Wikipedia:Reference desk/Archives/Science/2011 August 19

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

August 19

Concave lens and a "projection" of a virtual image

The words used in optics are confusing. A virtual image cannot be "projected" onto a screen, like when it passes through a concave lens according to most things I have read. But, when I use that term, the light that has been reflected off of an object through a concave lens can appear on say a piece of tin foil or a piece of paper. How does this terminology make any sense and why don't people make this clarification? --Melab±1 ☎ 00:14, 19 August 2011 (UTC)

You seem to be confused. Virtual images Cannot be projected into a screen. You must be producing a real image. Dauto (talk) 05:22, 19 August 2011 (UTC)

I'm talking about the light rays that come out of a diverging lens. Reread my question. --Melab±1 ☎ 15:05, 19 August 2011 (UTC)

If you got to project it in a screen then it was a real image, not a virtual image. Dauto (talk) 00:59, 20 August 2011 (UTC)

If you just mean that the light rays exiting a concave lens can illuminate a piece of paper, that's true, but that's not the same as forming an image. -- BenRG (talk) 02:27, 20 August 2011 (UTC)

Well, why can't they? They must carry the same frequencies and configurations as the light reflected off of the object. --Melab±1 ☎ 14:36, 20 August 2011 (UTC)

They don't form an image because the lens doesn't cause rays that come from one point on the object to reconverge at a single point on the piece of paper. With a convex lens, on the other hand, if the paper is at the right distance all the rays from any given point on the object reconverge at a single point on the paper.--Srleffler (talk) 16:48, 20 August 2011 (UTC)

Well, surely they can be used to project an image if you put them through another lens or curved mirror ... ;) Seriously though, Virtual image and Real image could use improvement. A somewhat better explanation for the nomenclature is made at Lens (optics)#Imaging properties. Wnt (talk) 17:12, 24 August 2011 (UTC)

Battery & Aerogel

Will battery wrap within aerogel able to survive extreme temperature? roscoe_x (talk) 04:39, 19 August 2011 (UTC)

Aerogel is a very good thermal insulator, but I don't think you'll get a much better answer then "it depends".. Vespine (talk) 05:23, 19 August 2011 (UTC)

I saw the article, it can protect flower against bunsen burner. But will it protect the battery against cold weather? Like -30~-40C. Most camera battery usually won't survive below -10C for 5~10 minutes. So if the battery is wrap with aerogel will it be useful as it is in normal temperature? But in -40C, probably the camera won't work too... roscoe_x (talk) 07:06, 19 August 2011 (UTC)

Well, the temperature difference for ambient and flame is way different than between ambient and -40 C. Why don't you just give it a try and see if it works? --Ouro (blah blah) 09:53, 19 August 2011 (UTC)

One thing you need to understand is that an insulator only slows how quickly the insulated item takes to reach the ambient temperature. So, that battery will eventually become the same temperature as the outside air (unless it's actually generating it's own heat). How long it takes to get down to the ambient temperature depends on many factors. There's the insulating material, but also it's thickness, and the presence of any gaps in it, such as those needed to connect to the terminals. StuRat (talk) 17:13, 19 August 2011 (UTC)

Lithium-ion batteries are very effective (notoriously so) for generating their own heat. (Which is why there are special restrictions on transporting them.) 67.169.177.176 (talk) 04:41, 20 August 2011 (UTC)

But only when in use, right ? So they could freeze between uses and burst into flame, due to the insulation, when in use. StuRat (talk) 04:46, 20 August 2011 (UTC)

Roscoe x, do you live in Alaska? If so, I'm sure there are cameras on the market that are specially designed for extreme cold weather. 67.169.177.176 (talk) 06:18, 20 August 2011 (UTC)

No, I don't live in Alaska. Is this aerogel rigid or easily mold like fabric? And will it also freeze in such a cold temperature? And if I wrap battery with it, I'm quite sure it won't fit into the battery socket. roscoe_x (talk) 16:17, 20 August 2011 (UTC)

Aerogel has the mechanical properties of styrofoam, but can shatter if pressed too hard (e.g. when you're trying to force the battery into its socket). And it can break down over time if exposed to moisture. And if you're quite sure that the battery won't fit into the socket when covered with aerogel, then why bother in the first place? I recommend that you look for a camera that's designed for extreme cold conditions. 67.169.177.176 (talk) 19:35, 20 August 2011 (UTC)

Follow up curious question: where to GET aerogel in the first place, and how much does it cost? Is there just one kind? --Ouro (blah blah) 16:24, 21 August 2011 (UTC)

There are several different kinds of aerogel, according to the article. As for how much it costs, I got no clue. 67.169.177.176 (talk) 23:27, 22 August 2011 (UTC)

Are there algorithms for numerical partial differential equations that are implicit in time and in space?

