burning sugar cubes
Gabriel Tojo
You approach a lighter flame to a sugar cube and it does not burn. But
if you apply previously some cigarette ash to the cube, it burns.
There must be some catalyst in the cigarette ash to sustain the
combustion of the sugar cube. Any idea?
Gabriel Tojo
Profesor Titular de Quimica Organica
Royal University of Santiago de Compostela
SPAIN
Alan "Uncle Al" Schwartz
Gabriel Tojo <qoga...@uscmail.usc.es> wrote:
>You approach a lighter flame to a sugar cube and it does not burn. But
>if you apply previously some cigarette ash to the cube, it burns.
>There must be some catalyst in the cigarette ash to sustain the
>combustion of the sugar cube. Any idea?
The bit of ash acts as a wick for molten sugar and its thermal
decomposition products. Try lighting a candle without a wick.
Solid fuels like hexamethylenetetramine or Sterno are sufficiently
volatile that gas phase flame propagation takes place without needing the
wick as a point of vaporization. Solid fuels like charcoal are solid
phase flames.
--
Alan "Uncle Al" Schwartz
Uncl...@ix.netcom.com ("zero" before @)
http://www.netprophet.co.nz/uncleal/ (best of + new)
http://www.ultra.net.au/~wisby/uncleal.htm (lots of + new)
(Toxic URLs! Unsafe for children, Democrats, and most mammals)
"Quis custodiet ipsos custodes?" The Net!
Gabriel Tojo
Alan "Uncle Al" Schwartz wrote:
>
> Gabriel Tojo <qoga...@uscmail.usc.es> wrote:
> >You approach a lighter flame to a sugar cube and it does not burn. But
> >if you apply previously some cigarette ash to the cube, it burns.
> >There must be some catalyst in the cigarette ash to sustain the
> >combustion of the sugar cube. Any idea?
>
> The bit of ash acts as a wick for molten sugar and its thermal
> decomposition products. Try lighting a candle without a wick.
>
> Solid fuels like hexamethylenetetramine or Sterno are sufficiently
> volatile that gas phase flame propagation takes place without needing the
> wick as a point of vaporization. Solid fuels like charcoal are solid
> phase flames.
>
The sugar cubes do not burn with a flame. They smolder. There is no
wick effect.
Alan "Uncle Al" Schwartz
Gabriel Tojo <qoga...@uscmail.usc.es> wrote:
>Alan "Uncle Al" Schwartz wrote:
>>
>> Gabriel Tojo <qoga...@uscmail.usc.es> wrote:
>> >You approach a lighter flame to a sugar cube and it does not burn. But
>> >if you apply previously some cigarette ash to the cube, it burns.
>> >There must be some catalyst in the cigarette ash to sustain the
>> >combustion of the sugar cube. Any idea?
>>
>> The bit of ash acts as a wick for molten sugar and its thermal
>> decomposition products. Try lighting a candle without a wick.
>>
>> Solid fuels like hexamethylenetetramine or Sterno are sufficiently
>> volatile that gas phase flame propagation takes place without needing the
>> wick as a point of vaporization. Solid fuels like charcoal are solid
>> phase flames.
>>
>
>The sugar cubes do not burn with a flame. They smolder. There is no
>wick effect.
Look closely. There is a pale blue flame about 1 millimeter high.
Look at it in total darkness. Get an observer below the age of 40 or a
pseudophakic so that the age-progressive yellowing of the lens of the eye
(which effectively filters out the blue C2 emission lines) does not
compromise the observation.
The ash acts as a wick.
Eric Lucas
Gabriel Tojo wrote:
>
> Alan "Uncle Al" Schwartz wrote:
> >
> > Gabriel Tojo <qoga...@uscmail.usc.es> wrote:
> > >You approach a lighter flame to a sugar cube and it does not burn. But
> > >if you apply previously some cigarette ash to the cube, it burns.
> > >There must be some catalyst in the cigarette ash to sustain the
> > >combustion of the sugar cube. Any idea?
> >
> > The bit of ash acts as a wick for molten sugar and its thermal
> > decomposition products. Try lighting a candle without a wick.
