Iodine

I"o*dine (ī"&osl;*d&ibreve;n or -dēn; 104), n. [Gr. 'iw`dhs violetlike; 'i`on a violet + e'i^dos form: cf. F. iode, iodine. The name was given from the violet color of its vapor. See Violet, Idyl.]

(Chem.) A nonmetallic element, of the halogen group, occurring always in combination, as in the iodides. When isolated it is in the form of dark gray metallic scales, resembling plumbago, soft but brittle, and emitting a chlorinelike odor. Symbol I. Atomic weight 126.5. If heated, iodine volatilizes in beautiful violet vapors.

&fist; Iodine was formerly obtained from the ashes of seaweed (kelp or varec), but is now also extracted from certain natural brines. In the free state, iodine, even in very minute quantities, colors starch blue. Iodine and its compounds are largely used in medicine (as in liniments, antisyphilitics, etc.), in photography, in the preparation of aniline dyes, and as an indicator in titration.

Iodine green, an artificial green dyestuff, consisting of an iodine derivative of rosaniline; -- called also night green. -- Iodine scarlet, a pigment of an intense scarlet color, consisting of mercuric iodide. -- Iodine yellow, a brilliant yellow pigment, consisting of plumbic iodide.