Le 2011-07-29 10:05, Invisible a écrit :
> On 29/07/2011 02:51 PM, Francois Labreque wrote:
>
>> Also, the bottle
>> says that it is NOT an anti-corrosive agent, and that it should be mixed
>> with one, preferably their own, of course.
>
> You can READ that?? o_O
>

Sure.

http://image.ebuyer.com/UK/P800-0179913-01.jpg

while fuzzy, it's big enough to read.

-- 
/*Francois Labreque*/#local a=x+y;#local b=x+a;#local c=a+b;#macro P(F//
/*    flabreque    */L)polygon{5,F,F+z,L+z,L,F pigment{rgb 9}}#end union
/*        @        */{P(0,a)P(a,b)P(b,c)P(2*a,2*b)P(2*b,b+c)P(b+c,<2,3>)
/*   gmail.com     */}camera{orthographic location<6,1.25,-6>look_at a }

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>> You can READ that?? o_O
>
> Sure.
>
> http://image.ebuyer.com/UK/P800-0179913-01.jpg
>
> while fuzzy, it's big enough to read.

Barely...

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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On 29/07/2011 05:51 PM, Darren New wrote:
> On 7/29/2011 1:26, Invisible wrote:
>> pH 2 is *very* acidic.
>
> Oh, I got that backwards.

Did I mention that my dad's a professional chemist and that I work for a 
lab company? Or that I scored 98% on my GCSE science exam? Or that my 
sister has an MSc in chemistry? Or that I personally own a chemistry 
set? :-P

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On 29/07/2011 06:15 PM, B. Gimeno wrote:

> I'ts also absolutey germ-free, suppose that it will keep virus away from your
> pc.
>
> ;-)

It's not the RNA viruses I'm worried about!

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On 01/08/2011 8:59 AM, Invisible wrote:
> Or that I personally own a chemistry set? :-P

Trust me, I own a chemistry set. ;-)
LOL

-- 
Regards
     Stephen

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On 29/07/2011 05:54 PM, Darren New wrote:
> On 7/29/2011 3:07, Warp wrote:
>> the "requires a degree" part is an exaggeration
>
> More like "requires remembering the first day of high-school chemistry
> class, that you've never touched since." :-)

Seriously. Everybody knows that water freezes at 0°C (actually no, it 
doesn't) and boils at 100°C. I've yet to meet anybody who didn't know 
that. Similarly, I was under the impression that knowing that water is 
pH 7 was common knowledge...

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On Mon, 05 Sep 2011 10:35:45 +0100, Invisible wrote:

>  that water freezes at 0°C (actually no, it
> doesn't) and boils at 100°C

It also doesn't always boil at 100C - reduce the atmospheric pressure and 
see when it boils.

Jim

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On 05/09/2011 04:43 PM, Jim Henderson wrote:
> On Mon, 05 Sep 2011 10:35:45 +0100, Invisible wrote:
>
>>   that water freezes at 0°C (actually no, it
>> doesn't) and boils at 100°C
>
> It also doesn't always boil at 100C - reduce the atmospheric pressure and
> see when it boils.

Or increase it. Or add impurities. Or whatever.

Yes, but under /normal/ circumstances, it boils at 100°C, which is why 
it's defined that way. :-P

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Le 2011/09/05 11:52, Invisible a écrit :
> On 05/09/2011 04:43 PM, Jim Henderson wrote:
>> On Mon, 05 Sep 2011 10:35:45 +0100, Invisible wrote:
>>
>>> that water freezes at 0°C (actually no, it
>>> doesn't) and boils at 100°C
>>
>> It also doesn't always boil at 100C - reduce the atmospheric pressure and
>> see when it boils.
>
> Or increase it. Or add impurities. Or whatever.
>
> Yes, but under /normal/ circumstances, it boils at 100°C, which is why
> it's defined that way. :-P

Pure water at average sea level presure boils/condense at 100°C and 
melt/freeze at 0°C at the same presure level. Both by definition. In 
fact, it's the definition of 0°C and 100°C.
(0°F is defined as the freezing poing of sea water and 100°F as the body 
temperature of a "healthy" human male, but the "healthy" human male who 
was used for the original mesure was somewhat feverish at the time, and 
had the flue the next day...)

Change the presure and you also change freezing temperature.


