Talk:Steam distillation

comments

Just a note: the article previously attributed the boiling point depression to colligative properties. Colligative properties generally apply to nonvolatile solutes, and as such lead to a boiling point elevation. The boiling point depression is related to the immiscible liquids contributing to the total vapour pressure as if each was the only liquid present. In this manner the total system can reach a combined vapour pressure equal to ambient at a temperature lower than the boiling points of the individual liquids, and thus the system can come to a boil. At least that's how I understand it. --199.126.26.202 01:48, 26 April 2006 (UTC)

The idea of "expos[ing] the surfaces of both the liquids to the vapor phase" is kind of odd - if thermodynamic conditions are met, a substance will phase shift wherever it wants to, not necessarily on a spacial phase boundary. That's why you can see bubbles in the middle of a boiling pot of water. Because maintaining a surface is energy intensive, phases will typically separate to limit surface formation, but that happens naturally, there's no need in a process environment to manually introduce them. 168.7.237.237 (talk) 07:17, 24 September 2008 (UTC)

Mayonnaise?

I removed the following:

Other industrial uses of steam distillation include the production of consumer food products such as sprayable or aerosolized condiments such as sprayable mayonnaise.<ref>Purves, ER. (1972), ''Method for producing mayonnaise''. U.S. Patent No. 3,804,957. Washington, DC: U.S. Patent and Trademark Office.</ref>

I read the patent, and it says nothing about steam distillation at all! --Slashme (talk) 20:07, 20 December 2010 (UTC)

"Principle" is incorrect?

The "Principle" section makes it seem that steam distillation is based on the existence of azeotropes with lower boiling point than water. I believe that is incorrect. Whether there is an azeotrope or not, it makes no significant difference.
Any substance has some vapor pressure even below its (1 atm) boiling point, but that would not allow effective distillation because a layer of vapor-rich air would form over the liquid and prevent further evaporation. The vapor would flow down the condenser only by diffusion, which is an extremely slow process.
Simple distillation is generally done by boiling, because once the vapor pressure exceeds 1 atm, there will be a steady flow of vapor from the boiling flask to the condenser.
In steam distillation, the flow of steam carries with it the vapor of the substance of interest, even if the latter itself is not boiling. It suffices that the substance has significant vapor pressure at 100 C.
Makes sense? --Jorge Stolfi (talk) 20:30, 16 March 2020 (UTC)

Good eye. That section is misleading and the azeotrope of PhBr and water seems irrelevant (probably written by someone who never ran a steam distillation - but no one does these anymore). The relative vapor pressures near the temperature of the steam is key. Another aspect is that the materials that steam distill are almost always hydrophobic, so they are easily separated from the huge amt of water that comes over.--Smokefoot (talk) 12:10, 17 March 2020 (UTC)

OK. Refurbished the article, correcting that section.
From some Google hits, I suspect that steam distillation is (or could be) also used for solid substances, like naphthalene or iodine. Is that so?
Also, it seems that the same principle could be used with other solvents besides water. In my teens I prepared Eau de Cologne, sort of, by distilling orange peel and ethanol; that would be "ethanol steam distillation", no? And also I gather that one can remove water from a mixture by distilling with a solvent of lower boiling point; would that be "reverse steam distillation"?
Just wondering... --Jorge Stolfi (talk) 00:44, 18 March 2020 (UTC)

Suitable images

The article needs better images. The current photo and diagram at the top right (presumably done by the same person) show the condensation happen in two steps: the aniline is condensed first in the middle flask, with no condenser, and the the water is then condensed through the Liebig into the flask at right. That does not seem to be the typical setup; is it?
In fact, the setup seems to fictional, rather than having been actually used for steam distillation. Being a simple "water distillation", the steam with the product of interest leaves the boiling container at 100 C. Even if the middle flask is somehow kept just above 100 C, most of the desired product should go through it and condense with the water. No?
--Jorge Stolfi (talk) 00:56, 18 March 2020 (UTC)