I have read List of numerical analysis topics and Numerical partial differential equations, both of which contain a large list of algorithms for solving numerical partial differential equations. Some of these are fully explicit (FDTD), others are implicit in time (Crank–Nicolson method), or (partially) implicit in space (Alternating direction implicit method). I have not found any fully implicit method (implicit in space and in time).157.193.175.207 (talk) 08:12, 19 August 2011 (UTC)

You might have more luck getting an informed response if you move this question to the Math reference desk (or perhaps to the Computing reference desk, since numerical analysis is at the intersection of applied math and computer science, but I have a hunch the Math reference desk would be the better bet). It might also help if you gave the specific PDE you need to find numerical solutions for, as someone might be able to reduce the problem to an equivalent problem that's easier to solve numerically. It might also help to know what the boundary conditions are, since initial value problems and boundary value problems are generally solved using different algorithms. Red Act (talk) 21:01, 19 August 2011 (UTC)

newtonian question

given the picture [[1]] (oh, the link doesn't show it, sorry. it's the first picture in google search apearing for newton-cannon-orbital-types-Seeds) and Conic Section article (the properties part, eccentricity, focus and directrix) I wonder is there a mathematical equation relating eccentricity and velocity for an object orbiting around a given celestial body?--Irrational number (talk) 10:45, 19 August 2011 (UTC)

You meant here. For external pages, use single square brackets (not double) and a space, not a pipe after the URL, for the displayed link text. CS Miller (talk) 11:55, 19 August 2011 (UTC)

thanks!--Irrational number (talk) 12:10, 19 August 2011 (UTC)

Well, you can combine the Vis-viva equation $v^{2}=G(M\!+\!m)\left({\frac {2}{r}}-{\frac {1}{a}}\right).$, The standard equation of an elipse in polar coordinates from Kepler's laws of planetary motion $r={\frac {p}{1+\varepsilon \,\cos \theta }},$ and the relation between the Semi-major axis and the Semi-latus rectum $a={\frac {p}{1-\varepsilon ^{2}}}.$ Dauto (talk) 15:10, 19 August 2011 (UTC)

Then you get $v^{2}={\frac {G(M\!+\!m)}{a}}\left({\frac {1+2\varepsilon \,\cos \theta +\varepsilon ^{2}}{(1-\varepsilon ^{2})}}\right).$ Dauto (talk) 15:21, 19 August 2011 (UTC)

Finally, setting $\theta =0\,$ you get $v={\sqrt {{\frac {G(M\!+\!m)}{a}}\left({\frac {1+\varepsilon }{1-\varepsilon }}\right)}}.$ Dauto (talk) 15:46, 19 August 2011 (UTC)

You may also use the Orbit equation ${\frac {1}{r}}={{1+e\cos \theta } \over {a(1-e^{2})}}$ to replace the semi-major axis with the distance at perigee ${\frac {1}{r}}_{perigee}={{1+e} \over {a(1-e^{2})}}={\frac {1}{a(1-e)}}$ and get

$v={\sqrt {\frac {G(M\!+\!m)(1+\varepsilon )}{r_{perigee}}}}.$ Dauto (talk) 16:03, 19 August 2011 (UTC)

If the perigee coincides with the planet's radius than you can use the expression for the Escape velocity $v_{e}={\sqrt {\frac {2GM}{r}}},$ and get $v=v_{e}{\sqrt {\frac {(M+m)(1+\varepsilon )}{2M}}}.$

And since that equation assumes the satellite has negligible mass, you get the simple equation $v=v_{e}{\sqrt {\frac {(1+\varepsilon )}{2}}}.$ Dauto (talk) 16:47, 19 August 2011 (UTC)

thanks a LOT I've learned a little bit of dynamics this year, above all is the circular motion, and I wonder where I can find the derivations of the equations you mentioned (I mean the ones you used in the first place)--Irrational number (talk) 17:56, 19 August 2011 (UTC)

The articles I linked have derivations for most, if not all, the equations I used. Let me know if you still have any questions after reading those articles. Dauto (talk) 21:29, 19 August 2011 (UTC)

Looking for a plastic strip for a DIY project

For a DIY project I need a strip of plastic but I don't know where I can get it. It needs to be approximately 20 inches long, 3/4 inch wide, 1/16 inch think (a little thinner is OK), and ideally colorless. Any idea what can be repurposed for the plastic piece? --98.114.98.84 (talk) 15:01, 19 August 2011 (UTC)

Flexible? Rigid? (Non-)shatterable? Plexiglas/polycarbonate sheeting is easily found in old screen/storm-door panes (and hardware stores and other places that stock them). Easy to cut into all sorts of sizes and shapes using various saws and knives. DMacks (talk) 15:12, 19 August 2011 (UTC)

The plastic piece doesn't need to be flexible, but would be OK if it's a little flexible. I've considered plexiglass sheets but I thought I'd have to get a fairly large sheet to get 20 inches in the longest dimension. --98.114.98.84 (talk) 15:38, 19 August 2011 (UTC)

Then check with yuur local window repair shop. They probably have some scraps that you can use without having to buy a whole sheet. Dominus Vobisdu (talk) 15:41, 19 August 2011 (UTC)

Try your local hardware store. The one near my house will cut a plexiglass sheet into any size you want. thx1138 (talk) 16:26, 19 August 2011 (UTC)

Tap's Plastics has a wide variety of plastic products, and they can cut it to any size required. 67.169.177.176 (talk) 04:44, 20 August 2011 (UTC)

How does the human brain process the failure to grasp/loss of Abstraction; or how does it process concrete interpretation of metaphors/symbollism?

