We have measured the heat release of pure (6N) aluminium in the time r
ange from 5h to 300h after cooling it from 85K to 200mK, in the normal
and superconducting states. We measured a heat release that resembles
quantitatively that from vitreous silica (SiO2) at times t greater th
an or equal to 4 x 10(5) s indicating the existence of tunneling syste
ms in agreement with previously published acoustic measurements. The t
ime dependence of the heat release in Al is, however, weaker as that f
ound in amorphous materials. No difference in the heat release has bee
n measured in the normal and superconducting states.