Talk:Phlogiston theory

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The last two paragraphs of this article appear to be plagarized from the Columbia Encyclopedia. They are attributed to this source in several other on-line encyclopedias.

InfoPlease Encyclopedia.Com

How is this handled in WikiPedia?

When in doubt (of copyright violation), take it out! As I will do, or edit it. - DavidWBrooks 19:52, 4 Jan 2005 (UTC)

Is the sentence, "This is a load of bull" really necessary for the scholarly development of the article?

The first sentence doesn't seem to be a sentence. —Preceding unsigned comment added by (talk) 22:59, 6 May 2010 (UTC)


The article doesn't seem consistent. First Phlogiston is described as being weightless, and then metals should lose weight when the phlogiston has been burned up.

There were many variations on the phlogiston theory, as people tried to correct some of the problems. For example, see , particularly around page 88 (you may need a google account). Ideally, this article should be expanded to mention the variations and attribute them to their respective proponents. Itub 15:37, 22 December 2005 (UTC)
I recall learning about Phologiston in a college history of science class, and I think some folks seriously claimed that it has negative weight, which would clear up the inconsistency. Aristophanes68 (talk) 13:38, 21 September 2012 (UTC)

Phlogiston is a member of the group of substances known as "Imponderable substances". It was known as an "imponderable fluid". There were many more imponderable fluids, some attatched to gravity, some to light, etc. There are no articles on the subjects of "imponderable fluids/substances" to tie all these old theories together. In addition, the biggest problem with phlogiston theory was with rusting metals (they gain weight but lose phlogiston). The main fix to this, I believe, was to fiddle with positive and negative phlogiston until the theory of conservation of mass came along. -- 07:13, 13 January 2007 (UTC)

I'd certainly encourage you to create such an article, or to nominate it for creation within the History of Science project. I'd read it! Jouster 15:40, 21 February 2007 (UTC)


I would like to suggest the title of this page be renamed "Phlogiston Hypothesis". Phlogiston never had the emperical weight to be called a theory. —Preceding unsigned comment added by (talkcontribs)

At the time of this theory/hypothesis's prominence, was there really enough refinement in the scientific method to assert a difference? Jouster  (whisper) 23:12, 9 June 2007 (UTC)
I'd class it as a model like electron shells and chemistry itself are models of physics.
Sleigh (talk) 02:08, 9 December 2010 (UTC)

Robert Boyle's experiment[edit]

The article contains the line "Mikhail Lomonosov attempted to repeat Robert Boyle's celebrated experiment in 1753"—what experiment does this refer to? Robert Boyle's article does not mention phlogiston. —pfahlstrom 04:49, 30 April 2007 (UTC)

There ought to be a mention of Boyle's experiment, hopefully someone has some documentation of this.--RLent 17:48, 25 October 2007 (UTC)
see here. Cesiumfrog (talk) 13:18, 14 January 2014 (UTC)


Why no mention of Stahl???

Rosa Lichtenstein 13:48, 17 June 2007 (UTC)

Because you haven't added it yet (with proper sources, of course). ;-) --Icarus (Hi!) 10:37, 21 January 2008 (UTC)


There has been a onslaught of vandalism to this page recently. I've tried to correct what I can. Keep your eyes open.


"Eventually, quantitative experiments revealed problems, including the fact that some metals, such as magnesium, gained weight when they burned, even though they were supposed to have lost phlogiston."

Magnesium was not first purified until the early 1800s. There's no way that it could have been used at the time to disprove the phlogiston theory. Other reactive metals (below carbon in the electrochamical series)such as iron and zinc were used to provide the example that burning metal would cause it to gain mass. If a flame is intense enough, even copper oxidizes such that the weight gain is significant.

