on the new Substance called Iode, or Iodine. 143 
vered with a white efflorescence. By these characters kelp con- 
taining iode in considerable quantity may readily be recognised. 
Those varieties of kelp which are of a greenish gray colour 
and crystalline fracture, which emit a strong sulphureous odour 
when moistened with water or dilute acids, which are of stony 
hardness, and do not readily attract water from a damp air, are 
almost unfit for the preparation of it; they yield but very little 
iode, and the means of extracting it from those varieties are 
tedious and difficult. 
The best kelp is said to be manufactured in those places where 
the sea-weeds are cut down by means of a scythe frem the rocks 
situated between the high- and low-water mark, as is the prac- 
tice in the North of Scotland; and the worst kelp is said to be 
made in those places where it is customary to pull up the alge, 
or leafy marine fuct, from the rocks by the roots, by means of 
takes or grappling irons, as is practised by the peasantry in some 
kelp districts on the Irish and English coasts. 
‘Those who are desirous of preparing iode [and who is there 
among the cultivators of chemistry that is not?] will do well to 
avoid useless trouble by first assaying the kelp they wish to em- 
ploy for that purpose, before they proceed to operate upon it. 
To accomplish this object, put a few ounces of it, previously 
pulverised, into a glass or earthenware funnel, and suffer eight 
or ten ounces of cold water to trickle or run over and through it, 
very slowly, so as to wash out the easily soluble matter which it 
contains. 
To cause the water to pass readily through the mass, and to 
obtain the fluid clear at once, a few large pieces of kelp ought 
first to be introduced into the throat of the funnel; a stratum of 
smaller pieces should be put upon these, and the finer powdered 
kelp placed over all. When the water has run through the mass, 
pour the obtained solution back again upon the kelp in the fun- 
nel, and repeat this operation for several times. This being done, 
evaporate the lixivium to about two-thirds of its bulk; a consi- 
derable quantity of salt will become deposited during the evapo- 
ration ; remove it from ‘time to time, and lastly evaporate the 
remaining fluid to dryness. Transfer the mass into a crucible, 
and fuse it for a few minutes. From the appearance of the 
melted substances when cold, some conjecture may be formed 
concerning the nature of the kelp with regard to its contents of 
iode. If the mass exhibits a bright peach-blossom colour, we 
may predict that it abounds in iode; if it possesses a. flesh or 
very pale rose colour, it contains a less quantity of this substance; 
and if it is colourless, porcellaneous, resembling white enamel, it 
then is almost destitute of it. 
The presence of iode may likewise be rendered obvious, by 
adding 
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