Abstract
The powdered sea-weed, Laminaria, has of late drawn attention of investigators of nutrition on account of its richness in iodine. The dried frond of Laminaria from Risiri, Hokkaido, which is on the market, was found to contain about 0•25% iodine. Immersion of this dried material in dilute acetic acid, which is the first step in manufacturing the powder, was proved to deprive the material of nearly half of its iodine content. The material thus treated is planed previous to final powdering. The successive layers thus made differ in iodine content ; the outermost layer which is mixed with detritus was found to contain 0•19%, the next blackish one 0•14%, still deeper whitish one 0•12%, and the middle one 0•1% iodine.
