Re: Electrical Generation.

"Is there a material or a combination of materials that 
when immersed in water would produce an electric current?" 
is your question.  You have asked:  "How do you make a 
battery?"

We usually reserve the word, "generation," for making 
electricity by electromechanical means.  You have asked 
how to make electricity with chemistry.  That's what 
batteries do.

First," battery"  is usually a misnomer.  The two cylinders 
in your flashlight are really "cells."  Cells in series 
packages make a battery, like an array of artillery make a 
battery.

Second, the water we want to use must be electrically 
conductive, as pure water is not.  Water serves as the 
"electrolyte," you see.

Finally, any two materials with differing tendencies of 
losing electrons to the electrolyte will work.  But 
saying this is like the Monty Python bit where John
Cleese teaches the television audience how to play the 
flute.  You blow in this end, and move your fingers 
up and down the pipe.  "Thanks, John -- that was
great!."

You'll get the idea if you put a copper and a zinc 
strip into a beaker of dilute sulphuric acid.  Now 
you have a cell.  Outside the beaker you can 
connect a penlight lamp to the strips.  Before you 
connect, note the bubbles forming on the zinc.  
After you connect, the bubbles form much more 
vigorously as the lamp lights.  In practical cell 
design, those bubbles get in the way and you have to
deal with that.

Just want to make a voltmeter needle quiver?  Take a 
dime and a dime-sized piece of blotter paper.  Wet 
the blotter paper with salt water and let it dry.  Tape
two wires to the sandwich, and when you drop it into 
water, you will get a voltage across the two wires.  
And check out Bill Beaty's site:

http://www.eskimo.com/~billb/emotor/duluc.txt

Good luck!  Larry Skarin