MANUFACTURE OF 8CXPHUKIC ACID.] 



CHEMISTRY. 



?69 



fluid, having considerable gravity. From this appearance, 

 sulphuric acid often is termed oil of vitriol. 



Fig. 58. 



JL 



Our diagram, Fig. 68, represents a section of a sul- 

 phuric acid chamber. On the left is the furnace supplying 

 the vapours of sulphur and nitric acid ; in the centre, 

 we have the large leaden chambers in which the two 

 vapours combine together with steam produced from a 

 boiler, represented on the right of the diagram. In 

 practice, a larger number of leaden chambers is employed ; 

 and the following engraving represents an arrangement 

 often used on the large scale for the manufacture of 

 sulphuric acid. 



Fig. S9. 

 o 



In the above, A represent* the place in which the 

 sulphur is first burned, which, at the same time, pro- 

 duces steam from water ; this passing, by means of pipes, 

 to chambers 1 and 3. The sulphurous acid proceeds by 

 M to a, where it is exposed to some nitric aci<l i>roceed- 

 ing from N, which passes over sheet* of lead placed 

 slantingly in a. These vapours, Arc., then pass on to 

 chambers 1, 2, and 3 ; when they come in contact with 

 a jet of steam, and so the chemical changes already de- 

 scribed take place, which result in the production of 

 sulphuric acid. In the remainder of the chambers, the 

 uncharged sulphurous acid is acted on by arrangements 

 at B and O, corresponding with those already described 

 at N and a at the right of the engraving. By such an 

 arrangement all the materials are utilised ; none are 

 suffered to go to waste ; and the manufacture of the acid 

 goes on without intermission, so long as a supply of the 

 materials is kept up. 



The student may easily master the details of the pro- 

 cess by means of the following plan : Put some mercury 



Fig. 60. 



and a little sulphuric acid into a glass flask, and connect 

 this, by means of a bent tube, with a larger flask, as seen 



VOL. I. 



in Fig. CO, in which A is the vessel receiving the vapours 

 of sulphurous acid, produced by boiling the sulphuric acid 

 and mercury in B. Pass some binoxide of nitrogen 

 from another vessel, C, containing some coppei 

 filings and nitric acid, into the large flask, A, which 

 should be moistened internally with water. As. 

 the sulphurous acid vapour comes in contact with 

 the binoxide of nitrogen and air in vessel A, the 

 decomposition, itc. , already described, proceed 

 just as they take place on the large scale in the 

 leaden chambers, and sulphuric acid is accordingly 

 produced. The preceding engraving illustrates 

 this arrangement. 



Sulphuric acid, in a concentrated state, is highly 

 corrosive, acting with great vigour on all organised bodies, 

 chiefly by the great attraction it has for water, which it 

 will seize wherever it can be found. It unites readily 

 with bases forming sulphates. It requires great heat to 

 evaporate it ; and the operation should only be con- 

 ducted in platina vessels, on the large scale, because the 

 vapour is disengaged so irregularly in glass vessels as to 

 be almost explosive in its action. It may, however, be 

 effected in small glass retorts, if a few pieces of platina 

 foil be cast therein to facilitate the disengagement of the 

 vapour. The following experiments 

 will illustrate some of the properties 

 of the acid. 



Experiment 58. Pour some strong 

 sulphuric acid suddenly into a vessel 

 containing an equal bulk of cold 

 water. Great heat will be disengaged, 

 which will sometimes rise so high as 

 300 Fah. 



Esjierimcnt 59. Into a strong so- 

 lution of sugar pour some concen- 

 trated sulphuric acid, which will 

 have so great an attraction for the 

 water as to set free the charcoal of 

 the sugar as a black spongy mass. 

 In a similar manner, if the strong 

 acid be dropped on wood, <tc., a 

 black spot is produced, owing to the liberation of its 

 charcoal. Sulphuric acid of commerce is thus often 

 discoloured by pieces of straw, etc., falling into it, and 

 so suffers partial decomposition. 



Experiment 60. Into an oily Florence flask pour 

 some strong sulphuric acid, and run it about over the 

 interior of the vessel The oil will be decomposed, and 

 the acid will turn black. By these means Florence 

 flasks may be easily cleansed from the oil they usually 

 contain. 



There are other combinations of sulphur with oxygen, 

 which, with the exception of hyposulphurous acid, .are 

 of no importance. The only combination of this acid 

 worthy of notice, is the hyposulphite of soda, which 

 is so largely employed as a " fixing" agent in photo- 

 graphy, and is produced by boiling soda with sulphur in 

 excess. 



/ / ijdromlphuric Acid. This is generally termed, in 

 chemical works, sulphuretted hydrogen ; and it is a 

 compound of one equivalent each of sulphur and hydro- 

 gen ; symbol, HS ; equivalent = 17. This gas is well 

 known as being the cause of the offensive smell of 

 house-draim, and arises therefrom, owing to the putre- 

 factive decomposition of matter containing sulphur and 

 hydrogen. It is a gaseous body, easily condensed by 

 water, and is readily procured by pouring dilute hydro- 

 chloric acid on any metallic sulphide, such as the sul- 

 phide of iron or antimony. Its solution in water is much 

 fin ployed in the laboratory as a test for the presence of 

 metals ; and the following plan may be adopted for thus 

 procuring it. 



Into a glass jar fit a cork, through which pass two 

 tubes, one of which should reach to the bottom of 

 the vessel, whilst the other just passes within its 

 neck. Attach this tube to another vessel, by means 

 of india-rubber connections, so that it may bo con- 

 tinued to the bottom of the second vessel : from this 

 another pipe should pass to act as a safety-till*. 



SB 