I'm working on a multidisciplinary paper right now on how the human brain processes complex metaphors; specifically, when a person fails to grasp the figurative meaning of, or only comprehends part of, a metaphor for an abstract object and interprets it literally. I'm culling data largely from neuroimaging studies; as well as incorporating work from the fields of psychology (neuro/cognitive), linguistics (neuro/psycho), philosophy, and the subsets of cognitive science in general; and while I can find a fair amount of information on the neural correlates of correct metaphor comprehension, I can't find much in the way of incorrect comprehension- save for some limited studies done on schizophrenics. Can anyone help me? Thanks a bunch! — Preceding unsigned comment added by 76.100.134.33 (talk) 15:13, 19 August 2011 (UTC)

If I interpret your question correctly, you're asking about what causes some people to be incapable of grasping the meaning of metaphors, and instead take them literally. For example, if somebody tells them to "put some elbow grease into it", they then rub their elbow on the work. Well, obviously there's the case of people who just haven't heard a particular metaphor, but I think you're asking about people who just don't get them, no matter how many times they've heard them.

I suspect that this ties in with the ability to use "symbolic logic". This develops in normal children somewhere around 3-4 years of age. One experiment in this area is to hide a "prize" in a room, then show a child a model of the room, and show them where the prize is hidden there, then ask them to find the prize in the real room. Younger children don't use this info to aid in their search, while older children do.

As for what physiological changes in the brain allow for symbolic logic, I don't think we know that yet. (For one reason, some types of brain scan involve subjecting the patient to risks, such as radiation, and that seems unethical, when used for research, especially on young children.)

Unfortunately, we don't have an article on the broader meaning of symbolic logic, it just redirects you to mathematical logic. Have you read Carl Jung's Man and His Symbols ? StuRat (talk) 16:43, 19 August 2011 (UTC)

Perhaps some of these autism related papers may be of interest.[2] Sean.hoyland - talk 16:52, 19 August 2011 (UTC)

The theory of mind may also apply here. That is, the ability to interpret what deeper meaning the speaker is trying to convey, versus just taking their words literally (AKA, the ability to "read between the lines"). StuRat (talk) 17:03, 19 August 2011 (UTC)

PMID 17081771 looks directly at this question in people with schizophrenia, who frequently have difficulty understanding metaphors. I expect it will give you pointers to other literature relating to the topic. You might also find this freely available review useful, if you haven't already seen it.Looie496 (talk) 18:07, 19 August 2011 (UTC)

I'm not sure if this is relevant at all, but I wonder if there is a way to describe "antiknowledge" and how it influences our perceptions. To give what to me is the classic example, there is a scene in Final Destination where a newspaper falls into a fan, revealing a clue about the next attack. The scrap of newspaper reads "Tod". To someone ignorant of German, the character's interpretation comes as no surprise: Todd is the next victim. But I didn't see that coming at all! Anyway, I would be curious if there is a competition in the brain, where the knowledge of the literal interpretation competes against more figurative ideas, with some regulatory mechanism providing a way to adjust their relative strengths. Wnt (talk) 22:02, 19 August 2011 (UTC)

Galvanic anodes

I'm not a very technical person but there seems to be a discrepancy between the two bolded texts. Perhaps someone can better explain:

Galvanic CPGalvanic anodes are designed and selected to have a more "active" voltage (more negative electrochemical potential) than the metal of the structure (typically steel). For effective CP, the potential of the steel surface is polarized (pushed) more negative until the surface has a uniform potential. At that stage, the driving force for the corrosion reaction is removed. The galvanic anode continues to corrode, consuming the anode material until eventually it must be replaced. The polarization is caused by the electron flow from the anode to the cathode. The driving force for the CP current is the difference in electrochemical potential between the anode and the cathode.[6]

Galvanic or sacrificial anodes are made in various shapes and sizes using alloys of zinc, magnesium and aluminum. ASTM International publishes standards on the composition and manufacturing of galvanic anodes.[7][8]

In order for galvanic cathodic protection to work, the anode must possess a lower (that is, more negative) potential than that of the cathode (the structure to be protected). The table below shows a simplified galvanic series to show which metals can thus be combined.[9]

Thanks

Mark — Preceding unsigned comment added by 204.13.216.2 (talk) 16:01, 19 August 2011 (UTC)