Alain

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Alain <aze### [at] qwertyorg> wrote:
> Pure water at average sea level presure boils/condense at 100°C and 
> melt/freeze at 0°C at the same presure level. Both by definition. In 
> fact, it's the definition of 0°C and 100°C.

  So, does water freeze or melt at exactly 0 degrees celsius?

-- 
                                                          - Warp

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On 9/5/2011 8:52, Invisible wrote:
> Yes, but under /normal/ circumstances, it boils at 100°C, which is
 why it's
> defined that way. :-P

No it doesn't. At 100°C, it's in equilibrium. Just like at 0°C,
 it's neither 
getting more frozen or less frozen.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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On Mon, 05 Sep 2011 16:52:50 +0100, Invisible wrote:

> On 05/09/2011 04:43 PM, Jim Henderson wrote:
>> On Mon, 05 Sep 2011 10:35:45 +0100, Invisible wrote:
>>
>>>   that water freezes at 0°C (actually no, it
>>> doesn't) and boils at 100°C
>>
>> It also doesn't always boil at 100C - reduce the atmospheric pressure
>> and see when it boils.
> 
> Or increase it. Or add impurities. Or whatever.
> 
> Yes, but under /normal/ circumstances, it boils at 100°C, which is why
> it's defined that way. :-P

Not here at 4,000 feet - "normal" circumstances here have it boiling at a 
slightly lower temperature. :P

IOW, it all depends on how you define "normal".  (Hence my suggestion of 
reducing the atmospheric pressure, because here, lower pressure is 
'normal').

Jim

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On Mon, 05 Sep 2011 13:17:32 -0400, Warp wrote:

> Alain <aze### [at] qwertyorg> wrote:
>> Pure water at average sea level presure boils/condense at 100°C and
>> melt/freeze at 0°C at the same presure level. Both by definition. In
>> fact, it's the definition of 0°C and 100°C.
> 
>   So, does water freeze or melt at exactly 0 degrees celsius?

Yes, at some altitudes, it does.

Jim

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>> Yes, but under /normal/ circumstances, it boils at 100°C, which is why
>> it's defined that way. :-P
>
> Not here at 4,000 feet - "normal" circumstances here have it boiling at a
> slightly lower temperature. :P

96.2°C, a piffling 3.8° lower.

> IOW, it all depends on how you define "normal".  (Hence my suggestion of
> reducing the atmospheric pressure, because here, lower pressure is
> 'normal').

This is why the /actual/ specification is far more complicated. But for 
any sane real-world purpose, you can more or less ignore such 
technicallities.

-- 
http://blog.orphi.me.uk/
http://www.zazzle.com/MathematicalOrchid*

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On 9/5/2011 10:47 AM, Darren New wrote:
> On 9/5/2011 8:52, Invisible wrote:
>> Yes, but under /normal/ circumstances, it boils at 100°C, which is why
>> it's
>> defined that way. :-P
>
> No it doesn't. At 100°C, it's in equilibrium. Just like at 0°C, it's
> neither getting more frozen or less frozen.
>
Worse than that, in certain conditions you can "hyper-heat" water, and, 
I assume, probably super cool it, without changing state. In the former 
case you just need a container that has "no" places for bubbles to form. 
Not sure what you would need to do in the later case to make it happen, 
if you could.

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Le 2011/09/05 13:17, Warp a écrit :
> Alain<aze### [at] qwertyorg>  wrote:
>> Pure water at average sea level presure boils/condense at 100°C and
>> melt/freeze at 0°C at the same presure level. Both by definition. In
>> fact, it's the definition of 0°C and 100°C.
>
>    So, does water freeze or melt at exactly 0 degrees celsius?
>
At sea level, yes. Melt if you add energy, freeze if it looses energy, 
but stay at 0°C as long as there is still ice and liquid water.

As you climb or reduce presure, the freezing point slowly climb, but not 
much.
As you go lower or increase presure, the freezing point goes into the 
negative.

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Le 2011/09/05 18:50, Patrick Elliott a écrit :
> On 9/5/2011 10:47 AM, Darren New wrote:
>> On 9/5/2011 8:52, Invisible wrote:
>>> Yes, but under /normal/ circumstances, it boils at 100°C, which is why
>>> it's
>>> defined that way. :-P
>>
>> No it doesn't. At 100°C, it's in equilibrium. Just like at 0°C, it's
>> neither getting more frozen or less frozen.
>>
> Worse than that, in certain conditions you can "hyper-heat" water, and,
> I assume, probably super cool it, without changing state. In the former
> case you just need a container that has "no" places for bubbles to form.
> Not sure what you would need to do in the later case to make it happen,
> if you could.

