Date: Tue, 17 Aug 2010 20:00:36

Author: Dan Bernoulli

Subject: Re: "Ice Spikes" as art photography

Post:

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I will only relate one story from a science night at a local elementary sch=
ool. We were doing the shrink a balloon in Ln2 demo when a fourth grader co=
mes up and says his teacher uses that stuff to make ice cream.The teacher a=
pparently saw it done at one of our departmental open houses. The student =
then says it was so cold it burned his tongue and it was sore for days. (To=
my knowledge no one at the open house had a problem with ice cream=20
that was too cold. What did the demo person know that the teacher=20
didn't?) I know demos are cool (no pun intended) but I am very careful to u=
se demos that make a learning point and that are either very difficult for =
others to do or which=2C if someone else tries it and fails the repercussio=
ns are minimal.

Too often I see people pour liquid nitrogen into styrofoam cups=2C glass co=
ntainers=2C you name it - no goggles=2C no gloves=2C no lab coat=2C open sh=
oes or tennis shoes=2C ignite explosive mixtures - no goggles=2C no gloves=
=2C no lab coat......=2C keep a mason jar of mercury in their office to sho=
w students what density means etc. The list goes on. I assume that if I try=
something and it works=2C someone else without my experience (and sometime=
s luck) will also try what I have done. And sometimes it may be better to n=
ot do a demo at all then to teach people that it is okay for some to follow=
good safety practices but that if you are good enough=2C smart enough=2C p=
rofessional enough you'll be okay. I am surprised after the recent safety i=
ssues with H2 that more comments were not made about some of the you tube v=
ideos that were referenced. I'll get off my soap box now.

Dan Beeker
Indiana University

> CC: Paul.Nord@valpo.edu
> From: Paul.Nord@valpo.edu
> Subject: Re: [tap-l] "Ice Spikes" as art photography
> Date: Mon=2C 16 Aug 2010 10:44:30 -0500
> To: tap-l@lists.ncsu.edu
>=20
> I'll pass on both the LN2 drink and the dry ice appetizer.
> While I have complete faith in the Leidenfrost effect=2C I too easily pic=
ture a little bit of LN2 getting into some crevice in a molar and causing s=
hock freezing=2C shattering and intense pain. It looks impressive. But it=
's not worth the cost of my dental work.
>=20
> Maybe someday when the teeth are all gone?
>=20
> Paul
>=20
>=20
> On Aug 16=2C 2010=2C at 7:07 AM=2C chuck britton wrote:
>=20
> > At 6:12 PM -0700 8/15/10=2C William Beaty wrote:
> >>=20
> >>=20
> >> Also new Youtube:
> >>=20
> >> - Drinking LN2 (warning=2C can shatter tooth surfaces!)
> >> see: http://amasci.com/amateur/physvids.html
> >=20
> > Said to be 'worse' than chewing Dry Ice.. (Not so).
> >=20
> > DON't drink your LN2 from a glass Dewar (as shown).
> > Your lips WILL blister from the cold glass rim.
> > Use a styrofoam cup (much lower heat capacity and thermal conductivity=
.)
> >=20
> > DO ensure that your mouth (teeth=2C tongue=2C lips etc.) are WET before=
drinking.
> > A wet surface will not get colder than zero C.
> > Teeth won't shatter at zero C.
> >=20
> > DO keep the LN2 moving in your mouth. Don't let it settle.
> >=20
> > DON't inhale!!! The first sensation of violently boiling liquid in your=
mouth can be a bit startling.
> >=20
> > (A colleague tried to imitate my 'act' without consulting me.
> > He swallowed a bit and survived.
> > After experiencing the 'most satisfying belch of his lifetime'.)
> >=20
> >=20
> >=20
> > Chewing dry ice insures that your teeth are making close contact with t=
he very cold stuff.
> > No Leidenfrost effect to protect you.
> > Chewing Dry ice seems DUMB to me.
> > An occasional sip of LN2 is delightfully refreshing. (if done correctly=
).
>=20
>=20
=

