Aluminium metal is dissolved in 3 M HNO3 with mercury(II) nitrate as a
catalyst. Visible oscillations in gas evolution are observed for 2 x
10(-4) M Hg(NO3)(2) dissolving solutions. The oscillations are followe
d quantitatively by monitoring both solution temperature and the inten
sity of a UV-visible transmittance peak at 369 nm. This peak is attrib
uted to mercury(I) species in solution.