Dear Steve and listmembers,

I have had bad experience with such teflon stopcock-sealed tubes. I used
them for Coleman-conversion of water to hydrogen, but I could never store
the hydrogen for more than a day in these tubes, because the N2 signal
became too high. There are two possibilities: either the teflon is porous, or
the O-ring is not viton. Try changing the O-rings to viton ones.
A second possibility is the O-ring joint. Use a touch of vacuum grease (not
Apiezon!) to help the gasket be deformed smoothly. This helped me when I
used such joints.
But why do you need the O-ring joint? Just have an Y tube sealed with a
stopcock. You can put the carbonate in one leg, then pour the acid by means
of a pipette. Then screw back the stopcock. This case you can save the
O-ring joints and have less possibility for leakage.

Cheers,
Attila


Dr. Attila Demeny
Laboratory for Geochemical Research
Hungarian Academy of Sciences
Budapest, Budaorsi ut 45, H-1112, Hungary
tel/fax: 36-1-319-3145
e-mail: [log in to unmask]