From: joec@fid.morgan.com (Joe Collins)
Subject: Fun at home - exploding soap bubbles. 
Organization: None
Date: Mon, 11 Jan 1993 20:30:17 GMT

Last night (inspired by a recent posting in this newsgroup) we 
made soap bubbles filled with Hydrogen and Oxygen. My son had
fun igniting them with a match and hearing them all POP!

Here is how we did it:

NEEDED:
Cotainer with a tight fitting top (glass, plastic, etc).
some wire (#18)
plastic hose, such as used in fish tanks (see your hardware store).
A train transformer or any other source of 12-20v of DC current.
water
Sulphuric acid (hardware store) or perhaps baking soda will work.
Soap

CONSTRUCTION:
We used an ehrlenmeyer flask but any container that has a tight-fitting
container will also work.
 
Drill three holes in the top. One larger and two smaller.
In the larger hole, snake some plastic hosing, as found in your local
hardware store. Get the type used in fish tanks. Have the hosing
go into the top such that it is barely through the top, i.e. it is
flush with one side of the top. This side of the top is the side that
faces into the container and the much longer section of this
hosing will go elsewhere (see below)

Through the other two holes you will push/pull some #18 wire,
Have the two wires go all the way through the top and be sure to scrape 
away the insulation. They should extend through such that they reach 
about 2/3 the way down into the container.

Ideally, you should not have the copper exposed in the water. Thus
you should connect the copper to an inert object like gold or a carbon
rod but this is not necessary for short usage.

Fill the container with water, all the way up. Put in 1-2 drops of sulphuric
acid but you could probably use 1/4 teaspoon of baking soda. This is 
is used to enhance the electrical flow through the water. Don't use table salt.
If you do, you will get chlorine+hydrogen instead of oxygen+hydrogen.

Put on the cap and then seal it by dripping melted paraffin over the
top. Snake the plastic hosing into a bowl filled with soapy water. Let the
end of the hosing sit under the soapy water.

OPERATION:
Connect the 2 wires to a power supply - we used a train transformer and
this supplied about 20 volts DC.

What happens is that the electricity breaks down the water and this
creates Hydrogen at the negatively charged wire and Oxygen at the
positively charged wire. Water is H2O so the negatively charged wire
will give off twice the bubbles as the positively charged wire.

The pressure will build up slightly and this will force the hydrogen/oxygen 
gas mixture up the plastic hose and this will then bubble through the soapy 
water. The soapy water will create bubbles which will collect the
hydrogen/oxygen mixture. 

As we collected some bubbles, my son held a lit match to them and they
all exploded with a loud POP. Since the volume of gas created was not
that much, it took a few minutes to collect enough gas bubbles to make it 
worthwhile. It was also safer this way.

NEXT:
Our next project will be to separate the two gases and then just bubble
hydrogen through the soapy water and get hydrogen bubbles.
The advantage of these will be they will float in the air.

Have fun out there and be careful....

Joe
joec@morgan.com