FREEZE THE DAISY!
Here's yet another science video 
that's "Not For Kids."
It's for science teachers and 
physics demonstrators.
You have to know the safety precautions 
dealing with cryogenic fluids in order 
to not injure yourself while doing 
the demonstration.
So, watch the video but don't mess with it
unless you know you're doing.
This time we're going to make our own liquid
nitrogen at home.
It's not real liquid nitrogen.  It's 
"Poor Man's" liquid nitrogen.
We need...
a couple pounds of Dry Ice,
and something to chop it up
Oh, um,
dry ice will last many days 
if you wrap it up in
Emergency Space Blanket.
Aluminized Mylar.
Also we need a 2-liter pop bottle,
a small bottle that fits inside,
and ninety nine percent
isopropyl "rubbing" alcohol.
scissors, big ones or little tiny scissors,
and that's it.
Poke a bunch of holes
in the bottom of
the small bottle,
and in the sides.
Now of course this isn't liquid nitrogen.
I was 
thinking about
the difference between dry ice
and liquid nitrogen, and I realized
that dry ice doesn't make good thermal contact.
If it was only a liquid, it would 
probably work just
as good as liquid nitrogen for
most of the 
science demonstrations.
So we're going to chill down some alcohol,
and use that instead.
Use scissors to cut the tops off
both of the bottles
then
test-fit
the small one inside the larger.
We're going to chop up dry ice 
into half-inch chunks.
then fill the space between the bottles evenly
with dry ice several inches deep.
Chop up the dry ice
however you want.
I use a butcher block in the sink.
and...
keep the dry ice in a bag so all the little
pieces don't end up getting lost.
Lots and lots of
little half-inch chunks.
And of course you could save 
lots of time by
buying the pellet type of dry-ice 
instead of chopping it yourself.
Most welding supply stores will have 
the pellet rather than the block type.
Keep the center bottle all the way down, and 
distribute chunks evenly, so
it doesn't get off to the side
There.  There's
three or four inches
thick of the chunks
and then slowly pour in the 99%
rubbing alcohol into
the dry ice itself.
Oh, you can use seventy percent
but it soon freezes into a
thick gel.
Ah, also
this is not like liquid nitrogen, 
in that the
liquid nitrogen
beads up off of your skin.
This stuff sticks.  So don't put 
your finger in it.  
It's like "cryogenic napalm."
You want about
two inches deep in there
so you have plenty of room to 
stick in flowers, and leafs
and rubber balls.
Okay, it's mostly stopped boiling, 
so it's down in temperature.
FREEZE THE DAISY.
Thin objects freeze very quickly.
Knock all alcohol off and...
Frozen flower!  Ready?
OOPS.
Yep, it
shattered pretty good.
Little pieces all over.
Another frozen flower...
Here's an un-frozen one.
No it doesn't shatter.
And I've got a couple of 
cherries down there.
That's where you need the tongs:
to get stuff back out.
Instant-frozen maple leaf 
from the front yard.
I couldn't find any rubber super-ball 
in my collection,
but we have
cherries and grapes.
Nope, didn't shatter.
Let's try again.   Oh...
don't put in your mouth.  It will
freeze to your tongue like a flagpole.
Nope.  It's more like a stone.