 —Preceding unsigned comment added by Hawkingfan (talkcontribs) 21:03, 19 October 2008 (UTC) 

Nearest modern analogue to Phlogiston[edit]

I'm thinking that the nearest modern analogue to phlogiston are actually valence electrons, not entropy. Entropy can be increased, say, by boiling water, which I highly doubt any chemist in Stahl's era would have confused with a chemical process, while metabolism, rust formation, and combustion are all redox reactions which involve the transfer of electrons.--Scigatt (talk) 01:17, 13 August 2009 (UTC)

lol the nearest modern analogue to phlogiston is called dark matter. It's a great way to get research funding.--feline1 (talk) 15:09, 19 December 2009 (UTC)

I would suggest that phlogiston and even caloric have both been superceded by the concept of energy. Both are associated with energy change, and could be regarded as precursors to the modern concept of energy. — Preceding unsigned comment added by Phicumbutfo (talkcontribs) 07:08, 18 May 2013 (UTC)

'Theory' and 'challenge and demise'[edit]

there appear to be several logical contradictions made in the discussion of the theory, which are then subsequently used as proofs for the challenging theories:

=== Theory ===

accepting the statement of difference as correct -- '"Phlogisticated" substances are those that contain phlogiston and are "dephlogisticated" when burned....When air had become completely phlogisticated it would no longer serve to support combustion of any material'

and that -- phlogiston is 'a substance without color, odor, taste, or mass' and 'Terra pinguis was the element which imparted oily, sulphurous, or combustible properties' as stated in the opening of the Theory section which do not contradict each other.

'...nor could phlogisticated air support life' should infact read 'nor could(DE)phlogisticated air support life'.

Hence the next paragraph's quotation is rendered fundamentally flawed in its argument:

  • 1- 'substances that burned in air were said to be poor in phlogiston
  • 2- the fact that combustion soon ceased in an enclosed space was taken as clear-cut evidence that the burning substance had the capacity to absorb only a definite amount of phlogiston
  • 3- that when air had become completely dephlogisticated it would no longer serve to support combustion of any material, nor would a metal heated in it yield a calx
  • 4- nor could dephlogisticated air support life, for the role of air in respiration was to add phlogiston to the body"
  • 5- then the element oxygen would probably have been called phlogiston today.'

since the theory of phlogiston holds that:

  • 1- substances that burnt in air are high in phlogiston;
  • 2- a burning substance is releasing phlogiston;
  • 3- in agreement with the theory given the correction of phlogisticated to DEphlogisticated
  • 4- again in agreement with the correction noted above and for point 3.
  • 5- oxygen itself is a material containing phlogiston, such that AIR when dephlogisticated contains no oxygen. (as mentioned at the start of the Theory section - 'The theory holds that all flammable materials contain phlogiston')
===Challenge and Demise===
  • - 'Eventually, quantitative experiments revealed problems, including the fact that some metals, such as magnesium, gained weight when they burned' -phlogiston is a massless substance. this is in no way related. as modern science understands when magnesium is burnt magnesium oxide compounds are formed. the mass of the metal atoms themselves do not alter.
  • - 'Phlogiston remained the dominant theory until Antoine-Laurent Lavoisier showed that combustion requires a gas that has weight (oxygen) and could be measured by means of weighing closed vessels.' - again a material is required to be 'burnt', ie a chemical reaction to occur, in order to release phlogiston. the theory of phlogiston does not curtail any specifics regarding the number of reactants, or phlogiston containing materials are present.
  • - 'In some respects, the phlogiston theory can be seen as the opposite of the modern "oxygen theory". The phlogiston theory states that all flammable materials contain phlogiston that is liberated in burning, leaving the "dephlogisticated" substance in its "true" calx form.' - phlogiston theory is not the opposite of oxygen theory. the description of phlogiston here is correct.
  • - 'In the modern theory, on the other hand, flammable materials (and unrusted metals) are "deoxygenated" when in their pure form and become oxygenated when burned.' - is correct with regards current understanding of combustion, it is however completely unrelated to the discussion
  • - 'However, the first part of the old theory requires that phlogiston has weight (since ashes weigh less), but the second requires that it have no weight or negative weight,...' - this is in contradiction to the definition of phlogiston as described in the article and noted above. furthermore baring definition in mind: the first (and only) theory SHOULD READ that phlogiston is considered massless, where adaptations of the theory to understand mass changes as Mikhail Lomonosov discovered to attempt to explain combustion products (where when any combustion is performed in a closed vessel, no mass change is observed) ie the experimental results of Mikhail Lomonosov are infact correct and debunk the attempts of others to ascribe a mass property to phlogiston. again, negative mass was also then concluded as a solution to the mass changes as a SUBSEQUENT ADDITION to the theory of phlogiston.

