Not P but Moby-Dick (43)

[Mike Jing]

>From Chapter 54:

“A moment! Pardon!” cried another of the company. “In the name of all us
Limeese, I but desire to express to you, sir sailor, that we have by no
means overlooked your delicacy in not substituting present Lima for distant
Venice in your corrupt comparison. Oh! do not bow and look surprised; you
know the proverb all along this coast—‘Corrupt as Lima.’ It but bears out
your saying, too; churches more plentiful than billiard-tables, and for
ever open—and ‘Corrupt as Lima.’ So, too, Venice; I have been there; the
holy city of the blessed evangelist, St. Mark!—St. Dominic, purge it! Your
cup! Thanks: here I refill; now, you pour out again.”

Does "purge it!" here mean "purge the corruption"? And what does "you pour
out again" mean?