A saturated solution of the gas, in water, is a colourless, oily, strongly fuming liquid which after a time decomposes, with separation of metaboric acid, leaving hydrofluoboric acid HF BF3 in solution.
Soc., 18 94, 6 5, p. 393) obtained fluorine by heating potassium fluorplumbate 3KF HF PbF 4.
Only one compound of hydrogen and fluorine is known, namely hydrofluoric acid, HF or H 2 F 2, which was first obtained by C. Scheele in 1771 by decomposing fluor-spar with concentrated sulphuric acid, a method still used for the commercial preparation of the aqueous solution of the acid, the mixture being distilled from leaden retorts and the acid stored in leaden or gutta-percha bottles.
Soc., 1889, 55, p. 163) determined the vapour density of hydrofluoric acid at different temperatures, and showed that there is no approach to a definite value below about 88° C. where it reaches the value 10.29 corresponding to the molecular formula HF; at temperatures below 88° C. the value increases rapidly, showing that the molecule is more complex in its structure.
This is recognized as the polar equation of a conic referred to the focus, the half latus-rectum being hf/u.
This coincides with the equation of motion of a simple pendulum [E 13 (15)] of length 1, provided 1= hf/h.
If we write l~ = h1 + K/lii, If = hf + K1/hf, we find, on elimination of K,
Hf?lr,dhead toekbrid ge 'a' 1 o olbor ne y?r ?