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Re: Moth Balls



The version I've used is baking soda soln. and lemon pits.

bc


Herbert H Gottlieb wrote:

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Your explanation sounds reasonable but others on this list-serv
might be better qualified to answer your question.

Herb

On Mon, 11 Feb 2002 08:56:21 +0100 Gorazd Planinsic
<gorazd@fiz.uni-lj.si> writes:
May I ask you about the experiment which is proposed on the Donald
Simanek's web site? The text goes like this:

VARIABLE DENSITY. Moth balls rolled in sodium bicarbonate and put into a
cylinder of very dilute hydrochloric acid will rise and fall with
regularity. [HG]

I didn't have time to try the experiment yet, but it sounds interesting.
Does it has to do with the small bubbles that are formed on the surface
of the moth ball due to the chemical reaction between the sodium
bicarbonate and acid? I suppose the bubbles will grow until they reach a
certain size (ball goes up) and then they will leave the ball (ball goes
down).

Looking forward to receive your answer

Best regards

Gorazd
Herbert H Gottlieb wrote:

Dear Gorazd,It was a pleasure to receive your e-mail with the attachment
of your "Water-Drop Projector" article. I do not recall seeing this
articlebefore. Perhaps the February 2001 copy of TPT arrived when I was
out ofthe country and I missed that particular issue. Your idea is
especiallygood for use with a small group of students as a laboratory
exercise inBiology or Physics classes.Perhaps you are unacquainted with
an older version of a water-dropmicroscope. To make one:1. Cut a 2 cm X
6 cm metal rectangle from a discarded can of soup orother food. 2. Using
a small blunt instrument, such as the back of a ball-point pen,press an
indentation, about the size of a water drop, near one end of themetal
rectangle.3. In the center of the indentation, drill a small hole
(approximately1-2 mm diameter). 4. Fold the metal in half (with the aid
of a ball point pen) under itscenter making sure that the end with the
indentation remains visible onthe upper section of the fold. 5. Fill the
indentation with water. It should form a drop with a curvedupper surface
due to the surface tension of the water. For the samereason, the water
will not leak through the hole at the bottom of thedrop.6. Look though
the water drop at microscopic specimens placed below.Because the
surface of the water drop is curved the specimen will appearto be
magnified. If the specimen is out of focus, try adjusting the distance to
thespecimen by pressing the halves of the bent metal closer together. IT
REALLY WORKS !hERBOn Sun, 10 Feb 2002 19:01:16 +0100 Gorazd
Planinsic<gorazd@fiz.uni-lj.si> writes:
Dear Mr. Gottlieb!I am sending you the description of a simple experiment
that may fit into your collection of experiments with lasers (published
in TPT last year). I am teaching Didactics of Physics at Phys. Dept.
University of Ljubljana + working at Slovenian Science center as exhibit
director.Best regardsGorazd PlaninsicPhys.Dept.University of
LjubljanaJadranska 191000 Ljubljana, SLOVENIA
Herb Gottlieb from New York City(Where it's nice to live but I
wouldn'twant to be a tourist here)herbgottlieb@juno.com

Herb Gottlieb from New York City
(Where it's nice to live but I wouldn't
want to be a tourist here)
herbgottlieb@juno.com

