Thenard in 1808 by heating boron trioxide with potassium, in an iron tube.
By strongly heating a mixture of boron trioxide and aluminium, protected from the air by a layer of charcoal, F.
Boron hydride has probably never been isolated in the pure condition; on heating boron trioxide with magnesium filings, a magnesium boride Mg 3 B 2 is obtained, and if this be decomposed with dilute hydrochloric acid a very evil-smelling gas, consisting of a mixture of hydrogen and boron hydride, is obtained.
This mixture burns with a green flame forming boron trioxide; whilst boron is deposited on passing the gas mixture through a hot tube, or on depressing a cold surface in the gas flame.
Thenard and is best obtained by heating a mixture of the trioxide and fluorspar with concentrated sulphuric acid.