After the wax melted, the children strained it in cheesecloth.
There was lots of dark matter left behind. The official name for this is "slumgum". It includes the pupal lining of the comb and excrement from the larvae. This means we were melting brood comb, as opposed to honey comb which is cleaner. Apparently slumgum warmed by the sun is used to attract swarms of bees when a hive needs to be filled. Bees are very attracted to it. Slumgum can also be a great fertilizer.