Well Ian, I think there is a little confusion going on here.
A "dry cell" of the type you speak of is indeed a galvanic cell with
just he minimum amount of moisture to allow galvanic reactions.
It is indeed a "less wet" version of a zinc bucket filled with
acid and a carbon rod partially submerged in the acid,
but with a "dry cell" they use a substance that contains the
liquid and there is no actual body of liquid sloshing around in it.
It's just the name they decided to use for a less wet cell.

The "dry pile" however is slightly different in that it was not
intended as a galvanic battery at all, it is simply a stack of
plates of two different metals, sandwiched between pieces of
paper. It behaves like an electret in that it also builds up a
(static) charge which can be used and will re-build again.
Originally it was thought this was a totally different effect that was
not related to the galvanic effect, and indeed it seemed to be
more closely related to the "work function"/"emission energy threshold"
and the relative Fermi levels of the different metals, as well as
the pressure applied to the stack (which in turn led to it being
categorised as a "contact potential" effect).
But soon after that the "dry galvanic cell" became popular,
and it didn't take long for people to suggest the seemingly dry paper
should in fact contain a certain level of moisture due to the air humidity,
and will act in a similar way as the "dry" electrolyte paste used in
"dry galvanic cells".
And indeed some dry piles were dissected and found to contain minute
amounts of moisture in the paper, which seemed to confirm the galvanic
interpretation of what was before categorised as a peculiar electrostatic
effect of the application of pressure on metals with different Fermi levels.
Mind you, that effect is also real and proven, but after more critical
analysis of the "dry pile" it was agreed this is most likely an effect that
does play a role in the "dry pile", but it is not the predominant process
that gives rise to the electret-like behaviour.
Or at least, that's what I know of the development of "dry cells" and
their relation to the "dry pile".

So Ian, you're entirely correct and I'm not sure why allcanadian found it so funny.

Quote from: xee on July 14, 2008, 11:09:32 AM
@ Jimboot
If you are interested in galvanic reactions your should learn about the electromotive series. The farther apart the two metals are in the series the higher the voltage will be between them in a battery. Here is a link to a not very good list. You can find better lists and discussions in basic college chemistry books and maybe on the web if you spend some time looking.

http://www.ipfw.edu/chem/104/kimble/Activity.htm

A battery needs a solution with free ion to work. The fewer the ions in the water the poorer the battery will work (lower current). It is hard to get pure water. Tap water has many impurities in it. Distilled water is mostly pure but there are grades of distilled water. Laboratory grade is much purer than what you get in a grocery store. But however pure the water is, it will probably not be pure once you put it into a container because most things have surface impurities even after coming out of a dishwasher.

Your last video was good at showing your setup.

Thanks for the link Xee. Your explanation about the metals being farther apart and voltage levels being higher means I can't let go of this experiment yet! I'll do some study.

@ Jimboot
Another term used for the series is Galvanic series. Here are some links I found for that term.

http://www.corrosionsource.com/handbook/galv_series.htm
http://www.brushwellman.com/alloy/tech_lit/AT0027_0800.pdf

These have the metal voltages listed so you can actually calculate the voltage the battery will have (the difference between the metal voltages),

test,I just wanted a link back to this thread.triffid

Quote from: Jimboot on July 10, 2008, 07:31:14 PM
This guy reckons he charges a mobile phone with it.

http://www.youtube.com/watch?v=pRPE6OG7Mp0

Here is the thread on this topic

http://www.overunity.com/index.php/topic,3691.msg62274/topicseen.html#msg62274