44 Further Observations 
adding first sulphuric atid in excess to a lixivium of kelp freed’ 
by simple evaporation, of the greatest portion of salt which it 
contains; then evaporating this solution to dryness, and again 
heating it in a flask or retort, with an additional quantity of sul- 
phuric acid. If it contains iode, the mass now will acquire a 
rose colour, more or less intense, according to the quantity of 
iode present ; the vesse! in which the assay is made will become 
filled with a beautiful violet-coloured vapour; aud a dense yel- 
low or orange-coloured fiuid, which is sulphuret of iode, will con- 
dense and run down in strie on the sides of the vessel. If the 
solution abounds in hydresulphurets, the sulphur which becomes 
precipitated by the admixture of suiphurie acid should be re- 
moved before the solution is distilled with sulphuric acid. 
Or, 
The before-mentioned dry salt, containing the iode cf soda, &e. 
may be heated for a few minutes with half a part of its weight 
of red oxide of lead, and then distilled with sulphuric acid. 
If it contains iode, a violet-coloured vapour will become. disen- 
gaged. : 
Methed of obtaining Iode. 
To procure iode (or iodine) in the most expeditious and 
cheapest manner, from kelp, proceed as follows : 
Fill a conical bag, made of coarse linen, or any porous ma- 
terial, with powdered ke!p. Suspend the bag in some convenient 
manner, and suffer cold water to trickle through the kelp in as 
slow a way as possible. Four parts of water are thus sufficient 
to lixiviate one of kelp. Pour the lixivium which runs from the 
bag, back again upon the kelp, and repeat this operation for three 
or four times successively. The obtained uid will be perfectly 
transparent, and almost colourless. Evaporate this solution in 
a Wedgwood-ware bason, and remove the salt which becomes 
deposited from time to time. The quantity of salt that falls 
down, will diminish as the lixivium becomes concentrated. When 
no more salt. becomes separated during the cbullition of the fluid, 
or when the quantity deposited is but sma! 
evaporated to dryness. This bein 
usier into a crucible 
odine of soda, &e. 
and expose it to a dull red heat. When the mass begins to melt, 
a lambent pale blue flame will make its appearance; and when 
this has ceased, pour out the melted matter upon aslab, pulverise 
it coarsely, aud preserve it for use. ; 
To obtain iode from this substance, mix it with one-fourth of its 
weight of red oxide of lead, and decompose it with sulphuric acid, 
taking care to add this fluid as long as any effervescence takes 
place, and proceed as stated No. 189, page 57, Phil. Magazine. 
If 
g cone, tra 
a 
1, the solution may be _ 
a a ee 
