DERIVATION.--Iodine exists in certain marine vegetables, particularly
the fuci or common sea weeds, which have long been its most abundant
natural source. Iodine is also found in the animal kingdom, as in the
sponge, oysters, cod liver oil and eggs, and in the mineral kingdom, in
sea water in small quantities, in certain salt springs. It is obtained
commercially from one of these sources.
PROPERTIES.--Iodine is heavy, bluish-black color, dry and friable,
rhombic plates, having a metallic luster, a distinctive odor, and a
sharp and acrid taste. Iodine imparts a deep brown, evanescent stain to
the skin, and slowly destroys vegetable colors. Soluble in about 5000
parts of water and in 10 parts of alcohol at 77° F., freely soluble in
ether, chloroform or carbon disulphide; its solution in alcohol or in an
aqueous solution of potassium iodide has a reddish color; its solution
in chloroform or carbon disulphide has a violet color.
ACTIONS.--Iodine internally is an antiseptic, alterative, resolvent and
irritant. Full doses persisted will produce a state of debility and
emaciation termed iodism. Externally it is applied as an antiseptic,
disinfectant, parasiticide, deodorant, stimulant, desquamatic, absorbent
and counter-irritant. Iodine is one of the best antiseptics for surgical
purposes. The tincture iodine especially kills all disease producing
bacteria in one minute, whereas it takes a one in one thousandth
solution of bichloride of mercury more than half an hour to destroy the
same micro-organisms. The tincture of iodine also possesses unusual
penetrating power on the dry skin, finding its way into the hair
follicles and cutaneous glands. Iodine must not be applied to the wetted
skin because the wetting causes the skin cells to swell and thus prevent
the iodine from penetrating into the sebaceous and sudoriparous glands,
the very action upon which the special germicidal action depends.
USES.--Iodine is of most value applied externally, or locally. In
sterilizing the skin for an emergency operation the hair should be
clipped and shaved dry and the tincture of iodine applied without
washing the skin. For other operations the skin may be scrubbed with
soap and shaved and dried before applying the tincture. The tincture
should always dry on the skin before the operation is begun.
The method used in human surgery for sterilizing the skin, and
recommended by leading surgeons, consists in first of cleansing the skin
with gasoline to remove the grease and then applying the tincture of
iodine in full or half strength.
Tincture of iodine applied is of some value in the treatment of
periostitis with osseous deposits, as splints, bone-spavin, ringbone,
sidebones, etc. It is used for enlargements of glands as goiter in dog.