• Um, what is the confusion? The bolded sentences say the same thing. The first says that anodes have to have a more negative electrochemical potential, and the second says that anodes have to have a more negative potential. Exact same thing. Some of the confusion may lie with the use of the word "lower", which most people in these contexts try to avoid, since lower may mean both closer to zero (that is lower absolute value) and less positive. With negative numbers, those two usages are in conflict, so words like "lower" and "higher" should be avoided altogether for more precise terms like "more negative" or "less negative". They don't tend to cause that confusion with positive numbers because the usages coincide. --Jayron32 16:41, 19 August 2011 (UTC)

bond order

which molecul has exception bond order — Preceding unsigned comment added by Pulak007 (talk • contribs) 18:16, 19 August 2011 (UTC)

What do you mean by exception? Can you provide more context or details to your question? --Jayron32 18:28, 19 August 2011 (UTC)

Well the highest order bond in Wikipedia is Sextuple bond, and it lists dimolybdenum and ditungsten. The Quintuple bond actually seems to appear in some more normal molecules at room temperature including the shortest metal to metal bond. Graeme Bartlett (talk) 04:11, 20 August 2011 (UTC)

Pls help me (what does valency mean?)

I have read in a wikipedia article that valency means the number of bonds formed by an atom of an element.But in some of the books i have read that valency is no.of unpaired electrons.Please clarify me which one among the two is correct. — Preceding unsigned comment added by 14.99.235.188 (talk) 18:33, 19 August 2011 (UTC)

um... don't these two definitions overlap in most cases, except dative bonds?--Irrational number (talk) 20:00, 19 August 2011 (UTC)

The former definition talks about in a specific compound whereas the latter talks about the capability or maximum possible bonding or if the atom is arranged with the maximum possible unpaired electrons. Whether an electron is paired or not in the parent atom is a purely academic excercise--actually dependent on a variety of parameters unrelated to bond-ability. Irrational number makes a good point too...a so-called dative bond is only different in academic discussions of how a bond was made in a particular actual reaction, it's not a chemical fact or distinct type of result from other covalent bonds. The unpaired-electron definition is definitely not "correct" because of so many examples that can be visualized as dative--"what's the valency of nitrogen in ammonium?" is a good one to consider. However (at the risk of contradicting) one could consider all covalent bonds as being one electron from each atom, so therefore the definitions are literally identical (atom contributes an unpaired electron of its own to pair with another's to form a bond). But on the third hand (?) many molecules have truely unpaired electrons other than the bonding ones, and I don't think these are considered "valencies". DMacks (talk) 21:21, 19 August 2011 (UTC)

Indeed. The ground state of dioxygen has two unpaired electrons, a fact which cannot be predicted via lewis theory but can be predicted via molecular orbital theory and is borne out by experimental evidence and physical/chemical properties. Valency just refers to how many bonds an element will normally form in molecules. This is (for the basic, first-time-they-have-ever-seen-it) chemistry student roughly equivalent to the number of unmatched dots in the lewis dot diagram of the atom. Pedagogically, it can make more sense to teach this to a student as an approximation, and then build up to more accurate models of molecular bonding, like MOT. --Jayron32 00:10, 20 August 2011 (UTC)

US presidents in the military

Have any US presidents served in the military (US or colonial), but were not an officer?

PS I just noticed I accidentally placed it on the science section. How can I move it to humanities? Googlemeister (talk) 19:49, 19 August 2011 (UTC)

List of Presidents of the United States by military service shows only Private James Buchanan. Clarityfiend (talk) 20:02, 19 August 2011 (UTC)

Seems like James Buchannon is the only one then. Thanks. Googlemeister (talk) 20:04, 19 August 2011 (UTC)

To answer your afterthought, you could just cut/copy and paste. Dismas|^(talk) 20:06, 19 August 2011 (UTC)

Trying to remember the name of bioinformatics / computational biology researcher [SOLVED]

I am trying to remember the name of a man who began his career in finance (investing, private equity, etc.) and now leads an eponymous independent research group doing interdisciplinary research in next-gen biology, medicine, computer science, mathematics, etc. I recall that his group is located in New York City, and it's one of those "I'll know it when I see it" sort of things. Does this ring a bell to anyone? I know I'm not giving you much to work with, but it's all I remember. Thanks! Registrar (talk) 19:55, 19 August 2011 (UTC)

David E. Shaw. Looie496 (talk) 20:14, 19 August 2011 (UTC)

Perfect!! Thank you so much! Registrar (talk) 20:15, 19 August 2011 (UTC)

Why is the moon (a) red and (b) missing the top?

