324 EXTRACTION OF IODINE FROM KELP SODA. 
ART. XLVTIL— METHOD OF EXTRACTING THE IODINE AND 
BROMINE CONTAINED IN THE SALTS AND MOTHER- 
LIQUOR OF KELP SODA. 
The Societe d'Encouragement, in its general meeting of 
the 5th June, 1 839, decreed a gold medal to Messrs. De- 
launay, Couturier and Villedieu, of Tourlaville, near Cher- 
bourg, for their processes for extracting iodine and bromine 
from soda obtained from the sea-weed, which is gathered 
in large quantities on the shores of Brittany. 
The importance of this manufacture was made known 
in a report inserted in the 6 Bulletin' of August, 1839 ; but 
it did not contain a description of the process. We will, 
therefore, make up for this omission, by giving an extract 
from the patent for ten years, taken by Messrs. Couturier, 
on the 22nd May, 1S35, and which has now become pub- 
lic property. 
1st. Extraction of Iodine from Kelp Soda. — The 
mother-waters of this soda having been concentrated to the 
greatest possible degree, are left in any suitable vessel, in 
order to allow the salts, which may be separated during its 
slow crystallization, to deposit; they are afterwards drawn 
off, and the small quantity of alkaline carbonate, which is 
always contained in these mother-liquors, is saturated by 
means of sulphuric acid. In order to be certain that the 
free alkali of the mother-liquors is saturated, the point of 
saturation must be slightly exceeded, which is ascertained 
when, after having sufficiently agitated the mother-liquor to 
which the sulphuric acid has been added, a strip of litmus 
paper plunged into it is slightly reddened. 
It often happens that the mother-liquors of kelp contain 
a considerable quantity of hyposulphites which precipitate 
sulphur, and by the decomposition of which sulphurous 
acid is disengaged ; in this case sulphuric acid is added, by 