You can have water that stay liquid down to -10°C and possibly even 
less. You need a container with very smooth surface and no particles in 
suspention. In this state, a vibration can be just enough to cause 
almost instant crystalisation.

If you slowly heat very pure water, it can bet a good bit warmer that 
100°C before it start to boil. There will be vapour escaping from the 
surface, but no ebulition, even in a open container. It's a dangerous 
situation, as any disturbance can cause explosive ebulition projecting 
scalding water everywhere.

If you slowly cool down steam and don't give it any nucleation point, 
that steam may stay totaly gaseous at relatively low temperature. You 
get hyper-saturated steam. It appens in, and around, clouds. Again, it's 
an unstable situation and even a very faint sound, or a dust particle 
can cause almost instant condensation.

But you can't prevent ice from melting as you slowly heat it.

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On Mon, 05 Sep 2011 21:12:15 -0400, Alain wrote:

> You can have water that stay liquid down to -10°C and possibly even
> less. You need a container with very smooth surface and no particles in
> suspention. In this state, a vibration can be just enough to cause
> almost instant crystalisation.

Which is actually quite cool to see - I've seen it done with beer before.

Jim

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On Mon, 05 Sep 2011 19:32:49 +0100, Orchid XP v8 wrote:

>>> Yes, but under /normal/ circumstances, it boils at 100°C, which is why
>>> it's defined that way. :-P
>>
>> Not here at 4,000 feet - "normal" circumstances here have it boiling at
>> a slightly lower temperature. :P
> 
> 96.2°C, a piffling 3.8° lower.

Which is still not 100C no matter how you slice it.  The difference in 
humidity, altitude, and other things makes cooking things that require 
precise measurements (usually baked goods) slightly different than at 
other altitudes and in other conditions.

>> IOW, it all depends on how you define "normal".  (Hence my suggestion
>> of reducing the atmospheric pressure, because here, lower pressure is
>> 'normal').
> 
> This is why the /actual/ specification is far more complicated. But for
> any sane real-world purpose, you can more or less ignore such
> technicallities.

Baking is a real-world purpose.  An awareness of the 'normal' as well as 
'current' environment are, for some things, absolutely *critical* in 
order to be successful.

Jim

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On 06/09/2011 06:25 AM, Jim Henderson wrote:
> On Mon, 05 Sep 2011 21:12:15 -0400, Alain wrote:
>
>> You can have water that stay liquid down to -10°C and possibly even
>> less. You need a container with very smooth surface and no particles in
>> suspention. In this state, a vibration can be just enough to cause
>> almost instant crystalisation.
>
> Which is actually quite cool

I see what you did there.

I've got a box of hand warmers at home. They contain a super-saturated 
solution (of what I don't know). Once you provide a nucleation point, 
the whole lot crystallises within a few seconds. It also gets quite warm 
in the process. (This is what makes it good for warming your hands.)

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On 06/09/2011 06:27 AM, Jim Henderson wrote:
> On Mon, 05 Sep 2011 19:32:49 +0100, Orchid XP v8 wrote:
>
>>>> Yes, but under /normal/ circumstances, it boils at 100°C, which is why
>>>> it's defined that way. :-P
>>>
>>> Not here at 4,000 feet - "normal" circumstances here have it boiling at
>>> a slightly lower temperature. :P
>>
>> 96.2°C, a piffling 3.8° lower.
>
> Which is still not 100C no matter how you slice it.  The difference in
> humidity, altitude, and other things makes cooking things that require
> precise measurements (usually baked goods) slightly different than at
> other altitudes and in other conditions.

I would suggest that the wild variations in oven temperatures have a 
vastly bigger impact than a 4% difference in the boiling point of water.

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On 9/5/2011 6:12 PM, Alain wrote:
> If you slowly heat very pure water, it can bet a good bit warmer that
> 100°C before it start to boil. There will be vapour escaping from the
> surface, but no ebulition, even in a open container. It's a dangerous
> situation, as any disturbance can cause explosive ebulition projecting
> scalding water everywhere.
>
Or, very fast, by heating it all more or less at the same time (i.e., 
with something like a microwave oven.