I am reasonably sure the answer to (b) is cloud cover, especially since after I started typing this the top of the moon has reappeared through the cloud leaving just a strip through the moon . But sitting here on my roof garden in London I am seeing an unmistakeably red moon. What's with that? Incidentally even through typing this the moon has moved enough it's now the bottom of it missing! That was damn quick! Egg Centric 21:05, 19 August 2011 (UTC)

If the moon is close to the horizon, I believe it appears red or orange due to the thickness of atmosphere. This coloring is caused by the same mechanics as a sunset. --Daniel 21:11, 19 August 2011 (UTC)

Same reason why the sky is blue, actually. — Kieff | Talk 21:12, 19 August 2011 (UTC)

The above explanations are rather prosaic. I prefer Tiamat. μηδείς (talk) 21:14, 19 August 2011 (UTC)

I believe this is called a blood moon, and is most common in autumn, as the Moon is low on the horizon just after sunset then. StuRat (talk) 21:19, 19 August 2011 (UTC)

Thanks all. Had I known about the blood moon article I'd have taken a pic - as with respect the one on that article doesn't really work. The moon is now jaundice yellow but I see no reason I can't capture it on Sunday night and will aim to. Egg Centric 21:24, 19 August 2011 (UTC)

I believe it is now known as a pee moon. jk -- Obsidi♠n Soul 00:18, 20 August 2011 (UTC)

Moon's apparent position in the sky is not seasonal, it is lunar-monthly. There's no special position for Moon during the autumn. Nimur (talk) 23:53, 19 August 2011 (UTC)

Our article says "the orbit of the Moon makes a narrow angle with respect to the horizon in the evening in autumn". Is that wrong ? StuRat (talk) 07:07, 20 August 2011 (UTC)

That statement is incorrect. First of all - observed from what point on Earth? Moon's apparent trajectory in Autumn in Florida is different than Autumn in Norway, let alone Australia! Latitude will have a much more significant effect on Moon's apparent traversal through Earth's sky. For the very interested reader, there are entire chapters in the book Strange World of the Moon (V.A. Firsoff, 1962), describing both technical and aesthetic qualities of Moon's orbit. Some quantitative analysis of Moon orbit is presented in the annex. If you're interested in graphically observing the Moon's orbit, I recommend the following software: Celestia, which is free software that renders a fly-around 3D universe and accurately depicts Moon's orbit. KStars is a free software tool for the more technical user, rendering sky-maps. Personally, I prefer a very old Windows program called CyberSky (or csky). It is neither free nor open-source, but it is excellent. You can set up an animation - for example, you could set each animation timestep of the sideral or solar year, to see each Autumn - and accurately simulate the variations in Moon's orbit as viewed from any time or place on Earth. We also have an article, Orbit of the Moon. Our links provide technical orbital parameters (ephemeris); I would say "by inspection! ...it is obvious, that there can be no such specific autumn trajectory for Moon-rise..." But, unfortunately, I don't think that they teach how to read or interpret orbit ephemerides by inspection. Schools these days... They canceled the space shuttle program, so what can we expect. Nimur (talk) 19:45, 20 August 2011 (UTC)

High levels of smog can cause the Moon to appear dark-red. FWIW 67.169.177.176 (talk) 04:33, 20 August 2011 (UTC)

Gas and carbon monoxide poisoning

From the Sylvia Plath article: "They found Plath dead of carbon monoxide poisoning in the kitchen, with her head in the oven, having sealed the rooms between herself and her sleeping children with wet towels and cloths." Why would she die of carbon monoxide poisoning? CO is the product of combustion, which was not happening here. Shouldn't she have died of asphyxiation by the gas? Quest09 (talk) 23:12, 19 August 2011 (UTC)

No. She died in London in 1963. At that time, the gas used for cooking was town gas, which contained ąbout 10% carbon monoxide. The switch to natural gas (methane) was undertaken several years later. Dominus Vobisdu (talk) 23:31, 19 August 2011 (UTC)

Sounds like bullshit. If there was inadequate combustion air, then carbon monoxide could have done her in, even if pure methane was the supplied gas. It is a wonder she did not inadvertently or carelessly kill the rest of her family, like careless assholes who have committed "suicide by automobile" in the attached garage. "Death from carbon monoxide present in the supplied gas" is absurd. Every customer of the gas company would have been at equal risk of such death. Edison (talk) 00:38, 20 August 2011 (UTC)

I'm not following that rant. There was no combustion. --Tagishsimon (talk) 00:42, 20 August 2011 (UTC)

(edit conflict)Coal_gas#Composition disagrees with your assessment that there wasn't any carbon monoxide in the gas. The same article also notes that accidental carbon monoxide poisoning because of its presence in coal gas was known to happen, and was part of the reason why the gas was discontinued in favor of natural gas. It's one thing to have a sense that something may be wrong, and it is another thing to look it up, and then find out the facts. It looks like you forgot to do the latter, Edison. --Jayron32 00:47, 20 August 2011 (UTC)

It is fair to request references. Edison (talk) 03:36, 20 August 2011 (UTC)