> >
> > Solid fuels like hexamethylenetetramine or Sterno are sufficiently
> > volatile that gas phase flame propagation takes place without needing the
> > wick as a point of vaporization. Solid fuels like charcoal are solid
> > phase flames.
> >
>
> The sugar cubes do not burn with a flame. They smolder. There is no
> wick effect.
>
> Profesor Titular de Quimica Organica
> Royal University of Santiago de Compostela
> SPAIN
A lot of ashes are metal oxides and carbonates and are alkaline. I
would presume that they can probably deprotonate sugar hydroxyls to some
extent. Alkoxide anions are presumably more subject to oxidation
(electron transfer) by the flame than are the sugar alcohols.
However, I'm still not convinced there isn't a bit of a wicking effect.
It may be a small amount of vapor (wicked away by the high surface area
ash) that starts the chain reaction, which then continues in the bulk
solid phase. The presence of a visible gas-phase flame would then
depend on whether or not the flame was hot enough to continue in the gas
phase.
Eric Lucas
Gabriel Tojo
Alan "Uncle Al" Schwartz wrote:
>
> Gabriel Tojo <qoga...@uscmail.usc.es> wrote:
> >Alan "Uncle Al" Schwartz wrote:
> >>
> >> Gabriel Tojo <qoga...@uscmail.usc.es> wrote:
> >> >You approach a lighter flame to a sugar cube and it does not burn. But
> >> >if you apply previously some cigarette ash to the cube, it burns.
> >> >There must be some catalyst in the cigarette ash to sustain the
> >> >combustion of the sugar cube. Any idea?
> >>
> >> The bit of ash acts as a wick for molten sugar and its thermal
> >> decomposition products. Try lighting a candle without a wick.
> >>
> >> Solid fuels like hexamethylenetetramine or Sterno are sufficiently
> >> volatile that gas phase flame propagation takes place without needing the
> >> wick as a point of vaporization. Solid fuels like charcoal are solid
> >> phase flames.
> >>
> >
> >The sugar cubes do not burn with a flame. They smolder. There is no
> >wick effect.
>
> Look at it in total darkness. Get an observer below the age of 40 or a
> pseudophakic so that the age-progressive yellowing of the lens of the eye
> (which effectively filters out the blue C2 emission lines) does not
> compromise the observation.
>
> The ash acts as a wick.
>
> --
> Alan "Uncle Al" Schwartz
Right! There is a flame. Although it does not prove conclusively the
wick theory.
If there is a wick any kind of solid matter of the right particle size
would do the trick. I tested flour, bread crust dust and domestic
dust. They all work. Domestic dust is particularly effective.
The wick theory holds.
As a chemist I find it regrettably trivial. I would prefer a chemical
explanation.
Gabriel Tojo
Alan "Uncle Al" Schwartz
My personal >belief< is that it is a manefestation of the Elvis in all
particulates. I am forging an elaborate hermeneutic of semantic
paradigms bursting with shibboleths and recursive dialectic. An Angel of
the Elvis has recently bestowed upon me spectacles of meteoric quartz
which decipher microfiches engraved in titanium nitride-clad
poly(methylpentene). You cannot get any more real than that.
(If you wish to be saved in the after-Elvis, very large cash donations
may be sent to the address below)
--
Alan "Uncle Al" Schwartz
Jeffrey Bodwin
On Thu, 3 Oct 1996, Gabriel Tojo wrote:
> Alan "Uncle Al" Schwartz wrote:
> > The ash acts as a wick.
>
> As a chemist I find it regrettably trivial. I would prefer a chemical
> explanation.
>
only "chemical explanation" is that sucrose burns. The reason the wicking
action of the cig. ash works is all because of physics: the sucrose is
vaporized before it burns, the wick provides a greater surface area which
leads to more evaporation which leads to more vapor which allows more
combustion {better burning}.
Too simple?