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On 06/09/2011 02:12 AM, Alain wrote:

> If you slowly heat very pure water, it can bet a good bit warmer that
> 100°C before it start to boil. There will be vapour escaping from the
> surface, but no ebulition, even in a open container. It's a dangerous
> situation, as any disturbance can cause explosive ebulition projecting
> scalding water everywhere.

Legend has it that boiling water in a microwave oven has this effect. I 
don't know of an authoritative source which can confirm or refute that...

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On 9/6/2011 1:04 AM, Invisible wrote:
> On 06/09/2011 06:25 AM, Jim Henderson wrote:
>> On Mon, 05 Sep 2011 21:12:15 -0400, Alain wrote:
>>
>>> You can have water that stay liquid down to -10°C and possibly even
>>> less. You need a container with very smooth surface and no particles in
>>> suspention. In this state, a vibration can be just enough to cause
>>> almost instant crystalisation.
>>
>> Which is actually quite cool
>
> I see what you did there.
>
> I've got a box of hand warmers at home. They contain a super-saturated
> solution (of what I don't know). Once you provide a nucleation point,
> the whole lot crystallises within a few seconds. It also gets quite warm
> in the process. (This is what makes it good for warming your hands.)
Seen those. There is also some expensive shirt that was made for 
joggers, which uses a similar principle, though, in that case, I get the 
impression they formulated the material so it crystalized faster than 
normal in cold temperatures, releasing heat, but softening faster than 
normal too, absorbing it, thus keeping you cooler, or warmer, depending 
on conditions.

Always wondered, in the case of the whole "heat pack" thing though if 
you couldn't make one that did the reverse, and was "recoolable", or 
whatever. The principle being, of course, than it is rechargable, so 
long as the solution doesn't change (often the plastic is 
semi-permiable, so loses moister over time, and stops working), so when 
you let it cool slowly, it "holds" the excess energy. When you apply 
kinetic energy to it, it instantly starts losing all of what it 
retained, and crystallizes. You would basically need to do the reverse, 
somehow, for a "cold pack", crystallizing it, so as to "lose" more heat 
than it needs in a stable state, then.. there comes the rub. Other than 
that it would liquify as it absorbed the heat, instead of crystallizing, 
like the supersaturation, I am not clear how you would manage to make it 
so it could recharge effectively.

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On 9/6/2011 2:36 AM, Invisible wrote:
> On 06/09/2011 02:12 AM, Alain wrote:
>
>> If you slowly heat very pure water, it can bet a good bit warmer that
>> 100°C before it start to boil. There will be vapour escaping from the
>> surface, but no ebulition, even in a open container. It's a dangerous
>> situation, as any disturbance can cause explosive ebulition projecting
>> scalding water everywhere.
>
> Legend has it that boiling water in a microwave oven has this effect. I
> don't know of an authoritative source which can confirm or refute that...
Uh.. Mythbusters? They tried it, and it did. lol

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> Always wondered, in the case of the whole "heat pack" thing though if
> you couldn't make one that did the reverse, and was "recoolable", or
> whatever.

Hmm. Plausibly.

I would imagine, like with other refrigeration technologies, the key is 
to find a material which has a phase change at the right temperature. 
Normal hand warmers become super-saturated solutions at very high 
temperatures. If you wanted to make something cold, you'd need something 
that becomes super-saturated at a low temperature.

I'm also not completely sure of the kinetics: a hand warmer releases 
heat quickly, and absorbs it slowly. That may or may not be useful for 
cooling purposes.

Unrelated, but I note that dissolving ammonia in water is an endothermic 
reaction. That, apparently, is how Victorian icecream was made. So I 
guess the question is, WOULD YOU EAT IT? ;-)

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On Tue, 06 Sep 2011 02:41:12 -0700, Patrick Elliott wrote:

> On 9/6/2011 2:36 AM, Invisible wrote:
>> On 06/09/2011 02:12 AM, Alain wrote:
>>
>>> If you slowly heat very pure water, it can bet a good bit warmer that
>>> 100°C before it start to boil. There will be vapour escaping from the
>>> surface, but no ebulition, even in a open container. It's a dangerous
>>> situation, as any disturbance can cause explosive ebulition projecting
>>> scalding water everywhere.
>>
>> Legend has it that boiling water in a microwave oven has this effect. I
>> don't know of an authoritative source which can confirm or refute
>> that...
> Uh.. Mythbusters? They tried it, and it did. lol

I've also had it happen to me.

