 8 or 9 parts, coarsely bruised, and 1 part of 

 common nitre, are mixed. One pound of the mixture for every 300 

 cubic feet of air, is placed in separate portions upon iron or leaden 

 plates, supported by stands of lead. The sulphur is lighted by a hot 

 iron and the door closed, f The combustion continues 30 or 40 

 minutes, and in three hours the acid gas is absorbed by the water on 

 the floor of the room, which is usually about six inches deep ; or 

 sometimes the acid vapors are carried by the current of air that sup- 

 ports the combustion, into another leaden room, where they are con- 

 densed by water, f 



(c.) The room is then ventilated, and the process repeated every 

 four hours, day and night, until the water at the bottom is sufficiently 

 acid. 



(d.) Then it is drawn off by a syphon, into a leaden reservoir. 



(e.) It is pumped from this into leaden boilers, and there concen- 

 trated|| by heat, until it is of the sp. gr. 1.350 to 1.450, or 1.560. 



(f.) It is finished in glass retorts, placed in sand baths, and the 

 retorts are now generally furnished with platinum wire to prevent the 

 concussion in boiling ; water, and nitrous and sulphurous acid gas be- 

 ing expelled, it then has the specific gravity 1.850, or, as Dr. Ure 

 says, 1.842, if pure. For economy, the concentration of sulphuric 

 acid is now often performed in platinum boilers, placed within iron 

 ones of the same size and form. 



The conversion of sulphur into an acid, is easily proved by burning 

 it in a pendent metal spoon, introduced into a bottle of oxygen or 

 common air, on the bottom of which is some litmus infusion.^ 



5. PROPERTIES. 



(.) Thick, oily looking fluid ; pours slowly from vessel to ves- 

 sel ; corrosive, and, with or without heat, destroys all animal and 

 vegetable bodies ; the first sensation when it is rubbed on the skin, 

 is that of lubricity, but immediately after, there is extreme burning. 



* Begun by Dr. Ward, in England, before 1746, by combustion in glass bells or 

 globes; in 1746 Dr. Roebuck introduced the leaden chambers at Birmingham. 

 Parkes' Essays, Vol. I, p. 476. 



t A red hot cannon ball is sometimes rolled in through a trough lined with iron. 



t The theory of this process cannot be fully elucidated until we have become ac- 

 quainted with the nitric compounds, when it will be resumed. It may be stated, 

 however, that sulphurous acid is formed from the sulphur, and nitric oxide gas from 

 the nitre ; this obtains oxygen from the air, becomes nitrous acid vapor, then oxy- 

 genizes the sulpburous acid, and turns it into sulphuric acid. 



The sulphurous. 



|| Concentration is when a volatile ingredient is driven off, and a more fixed one is 

 Saved. Distillation when the volatile ingredient is saved. 