-------------------------------**-------------------------------
| Jeffrey J. Bodwin I consider myself a pretty good judge |
| bodw...@umich.edu of people. That's why I don't |
| Just me, not you, not UM. like none of them.-Roseanne |
~~~~~~~~~~**~~~~~~~~~**~~~~~~~~~**~~~~~~~~~**~~~~~~~~~**~~~~~~~~~~
Don Ulin
OK, but how can the ash act as a wick unless the sucrose spends some time as a liquid,
at which point it could indeed travel up the "wick," where the greater surface area
allows for more evaporation. Or IS that what happens? And is that the way a candle
works, or is the wax burning AS a liquid?
I think this is a fascinating question, and as soon as I can get a-hold of a sugar cube
I'm going to try it out.
Don Ulin
ul...@indiana.edu
Jeffrey Bodwin
On Fri, 4 Oct 1996, Don Ulin wrote:
> Jeffrey Bodwin wrote:
> > On Thu, 3 Oct 1996, Gabriel Tojo wrote:
> > > As a chemist I find it regrettably trivial. I would prefer a chemical
> > > explanation.
> > Regrettably trivial, perhaps, but that does not make it incorrect. The
> > only "chemical explanation" is that sucrose burns. The reason the wicking
> > action of the cig. ash works is all because of physics: the sucrose is
> > vaporized before it burns, the wick provides a greater surface area which
> > leads to more evaporation which leads to more vapor which allows more
> > combustion {better burning}.
> time as a liquid, at which point it could indeed travel up the "wick,"
> where the greater surface area allows for more evaporation. Or IS that
> what happens? And is that the way a candle works, or is the wax
> burning AS a liquid?
you let a candle burn for a fairly long time, a large puddle of wax
accumulates around the wick, and if this wax would burn as a liquid, the
whole candle would burst into flames. I am assuming that the sugar acts
similarly to wax in a candle: the wick itself burns long enough to liquify
and then vaporize the fuel (wax or sugar), the vaporized fuel then burns,
creating heat which melts more of the fuel, which travels up the wick
where it is vaporized, etc., etc., etc.
One of the reasons candles are designed the way they are is that the
molten wax does not evaporate readily from the puddle surrounding the
wick. An oil lamp is a similar device, however, oil lamps isolate the fuel
from the flame because at lower temperatures, the oil will have sufficient
vapor over it to ignite.
Don Ulin
out. But (back to the sugar cube with the cigarette ash), then are we to assume that
the sucrose melts to a liquid, like wax in a candle, and then seeps up the ash-wick
before being evaporated and burnt? My impression is that sucrose doesn't liquify that
easily. Or is "Uncle Al" just plain wrong? In which case we still don't have an
explanation for what strikes me as a very interesting phenomenon (for those new to this
thread: the fact that you can't light a sugar cube with a match, but if you drop some
cigarette ash on it, you can get it to burn with a small blue flame--one explanation was
that the ash acted as a wick, others have questined that explanation).
Don Ulin
ul...@indiana.edu
bilphus_frauhausen
Don Ulin <ul...@indiana.edu> wrote:
Lengthy discussion of wick action snipped.
>That's kind of what I assumed, but not being a chemist, I didn't want to stick my neck
>out. But (back to the sugar cube with the cigarette ash), then are we to assume that
>the sucrose melts to a liquid, like wax in a candle, and then seeps up the ash-wick
>before being evaporated and burnt? My impression is that sucrose doesn't liquify that
>easily. Or is "Uncle Al" just plain wrong? In which case we still don't have an
>explanation for what strikes me as a very interesting phenomenon (for those new to this
>thread: the fact that you can't light a sugar cube with a match, but if you drop some
>cigarette ash on it, you can get it to burn with a small blue flame--one explanation was
>that the ash acted as a wick, others have questined that explanation).
>Don Ulin
>ul...@indiana.edu
Sucrose melts at 185 degrees C which is not an unreasonably high
temperature. While I don't know which wax is used in candles, I am
fairly certain that it melts at a lower temperature than sucrose (most
of the waxes I am familiar with melt below 100 C); however, that
should in no way diminish the validity of the "wick hypothesis."
Also, if you hold a sugar cube (preferrably not in your hand) and
place a match under it to light it, you can produce a lovely shower of
flaming balls of molten sucrose which, upon on contact with your work
area, create a delightfully stubborn mess.