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I will only relate one story from a science night at a local elementary sch=
ool. We were doing the shrink a balloon in Ln2 demo when a fourth grader co=
mes up and says his teacher uses that stuff to make ice cream.The teacher a=
pparently saw it done at one of our departmental open houses. =3B The s=
tudent then says it was so cold it burned his tongue and it was sore for da=
ys. (To my knowledge no one at the open house had a problem with ice cream=
=20
that was too cold. What did the demo person know that the teacher=20
didn't?) I know demos are cool (no pun intended) but I am very careful to u=
se demos that make a learning point and that are either very difficult for =
others to do or which=2C if someone else tries it and fails the repercussio=
ns are minimal.Too often I see people pour liquid nitrogen into sty=
rofoam cups=2C glass containers=2C you name it - no goggles=2C no gloves=2C=
no lab coat=2C open shoes or tennis shoes=2C ignite explosive mixtures - n=
o goggles=2C no gloves=2C no lab coat......=2C keep a mason jar of mercury =
in their office to show students what density means etc. The list goes on. =
I assume that if I try something and it works=2C someone else without my ex=
perience (and sometimes luck) will also try what I have done. And sometimes=
it may be better to not do a demo at all then to teach people that it is o=
kay for some to follow good safety practices but that if you are good enoug=
h=2C smart enough=2C professional enough you'll be okay. I am surprised aft=
er the recent safety issues with H2 that more comments were not made about =
some of the you tube videos that were referenced. I'll get off my soap box =
now.Dan BeekerIndiana University>=3B CC: Paul.Nord@va=
lpo.edu>=3B From: Paul.Nord@valpo.edu>=3B Subject: Re: [tap-l] =
"Ice Spikes" as art photography>=3B Date: Mon=2C 16 Aug 2010 10:44:30=
-0500>=3B To: tap-l@lists.ncsu.edu>=3B >=3B I'll pass on=
both the LN2 drink and the dry ice appetizer.>=3B While I have compl=
ete faith in the Leidenfrost effect=2C I too easily picture a little bit of=
LN2 getting into some crevice in a molar and causing shock freezing=2C sha=
ttering and intense pain. It looks impressive. But it's not worth the cos=
t of my dental work.>=3B >=3B Maybe someday when the teeth are =
all gone?>=3B >=3B Paul>=3B >=3B >=3B On Aug =
16=2C 2010=2C at 7:07 AM=2C chuck britton wrote:>=3B >=3B >=
=3B At 6:12 PM -0700 8/15/10=2C William Beaty wrote:>=3B >=3B>=3B=
>=3B >=3B>=3B >=3B >=3B>=3B Also new Youtube:>=
=3B >=3B>=3B >=3B >=3B>=3B - Drinking LN2 (warning=2C can s=
hatter tooth surfaces!)>=3B >=3B>=3B see: http://amasci.com/ama=
teur/physvids.html>=3B >=3B >=3B >=3B Said to be 'worse' th=
an chewing Dry Ice.. (Not so).>=3B >=3B >=3B >=3B DON't dri=
nk your LN2 from a glass Dewar (as shown).>=3B >=3B Your lips WILL=
blister from the cold glass rim.>=3B >=3B Use a styrofoam cup (mu=
ch lower heat capacity and thermal conductivity.)>=3B >=3B >=
=3B >=3B DO ensure that your mouth (teeth=2C tongue=2C lips etc.) are WET=
before drinking.>=3B >=3B A wet surface will not get colder than =
zero C.>=3B >=3B Teeth won't shatter at zero C.>=3B >=3B <=
br>>=3B >=3B DO keep the LN2 moving in your mouth. Don't let it settle.=
>=3B >=3B >=3B >=3B DON't inhale!!! The first sensation of =
violently boiling liquid in your mouth can be a bit startling.>=3B &g=
t=3B >=3B >=3B (A colleague tried to imitate my 'act' without cons=
ulting me.>=3B >=3B He swallowed a bit and survived.>=3B &g=
t=3B After experiencing the 'most satisfying belch of his lifetime'.)=
>=3B >=3B >=3B >=3B >=3B >=3B >=3B >=3B Chewing=
dry ice insures that your teeth are making close contact with the very col=
d stuff.>=3B >=3B No Leidenfrost effect to protect you.>=3B &=
gt=3B Chewing Dry ice seems DUMB to me.>=3B >=3B An occasional sip =
of LN2 is delightfully refreshing. (if done correctly).>=3B >=
=3B
=

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