I will make the changes discussed in the next few days if i recieve no objections. Daenumen (talk) 12:16, 3 September 2010 (UTC)

Hi Daenumen, it's better to sign each section individually when posting multiple sections to a talk page, (typically one section at time is good too). I've reformatted the subsections into bold headers so that they won't appear to remain unaddressed later on...
The perceived contradictions were actually correct:
A: "accepting the statement of difference as correct -- '"Phlogisticated" substances are those that contain phlogiston and are "dephlogisticated" when burned....When air had become completely phlogisticated it would no longer serve to support combustion of any material'"; B: "and that -- phlogiston is 'a substance without color, odor, taste, or mass' and 'Terra pinguis was the element which imparted oily, sulphurous, or combustible properties' as stated in the opening of the Theory section which do not contradict each other."; C: "'...nor could phlogisticated air support life' should infact read 'nor could(DE)phlogisticated air support life'".
  • Generally, the theory said that phlogiston escapes from a substance that's burning, (picture something similar to the glowing hot gases that are emitted from a burning log).
  • However, it wasn't smoke they were referring to... today, it's understandable why nothing like it could be detected in objects prior to burning them. Terra pinguis was Becher's theory which Stahl popularized as "phlogiston". This seems to be clearly presented in the second paragraph of the article's History section.
  • The article is correct in saying the so–called phlogisticated air, i.e. oxygen–depleted air, could not support life. As it states in the first two paragraphs of the Theory section, the term "DEphlogisticated" [sic] referred to ashes or rust, (calx). Air doesn't burn; and breathable air was not said to be dephlogisticated. The theory most definitely was not that something from air combines with a burning substance... (the theory got it backwards).
The first set of numbered items refer to the "next paragraph", paragraph three of the Theory section, which explicitly recites the inline quote given just above it, in paragraph two, the opposite way. That's not very encyclopedic, however, it is correct, (not at all "fundamentally flawed"). Points 1 and 2 of your second set of numbered items were, of course, from the quote in paragraph two. Regarding items 3 and 4, the term from earlier should not be "DEphlogisticated" [sic], (see here). In regard to #5, "oxygen itself is" not "a material containing phlogiston"... (?) oxygen (and hydrogen, btw) were eventually discovered... If anything, breathable air would be something like phlogiston unsaturated air, (I don't recall), but the double negative that follows, "such that AIR when dephlogisticated contains no oxygen", seems to conflate the theory with that of oxygen and "'[t]he theory holds that all flammable materials contain phlogiston'" doesn't indicate that nonflammable materials, like air, theoretically harbor no phlogiston... Elsewhere, you can find anachronistic references to nitrogen or carbon dioxide being "dephlogisticated air"... That's way more wrong, but maybe you'd be interested to research such usage and explicate it?
Briefly, from your "Challenge and Demise" section regarding mass and "the theory of phlogiston does not curtail any specifics regarding the number of reactants", etc. (?) I'd rather not speculate... I believe if you re–read the article more carefully you'll see it really was sufficiently clear that the theory had been debated and modified throughout its long shelf–life in 18th century science, and at one point, negative mass hypotheses were fielded... The theory was never correct and, eventually, it was superseded by the oxygen theory of combustion. The article is no where near as bad as you seem to think, so please don't go forward with the changes that you've outlined. On the other hand, if you'd like to do some verifiable research on the terms, please go right ahead. Thanks—Machine Elf 1735 (talk) 19:57, 3 September 2010 (UTC)

thanks, im new and still figuring out all the formalities of formatting on this platform architecture.

if dephlogisticated refers to (calx) ie material 'devoid' of phlogiston, then to phlogisticate a material you must ADD phlogiston to it. they are grammatically diametric opposites. hence dephlogisticated air is de-oxygenated.

the statement made in the article is linguistically erroneous, not to mention scientifically contradictory.

i think you are completely viewing this from the wrong angle.

the theory claims that all materials contain phlogiston, hence oxygen would contain phlogiston under the theory. the fact that we do not 'find' phlogiston doesnt mean it doesnt exist.

