’which Iodine can he 'procured. S57 
was mixed with charcoal in powder, and a high heat applied to 
it. When cold, the mixture was treated with sulphuric acid, 
but without obtaining any iodine. • 
The saline matter of sea-water was subjected to various other 
trials, but uniformly with the same result. 
In the experiments on the substances mentioned, from which 
iodine was procured, and also, as I have said, in the preparation 
of kelp, the bodies are subjected to a high temperature, — are we 
to infer from this, that the iodine is a product of the combus- 
tion ? 
To determine this, a quantity of the Fucus serratus was infused 
in water for some hours. On evaporating the solution, a mass 
of a syrupy consistence was obtained. When this was subjected 
to the action of sulphuric acid, with the aid of heat, iodine in 
vapour appeared. The stem of the Fucus digitatus^ treated in 
the same way, afforded iodine. It is remarkable, however, that 
the infusion of sponge did not in this way yield iodine, though 
the sponge which had been kept in water for some time, afford- 
ed it after being burned and acted on by sulphuric acid. 
From the above, we may conclude, as far as these experi- 
ments go, 
1. That iodine is not contained in sea-water, 
2. That it is confined alone to marine productions. 
3. That the iodine contained in kelp, is not a product of the 
combustion. 
4. That the substances which afford iodine, belong to the class 
Cryptogamia, unless, with some naturalists, we consider Sponge 
as belonging to the animal world, In the classification of Lin- 
njeus, however, the Fuci, Ulvae, and Confervas, from which I 
have procured iodine, belong to the class Cryptogamia, subdivi- 
sion, Algae aquaticae. Along with these, Linnaeus was inclined 
to place the sponge, though he was doubtful of the correctness 
of this arrangement. If, then, we adopt the opinion of Linnaeus, 
we must conclude, that iodine is confined to the vegetable world ; 
if we incline to the former opinion, iodine must be considered a 
product likewise of the animal kingdom. 
May not the fact, that sponge contains iodine, be an argu- 
ment in favour of the opinion of Linnaeus, that this substance,- 
