Science desk
< April 17	<< Mar \| April \| May >>	April 19 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is a transcluded archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

April 18

"Закрой сифон и поддувало"?

I wanted to ask this for the past few weeks: according to my mother, when she was a child (back when many trains in Russia still used steam traction), one would sometimes see trackside signs saying "Закрой сифон и поддувало" ("Close blower and damper"), or maybe "Открой сифон и поддувало" ("Open blower and damper"), but she did not remember anything more about this (other than the fact that she and her friends got a good laugh out of these signs). So, several questions: (1) Am I right that "сифон" = blower and "поддувало" = damper? (2) Is it "open" or "close" blower and damper? (3) Where exactly would these signs be found (my guess is these would be found before tunnels, to reduce the amount of smoke in tunnels and/or to prevent dangerous blowbacks from the firebox -- is that correct)? 2601:646:9882:46E0:B0D1:2E92:F1FD:9C73 (talk) 01:41, 18 April 2023 (UTC)[reply]

As to question 2, the obvious thing would be to see "close" at the start of a zone where they should be closed, and "open" at the end of it. It's like the way some highways in the US states have signs alternately reading NO PASSING ZONE and PASS WITH CARE (meaning "end no-passing zone"). --174.89.12.187 (talk) 05:43, 18 April 2023 (UTC)[reply]

Such signs would be posted at underpasses or railway stations; see this video at 1:34. With these things open, sparks could fly off and cause fire damage. For the normal operation, to keep the coal burning hot, they needed to be open. --Lambiam 07:47, 18 April 2023 (UTC)[reply]

(edit conflict) Regarding point (1). Air normally enters below the grate and passes through the fire for efficient combustion. Some "secondary air" can be introduced above the fire to promote complete combustion (and hence cleaner exhaust). At the point where the primary air enters the ashpan below the grate, the dampers are fitted. They restrict the flow of air, so can "damp down" the fire. They also need to be closed when firing or the hot gasses will come out of the firebox door which is rather dangerous for the crew! The blower would not need to be shut off for firing though, it would pull the gasses away from the crew. Your link show that you've found information on the blower. Invented by either Hackworth or Stephenson (Trevithick mentioned the effect but didn't fully develop the idea) it draws the hot gas through the boiler pipes by using Bernoulli's principle. When would you shut off both? Well tunnels makes sense, you want the minimum amount of smoke hanging around as the train passes. Possibly also in stations or where people might be waiting lineside or where there is a fire risk. A lot depends upon the quality of the fuel and skill of the drivers. Poor quality fuel, poor drivers or slow, heavy freight can eject sparks as well as smoke. One last point, having the blower on implies that the trains are travelling slowly or coasting downhill at that point. At speed the blast from the steam used in the cylinders is powerful enough to draw the fire through the boiler. Martin of Sheffield (talk) 08:07, 18 April 2023 (UTC)[reply]

For an explanation of the role of the сифон, see Thermic siphon. I am not sure of the role of the поддувало ("blower"). It could be a stack blower pulling the hot firebox smoke through the tubes of the boiler, but it could also refer to a soot blower. --Lambiam 08:08, 18 April 2023 (UTC)[reply]

@Lambiam: I've browsed a bit through related articles in ruwiki and plwiki as well as Google Translate, and it looks like the ru:поддувало is a chamber below the fire grate, where ash and slag fall from the grate. Its name consists of 'дувало' (a device to blow) prefixed with a preposition 'под-' (under, below), and it's actually a channel (when open) where the fresh air is sucked from below into the fire in a coal kitchen stove or a masonry heater. Closing its door significantly reduces the air flow through the stove, so it also temporarily reduces the amount of smoke. --CiaPan (talk) 11:43, 18 April 2023 (UTC)[reply]

Regarding thermic siphons, I don't buy it -- first of all, they cannot be selectively closed off (why would they be?), and in any case most Russian steam locomotives did not have them, but only had circulation tubes if anything (thermic siphons only work well on engines with very big grate areas, like the Big Boy, and no Russian engine was anywhere near that size!) So, for "сифон", I'm sticking with "blower" for the translation. 2601:646:9882:46E0:A899:1187:7D82:CC7B (talk) 22:06, 21 April 2023 (UTC)[reply]

I don't speak or read Russian, so can't help with questions 1 and 2. To prevent backblows, you want low pressure in the firebox, so you open the blower and close the dampers (not necessarily completely). Closing the firebox doors also helps, but then you can't put coal on the fire.

