PRONOUNS, RELATIVE AND INTERROGATIVE. Which parenthetically for "which thing"Which for "which thing," often parenthetically.
Very often the "thing" must be gathered not from what precedes but from what follows, as in
As you are certainly a gentleman, thereto
Clerk-like experienced, which no less adorns
Our gentry, than our parents' noble names.
“And, which became him like a prince indeed,
He made a blushing 'cital of himself.
That is rarely thus used by Shakespeare:
“And, which was strange, the one so like the other
As could not be distinguished.
Often, however, in our A. V. that in "that is, being interpreted," is the relative, though a modern reader would not perceive it.
“And, that is worse,
The Lord Northumberland, his son young Henry Percy,
With all their powerful friends, are fled to him.
“I was never so berhymed since Pythagoras' time that (when) I
was an Irish cat, which I can hardly remember.
i.e. "I will explain to you (and the explanation shall seem probable) every one of these accidents."
“I'll resolve you,
Which to you shall seem probable, of every
These happen'd accidents.
“Even as I have tried in many other occurrences, which Cæsar
“My honour's at the stake, which (danger) to defeat
I must produce my power.
affirmed (ce que dit César), that often, &c.” MONTAIGNE, 36.