Dear Bruce et al:  On some pipe organ reed pipes, the voicer will add
weights to some of the brass tongues.  On smaller pipes it's usually
done with a little blob of solder.  On larger pipes they'll use cast
brass or lead weights that are screwed onto the reed.

In the case of your Aeolian Free Reed Clarinet, they used a resin
substance called Chatterton's Compound (see link below for its other
uses).  It is heated with a torch and melted like wax onto the reed.
It is extremely hard to find today and only a few 'organ men' still
have a supply of it or use it.

  http://en.wikipedia.org/wiki/Chatterton's_compound 

I hope this information is helpful.  I'm sure there are more qualified
people on this and other lists who know more about it.  I was surprised
I remembered the name of it!

If I'm reading your other question properly, you are saying that some
of the resonators have split along the solder seams?  If this is the
case, they'll have to be repaired in order to tune correctly as they'll
fly off speech and/or won't tune properly.  With a normal organ reed
pipe you have two methods of tuning (shortening or lengthening the reed
tongue with the tuning wire and with the slide tuner or scroll at the
top of the resonator.  Unfortunately with your free reed pipes, you
have only the slide tuner for fine tuning.

You can easily repair the pipes yourself if you have the correct
soldering iron, whiting or paraffin, and solder.  I would, however,
suggest practising on some miscellaneous pipes before you try it on
your clarinet.  If you have any questions about the soldering process,
please feel free to email me about it.

Steven Durham
Portland, Oregon, USA