@Edison: Check your facts before you spout off. Yes, every customer WAS at risk. Suicides and accidental deaths were a major problem with town gas. That's why the British government invested so much money to switch over to natural gas when the North Sea reserves were found. Read the article. Dominus Vobisdu (talk) 00:48, 20 August 2011 (UTC)

Ok, references, please that the smelly, obsolete and dangerous "town gas" was still supplied to her London apartment in 1963, rather than natural gas. And was there an inquest? Did it say she died from CO poisoning rather than asphyxiation (lack of oxygen)? CO poisoning would have left her complexion cherry red and blood tests would have been clearly determinative. If her apartment was supplied with "town gas," did it incorporate a mercaptan odorant which would have alerted neighbors, or was it odorless in its deadliness through negligence by the local gas company? Edison (talk) 02:36, 20 August 2011 (UTC)

Once again, the clues are in the Coal_gas#Change_over_to_natural_gas article, did you but have time to read it. Sentences such as ""The slow death of the town gas industry in the UK was signalled by the discovery of natural gas, by the ill-fated BP drilling rig Sea Gem on 17 September 1965" and "The Fuel Policy White Paper of 1967 (Cmd. 3438) pointed the industry in the direction of building up the use of natural gas speedily to 'enable the country to benefit as soon as possible from the advantages of this new indigenous energy source'." When in a hole, etc. --Tagishsimon (talk) 02:43, 20 August 2011 (UTC)

The late introduction of natural gas in the UK is indeed described in the section Coal_gas#Change_over_to_natural_gas, but it is odd that the introduction to the article says "It was the primary source of gaseous fuel both the United States and Great Britain until the widespread adoption of natural gas during the 1940s and 1950s." This earlier section implies earlier introduction of natural gas in the UK, and a tweak might clarify the much later availability in the UK than in the US, which led to my initial confusion. Edison (talk) 02:32, 21 August 2011 (UTC)

I've taken a flyer at rectifying that delinquency in this edit. --Tagishsimon (talk) 02:40, 21 August 2011 (UTC)

One more third party reference for you:

"The country was divided into sectors and an army of gasfitters went to work converting one sector at time, burning off the town gas from the pipes and fitting every house with new fittings. Over 40 million appliances were converted from 1967 to 1977 and cost British Gas £563 million. Although this was an amazingly large and expensive project it had the benefit of safety checking every gas appliance in the country. As a result deaths by burns or inhalation of gas went from 1,270 in 1963 to 745 in 1965 to just 271 in 1970; a significant reduction and saving of lives. " [3] --Tagishsimon (talk) 02:51, 20 August 2011 (UTC)

WP:OR here, but as I recollect it, town gas was anything but 'odourless' - when natural gas was introduced, they had to add a stink to it, to alert people to leaks. And yes, people could, and did, kill themselves by 'putting their head in the oven'. Indeed, you could kill yourself by carbon monoxide poisoning accidentally too, by turning the gas on, and not lighting it. These days, you'll blow yourself up instead - though I think that the gas concentration needs to be a little higher for this? AndyTheGrump (talk) 02:55, 20 August 2011 (UTC)

Town gas is odorless, too, and they had to add the stink to it as well. Also, methane isn't toxic, so you don't die of poisoning from natural gas, you die of lack of oxygen. The gas displaces the air in the space around you. The concentration of natural gas therefore has to be a lot higher than the concentration of highly toxic town gas. Dominus Vobisdu (talk) 03:18, 20 August 2011 (UTC)

They had to add a lot more stink to town gas because the gas was deadly in much lower concentrations than natural gas. So your memory is right. Town gas did smell a lot stronger. Dominus Vobisdu (talk) 03:33, 20 August 2011 (UTC)

Town gas has a natural odor from the hydrogen sulfide that forms from the sulfur in the coal during the coking process. 67.169.177.176 (talk) 04:31, 20 August 2011 (UTC)

There was no hydrogen sulfide in town gas when it reached the consumer. It had to be removed before the gas was routed to the consumer because it's extremely corrosive to the gas mains. The recovered sulfide was used to produce other sulfur based chemicals like sulfuric acid. Natural gas also has hydrogen sulfide in it that has to be removed. The stuff you get in your home is only the methane contained in the gas. All other substances are removed. Dominus Vobisdu (talk) 11:48, 20 August 2011 (UTC)

@Edison: Lost your reading glasses? The gas didn't become obsolete until the early 1970s. It's explained in the article on coal gas. And the source in the Sylvia Plath article is her biography by Connie Ann Kirk. Furthermore, town gas and natural gas by themselves are both odorless. There were a lot more accidental deaths and accidental fires and explosions from town gas until they started adding a smelly chemical to it so that consumers would notice if there was a leak. Town gas was used because it was made from coal, which Britain had plenty of at the time. Exploitation of the natural gas fields in the North Sea and deliver of it throughout the country became possible only in the mid 1960's. Besides, every gas stove in the UK had to be replaced or converted at considerable cost. Yes, she was probably cherry red as you say. There was no need to do any lab tests because there was no reason to doubt that she died of carbon monoxide poisoning. Like I said, suicide by inhaling town gas was a common occurence in those days. And yes, the cause of death by inhaling town gas is carbon monoxide poisoning, not asphyxiation. Dominus Vobisdu (talk) 03:18, 20 August 2011 (UTC)