(this is an issue of the logical clarity of the article, at current, the theory contradicts itself as it has been described, and you support, and i do not mean in terms of the later discovery of oxygen. again, the theory does not define how many materials are required for phlogiston to be present, it may be 1, 2, or 1000).

if breathable air is phlogiston unsaturated air...why then does wood burn in breatheable air??? can you see that you are fundamentally wrong!

i am not contradicting that FROM THE THEORIES, NEW THEORIES EMERGED (and where very close to the original theory, ie a possible addition to resolve for greater applicability of the theory. THIS DOES NOT JUSTIFY ERRONEOUS ADDITIONS RESULTING IN THE DEMISE OF THE THEORY.

look if i add a cosmo-non-sensical constant to einsteins general relativity, yes! it wouldnt work! this is what the article is using to justify the demise of phlogiston.

if this is the historical discussion, then fine, but it should be labelled as such. it should not however be viewed as a logical or scientific demise in ANY REGARD. Daenumen (talk) 19:14, 4 September 2010 (UTC)

fruthermore, the oxygen theory and phlogiston theories are not conflated by the linguistic corrections; in terms of the null hypothesese, they are not contraditory.Daenumen (talk) 21:36, 4 September 2010 (UTC)

Daenumen, I've responded in detail and I'm not going to argue with you about things that don't exist.—Machine Elf 1735 (talk) 06:45, 5 September 2010 (UTC)
then this is rediculous! how can you claim this article is correct? THE ARTICLE HAS NOT EVEN BEEN CHECKED RELATIVE TO A DICTIONARY!!!! THE CONCLUSION IS MADE FROM A LINGUISTIC ERROR.
if i make an edit, will you remove it?Daenumen (talk) 10:19, 5 September 2010 (UTC)
you also appear to have misunderstood the DISCUSSION i was having on this topic is not how i wish to edit the page, also that in the first section i highlight the points and provide explanations seperately (but numbered) clearly showing the logical link between the first and second sets, in the second section i have simply commented on each questionable comment from the article and commented after it on each point. Daenumen (talk) 10:29, 5 September 2010 (UTC)

you will notice that the numbered points 3 and 4 clearly show the discrepancy in the article, ie where phlogisticated is used to mean deprived of phlogiston in one scentence, and in another the same word PHLOGISTON is used to mean something that has a high phlogiston content.
if you cannot understand this, you should not be commenting on this discussion, not making edits.
remember, there is the article itself in which can be seen the error directly, i have attempted to highlight it, as it is clearly not come to your attention(?) if you are moderating this page Daenumen (talk) 10:33, 5 September 2010 (UTC)
perhaps this is your difficulty: to dephlogisticate a closed combustion vessel, one must either remove the oxygen, or the wood (as example). IT DOES NOT CONFLATE OXYGEN THEORY!!!! Daenumen (talk) 10:39, 5 September 2010 (UTC)
and of course, a calx, with respect to a closed combustion vessel, would be a vessel in which only a single element exists. ie air itself can be combusted as is observed with lightning wrt nitrogen and oxygen. hence a true calx is one that is either a pure isolated element, or several compounds such that when ignited there is no net phlogiston released (ie there is no change of state of the reactants, though dynamic alteration of distinguishable particles may occur).
it is on this fundamental basis that the article is in error. Daenumen (talk) 11:03, 5 September 2010 (UTC)
Just to be clear, All materials which burn were said to have phlogiston in them. wether the phlogiston had a positive or negative mass depended on wether the thing burning formed an oxide or decomposed thermally. The main theory still stood that things that burnt had phlogiston, and the surroundings 'took in' that phlogiston, hence priestly's de-phlogisonated air, lavoisier's oxygen. I hope this clears up the discussion aboveTytrox9240 (talk) 17:16, 9 December 2014 (UTC)Tytrox

Phlogiston 20th Century interpreting 18th century wrongly!!!![edit]

I will attempt to prove that the discussions i have held can be shown valid, given what was known in the 18th century.

it is well accepted that:

phlogiston containing wood + dephlogisticated air --> calx(phlogiston depleted wood) + phlogisticated air.
phlogisticated air --> dephlogisticated air + phlogiston (which must be contained within a material, otherwise it is still in the air)

thus it 'should' be possible to:

calx(phlogiston depleted wood) + phlogisticated air ----> phlogiston containing wood + dephlogisticated air

we also know this is contradictory to the definitions of calx and phlogistication! HOWEVER, it can also be understood that it is NOT possible, by considering Iron and Iron Calx to show that:

Iron + dephlogisticated air --> Iron Calx + phlogisticated air
Iron Calx + phlogiston containing wood + dephlogisticated air --> Iron + Wood Calx + phlogisticated air

this can be understood as a resistance to reversibility in irons case, and irreversibility with wood (unless phlogistication of wood calx were discovered), and would be in agreement with the modern understanding of the second law of thermodynamics, without requiring modern understanding.

