ON A DIRECT METHOD OF OBTAINING IODINE. 
345 
tant element, which under ordinary circumstances is entire- 
ly lost; on the other, reducing all that is valuable for farm 
purposes into a concentrated form, admitting of transit with 
great economy of labor and expense. Taking Professor 
Forchhammer's estimate, that each ton of sea- weed is re- 
duced by drying to 500 lbs. of solid matter (and, so far as 
the writer's experience is concerned, this estimate is far 
above the mark,) in every ton of wrack conveyed to the 
land, the farmer actually carts away, and that sometimes 
for miles, 1740 lbs. of water, which is all but lost labor, 
his object being merely to supply his land with the salts of 
potash and soda. By pursuing the following method, not 
only may a large saving be effected, but in many small 
holdings intelligence and industry may, from the sea-weed 
alone, secure a greater return than the whole produce 
of the farm taken collectively. It is now the writer's 
object to project a plan for the accomplishment of this 
result; but it will be previously necessary to make a slight 
digression. 
The mutual reaction of free iodine and starch is well 
known ; but little attention has hitherto been bestowed on 
the circumstance, that the facility with which iodine, is pre- 
cipitated from its solutions by means of starch varies ex- 
ceedingly. The object of the writer being to fall on some 
plan, involving little expense and chemical knowledge, to 
effect the complete precipitation of free iodine from its so- 
lutions, he was led to the more minute investigation of the 
subject in detail; and, in the first place, it was found out, 
that the facility with which the iodide of amylon was pre- 
cipitated depends in a great measure on the size of the 
starch-granule. This would lead one to suppose that the 
vesicular covering of the granule is the substance which 
more immediately combines with the iodine, or that the so- 
lution of iodine enters the vesicle by means of endosmose • 
in either case the practical result will be the same. Now, 
according to Raspail's observations, the granule of millet 