It looks like these messages are instructions or hints (I suppose the Soviet Union would issue instructions, whilst the UK would issue hints) to the fireman (whose job it was to manage fire and boiler). Opening the blower or dampers increases the flow or air through the fire, boosting the rate of combustion and production of heat and steam. Way too much air, and burning pieces of coal could be blown out of the chimney, wasting fuel and posing a fire risk. Slightly too much air would still waste fuel and generate too much steam, leading to a very noisy application of the safety valves, something you really want to avoid in a station. Too little air leads to low boiler pressure and, after some minutes, an inability to stick to the timetable, and incomplete combustion, leading to soot and carbon monoxide. In Western Europe, soot was to be avoided in cities and was one reason for electrification, but something tells me that wasn't so much of a consideration in the Soviet Union. Carbon monoxide can be a big problem in tunnels, but those aren't very common in Russia.

Properly managing fire and boiler takes some intelligence. On approach to a station, you stop shovelling coal. Shovelling coal lowers the temperature of the fire, so lower the airflow a bit to compensate. During approach, the regulator is closed, already lowering the flow of air, and the firebox doors may be closed. In the station, you use hardly any steam, so to prevent the smoke from reaching the footplate and the fire from dying completely, you have to open the blower. When departure time nears, you have to anticipate the larger steam demand by putting more coal on the fire. Fresh fuel lowers the temperature, creating more soot, which you don't want in a station, so open de blower a bit more to boost the rate of combustion. Steam production increases; use some to fill up the boiler. If the fireman does his job right, the boiler reaches full pressure and maximum water level right at departure time, with a big fire burning hot to provide steam for acceleration. Now hope that the signal is cleared right away, or you'll get that nasty in-station safety valve application. PiusImpavidus (talk) 10:36, 18 April 2023 (UTC)[reply]

Thanks, everyone! Yes, it makes perfect sense that they would have signs to close the blower and damper before stations, underpasses, tunnels and where there's a fire hazard! And yes, back in the days of steam traction, Russian railways often had to use low-quality coal (ironically, the closer to Moscow it was, the worse the quality of coal -- in the remote regions like Siberia, the far north and the southern prairies, they could use locally-mined coal (Novokuznetsk, Vorkuta and Donetsk coal, respectively), which was of decent quality, but in the Moscow area they used Tula lignite, which was not much better than what the Belgian railways used (Belgian lignite was so bad that their trains had to use square smokestacks just to get it to burn properly), or even (get this!) peat from the Shatura and Torzhok areas!) So, soot was seen as an unavoidable nuisance -- but by the same token, firing a Russian engine using Russian coal (especially the muck from the Tula mines) took quite a bit of skill! And yes, they did run a lot of slow, heavy freights (as evidenced by the popularity of the FD-class heavy freight engine). As for tunnels, they were not very common on most lines in Russia -- but there were some lines with lots of tunnels, including many of the lines in the Caucuses (such as the line from Moscow to Sochi and Batumi -- which, incidentally, was the one my mother frequently rode back in the day), as well as the Trans-Siberian. 2601:646:9882:46E0:A899:1187:7D82:CC7B (talk) 22:06, 21 April 2023 (UTC)[reply]

Parrot communication

Has anyone ever studied captive parrots that speak to each other in English/other human languages? They absolutely do sometimes (multiple youtube vids showing it). Thought I might add something to the talking bird or companion parrot article if there was. Iloveparrots (talk) 20:35, 18 April 2023 (UTC)[reply]

Presumably NOT this:[1] ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:11, 19 April 2023 (UTC)[reply]

Did you read Talking_bird#Cognition_controversy? Shantavira|^{feed me} 08:14, 19 April 2023 (UTC)[reply]

Vocal communication between parrots in the wild is known to be at least partially learned, since they develop different regional dialects.^[2] I did not see anything about studies of (meaningful) inter-parrot communication using vocalizations of words from human languages. This appears plausibly possible but difficult to test and establish unless we have a better understanding of the needs for semantic communication between individuals bred in captivity, since they will have to be trained to associate the same words with specific parroty messages. But when it comes to vocalization: "Interactions between parrots within a flock are complex and poorly understood: this is an area where much more research is required."^[3] This deserves (IMO) priority over studying parrot communication using words from human languages. --Lambiam 08:15, 20 April 2023 (UTC)[reply]

Suggest an experiment

Can you suggest a scientific experiment somewhere, if you have the temerity to think you've come up with something worth trying? 2A02:908:424:9D60:5D94:1364:826B:B022 (talk) 20:55, 18 April 2023 (UTC)[reply]

Not on Wikipedia. However, you could write a letter with the suggestion to a scientific news or other journal such as New Scientist, Scientific American, Nature, or various others, many of which specialise in particular fields. The worst that can happen is that you receive no response or a polite dismissal, but if your idea has any possible merit, the Editors(s) might decide to print it in the Letters column where some scientist might be intrigued enough to follow it up. (For possible interest; I have had two letters published in New Scientist, though neither were suggesting experiments, and a thoughtful reply to a third from the Editor, agreeing that a previous article had omitted some relevant facts.) {The poster formerly known as 87.81.230.195} 90.213.18.208 (talk) 22:52, 18 April 2023 (UTC)[reply]