Jim

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On Tue, 06 Sep 2011 09:05:23 +0100, Invisible wrote:

> On 06/09/2011 06:27 AM, Jim Henderson wrote:
>> On Mon, 05 Sep 2011 19:32:49 +0100, Orchid XP v8 wrote:
>>
>>>>> Yes, but under /normal/ circumstances, it boils at 100°C, which is
>>>>> why it's defined that way. :-P
>>>>
>>>> Not here at 4,000 feet - "normal" circumstances here have it boiling
>>>> at a slightly lower temperature. :P
>>>
>>> 96.2°C, a piffling 3.8° lower.
>>
>> Which is still not 100C no matter how you slice it.  The difference in
>> humidity, altitude, and other things makes cooking things that require
>> precise measurements (usually baked goods) slightly different than at
>> other altitudes and in other conditions.
> 
> I would suggest that the wild variations in oven temperatures have a
> vastly bigger impact than a 4% difference in the boiling point of water.

My point is that 4% is still 4%.

Jim

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On Tue, 06 Sep 2011 09:04:13 +0100, Invisible wrote:

> On 06/09/2011 06:25 AM, Jim Henderson wrote:
>> On Mon, 05 Sep 2011 21:12:15 -0400, Alain wrote:
>>
>>> You can have water that stay liquid down to -10°C and possibly even
>>> less. You need a container with very smooth surface and no particles
>>> in suspention. In this state, a vibration can be just enough to cause
>>> almost instant crystalisation.
>>
>> Which is actually quite cool
> 
> I see what you did there.

Wow, *completely* unintentional, that one.  Honest. :)

Jim

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On 9/6/2011 11:34, Jim Henderson wrote:
> I've also had it happen to me.

Me too.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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Le 2011/09/06 15:59, Darren New a écrit :
> On 9/6/2011 11:34, Jim Henderson wrote:
>> I've also had it happen to me.
>
> Me too.
>

Put a pinch of croase sand in the container. It provide some angular 
surfaces that will stimulate the bubble formation as the liquid reatch 
the ebulition point. It will allow a gradual transition.
You can also rub the inside bottom of a container with fine sand paper.

About any rough surfaced material will do the trick.

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Le 2011/09/06 01:27, Jim Henderson a écrit :
> On Mon, 05 Sep 2011 19:32:49 +0100, Orchid XP v8 wrote:
>
>>>> Yes, but under /normal/ circumstances, it boils at 100°C, which is why
>>>> it's defined that way. :-P
>>>
>>> Not here at 4,000 feet - "normal" circumstances here have it boiling at
>>> a slightly lower temperature. :P
>>
>> 96.2°C, a piffling 3.8° lower.
>
> Which is still not 100C no matter how you slice it.  The difference in
> humidity, altitude, and other things makes cooking things that require
> precise measurements (usually baked goods) slightly different than at
> other altitudes and in other conditions.
>
>>> IOW, it all depends on how you define "normal".  (Hence my suggestion
>>> of reducing the atmospheric pressure, because here, lower pressure is
>>> 'normal').
>>
>> This is why the /actual/ specification is far more complicated. But for
>> any sane real-world purpose, you can more or less ignore such
>> technicallities.
>
> Baking is a real-world purpose.  An awareness of the 'normal' as well as
> 'current' environment are, for some things, absolutely *critical* in
> order to be successful.
>
> Jim

That's why, in some areas, you have cook books that gives several 
cooking times sorted by altitude ranges.

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On Tue, 06 Sep 2011 21:15:32 -0400, Alain wrote:

> That's why, in some areas, you have cook books that gives several
> cooking times sorted by altitude ranges.

Yep, indeed it is.

Jim

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On 9/6/2011 18:11, Alain wrote:
> Le 2011/09/06 15:59, Darren New a écrit :
>> On 9/6/2011 11:34, Jim Henderson wrote:
>>> I've also had it happen to me.
>>
>> Me too.
>>
>
> Put a pinch of croase sand in the container.

Yeah, because Croase sand goes so well with tea.


-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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>> Put a pinch of croase sand in the container.
>
> Yeah, because Croase sand goes so well with tea.

Personally, I put sugar in it...

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On 9/7/2011 1:12, Invisible wrote:
>>> Put a pinch of croase sand in the container.
>>
>> Yeah, because Croase sand goes so well with tea.
>
> Personally, I put sugar in it...

