

164 METALLOIDS. 



the process. The air is, therefore, the real oxidizer, 

 while the changed nitric acid only acts to transfer it 

 to the sulphurous fumes. 



Describe the 395. DESCRIPTION OF ACID CHAMBERS. 



acid chambers, rp ne fjg ure represents one form of the 

 leaden chambers 

 employed in the 

 above manufac- 

 ture. Connect- 

 ed with them 

 are a steam boiler and two furnaces, in one of which 

 sulphur is burned, and converted into sulphurous acid. 

 Over the sulphur is another vessel, containing the 

 materials for making nitric acid, the formation of which 

 commences as soon as the sulphur flame has imparted 

 the requisite heat. The vapors thus produced, are 

 mingled with air and steam in the leaden chamber. 

 How they act together to produce sulphuric acid, has 

 been already explained. The space is divided by a 

 partition, in order that all the materials may be more 

 thoroughly mixed, as they pass through the narrow 

 opening below it. The acid, as it forms, dissolves in 

 water which covers the bottom of the chamber, and is 

 thus collected. Lead is used as a lining for the cham- 

 bers, because the acid woul-d destroy almost any other 

 material that might be employed. 



396. The dilute acid obtained from the 



How is the 



chamber acid chambers, is concentrated first in leaden 



concentrated? vessels? and afterward) when it hag become 



strong enough to corrode the lead, in retorts of platinum. 

 The metal platinum, being of about half the value of 