Yes, I'm going to remove this pic. Look at its comment: "Note: This diagram seems incorrect: the vessel in the middle should not exist, and both liquids should be collected in the flask at right." 38.73.253.217 (talk) 10:46, 24 August 2021 (UTC)

Invention of steam distillation by Avicenna

There is a claim that steam distillation was invented by the 11th-century physician and philosopher Avicenna which makes the rounds in all kinds of non-expert sources, and now also in our article here. However, I have not been able to find a truly reliable source for this. If it the claim is true, which I do not itself dispute, we should be able to find it in a work written by a historian of alchemy and chemistry, or by another historian of science. From WP:CONTEXTMATTERS: The reliability of a source depends on context. Each source must be carefully weighed to judge whether it is reliable for the statement being made in the Wikipedia article and is an appropriate source for that content. I do not consider the sources currently cited to be appropriate for the content, and therefore not reliable in context. We should either find a better source, or remove the statement. ☿ Apaugasma (talk ☉) 14:30, 15 December 2021 (UTC)

All of these sources fits in the definition of reliable source and comes under domain of distillation. These sources are all verifiable. You can add a note or tag or modify this statement but this can't be removed 2409:4050:2DCD:F77D:8D42:2711:B9F0:9655 (talk) 03:56, 18 December 2021 (UTC)

Claims about the history of science should be based on the works of historians of science, not on some random non-historiographical sources all repeating a claim without ever giving a clear reference. The fact that, despite efforts from my side as well as yours, no historian of science can be found to support this claim, is highly suspicious.

But if you insist, for whatever reason, to keep in the poorly sourced information you added, I'm not going to waste more time on this. I added a {{better source needed}} tag to the statement in this article as well as in Distillation. ☿ Apaugasma (talk ☉) 12:11, 18 December 2021 (UTC)

The edit that I recently made isn't about "invention" ≈of steam distillation. It just mention that steam distillation was used by ibn sina. Since you want a source that is on history of science, here you go https://books.google.co.in/books?id=oSFCEAAAQBAJ&pg=PA103&dq=refrigerated+coil+distillation+ibn+sina&hl=en&newbks=1&newbks_redir=0&source=gb_mobile_search&sa=X&ved=2ahUKEwi5hva_39X5AhWUSmwGHX1kCCoQ6AF6BAgGEAM#v=onepage&q=refrigerated%20coil%20distillation%20ibn%20sina&f=false 223.233.69.34 (talk) 15:42, 20 August 2022 (UTC)

Thanks for that. Yes, you wrote that Avicenna made use of steam distillation, it's another editor here before you who wrote that he invented it.

Thanks for citing the history of science source, but since the December 2021 discussion above I have found a much clearer basis in policy for what is an acceptable source in cases like this. What we need, and what policy requires, is a truly secondary source. See WP:SECONDARY:

A secondary source provides an author's own thinking based on primary sources, generally at least one step removed from an event. It contains an author's analysis, evaluation, interpretation, or synthesis of the facts, evidence, concepts, and ideas taken from primary sources. Secondary sources are not necessarily independent sources. They rely on primary sources for their material, making analytic or evaluative claims about them.

Policy: Wikipedia articles usually rely on material from reliable secondary sources. Articles may make an analytic, evaluative, interpretive, or synthetic claim only if that has been published by a reliable secondary source.

Sources are only truly secondary for a claim if they rely on primary sources for their material, and the existence of such a secondary source based on the primary evidence is needed for a Wikipedia article to make that claim.