I just stick a spoon in it.

-- 
Darren New, San Diego CA, USA (PST)
   How come I never get only one kudo?

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On 08/09/2011 05:11 AM, Darren New wrote:
> On 9/7/2011 1:12, Invisible wrote:
>>>> Put a pinch of croase sand in the container.
>>>
>>> Yeah, because Croase sand goes so well with tea.
>>
>> Personally, I put sugar in it...
>
> I just stick a spoon in it.

Not while it's in the oven, I hope...

Post a reply to this message

On Thu, 08 Sep 2011 09:14:43 +0100, Invisible wrote:

> On 08/09/2011 05:11 AM, Darren New wrote:
>> On 9/7/2011 1:12, Invisible wrote:
>>>>> Put a pinch of croase sand in the container.
>>>>
>>>> Yeah, because Croase sand goes so well with tea.
>>>
>>> Personally, I put sugar in it...
>>
>> I just stick a spoon in it.
> 
> Not while it's in the oven, I hope...

I find a chopstick works well.

Jim

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On 9/5/2011 10:52 AM, Invisible wrote:

> Yes, but under /normal/ circumstances, it boils at 100°C, which is why
> it's defined that way. :-P

And get it under the right condition and ice sublimates. Even more 
interesting at certain temperature/pressure combinations water can be 
kind of a liquid that's almost a gas, and can smoothly change phases 
between the two.

-- 
~Mike

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On 9/5/2011 12:17 PM, Warp wrote:
>
>    So, does water freeze or melt at exactly 0 degrees celsius?
>

Actually, an interesting question: does water's liquid-solid phase 
change at standard atmospheric pressure exhibit hysteresis?

-- 
~Mike

Post a reply to this message

On 9/5/2011 5:50 PM, Patrick Elliott wrote:

> Worse than that, in certain conditions you can "hyper-heat" water, and,
> I assume, probably super cool it, without changing state. In the former
> case you just need a container that has "no" places for bubbles to form.
> Not sure what you would need to do in the later case to make it happen,
> if you could.

You can super-cool water. Fun trick:

Get some bottled water, leave it in the freezer for approximately 30 
minutes (some experimentation will be needed to determine the exact 
amount of time needed for the best effect) remove it from the freezer, 
note that it is still liquid, bang it against something to get a crystal 
to nucleate, then watch the ice form right in front of you. Enjoy your 
slushy, cold water.

-- 
~Mike

Post a reply to this message

On 9/6/2011 3:04 AM, Invisible wrote:

> I see what you did there.
>
> I've got a box of hand warmers at home. They contain a super-saturated
> solution (of what I don't know). Once you provide a nucleation point,
> the whole lot crystallises within a few seconds. It also gets quite warm
> in the process. (This is what makes it good for warming your hands.)

Sodium acetate. I've made my own countless times in my life. And 
recently made a big enough batch to create the super-saturated solution 
(actually melted crystals) to crystallize. Very cool to watch. Drop a 
tiny sodium acetate crystal in, and it grows out from that and warms the 
container nicely.

-- 
~Mike

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On 9/6/2011 5:08 AM, Invisible wrote:

> Unrelated, but I note that dissolving ammonia in water is an endothermic
> reaction. That, apparently, is how Victorian icecream was made. So I
> guess the question is, WOULD YOU EAT IT? ;-)

There is a certain type of candy or treat (Finnish, I believe?) that is 
seasoned with ammonium chloride ....) They eat it, though ammonia 
solution I think I would avoid.

-- 
~Mike

Post a reply to this message

>> I've got a box of hand warmers at home. They contain a super-saturated
>> solution (of what I don't know). Once you provide a nucleation point,
>> the whole lot crystallises within a few seconds. It also gets quite warm
>> in the process. (This is what makes it good for warming your hands.)
>
> Sodium acetate. I've made my own countless times in my life. And
> recently made a big enough batch to create the super-saturated solution
> (actually melted crystals) to crystallize. Very cool to watch. Drop a
> tiny sodium acetate crystal in, and it grows out from that and warms the
> container nicely.

And here I was thinking it was sodium thiosulphate...