If you're feeling really daring, and your idea has to do with nuclear physics, you can even try writing directly to CERN with your experiment proposal (I remember that the article about the Large Hadron Collider mentions this possibility) -- fat chance of your proposal actually being accepted, but you never know, they might just try it and discover something new! 2601:646:9882:46E0:B06E:637E:D483:879D (talk) 03:02, 19 April 2023 (UTC)[reply]

There are several subreddits devoted to physics. There is even an r/ExperimentalPhysics, but it is not particularly active. If you post your proposal at r/Physics, it may be seen by physicists and picked up if it looks promising. Or readers may offer suggestions, depending on the nature of the experiment, for a better place to forward the proposal. --Lambiam 06:37, 19 April 2023 (UTC)[reply]

Another avenue is to contact a local institution of higher learning, especially if one has a contact in the relevant faculty. Good luck! cmɢʟee⎆τaʟκ 09:41, 19 April 2023 (UTC)[reply]

If the experiment requires no specialist equipment, you're quite allowed to just "do it yourself". There's generally nothing stopping you (unless the experiment involves activities that are illegal in your jurisdiction). You can even order equipment and supplies, if you have the money to do so. If you want inspiration, there's a YouTube channel, [NileRed, which is run by a guy who rents lab space and has a bunch of equipment to run experiments and film YouTube videos about it. AFAIK, he has no affiliation with any lab or other organization, he's just a guy who likes to do chemistry. If you want more formal structure, you can get involved in various citizen science organizations as well. While having the requisite training and experience in a particular field (like, say, a proper University Degree) and the backing of an organized lab or company certainly helps giving people access to the tools and resources to do scientific experiments, people can do these things all on their own; it's harder, but not impossible, if you have the money and time. --Jayron 32 12:14, 19 April 2023 (UTC)[reply]
That brings to mind the story of the Mpemba effect, discovered by a Tanzanian secondary-school student who then asked a visiting scientist about his observation, got the scientist interested enough to repeat his experiment, and published a paper together. cmɢʟee⎆τaʟκ 12:33, 19 April 2023 (UTC)[reply]
Lots of astronomy is done by amateurs as well. David H. Levy is famously the discoverer or co-discoverer of dozens of minor objects orbiting the Earth; he's a trained writer and has little to no formal education in astronomy. --Jayron 32 14:01, 19 April 2023 (UTC)[reply]
BTW, used to be that amateur astronomers could even rent out observation time on the Hubble (subject to very stringent approval criteria, of course) -- but this is no longer the case. 2601:646:9882:46E0:A899:1187:7D82:CC7B (talk) 21:29, 21 April 2023 (UTC)[reply]

Note that the Mpemba effect is a rather contentious topic. To my eyes it’s a rather standard example of a group-induced motte-and-bailey fallacy.

The motte is that certain experimental setups, under certain conditions, show that water freezing time depends on the thermal cycle followed. That is true. There are mundane theoretical explanations for it (differences in water composition due to dissolved gases and/or heat transfer mechanisms), but in the words of Philip Ball, they are "trivial" rather than "illuminating".

The bailey "the latent heat of pure water depends on its past history" is most likely wrong. That would overturn most modern understanding of thermodynamics, and all experiments that carefully controlled for water composition etc. have failed to show that.

(The Mpemba effect is still an interesting piece of trivia, but one about (1) experiments sometimes behaving differently from what you would intuitively expect and (2) the difficulties of properly controlling an experimental setup; not about the properties of water.) Tigraan^{Click here for my talk page ("private" contact)} 13:31, 20 April 2023 (UTC)[reply]

Also tetranitratoxycarbon. DMacks (talk) 06:10, 21 April 2023 (UTC)[reply]
Now that kind of experiment would have to be done under extremely strict safety regulation, because even the slightest error (especially with temperatures) might make the reaction blow up -- and it would probably have to be monitored by someone from Homeland Security, given that any not-quite-correct experimental design is likely to produce PETN! (In fact, now that I've examined the structural model in detail, I'm quite sure that at anything above cryogenic temperatures, it will either spontaneously detonate ~~or (less likely) spontaneously rearrange into PETN~~!) 2601:646:9882:46E0:A899:1187:7D82:CC7B (talk) 21:29, 21 April 2023 (UTC)[reply]
Theoretical studies, such as that one, are totally valid science (if one is correctly using actual scientific theories, obviously:). A ton of work was done by scientists during COVID lockdown without setting foot in research labs. DMacks (talk) 02:59, 22 April 2023 (UTC)[reply]

Given PETN contains hydrogens and tetranitratoxycarbon does not, the latter cannot possibly rearrange into the former. The theoretical-analysis paper cited in the tetranitratoxycarbon article is a great example of doing good real science with really-unstable chemicals without blowing oneself up. It even discusses (with actual evidence) what rearrangement or accidental other product might be likely. DMacks (talk) 14:54, 22 April 2023 (UTC)[reply]