Hence: either the article is claiming that the scientists did not know what they were doing, or many misinterpretations have been made, ON LINGUISTIC AND ETYMOLOGICAL GROUNDS!!! Daenumen (talk) 17:08, 5 September 2010 (UTC)

Furthermore, to clarify,

The key difference assumed is that:

phlogiston rich air does not burn
phlogiston rich wood does burn

which again are in contradiction to the Null hypothesis definitions of Phlogiston and Calx: And it is in this sense that the definitions utilised in the 'challenge and demise' are inconsistent, and hence have exacted a conclusion that phlogiston is not correct, where it is infact the alternative hypothesese namely, that phlogiston has mass, that are invalidated.

whether this is by hands of the scientists themselves, or by modern misunderstanding is the topic of discussion; where i believe the later to be true; in that it has been misunderstood when the article was compiled.

Daenumen (talk) 17:45, 5 September 2010 (UTC)

perhaps it would be most correct to refer to the process of phlogistication with regard a closed system only, such that:

the closed system of a combustion vessel containing lit wood and air is dephlogisticated once the flames have disappeared.

such that fire itself signifies a change in phlogiston, baring in mind that the flame itself is not necessarily phlogiston (as per the definition).

hence a closed system can be described as phlogisticated, ie rich in phlogiston and able to support combustion (or life), or dephlogisticated, and hence unable to support combustion (or life).

ie 'elemental fire' must be available within the materials that are combusting in order for that combustion to occur, such that the description should read:

air or wood containing phlogiston are phlogisticated and can support combustion or life.
air or wood that contains no phlogiston are dephlogisticated and cannot support combustion or life.

then when considering the calx, it should be noted that a piece of wood, burnt in a vessel may not completely be combusted, such that, on the addition of 'new air' the wood may continue to burn. hence:

a piece of wood, becomes a calx when combusted in enough air to convert all the wood into a calx
air is transformed into a calx when, in a closed vessel, the process of combustion has stopped prior to the conversion of all the wood into calx.

again this is information that would have been readily available to the scientists investigating phlogiston.

and once more 'phlogistication', because it sounds good. Daenumen (talk) 18:17, 5 September 2010 (UTC)

FINALLY Phlogiston could be understood by modern understanding as the 'diametrically opposite concept' to that of 'Entropy', in all cases the laws of entropy must hold true: The difference between Phlogiston and Entropy of course is in the subjective aapproach to the phenomena. 18:57, 5 September 2010 (UTC) Daenumen (talk) 19:00, 5 September 2010 (UTC)

Correction needed...[edit]

In the section "Enduring aspects", reference is made to "the metabolism of living orgasms"... possibly the author had something else on his/her mind at the time...  ;-)

Elio1 (talk) 14:56, 24 March 2011 (UTC)

Glad to note that the requisite correction has been applied by some kindly editor... it was funnier before, though... :-) Elio1 (talk) 10:10, 2 March 2012 (UTC)

Theories that fit the data yet become abandoned due to other reasons[edit]

Both Deferent and epicycle and Phlogiston theory were theories that fit the data but were abandoned due to other reasons. (talk) 00:53, 27 February 2012 (UTC)

I wondered why D&E was listed under "See Also"! I think if you want to include it, you need to explain why it's listed there; otherwise, it really isn't linked enough to Phlogiston to be included on this page. Aristophanes68 (talk) 13:40, 21 September 2012 (UTC)

Apparent Contradiction[edit]

The first paragraph under Challenge and demise and the quote that follows seem to contradict each other. The article reads, "Mikhail Lomonosov repeated this experiment in 1753 and concluded that the phlogiston theory was false." By disproving Boyle, did not Lomonosov support the theory given "magnesium, gained mass when they burned, even though they were supposed to have lost phlogiston"? Apologies if my understanding is wrong. wneo (talk) 03:07, 31 May 2014 (UTC)