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On 9/6/2011 11:20 PM, Darren New wrote:
> On 9/6/2011 18:11, Alain wrote:
>> Le 2011/09/06 15:59, Darren New a écrit :
>>> On 9/6/2011 11:34, Jim Henderson wrote:
>>>> I've also had it happen to me.
>>>
>>> Me too.
>>>
>>
>> Put a pinch of croase sand in the container.
>
> Yeah, because Croase sand goes so well with tea.
>
>

It adds a nice crunch.

-- 
~Mike

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Le 06/09/2011 12:08, Invisible a écrit :
> 
> Unrelated, but I note that dissolving ammonia in water is an endothermic
> reaction. That, apparently, is how Victorian icecream was made. So I
> guess the question is, WOULD YOU EAT IT? ;-)

Hydration of common salt is endothermic. The fusion temperature of the
mix is usually lower than the fusion of clear water.
(For road usage: Hydration of CaCl2 is exothermic, but the one of NaCl
is endothermic; CaCl2 is used in countries with very low temperatures on
their road)

For the preparation of ice-cream (well, rather sorbet (water-based
ice-cream, using fruit juice, water), than the rich ice-cream with cream
of milk, eggs and other stuff), you only have to cool the recipient and
the preparation a bit below 0°C (which can take a lot, as freezing water
has a lot of joules to expel): using a recipient with an internal
container and an external container, you prepare the sorbet in the
internal container, and have the water+ammoniac mixed in the external
container.

(If you remember your chemistry about mixing acid and water (you drop
one in the other, but avoid the other way round), can you guess what
must be added to what (ammoniac is a base)) ?

Nothing related to the fancy preparation of ice-cream with liquid
Nitrogen (pour liquid nitrogen over the preparation, and mix with energy
and a wood spatula (and some goggles, and some heavy gloves)!).

I would be interested in a preparation with liquid Oxygen, served at a
table of smoking people... well, soon-ex-people. I'm just afraid the
reaction with liquid Oxygen would also change the taste too much.
(oxidation power is very strong)

-- 
Software is like dirt - it costs time and money to change it and move it
around.

Just because you can't see it, it doesn't weigh anything,
and you can't drill a hole in it and stick a rivet into it doesn't mean
it's free.

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Am 20.09.2011 15:11, schrieb Mike Raiford:
> You can super-cool water. Fun trick:
>
> Get some bottled water, leave it in the freezer for approximately 30
> minutes (some experimentation will be needed to determine the exact
> amount of time needed for the best effect) remove it from the freezer,
> note that it is still liquid, bang it against something to get a crystal
> to nucleate, then watch the ice form right in front of you. Enjoy your
> slushy, cold water.

NOT recommended with glass bottles >_<

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On 9/20/2011 10:11 AM, clipka wrote:
> Am 20.09.2011 15:11, schrieb Mike Raiford:
>> You can super-cool water. Fun trick:
>>
>> Get some bottled water, leave it in the freezer for approximately 30
>> minutes (some experimentation will be needed to determine the exact
>> amount of time needed for the best effect) remove it from the freezer,
>> note that it is still liquid, bang it against something to get a crystal
>> to nucleate, then watch the ice form right in front of you. Enjoy your
>> slushy, cold water.
>
> NOT recommended with glass bottles >_<

Just don't bang it too hard... ;)

-- 
~Mike

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Am 21.09.2011 14:41, schrieb Mike Raiford:
> On 9/20/2011 10:11 AM, clipka wrote:
>> Am 20.09.2011 15:11, schrieb Mike Raiford:
>>> You can super-cool water. Fun trick:
>>>
>>> Get some bottled water, leave it in the freezer for approximately 30
>>> minutes (some experimentation will be needed to determine the exact
>>> amount of time needed for the best effect) remove it from the freezer,
>>> note that it is still liquid, bang it against something to get a crystal
>>> to nucleate, then watch the ice form right in front of you. Enjoy your
>>> slushy, cold water.
>>
>> NOT recommended with glass bottles >_<
>
> Just don't bang it too hard... ;)

Well, bang as softly as you might - I wouldn't want to be close to /any/ 
glass bottle in which water is busy crystallizing.

(Hint: The specific density of ice is only about 92% that of ice-cold 
water.)

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On 9/21/2011 1:00 PM, clipka wrote:

> (Hint: The specific density of ice is only about 92% that of ice-cold
> water.)

Oh, right... Water expands when freezing.

So long as there's sufficient air at the top, and the glass bottle is 
thick enough....

-- 
~Mike

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