Luckily, the original pouches in the 1926 Mason & Hamlin are still
good.  The leather is strong in the few valves that I have split.
(They split very easy and clean after placing them in the desert
sun for an hour).  I will need to seal pouches and cannot find
rubber cement thinner anywhere.  My question is, what can be used
as a solvent to thin down the rubber cement?

Apparently the solvent for rubber cement is banned in California.
I have yet to find any of the places that sell rubber cement.  I am
wondering if there are other solvents that can be used to dilute the
rubber cement to make it useable for sealing pouches.  Naphtha is
available in bulk, and if my nose serves me well, it is used as old
fashioned cigarette lighter fluid.  Since gasoline is a real solvent
for rubber, could that be used?  Or perhaps white gas that was used
in Coleman lanterns?

Speaking of glues, is Weld-Bond still made?  It is missing from all the
hardware stores in the desert.  I have found it to be a good universal
adhesive, making a fairly strong, somewhat flexible bond, drying almost
clear and good for sealing where nipples meet wood.

Bill Chapman - in sunny La Quinta, Calif., 98 deg. F. (36.6 C.)
& 12% relative humidity