Thanks to all. It is saddening to read of such massive loss of life due to the government allowing the coal industry to perpetuate "town gas." Seems like reckless disregard for the safety of the public to supply such a gas to residences, into the 1960's when they knew better. In my city it went away decades before the 1960's. The sites where it was made became expensive toxic waste remediation sites, because the carcinogen byproducts such as tar were dumped into the ground. The mercaptan odorants are so powerful that it is surprising no one noticed the gas early enough to save her. Presumably death from natural gas would be due to asphyxiation or explosion rather than CO poisoning as in the case of the older "town gas." Edison (talk) 03:36, 20 August 2011 (UTC)

surprising no one noticed the gas early enough to save her. Once again, the clue is in the article. She's reckoned to have put her head in the oven around 4.30 in the morning, having taken steps to limit the outflow of gas from the room. Is it really all that very odd that sleeping people in other properties slept undisturbed? --Tagishsimon (talk) 21:47, 20 August 2011 (UTC)

No problem. And yes, the cause of death with natural gas is asphyxiation because methane is not toxic. Dominus Vobisdu (talk) 03:46, 20 August 2011 (UTC)

It's hard to find news archive cases of oven monoxide suicide in the US. Just car-in-garage monoxide suicide. Found a 1976 article about how would-be suicides in Britain found extinguishing life more difficult, in fact "almost impossible," when they attempted the traditional oven-gas suicide during the "New Depression," because of the switch to North Sea natural gas.[4] says the suicide rate in Britain dropped by a third when they switched to natural gas. It was like providing a cyanide capsule to every citizen back in the "town gas" days. It's surprising that new stoves-kitchen ranges-hobs were required. Couldn't they have re-jetted or installed different orifices as when a new range is adapted from natural gas to propane? Edison (talk) 04:05, 20 August 2011 (UTC)

Yes, they did just replace the jets. I remember this being done in the 1970s. Wealthier homeowners were persuaded that they needed new appliances. Many things in life are toxic, and most of us just just took appropriate precautions. Your "cyanide capsule" is still available in every engine, and even in your electricity supply. Dbfirs 07:16, 20 August 2011 (UTC)

Regarding Edison's rant about "the government allowing the coal industry to perpetuate town gas", "reckless disregard for public safety", etc.: Yes, town gas was dangerous and could lead to accidental poisoning -- but the problem was, until the discovery of the North Sea deposits there simply wasn't any better option -- so your accusations of reckless disregard are completely baseless. And for the record, coal tar was not dumped into the ground, but processed into petrochemicals (aniline, phenol, naphthalene, etc.) or used as a substitute for fuel oil. (At least in American gasworks.) That stuff was valuable, and dumping it would have made no economic sense. 67.169.177.176 (talk) 04:29, 20 August 2011 (UTC)

It would be more productive to provide refs for your claims than to indulge in the personal attack of characterizing my posts as "rants." You haven't provided any referenced information "for the record," just assertions. I agree that coal tar was a valuable and useful substance, used for roofing, roads, preservation of timbers, and a feedstock for the chemical industry. By the 1970's its carcinogenic qualities led to its not being used much for roofs in the US. Maybe there was a manufactured gas plant, somewhere, where the byproducts were all converted to useful products and sold, without leaving serious pollution in the ground for future generations to deal with. But ground pollution was a serious problem at many. I have been involved in planning the re-use of such sites, and know the costs and project delays due to removing the contaminated soil. I have also been at present day refineries, and seen "valuable" petroleum distillates dripping onto the ground from valves in need of service. Your blanket claim of no pollution, especially no coal tar residue, is disproved by news archive results: [5]: "Heavy metals, tars and a gas-manufacturing by-product known as Blue Billy, which may pose a health risk if ingested, have been found about a foot below the surface." And wear heavy gloves when weeding. "Billy Rose" may be a residue from the process to clean the gas. See also [6]. See [7], which says many manufactured gas sites are now toxic waste sites. [8] says manufactured gas production left coal tar deposits at 150 sites in Illinois. [9] says cleaning up coal tar from those sites could cost taxpayers or utility ratepayers millions of dollars. [10] describes one town gas with lots of ground pollution from petroleum products. [11] notes that the final cleanup of the gas left much of the present pollution,including various poisons, besides the coal tar resulting directly from the coal gasification. [12] documents one site with countless tons of coal tar to be removed from the ground. [13] discusses the many contaminated gas plant legacy sites in Britain, and says that British Gas has tested the soil, but claims the results are "commercially confidential information." Edison (talk) 19:43, 20 August 2011 (UTC)

Regarding my characterization of your rants about "reckless disregard", I stand by that assertion because that's what they are -- completely unreferenced, unsupported and counterfactual. Just because a product (town gas, in this case) is dangerous to use without special precautions DOES NOT make selling it "reckless disregard" of anything -- the essential requirement for reckless disregard is that the industry COULD HAVE offered a substantially safer product instead (which they COULD NOT until the discovery of the North sea deposits) but didn't. And just so you know, these kinds of false accusations have legal consequences.

