When we have introduced in advance in the small platinum apparatus a
determined amount of hydrofluoric acid cooled with chloride of methyl,
in tranquil ebullition at a temperature of -23 deg., the current of 20
cells of Bunsen large size, arranged in series, is passed through by
means of the electrodes. An amperemeter in the circuit admits of the
intensity of the current being observed.
If the hydrofluoric acid contains a small quantity of water, either by
accident or design, there is always disengaged at the positive pole
ozone, which has no action on crystallized silicium. In proportion as
the water contained in the acid is thus decomposed, it is seen by the
amperemeter that the conductivity of the liquid rapidly decreases.
With absolutely anhydrous hydrofluoric acid the current will no longer
pass. In many of our experiments we have succeeded in obtaining an
acid so anhydrous that a current of 25 amperes was entirely arrested.
To render the liquid conducting, we have added before each experiment
a small quantity of dried and fused fluorhydrate of fluoride of
potassium. In this case, decomposition proceeds in a continuous
manner; we obtain at the negative pole hydrogen, and at the positive
pole a regular disengagement of a colorless gas in which crystallized
silicium in the cold burns with great brilliancy, becoming fluoride of
silicium.
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