We were somewhere around Barstow, on the edge of the desert, when the
drugs began to take hold. I remember "Spamlet"
saying something like:

I once asked about how compound lenses are stuck together, on the Wikipedia
pages about lenses. I have an old, but much loved. pair that had like a
gold iris effect on one side. I've cleaned and realigned both barrels, and
the optics quite nicely, but I never had the nerve to try tackling the 'gold
iris effect', which is where the two parts of a compound lens are presumably
suffering from the balsam that holds them together drying out and
crystallising from the edge.

I did wonder if soaking the lens in xylene might gradually swell the dried
balsam back into a more see through condition. If not, how does one
separate the elements and what are they stuck together with these days?

You can seperate balsam-glued lenses and reglue them back with fresh
balsam. You can make a jig to hold them in registration, with a due
degree of care and attention to detail. Whatever you do, don't try this
on a valuable lens as a first attempt; indeed, pick up a scrap lens for
practice.
You could also use modern glue, but it's very much a fit and never take
apart exercise. Balsam has the saving grace (age though it might) of
being re-doable.