Definition of "expatiating"

Surely the time passed in expatiating on the reverend Doctor's faults was rather profitably passed than otherwise.

1831, L[etitia] E[lizabeth] L[andon], chapter XII, in Romance and Reality. […], volume II, London: Henry Colburn and Richard Bentley, […], page 167

[…] we can scarcely open, a book in which the habits and manners of animals are treated of, without meeting with numerous, fervent, and eloquent expatiatings on their sagacity […]

1837, Charles Frederick Partington, The British Cyclopæedia of Natural History