PETER SPENCE 265 



and the sulphide of the alkali remains in 

 solution. This solution is pumped into a 

 tank, in which it is heated to boiling, and 

 then run through a tower packed with coke, 

 through an atmosphere of carbonic acid gas; 

 carbonate of the alkali is formed and sulphur- 

 etted hydrogen is given off, which is collected 

 and burnt to produce sulphuric acid ; the 

 liquor which runs through the tower is 

 collected in a tank and evaporated to soda 

 ash, or is made into soda crystals. Spence 

 says, " I am aware that a process similar to 

 this has been previously described, but the 

 temperature was not raised, my point being 

 that the liquor must be acted on at an 

 elevated temperature." 



Spence's alum process was a great success, 

 both chemically and commercially, and at 

 Pendleton his business rapidly grew, until he 

 was the chief alum manufacturer in the world. 

 After a time he established two other works 

 (at Birmingham and Goole), and entered 

 into other branches of manufacture (copper 

 smelting, copper precipitate, carbonate, 

 muriate and sulphate of ammonia, sulphate 

 of potash, aluminoferric, and sulphate of 

 alumina). 



The prosperity that attended him enabled 



