ON A DIRECT METHOD OF OBTAINING IODINE. 341 
quent occurrence, being lost by mechanical agency, a very 
brisk current of hot air being set in motion by the very na- 
ture of the operation, accompanied as it usually is by a 
slight breeze. But another important point remains to be 
considered, which is indeed almost prohibitive of obtaining 
kelp rich in iodine in districts thickly inhabited. The smoke 
arising from the combustion of the Laminaria digitata 
particularly, is most offensive; and, unless the wind is blow- 
ing off shore, the burning the weed on the large scale would 
be prohibited, or the party who undertakes the process be 
constantly engaged in law proceedings ; and as the laws in 
the Isle of Man are either peculiar or peculiarly adminis- 
tered, no reasonable prospect could be entertained of ulti- 
mate success. All these circumstances, taken collectively, 
induced the writer to seek out a method by which these 
evils might be obviated ; and in doing so it became neces- 
sary to determine in what portion of the plant the element 
sought after is contained in greatest abundance, 'and wheth- 
er it would not be practicable by mechanical means to ar- 
rive at the desired result. Excluding then for the future 
the shallow-water species, we confine our remarks to the 
modes pursued with reference to the Laminaria digitata 
and L. saccharina, principally indeed to the first, as it not 
only presented the greater difficulty, but also was furnished 
in greater abundance. 
On making then a transverse section of the stem of the 
L. digitata, we observe externally a thin cortical layer, 
next a mass of condensed cellular tissue, and internally a 
transparent medullary central portion, generally of an 
elliptical form. Applying to one of these surfaces a weak 
solution either of acetic or hydrochloric acid, we cover it with 
a very slight layer of starch-paste, and cautiously expose 
it to the action of chlorine, from the mouth of a bottle con- 
taining a solution of that gas. The iodine being set free, 
and rendering its presence perceptible^through combination 
with amylon, will be immediately proved to be enveloped 
27* 
