There was some confusion with the original Fluorine cache. It had
been reported that it was muggled, and indeed, when I went to check
on it, I couldn't find it either. Having seen two different caches
disappear from the park, I decided to move it.
Imagine my surprise when people began finding it at the original
site. I had already moved it, then archived it.
The original cache is back in it's original spot, but Fluorine
is so darned interesting I moved the second cache and revealed more
information on Flourine. So be enlightened and find both
caches!
First: The junior high chemistry lesson:
Fluorine is the most reactive of all elements and no chemical
substance is capable of freeing fluorine from any of its compounds.
For this reason, fluorine does not occur free in nature and was
extremely difficult for scientists to isolate. The first recorded
use of a fluorine compound dates to around 1670 to a set of
instructions for etching glass that called for Bohemian emerald
(CaF2). Chemists attempted to identify the material that was
capable of etching glass and George Gore was able to produce a
small amount of fluorine through an electrolytic process in 1869.
Unknown to Gore, fluorine gas explosively combines with hydrogen
gas. That is exactly what happened in Gore's experiment when the
fluorine gas that formed on one electrode combined with the
hydrogen gas that formed on the other electrode.
Ferdinand Frederic Henri Moissan, a French chemist, was the
first to successfully isolate fluorine in 1886. He did this through
the electrolysis of potassium fluoride (KF) and hydrofluoric acid
(HF). He also completely isolated the fluorine gas from the
hydrogen gas and he built his electrolysis device completely from
platinum. His work was so impressive that he was awarded the Nobel
Prize for chemistry in 1906. Today, fluorine is still produced
through the electrolysis of potassium fluoride and hydrofluoric
acid as well as through the electrolysis of molten potassium acid
fluoride (KHF2).
Fluorine is added to city water supplies in the proportion of
about one part per million to help prevent tooth decay. Sodium
fluoride (NaF), stannous(II) fluoride (SnF2) and sodium
monofluorophosphate (Na2PO3F) are all fluorine compounds added to
toothpaste, also to help prevent tooth decay. Hydrofluoric acid
(HF) is used to etch glass, including most of the glass used in
light bulbs. Uranium hexafluoride (UF6) is used to separate
isotopes of uranium. Crystals of calcium fluoride (CaF2), also
known as fluorite and fluorspar, are used to make lenses to focus
infrared light. Fluorine joins with carbon to form a class of
compounds known as fluorocarbons. Some of these compounds, such as
dichlorodifluoromethane (CF2Cl2), were widely used in air
conditioning and refrigeration systems and in aerosol spray cans,
but have been phased out due to the damage they were supposed to be
causing to the earth's ozone layer. The ozone hole has since been
shown to be a natural phenomenon with an 11 year cycle
corresponding to the sunspot cycle.