Neal Stephenson got me thinking about phosphorus; and the Internet was there for me.

As is before shewed, take Urine well putrefied in a Tub, exposed to the Air for seven Weeks, all one as you do when you're to make a Spirit of it; the Spirit being drawn, or rather the whole of it being evaporated to the consistance of Honey, in which lies the Fosperus; but the Art is somewhat difficult to get it from thence, in two cases, the one is in making choice of a proper Agent to be mixed therewith, and the other is the exact regiment of the Fire.

I cannot, however, track down an online edition of Boyle's The aerial noctiluca: or some new phoenomena, and a process of a factitious self-shining substance.

Please don't try the last experiment on the above website. There exist easier ways.