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<DIV>Your explanation sounds reasonable but others on this list-serv<=
/DIV>
<DIV>might be better qualified to answer your question.</DIV>
<DIV>&nbsp;</DIV>
<DIV>Herb</DIV>
<DIV>&nbsp;</DIV>
<DIV>On Mon, 11 Feb 2002 08:56:21 +0100 Gorazd Planinsic &lt;<A=20
href=3D"mailto:gorazd@fiz.uni-lj.si";>gorazd@fiz.uni-lj.si</A>&gt; wri=
tes:</DIV>
<BLOCKQUOTE dir=3Dltr=20
style=3D"PADDING-LEFT: 10px; MARGIN-LEFT: 10px; BORDER-LEFT: #000000 =
2px solid">
<DIV>May I ask you about the experiment which is proposed on the Do=
nald=20
Simanek's web site? The text goes like this: <BR><BR>VARIABLE DENSI=
TY. Moth=20
balls rolled in sodium bicarbonate and put into a cylinder of very =
dilute=20
hydrochloric acid will rise and fall with regularity. [HG]&nbsp; <B=
R><BR>I=20
didn't have time to try the experiment yet, but it sounds interesti=
ng. Does it=20
has to do with the small bubbles that are formed on the surface of =
the moth=20
ball due to the chemical reaction between the sodium bicarbonate an=
d acid? I=20
suppose the bubbles will grow until they reach a certain size (ball=
goes up)=20
and then they will leave the ball (ball goes down). <BR><BR><BR>Loo=
king=20
forward to receive your answer<BR><BR>Best regards<BR><BR>Gorazd<BR=
Herbert H=20
Gottlieb wrote:<BR></DIV>
<BLOCKQUOTE cite=3Dmid:20020211.200835.-16415921.4.herbgottlieb@jun=
o.com=20
type=3D"cite"><PRE wrap=3D"">Dear Gorazd,<BR><BR>It was a pleasure =
to receive your e-mail with the attachment of your <BR>"Water-Drop Pr=
ojector" article. I do not recall seeing this article<BR>before. Perh=
aps the February 2001 copy of TPT arrived when I was out of<BR>the co=
untry and I missed that particular issue. Your idea is especially<BR>=
good for use with a small group of students as a laboratory exercise =
in<BR>Biology or Physics classes.<BR><BR>Perhaps you are unacquainted=
with an older version of a water-drop<BR>microscope. <BR>To make on=
e:<BR><BR>1. Cut a 2 cm X 6 cm metal rectangle from a discarded can o=
f soup or<BR>other food. <BR><BR>2. Using a small blunt instrument, =
such as the back of a ball-point pen,<BR>press an indentation, about =
the size of a water drop, near one end of the<BR>metal rectangle.<BR>=
<BR>3. In the center of the indentation, drill a small hole (approxim=
ately<BR>1-2 mm diameter). <BR><BR>4. Fold the metal in half (with t=
he aid of a ball point pen) under its<B r>center making sure that the=
end with the indentation remains visible on<BR>the upper section of =
the fold. <BR><BR>5. Fill the indentation with water. It should form =
a drop with a curved<BR>upper surface due to the surface tension of t=
he water. For the same<BR>reason, the water will not leak through the=
hole at the bottom of the<BR>drop.<BR><BR>6. Look though the water d=
rop at microscopic specimens placed below.<BR>Because the surface o=
f the water drop is curved the specimen will appear<BR>to be magnifie=
d. <BR>If the specimen is out of focus, try adjusting the distance to=
the<BR>specimen by pressing the halves of the bent metal closer toge=
ther. <BR><BR>IT REALLY WORKS !<BR><BR>hERB<BR><BR><BR><BR><BR>On Su=
n, 10 Feb 2002 19:01:16 +0100 Gorazd Planinsic<BR><A class=3Dmoz-txt-=
link-rfc2396E href=3D"mailto:gorazd@fiz.uni-lj.si";>&lt;gorazd@fiz.uni=
-lj.si&gt;</A> writes:<BR></PRE>
<BLOCKQUOTE type=3D"cite"><PRE wrap=3D"">Dear Mr. Gottlieb!<BR>I =
am sending you the description of a simple experiment that may fit <B=
R><BR>into your collection of experiments with lasers (published in T=
PT <BR>last <BR>year). I am teaching Didactics of Physics at Phys. De=
pt. University <BR>of <BR>Ljubljana + working at Slovenian Science ce=
nter as exhibit <BR>director.<BR><BR>Best regards<BR><BR>Gorazd Plani=
nsic<BR>Phys.Dept.<BR>University of Ljubljana<BR>Jadranska 19<BR>1000=
Ljubljana, SLOVENIA<BR><BR></PRE></BLOCKQUOTE><PRE wrap=3D""><!---->=
<BR><BR>Herb Gottlieb from New York City<BR>(Where it's nice to live =
but I wouldn't<BR>want to be a tourist here)<BR><A class=3Dmoz-txt-li=
nk-abbreviated href=3D"mailto:herbgottlieb@juno.com";>herbgottlieb@jun=
o.com</A><BR><BR></PRE></BLOCKQUOTE><BR></B>
<DIV>&nbsp;</DIV></BLOCKQUOTE><BR>Herb Gottlieb from New York City<=
BR>(Where=20
it's nice to live but I wouldn't<BR>want to be a tourist=20
here)<BR>herbgottlieb@juno.com<BR></BODY></HTML>

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