Date: December 2006
As a child my mother put mothball into a tall
cylinder filled with water and set that cylinder on a coffee can
with a light inside it. She would add a substance(s)...either
baking soda or boric acid and maybe vinegar. The moth balls would
rise and fall at various intervals and was beautiful to look at
...similar to the Lava Lamps that you see in the stores today. My
search is to find the formula for the Dancing Moth Balls. Water +
Vinegar + baking soda + or boric acid. I have searched the
Internet and found Circulation Moth Balls, but no formula or recipe
for making that same experiment. I am looking for exact
proportions. I would love to do this for my grandchildren because
it was such a beautiful memory for me. The heat from the light bulb
may be necessary for the moth balls to rise and fall or it may have
been a pretty addition to the colored water Mother used. Thank you
for your time in researching this and your assistance especially
during this very busy Holiday season. If you have an answer you
will make eight families plus generations to come very happy.
The "dancing mothballs" effect is really the result of bubbles
forming on the underside of the mothballs causing it to be lifted to
the surface. At the surface, the mothballs tend to roll around and
the bubbles are released, causing the mothballs to sink back to the
bottom. As such, the mothballs do not have to be used. I have seen
the same effect replicated using raisins or sultanas - this is
probably safer since some people have an allergic reaction to the
naphthalene in mothballs, and raisins do not have that mothball smell.
The trick then is to develop bubbles at a regular and slow basis.
This is often accomplished by placing vinegar in a tall, thin
vessel, adding the raisins (which should sink) and slowly adding
baking soda to the vinegar mixture. The reaction of the vinegar and
the baking soda will produce carbon dioxide which will buoy up the
raisins. Since the initial reaction is strong, the raisins will be
buoyed up pretty fast. However, when the reaction subsides, the
production of bubbles diminish, the raisins sink - until more gas
bubbles are trapped on the underside of the raisins to once again buoy them up.
Thus, the "recipe" calls for vinegar and the slow addition of baking
soda (and further slow addition when the rising and falling of the
raisins subsides). There will come a time when the acetic acid in
the vinegar will all have been consumed and the liquid will have to
be replaced - you will note that further addition of baking soda
does not cause any more bubbling.
Since bubble formation is the key, I imagine plain water and
AlkaSeltzer (which is nothing more than some analgesic in baking
soda and citric acid) will work just as well, and may have the added
advantage that one could just drop a tablet in a tall cylinder of water.
Greg (Roberto Gregorius)
The mothballs now are para-dichloro-benzene, but they don't work
because they are 30% heavier than water,
and the bubbles are not strong enough float them up.
Old mothballs were naphthalene; they work but are hard to find now.
Some places well outside cities still have them.
Naphthalene is only ~3% heavier than water, so it lightly tries to sink
until some bubbles stick to it and push it upwards.
When it gets to the top, the bubbles pop off, and it sinks again.
Making some bubbles does not need heat, just baking soda and
enough of any acid (vinegar or boric acid).
So your lamp is just for looks, which is of course what it is all for...
I suspect you really _do not_ want the whole thing to get warm,
because it might emit a much stronger mothball smell.
so feel free to put ventilation holes
at top and bottom of your lamp-cylinder,
and a window-glass across the top.
Maybe I will try to figure out a way to make water 30% heavier,
so the ParaDichloroBenzene mothballs will work.
Some unusually heavy salt...
It is also possible some crafts person will make similar-looking balls
out of grains of some translucent wax and/or plastic,
with density adjusted to match water,
and then we'll be back in business, sort-of.
You are the second letter I have had about this.
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Update: June 2012