In the original invention, bromide-containing brines are treated with sulfuric acid and bleaching powder to oxidize bromide to bromine, which remains dissolved in the water.
The aqueous solution is dripped onto burlap, and air is blown through causing bromine to volatilize.
Bromine is trapped with iron turnings to give a solution of ferric bromide.
Where desired, free bromine may be obtained by thermal decomposition of ferrous bromide.
[1] Before Dow entered the bromine business, brine was evaporated by heating with wood scraps and then crystallized sodium chloride was removed.