There my uncle, laying himself down upon a sail cloth, which was spread for him, called twice for some cold water, which he drank, when immediately the flames, preceded by a strong whiff of sulphur, dispersed the rest of the party, and obliged him to rise.

–Letter to Cornelius Tacitus,
Pliny the Younger

What would be needed to verify this story?

a more detailed description
evidence to corroborate the details
proof that cold water was available
a secondary source analyzing Pliny’s writing