_Sulphureted Hydrogen._--When the horizontal tube shown in Fig. 3 is
filled with sulphureted hydrogen gas and fluorine is allowed to enter,
a blue flame is observed on looking through the fluorspar windows
playing around the spot where the fluorine is being admitted. The
decomposition continues until the whole of the hydrogen sulphide is
converted into gaseous fluorides of hydrogen and sulphur.
_Sulphur dioxide_ is likewise decomposed in the cold, with production
of a yellow flame and formation of fluoride of sulphur.
_Hydrochloric acid_ gas is also decomposed at ordinary temperatures
with flame, and, if there is not a large excess of hydrochloric acid
present, with detonation. Hydrofluoric acid and free chlorine are the
products.
Gaseous _hydrobromic_ and _hydriodic acids_ react with fluorine in a
similar manner, with production of flame and formation of hydrofluoric
acid. Inasmuch, however, as bromine and iodine combine with fluorine,
as previously described, these halogens do not escape, but burn up to
their respective fluorides. When fluorine is delivered into an aqueous
solution of hydriodic acid, each bubble as it enters produces a flash
of flame, and if the fluorine is being evolved fairly rapidly there is
a series of very violent detonations. A curious reaction also occurs
when fluorine is similarly passed into a 50 per cent. aqueous solution
of hydrofluoric acid itself, a flame being produced in the middle of
the liquid, accompanied by a series of detonations.
_Nitric acid_ vapor reacts with great violence with fluorine, a loud
explosion resulting. If fluorine is passed into the ordinary liquid
acid, each bubble as it enters produces a flame in the liquid.
_Ammonia gas_ is decomposed by fluorine with formation of a yellow
flame, forming hydrofluoric acid and liberating nitrogen. With a
solution of the gas in water, each bubble of fluorine produces an
explosion and flame, as in case of hydriodic acid.
_Phosphoric anhydride_, when heated to low redness, burns with a pale
flame in fluorine, forming a gaseous mixture of fluorides and
oxyfluoride of phosphorus. _Pentachloride and trichloride of
phosphorus_ both react most energetically with fluorine, instantly
producing a brilliant flame, and evolving a mixture of phosphorus
pentafluoride and free chlorine.
_Arsenious anhydride_ also affords a brilliant combustion, forming the
liquid trifluoride of arsenic, AsF_{3}. This liquid in turn appears to
react with more fluorine with considerable evolution of heat, probably
forming the pentafluoride, AsF_{5}. _Chloride of arsenic_, AsCl_{3},
is converted with considerable energy to the trifluoride, free
chlorine being liberated.
_Carbon bisulphide_ inflames in the cold in contact with fluorine, and
if the fluorine is led into the midst of the liquid a similar
production of flame occurs under the surface of the liquid, as in case
of nitric acid. No carbon is deposited, both the carbon and sulphur
being entirely converted into gaseous fluorides.
_Carbon tetrachloride_, as previously mentioned, reacts only very
slowly with fluorine. The liquid may be saturated with gaseous
fluorine at 15°, but on boiling this liquid a gaseous mixture is
evolved, one constituent of which is carbon tetrafluoride, CF_{4}, a
gas readily capable of absorption by alcoholic potash. The remainder
consists of another fluoride of carbon, incapable of absorption by
potash and chlorine. A mixture of the vapors of carbon tetrachloride
and fluorine inflames spontaneously with detonation, and chlorine is
liberated without deposition of carbon.
_Boric anhydride_ is raised to a most vivid incandescence by fluorine,
the experiment being rendered very beautiful by the abundant white
fumes of the trifluoride which are liberated.
_Silicon dioxide_, one of the most inert of substances at the ordinary
temperature, takes fire in the cold in contact with fluorine, becoming
instantly white-hot, and rapidly disappearing in the form of silicon
tetrafluoride. The _chlorides_ of both _boron_ and _silicon_ are
decomposed by fluorine, with formation of fluorides and liberation of
chlorine, the reaction being accompanied by the production of flame.