OK, as you may have gathered from other questions I've asked, I've been
browsing through some old cookbooks to try and find some new ideas for
cookies. In one of them I just read, "Wash the butter to remove the
salt."

Say what? When salt is added to butter, it's beaten into the cream when
the butter is being churned, is it not? Washing wouldn't do any good.
Am I missing something?

I'm just curious.....in 30 years of cooking, and owning hundreds of
cookbooks, I don't recall ever having seen this particular instruction
before - and I'm sure it's something I'd remember!