SULPHURIC ACID MANUFACTURE. The manufacture of this important acid in volves arrangements of great magnitude and interest. At the chemical works of Glasgow, Newcastle, and a few other large towns, the production of sulphuric acid is carried" on upon a vast scale. The process consists mainly in bringing sulphur in contact with the air and combining the fumes thus pro duced with water. As the fumes are very deleterious to the workmen, and as both the fumes and the liquid exert a corrosive action on the vessels which contain them, the apparatus requires to be of a very peculiar kind.
In the first place the Sicilian sulphur is placed in a series of close-fitting iron furnaces, where it is kindled ; it combines with oxygen in the act of burning, and produces sulphurous acid gas, which gas finds an exit into a hollow wall behind the row of furnaces. The gas passes from thence into vessels which are among the largest known in any department of manufactures. At the Felling chemical works near Newcastle, there are two sulphur ous acid chambers, each 200 feet long, 20 wide, and 20 high ; and four others about half this length ; they are formed of sheet lead, framed strongly together.
In the leaden chambers a conversion takes place of sulphurous acid into sulphuric acid, and from a gas to a liquid. While the sul
phur has been burning in the furnaces, such other ingredients as will yield a little nitrous acid vapour are also heated in the furnace ; the nitrous acid vapour accompanies the sulphu rous acid gas into the chamber : steam is also admitted into the chamber, and a curious chemical result follows. The acid gas, moist ened by the steam, abstracts oxygen from the nitrous acid vapour, and becomes thereby changed from sulphurous into sulphuric acid; and this sulphuric acid, combining with the water of the condensed steam in the bottom of the chamber, becomes a liquid, and then con stitutes the sulphuric acid, or oil of vitriol of the shops. In order to concentrate the acid for some purposes, it requires to be distilled ; but such is its corroding nature, that few mate. rials will resist its action ; and hence the costly metal platinum is used, for the stills for distilling this acid. At the Felling works a platinum still was provided some years ago, which cost one thousand guineas, its weight being about one thousand ounces ; it there fore cost about four times its weight in pure silver ! Platinum has, however, become less costly in recent years.