The question thus becomes: is there a source claiming that Avicenna made use of steam distillation which also discusses the primary evidence for this? Of course this would also be a history of science source, but that's not what is important: the mark of it being an acceptable source would be that it discusses the medieval texts written by Avicenna which deal with steam distillation. If there is such a source, let's cite it in our article. If there isn't, we cannot include the claim in our article. Thanks, ☿ Apaugasma (talk ☉) 16:06, 20 August 2022 (UTC)

I read the policy. It doesn't say that secondary source MUST contain information from primary source. As long as the secondary source is reliable the information can be added to Wikipedia article. The sources I cited fits in the Wikipedia definition of reliable sources. Also it is not off-topic 223.233.69.34 (talk) 16:28, 20 August 2022 (UTC)

That a source relies on and cites primary sources is what defines a secondary source. The source you used does not. I have requested a third opinion (see WP:3O). ☿ Apaugasma (talk ☉) 16:45, 20 August 2022 (UTC)

But since there are multiple reliable secondary sources stating this, there must be a primary source. This info can hardly be untrue. There is no problem in stating this. If your criteria be followed then 90% of the contents from history section of various articles will be removed. What appears to be the case is that avicenna's original work on steam distillation may have been lost but it is very clear that many authors of middle ages like Conrad Gesner mentions avicennas steam distillation techniques in their work https://books.google.co.in/books?id=XeqWOkKYn28C&printsec=frontcover&dq=History+steam+distillation&hl=en&newbks=1&newbks_redir=0&source=gb_mobile_search&sa=X&redir_esc=y#v=onepage&q=Avicenna&f=false 223.233.69.34 (talk) 17:20, 20 August 2022 (UTC)

The Forbes source you cite here says nothing about steam distillation. Claims widely accepted by mainstream scholars can usually very easily be traced to primary sources. Sometimes particular claims only make the rounds in non-expert tertiary sources, but such claims are not included on Wikipedia. When digging them out, they often turn out to be based on some long-since rejected 19th-century study. Believe me, I'm also curious as to where the claim that Avicenna made use of steam distillation originated. I would be very excited if a good source for that would be found, since if it could really be shown that Avicenna knew how to cool distillates, that would solve a number of outstanding problems in the history of chemistry. ☿ Apaugasma (talk ☉) 18:23, 20 August 2022 (UTC)

Al-Kindi?

Found a couple of sources on al-Kindi:

It is fairly clear from the book of al-Kindi that all the perfume-oil processes were steam-distillations (cf. p. 120) even if no water was added to the fresh plant material; and generally done on the water-bath, i.e. much below the boiling temperatures of the oils themselves, thus preventing any decomposition. But since their boiling-points are so much higher than that of water they condense very easily without any cooling devices. Science and Civilisation in China, Volume 5, p.128, N.h

Another source quotes al-Kindi's 9th-century text al-Taraffuq fi-l-ʿiṭr: distill it by steam [1]. The Arabic phrase used is taṣʿīd bi al-ruṭūba (per Note 23 and the Glossary on p.602), but I'm not sure if that corresponds to steam distillation. I think we need more sources per WP:EXCEPTIONAL or maybe an "according to" statement would do. Wiqi⁽⁵⁵⁾ 00:05, 21 August 2022 (UTC)

Yes, as usual, these are excellent sources you cite. And yes, what both sources describe does indeed correspond to steam distillation: either simple hydrodistillation (as in the recipes given by Nasrallah, though her translation of ruṭūba as 'steam' is misleading: this is just the heat source, i.e. the water-bath or Bain-marie (cf. Needham p. 126), not the steam with which the oils are distilled, which comes from the water mixed with the starting substances) or as what our article calls 'direct steam distillation' (when no water is added, as mentioned by Needham): the steam of the water with which the starting material is mixed –or the steam of the water-bath itself in the case of direct steam distillation– is used to create a steady flow of vapor even at temperatures far below the boiling points of the essential oils, so as to avoid their decomposition. We should definitely add that to our article.