Finally, shame on you for suggesting that "Uncle Al" could be
incorrect. 8-}
Bilphus
Alan "Uncle Al" Schwartz
Short of an ab initio quantum mechanical calculation, the posted
observation that ANY refractory particulate serves as "catalyst" is
telling. The counter-test is trivial:
Find a particulate which is not wet by molten sucrose (e.g., maybe
silanized powdered glass vs. unadorned powdered glass). You will thereby
get capillary depression, not elevation, the wick won't wick, and the
stuff should not work.
Helmut Drobny
A...@indiana.edu>
Distribution:
NO NO NO ! the traces of Fe2O3 in the ash of cigaretts
act as a catalysator in the burning of succrose.
Helmut
PS Test this hypothesis by substituting ash from cigarettes
with those from a burned piece of filterpaper soaked
with a tiny amount of Fe3+.
Don Ulin (ul...@indiana.edu) wrote:
: Jeffrey Bodwin wrote:
: >
: > On Thu, 3 Oct 1996, Gabriel Tojo wrote:
: > > Alan "Uncle Al" Schwartz wrote:
: > > > The ash acts as a wick.
: > > The wick theory holds.
: > >
: > > As a chemist I find it regrettably trivial. I would prefer a chemical
: > > explanation.
: > >
: > Regrettably trivial, perhaps, but that does not make it incorrect. The
: > only "chemical explanation" is that sucrose burns. The reason the wicking
: > action of the cig. ash works is all because of physics: the sucrose is
: > vaporized before it burns, the wick provides a greater surface area which
: > leads to more evaporation which leads to more vapor which allows more
: > combustion {better burning}.
: >
: > Too simple?
: >
: > -------------------------------**-------------------------------
: > | Jeffrey J. Bodwin I consider myself a pretty good judge |
: > | bodw...@umich.edu of people. That's why I don't |
: > | Just me, not you, not UM. like none of them.-Roseanne |
: > ~~~~~~~~~~**~~~~~~~~~**~~~~~~~~~**~~~~~~~~~**~~~~~~~~~**~~~~~~~~~~
: OK, but how can the ash act as a wick unless the sucrose spends some
time as a liquid,
: at which point it could indeed travel up the "wick," where the greater
surface area
: allows for more evaporation. Or IS that what happens?
And is that the way a candle
: works, or is the wax burning AS a liquid?
: I think this is a fascinating question, and as soon as I can get
Gabriel Tojo
For those new to this thread, this was the first posting:
>You approach a lighter flame to a sugar cube and it does not burn. But
>if you apply previously some cigarette ash to the cube, it burns.
>There must be some catalyst in the cigarette ash to sustain the
>combustion of the sugar cube. Any idea?
It seems that there was a solid consensus within this group supporting
the wick theory, but Ralph Puchta from Bavaria passed me the following
information:
³I never tried this experiment, but I'll report an explanation I found
in:
Hermann Römpp, Herrmann Raaf, Organische Chemie im Probierglas,
Franckh'sche Verlagsbuchhandlung Stuttgart, 1982, 15. Auflage. Page
108.
(A nice little book for interested persons.)
The author explanes, that he tested the problem himself and found that
a
few drops of FeCl3-solution will do the same job. So his idee was,
that iron
salts, you can find in cigarette ash, will behave as a sort of
catalyst. He
found that ZnO, K2CO3, Na2CO3, SiO2, and Pb(CH3COO)2 will work, too.
The author denies, that the ash will work as a wick. He thinks, that
if it would work like a wick, every similiar stuff like whitening
should allow to burnsugar cubes in
this easy way².
I will get hold of the article in the little book and tell the group
about it.
Gabriel Tojo
Roger W. Faulkner
Helmut Drobny wrote:
> NO NO NO ! the traces of Fe2O3 in the ash of cigaretts
> act as a catalysator in the burning of succrose.
> PS Test this hypothesis by substituting ash from cigarettes
> with those from a burned piece of filterpaper soaked
> with a tiny amount of Fe3+.
If you are right, a better test would entail comparison of various ash
types with a cotton wich, or perhaps a mineral wick with no chance of
working as a catalyst. If somebody does do a test, please post the
results!
