226 EXTRACTION OF BROMINE PROM KELP SODA. 
When the vapours cease to be perceptible, the operation is 
completed ; care must be taken to keep a cloth constantly 
wetted with cold water upon the whole surface of the tube. 
In working on a large scale, the products of several opera- 
tions are united, left to drain, and sublimed as above de- 
scribed. 
2nd. Extraction of the Bromine from Kelp Soda. — 
The mother-liquor having been completely exhausted of 
iodine, is introduced into a tubular retort until it is half-full; 
powdered peroxide of manganese and concentrated sulphu- 
ric acid of commerce are to be added to it, and an appara- 
tus composed of three recipients, which communicate by 
means of pipes ground with emery, is adapted to the neck 
of the retort : the distillation is then proceeded with, care 
being taken not to let it boil too fast. The bromine which 
is separated by this operation is volatilized and disengaged 
in the form of gold-coloured vapours, which are partially 
condensed in the neck of the first receiver in the form of 
streaks and drops of a reddish-brown liquid, which run 
down by degrees into the receiver ; but as a considerable 
quantity of water is volatilized at the same time, it is con- 
densed also, and floats upon the bromine, which occupies 
the lowest part of the liquor. When the coloured vapours 
cease to be disengaged from the retort, the fire is removed ; 
a fresh quantity of peroxide of manganese and sulphuric 
acid are then added, the retort is closed, and the fire again 
applied. If a sufficient quantity of these substances has 
been added at first, all the bromine will have been ex- 
tracted ; it then only remains to collect that which is below 
the liquor condensed in the receiver ; this is done by means 
of a glass funnel furnished with a cock. When the separa- 
tion is well effected, the end of the funnel is placed in a 
bottle, the cock is gently opened, and the bromine runs into 
the bottle ; the cock is shut the instant all the bromine has 
run through and the water is about entering. This water 
holds a considerable quantity of bromine in solution, which 
