I've tried to identify the density of metal.
I managed to get a graduated fit and have immersed the coin in water.
Then I've repeated the experiment with a Vespasian's
denarius of the same
weight (3,24 grams).
The displacement of water was found absolutely identical for the two coins.
It 'is therefore possible that also the
denarius of
Titus is silver even if completely covered by oxidation.
I think however that I will not attempt to clean it.