...Roger Faulkner
Gabriel Tojo
Ralph Puchta from Bavaria passed me very kindly a copy of pages
107-109 of the book:
Roempp and Raaf, Organische Chemie im Probierglas, Franckh´sche
Verlagsbuchhandlung Stuttgart, 1982, 15 Auflage
I made the following translation:
Tobacco ash, a catalyst
Some years ago, a Kosmos reader asked the following question to the
editorial: <why one is able to set fire to a sugar cube with a match
only if tobacco ash is previously applied to the point of ignition?> I
tried the test immediately; the observation was right. Afterwards, I
looked up many thick textbooks, handbooks, journalsand in no place I
found any explanation (in the mean time a student of Prof. Dr. Kurt
Moack in Berlin kindly told me that in the Pflanzenphysiologischen
Institute of Berlin they had already made this observation a long time
ago). Finally, I spent a pound of sugar cubes to find an answer to
this question through several tests. The results are briefly presented
here:
If a small portion of sugar is heated in a test tube, after a long
time a thick white gas, which one can ignite in the mouth of the test
tube, is produced from the melting carbonized mass. This result shows
that it is not the solid or melted sugar the material that is burnt,
but the flame must be produced from the gas evolved from the heated
melting sugar. In a candle or a petrol lamp the evaporation of the
melted paraffin or petrol is accelerated by the wick. In the wick the
liquid is sucked up in order to facilitate the evaporation and
combustion. If the tobacco ash worked in this way, then any other
powdery material (for instance talc, chalk, white clay) would allow
the combustion of the sugar cubesand this is not the case.
Consequently, as only a very small amount of cigarette ash is
necessary for combustion, and it is mixed inside the melting sugar, it
is difficult to imagine a wick effect.
If finely powdered iron, zinc, aluminum, or magnesium are applied on
the sugar, it is possible to set fire with one or two matches. In
these cases the glowing metal delivers a great quantity of heat, and
evaporation occurs in these spots, allowing the sugar combustion. As
in the tobacco ash the metal does not occur as a pure substance, we
have to discard this latter explanation.
If a small amount of saltpeter, minium, potassium permanganate or some
drops of a solution of lead nitrate is applied to the lower part of a
sugar cube, the ignition begins with a single match, because these
compounds liberate easily oxygen and consequently help the ignition in
the best way. As in the tobacco ash no oxidizing agent of the above
type exists in a noticeable quantity, we must also discard this
explanation.
Tobacco contains IRON OXIDE; the iron may be easily detected with
potassium hexacyanoferrate(II), after heating the ash with
hydrochloric acid (after filtering); a deep blue precipitate of Berlin
blue is obtained. Iron compounds play an important role as catalyst
in many chemical transformations. For example, in the cells of the
body the glucose is oxidized at 37 degrees centigrade under the
influence of iron containing enzymes, while in the laboratory about
100 degrees centigrade are needed for the combustion of sugar.
Probably the finely divided iron in the cigarette ash works also as a
catalyst in the combustion of sugar cubes. This supposition is
supported by the fact that some drops of a solution of iron sulfate or
chloride allow the combustion of sugar cubes in an analogous way, and
the ash works in very small traces like a real catalyst. Blood coal, a
material also containing iron in small particles, acts on sugar like
tobacco ash. As well as iron compounds, many other compounds may work
as catalysts. A sugar cube may be easily ignited with a single match
with a small amount of zinc oxide, silica, lead acetate, potash or
soda. In the very potasic cigarette ash, probably the potash and iron
oxide work simultaneously in the same way.
I think that this strongly discards the wick theory.
Any fault in the translation is exclusively due to me. My mother
tongue is neither English nor German.
Gabriel Tojo
Alan "Uncle Al" Schwartz
"Roger W. Faulkner" <rfau...@interramp.com> wrote:
>Helmut Drobny wrote:
>
>
>> NO NO NO ! the traces of Fe2O3 in the ash of cigaretts
>> act as a catalysator in the burning of succrose.
>
>
>> PS Test this hypothesis by substituting ash from cigarettes
>> with those from a burned piece of filterpaper soaked
>> with a tiny amount of Fe3+.
