^55 
Dr Fjfe on Plants containing Iodine. 
and heat was applied, by which means the iodine, when present, 
was driven off in vapour. In those cases in which iodine did 
not appear by the above method, recourse was had to the more 
delicate test of the presence of this substance. 
In this way I procured iodine from the residue of the com- 
bustion of the Fucus nodosus, the Fucus serratuSy the Fucus 
falmatus.i and the Fucus digitatus ; the last of which seemed to 
afford it in gi’eatest quantity, both from the leaf and stem. 
I likemse obtained it from the ashes of the Ulva umhilicalis, 
and of a species of Conferva. I repeatedly attempted, but 
without success, to procure it from the Fucus vesicidosus, the 
. ashes o which did not yield the vapour of iodine, on the addi- 
tion of sulphuric acid, nor did the more delicate test indicate 
the presence of their substance in their solution. This confirms 
an experiment of Professor John, in which he failed in obtain- 
ing iodine from the Fucus vesiculosus Dr Thomson like- 
wise mentions, that a foreign chemist did not succeed in pro- 
curing it from the above plant -f*. 
I next endeavoured to procure iodine from plants growing 
near the sea,, not belonging to the class Cryptogamia. With 
this view the Plantago marUima^ and Arenaria peploides^ were 
subjected to the usual trials, but without success. I also failed 
in my attempts to obtain it from the ashes of the Salsola Kali. 
I was led to expect this, as I did not succeed in procuring 
iodine from barilla, the product of the combustion of different 
species of Salsola and Salicornia. 
From the above experiments, I concluded that iodine was 
contained only in the plants of the class Cryptogamia. I was 
naturally led to examine, if all the plants of this class afforded 
this substance. 
For this purpose I procured several of the fresh water crypto- 
gamous plants, and subjected them, after incineration, to the 
action of sulphuric acid ; but no iodine was given off. I like- 
wise attempted to obtain it from the Agaricus campestris, and a 
Boletus growing near the sea, from t]|e, filices (Polypodium fi- 
lix and aculeatum), from the musci, and from several species of 
* Vid. November 1815. 
i* Ibid. January 1816. 