Do note though Needham's emphasis throughout on the fact that no evidence has been found so far in Arabic sources for any knowledge of distillate cooling techniques, which were essential to the isolation of ethanol and the discovery of various mineral acids such as hydrochloric acid, both of which are thought to have occurred in 12th-/13th-century Europe. We should thus also carefully explain that direct steam distillation can be performed without cooling devices (because essential oils have high boiling points and thus easily condense of themselves), and that the Kitāb al-Taraffuq fī l-ʿiṭr does indeed not describe any such devices.

Of course, we also still need a decent source for Avicenna. The fact that the source currently used claims that Avicenna invented the refrigerated coil without giving any reference for this speaks volumes. ☿ Apaugasma (talk ☉) 02:23, 21 August 2022 (UTC)

Al dimashqi also performed steam distillation. https://books.google.co.in/books?id=96UxEAAAQBAJ&pg=PA87&dq=al+dimashqi+steam+distillation&hl=en&sa=X&ved=2ahUKEwix0q3Ssdv5AhUjRWwGHfbBCqUQ6AF6BAgJEAM#v=onepage&q=al%20dimashqi%20steam%20distillation&f=false 223.233.69.34 (talk) 21:32, 22 August 2022 (UTC)

Unfortunately, this source (Donald R. Hill) also fails to cite primary evidence for al-Dimashqi (1256–1327). Hill often collaborated with Ahmad Y. al-Hassan, a similarly careless scholar making a lot of claims without properly backing them up (see, e.g., the negative reviews [2] [3]; this was already addressed by several Wikipedia editors in this 2010 thread). Given the fact that steam distillation is clearly attested for the 9th-century al-Kindi I guess it's fairly credible that al-Dimashqi would have known it in the 14th century, even if we don't know what primary source Hill bases his claims upon. Not sure how relevant it is though. However, since Hill is a historian of science and doesn't contradict highly respected experts such as Needham, I will not object to using him here for the time being. If we mention al-Kindi and al-Dimashqi, will you agree to leaving out Avicenna? We still haven't got a good source for him. ☿ Apaugasma (talk ☉) 23:14, 22 August 2022 (UTC)

Mention them along with avicenna. This conflict isn't resolved yet. The primary source for al-Dimashqi is kitab nukhbat al-Dahr' ' https://books.google.co.in/books?id=it2E29EkCkUC&q=kitab+nukhbat+al+dahr+steam+distillation&dq=kitab+nukhbat+al+dahr+steam+distillation&hl=en&newbks=1&newbks_redir=0&source=gb_mobile_search&sa=X&ved=2ahUKEwjU-9nwwf_5AhVPwosBHafECnwQ6AF6BAgGEAM#kitab%20nukhbat%20al%20dahr%20steam%20distillation

223.233.69.34 (talk) 14:36, 23 August 2022 (UTC)

I updated the section, including al-Kindi (c. 801–873), Avicenna (980–1037) and al-Dimashqi (1256–1327). I left out the 'refrigerated coil' bit because it is directly contradicted by Needham 1980 (and other reliable sources):

[Needham p. 128:] Perhaps the reason why the great Arabs found the distillate of wine uninteresting was because its alcohol-content was so low. None of them make any reference to cooling, either of still-head, receiver or side-tube, and they were probably quite unaware that there could be any' spirits' with (as we should say) a boiling-point lower than water, and therefore likely to be lost in the surrounding air if not expressly cooled. [...] [Needham p. 129:] Von Lippmann's final opinion was that lack of special cooling arrangements among the Arabs was beyond doubt, so that separation of substances of low boiling-point would have been impossible. This would be true also of the later Arab chemists such as Abu Bakr ibn Zakariya al-Razi (+ 865 to + 925) or Abu'l-Qasim al-Simawi al-'Iraqi about + 1270.

I do maintain that most of the sources used are subpar (some of them downright unacceptable), and that the section as written is very likely to be misleading. However, since the only way to properly remedy this is to do a month of research and actually come up with something better, I'm happy to leave it as is. I have better things to do for the moment. ☿ Apaugasma (talk ☉) 12:47, 6 September 2022 (UTC)