>
>If you are right, a better test would entail comparison of various ash
>types with a cotton wich, or perhaps a mineral wick with no chance of
>working as a catalyst. If somebody does do a test, please post the
>results!
>...Roger Faulkner
A pinch of powdered Pyrex ought to do it, or fine sand. There isn't any
catalysis of any kind in either surface. Powdered soda lime glass
catalyzes high temperature decarboxylation.
Eric Lucas
Gabriel Tojo wrote:
>
> For those new to this thread, this was the first posting:
>
> >You approach a lighter flame to a sugar cube and it does not burn. But
> >if you apply previously some cigarette ash to the cube, it burns.
> >combustion of the sugar cube. Any idea?
>
> It seems that there was a solid consensus within this group supporting
> information:
>
> łI never tried this experiment, but I'll report an explanation I found
> in:
> Hermann Römpp, Herrmann Raaf, Organische Chemie im Probierglas,
> Franckh'sche Verlagsbuchhandlung Stuttgart, 1982, 15. Auflage. Page
> 108.
> (A nice little book for interested persons.)
>
> The author explanes, that he tested the problem himself and found that
> a
> few drops of FeCl3-solution will do the same job. So his idee was,
> that iron
> salts, you can find in cigarette ash, will behave as a sort of
> catalyst. He
> found that ZnO, K2CO3, Na2CO3, SiO2, and Pb(CH3COO)2 will work, too.
>
> The author denies, that the ash will work as a wick. He thinks, that
> if it would work like a wick, every similiar stuff like whitening
> should allow to burnsugar cubes in
> this easy way˛.
>
> I will get hold of the article in the little book and tell the group
> about it.
>
> Gabriel Tojo
If you recall, I suggested the catalyst explanation very early in the
thread. My suggestion was alkaline oxides and carbonates deprotonating
the sugar alcohols, rendering them more susceptible to electron-transfer
oxidation. Apparently from what you say, acids work as well (e.g.
FeCl3). In this case, I would guess that acids catalyze the dehydration
of the sugar to an olefin or ketone, which can then undergo oxidation
more readily than an alcohol.
However, I thought the data in this case supported the fact that any
sufficiently high surface area solid that is wetted by sugar would
work. For example, I thought that someone said that talc worked.
Just because things that can act as catalysts will work doesn't mean
that is isn't still at keast partly a wicking phenomenon. The
definitive experiment is to try it with something that has little or no
chance of catalyzing the oxidation reaction--for example, very fine
fumed silica would be a good place to start (silated to rid the surface
of acidic--ie catalytic--functionality). Then if it burns under those
conditions, you have proven that the wicking phenomenon is at least part
of the explanation under some conditions.
Eric Lucas
Jan-Hendrik Jördens
I am very interested as I am unsure about showing students the combustion of sucrose with ash as an example of a catalysed reaction.
Jan Jördens
Martin Brown
>> definitive experiment is to try it with something that has little
>> or no chance of catalyzing the oxidation reaction--for example,
>> very fine fumed silica would be a good place to start (silated to
>> rid the surface of acidic--ie catalytic--functionality). Then if it
>> burns under those conditions, you have proven that the wicking
>> phenomenon is at least part of the explanation under some
>> conditions. Eric Lucas
>
> Hey guys, any new ideas regarding the problem? I am very interested
> as I am unsure about showing students the combustion of sucrose with
> ash as an example of a catalysed reaction.
the most impressive catalysed reaction for getting students attention.
https://en.wikipedia.org/wiki/Elephant%27s_toothpaste
My instinct with this ash claim is that the ash is merely providing an
inert medium to be wetted and wick up melted sugar and with enough
surface area to facilitate ignition and burning away from the bulk hot
molten sugar. Fumed silica or diatamaceous earth would be my choice of
test material to see which characteristic of the ash is important.
The B-Z reaction is also eye catching although takes some explaining
since Ce2+ self catalyses its own oxidation to Ce3+ which self catalyses
it own reduction to Ce2+. Aka a chemical clock that actually ticks from
yellow to clear (or other colours with eg Ferroin in as an indicator).
The recipe is easy provided that your water is chlorine free.
