330 



Manufacture of Sulphuric Acid. 



Vol. XI 



iraportance during the war of Napoleon. In 

 a very short time it was manufactured to an 

 extraordinary extent, especially at the seat 

 of the soap manufactories. Marseilles pos- 

 sessed for a time a monopoly of soda and 

 soap. The policy of Napoleon deprived that 

 city of the advantages derived from this 

 great source of commerce, and thus excited 

 the hostility of the population to his dynasty, 

 which became favourable to the restoration 

 of the Bourbons. A curious result of an 

 improvement in a chemical manufacture! 

 It was not long, however, in reaching Eng- 

 land. 



In order to prepare the soda of commerce 

 * — which is the carbonate — from common 

 salt, it is first converted into Glauber's salt, 

 — sulphate of soda. For this purpose 80 

 pounds weight of concentrated sulphuric 

 acid — oil of vitriol — are required to 100 

 pounds of common salt. The duty upon 

 salt checked, for a short time, the full ad- 

 vantage of this discovery; but when the 

 government repealed the duty, and its price 

 was reduced to its minimum, the cost of soda 

 depended upon that of sulphuric acid. 



The demand for sulphuric acid now in- 

 creased to an immense extent; and, to sup- 

 ply it, capital was embarked abundantly, as 

 it afforded an excellent remuneration. The 

 origin arid formation of sulphuric acid was 

 studied most carefully; and from year to 

 year, better, simpler, and cheaper methods 

 for making it were discovered. With every 

 improvement in the mode of manufacture, 

 its price fell ; and its sale increased in an 

 equal ratio. 



Sulphuric acid is now manufactured in 

 leaden chambers, of such magnitude that 

 they would contain the whole of an ordinary 

 sized house. As regards the process and 

 ithe apparatus, this manufacture has reached 

 •its acme — scarcely is either susceptible of 

 'improvement. The leaden plates of which 

 rthe chambers are constructed, requiring to 

 tbe joined together with lead, — since tin or 

 solder would be acted on by the acid, — this 

 process was, until lately, as expensive as 

 the plates themselves; but now, by means 

 of theoxyhydrogen blow-pipe, the plates are 

 ■ cemented together at their edges, by mere 

 fusion, without the intervention of any kind 

 of solder. 



And then, as to the process ; according to 

 theory, 100 pounds weight of sulphur ought 

 to produce 306 pounds of sulphuric acid ; in 

 practice, 300 pounds are actually obtained ; 

 the amount of loss is therefore too insignifi- 

 •cant for consideration. 



Again ; saltpetre being indispensable in 

 making sulphuric acid, the commercial value 

 • of that salt had formerly an important influ- 



ence upon its price. It is true that 100 

 pounds of saltpetre only are required to 1000 

 pounds of sulphur; but its cost was four 

 times greater than an equal weight of the 

 latter. 



Travellers had observed, near the small 

 seaport of Yquiqui, in the district of Ata- 

 cama, in Peru, an efflorescence covering the 

 ground over extensive districts. This was 

 found to consist principally of nitrate of soda. 

 Advantage was quickly taken of this disco- 

 very. The quantity of this valuable salt 

 proved to be inexhaustible, as it exists in 

 beds extending over more than 200 square 

 miles. It was brought to England at less 

 than half the freight of the East India salt- 

 petre — nitrate of potassa ; and as, in the 

 chemical manufacture, neither the potash 

 nor the soda was required, but only the 

 nitric acid, in combination with the alkali, 

 the soda-saltpetre of South America soon 

 supplanted the potash-nitre of the East. The 

 manufacture of sulphuric acid received a 

 new impulse; its price was much diminished 

 without injury to the manufacturer; and, 

 with the exception of fluctuations, caused 

 by the impediments thrown in the way of 

 the export of sulphur from Sicily, it soon 

 became reduced to a minimum, and remain- 

 ed stationary. 



Potash-saltpetre is now only employed in 

 the manufacture of gunpowder; it is no 

 longer in demand for other purposes; and 

 thus, if government effect a saving of many 

 hundred thousand pounds annually in gun- 

 powder, this economy must be attributed to 

 the increased manufacture of sulphuric acid. 



We may form an idea of the amount of 

 sulphuric acid consumed, when we find that 

 50,000 pounds weight are made by a small 

 manufactory, and from 200,000 to 600,000 

 pounds by a large one, annually. This man- 

 ufacture causes immense sums to flow annu- 

 ally into Sicily. It has introduced industry 

 and wealth into the arid and desolate dis- 

 tricts of Atacama. It has enabled us to ob- 

 tain platina from its ores at a moderate and 

 yet remunerating price; since the vats em- 

 ployed for concentrating this acid are con- 

 structed of this metal, and cost from £1000 

 to £2000 sterling. It leads to frequent im- 

 provements in the manufacture of glass, 

 which continually becomes cheaper and 

 more beautiful. It enables us to return to 

 our fields all their potash — a most valuable 

 and important manure — in the form of ashes, 

 by substituting soda in the manufacture of 

 glass and soap. 



It is impossible to trace, within the com- 

 pass of a letter, all the ramifications of this 

 tissue of changes and improvements result- 

 ing from one chemical manufacture; but I 



