Veronica, being on the other side of the table and the urn, could not possibly see what she did.
Gregorio came in.

Elettra had opened the door from without, for him to pass.

She stood on the threshold a moment, and looked towards the table, to see whether anything had been forgotten.

Then she closed the door, and went away, leaving the three together.

The water boiled almost immediately; and Gregorio was just sitting down when Matilde poured the water out of the teapot, and part in the tea.