Quite hypnotic in a petri dish on an OHP.
https://en.wikipedia.org/wiki/Belousov–Zhabotinsky_reaction
--
Martin Brown
Jan-Hendrik Jördens
He prepared sugar cubes with various substances (including SiO2) and came to the conclusion that no catalytic effect could be proven, only the wicking effect.
According to him, the important thing is that the substance used prevents the sucrose from dripping off.
He also claims to have produced a candle consisting of sucrose.
"Es ist lediglich die Anwesenheit eines Stoffes nötig, der den durch die erste Wärmezufuhr geschmolzenen Zucker aufsaugt und dadurch festhält,
so daß er durch die weitere Wärmezufuhr vergast wird in dem Sinne, wie Kohle in der Retorte des Gaswerkes."
="All that is necessary is the presence of a substance which absorbs the sugar melted by the first application of heat and thereby holds it in place
so that it can be gasified by the further supply of heat like coal in the retort of the gasworks."
For the translation I recommend Deepl.com
--
Jan Jördens
Martin Brown
> Martin Brown schrieb am Dienstag, 2. Mai 2023 um 20:14:35 UTC+2:
>> On 02/05/2023 18:05, Jan-Hendrik Jördens wrote:
>>> Eric Lucas schrieb am Mittwoch, 9. Oktober 1996 um 09:00:00
>>> UTC+2:
with lowish vapour pressure are difficult to ignite without a wick.
That candle made of sucrose sounds like an interesting test if slightly
dangerous from a point of view of working with very hot concentrated
sucrose solution ~120C and some ordinary candle wick to make a sugar
candle by dipping.
Basically a lead washer on the end of a piece of wick dipped into a tall
container of hot concentrated sugar solution a la jam making. Allowed to
cool and keep going until you have a candle of sucrose. My betting is it
will burn with a rather dirty flame but that it will work OK.
The problem otherwise is that the molten/dissolved in its own water of
crystalisation sugar is a very good conductor of heat and so there is
always some more sugar to dissolve/melt at the interface. The wick
provides a location that is thermally isolated from the bulk liquid
where it can get hot enough for ignition and then away we go.
Do let us know if you manage this feat!
--
Martin Brown
dlzc
> I think it might be down to simple physics and also why many liquids
> with lowish vapour pressure are difficult to ignite without a wick.
>
> That candle made of sucrose sounds like an interesting test if slightly
> dangerous from a point of view of working with very hot concentrated
> sucrose solution ~120C and some ordinary candle wick to make a sugar
> candle by dipping.
>
> Basically a lead washer on the end of a piece of wick dipped into a tall
> container of hot concentrated sugar solution a la jam making. Allowed to
> cool and keep going until you have a candle of sucrose. My betting is it
> will burn with a rather dirty flame but that it will work OK.
>
> The problem otherwise is that the molten/dissolved in its own water of
> crystalisation sugar is a very good conductor of heat and so there is
> always some more sugar to dissolve/melt at the interface. The wick
> provides a location that is thermally isolated from the bulk liquid
> where it can get hot enough for ignition and then away we go.
>
> Do let us know if you manage this feat!
David A. Smith
Martin Brown
UK "Seaside Rock" is a solid cylinder of mint flavoured white caramel
candy with a brightly coloured thin layer on the outside and the name of
the resort spelt around the perimeter in red. No wick down the middle.
Fairground Candy floss which comes on a stick strikes me as something
that will probably burn impressively well with or without a catalyst.
(hence refuting the need for a catalyst for it to burn)
Much the same way as wire wool burns whilst bulk iron does not.
My instinct is that it just needs to get hot enough to ignite...
(and have enough surface area to sustain the reaction)
--
Martin Brown
dlzc
> Fairground Candy floss which comes on a stick strikes me
> as something that will probably burn impressively well with
> or without a catalyst. (hence refuting the need for a
> catalyst for it to burn)
>
> Much the same way as wire wool burns whilst bulk iron does not.
>
> My instinct is that it just needs to get hot enough to ignite...
> (and have enough surface area to sustain the reaction)
I think the wicking is still required, since "caramelization" tends to cut off good air flow.
David A. Smith