As for dumping of coal tar into the ground vs. reporcessing it: see Coke and Coal Chemicals for the various separation techniques and uses of coal tar byproducts (some of the light fractions were even used as gasoline additives at one time, and in fact a large part of the world's naphthalene production is still derived from coal tar). In fact, if you do read that book, you will see that coal tar was completely utilized at most coke plants. Which is not to deny that there was a lot of accidental contamination (from leakage and the like), so you're on somewhat more solid ground there (as opposed to your wild and slanderous claims of reckless public endangerment with town gas); however, your wording in the original post seems to imply that there was large-scale deliberate dumping of coal tar or its fractions at many British gasworks, which is demonstrably not the case. 67.169.177.176 (talk) 20:59, 20 August 2011 (UTC)

Your apparent threat of legal action for defamation violates the Wikipedia policy WP:NLT, so I request that you remove it. Edison (talk) 02:09, 21 August 2011 (UTC)

Still digging, eh? Asserting that you slandered the British government does not amount to a legal threat. Ah well. --Tagishsimon (talk) 02:15, 21 August 2011 (UTC)

The post in question, from an IP account, linked to the article on actions for defamation, and is definitely a threat of legal action as the Wikipedia policy interprets same. Edison (talk) 02:21, 21 August 2011 (UTC)

Yup, on a second reading, I concur, and so apologise. --Tagishsimon (talk) 02:22, 21 August 2011 (UTC)

Correction: the book I referred to is called Coal, Coke, and Coal Chemicals, by Philip J. Wilson. It's really old, but it does have a lot of useful info on byproduct recovery from coke and town-gas production, as well as environmental protection at coke plants and gas works. (And since then, the pollution abatement technologies could only have improved, no?) Anyone who is interested in any aspect of the coke and town gas industry would do well to check it out. 67.169.177.176 (talk) 22:01, 20 August 2011 (UTC)

And just so you know, I never said there was ZERO pollution from coal tar residue (totally unrealistic); the claim I made was that coal tar was reprocessed and not discarded (demonstrably true). I've worked in an oil refinery, so I know whereof I speak -- there, too, ALL products are put to use (through various upgrading processes, if need be) and none are just thrown away, but there is still considerable pollution from fugitive emissions. I wonder why don't you also slam all the oil refineries in the world for "dumping toxic petroleum residues in the ground and turning it into a waste dump"? Oh, I get it now -- it's because oil refineries are still essential to our way of life, while gas works are no longer so and therefore it's OK to drag the coal-gas industry through the mud but not the oil industry. Well, my answer to that is: even though gas works are no longer needed, they used to be essential in the recent past, and without them lots of Englishmen, Americans, etc. would have faced much worse pollution (not to mention enormous hassles and inconvenience) from having to burn coal in their own homes. Next time you feel like maligning the town gas industry, remember what I said to you just now. 67.169.177.176 (talk) 21:19, 20 August 2011 (UTC)

Note that it is possible to die of carbon monoxide poisoning from methane. Here's a typical scenario:

1) Homeowner has all the burners and oven on full, with the oven door open, say to heat home when their furnace is out of order. Kitchen doors are all shut, to warm up kitchen.

2) Homeowner goes to sleep in bedroom, with door closed, and say an electric space heater keeping that room warm.

3) Meanwhile the stove and oven are using up the available oxygen in the kitchen more quickly than it can be replenished from leaks in the walls and around windows and doors.

4) After several hours, the free oxygen is so scarce in the kitchen that combustion starts to create large quantities of carbon monoxide, rather than carbon dioxide.

5) Homeowner awakes, goes to kitchen to make breakfast, and gets a fatal dose of carbon monoxide, dying some time later. (They might also suffer the effects of low oxygen, but those alone would be quickly remedied by leaving the kitchen, while the CO poisoning is not.) StuRat (talk) 07:01, 20 August 2011 (UTC)

Possible, but IMHO this scenario (with all the burners and oven going full blast overnight) would be more likely to cause a house fire from backdraft than CO poisoning. Explanation: At stage (5), when the homeowner opens the kitchen door, the hot, CO-rich gases filling the kitchen mix with the oxygen-rich air in the bedroom (remember, CO is a flammable gas as well as toxic) -- a classic backdraft scenario which causes the CO to ignite explosively, starting an intense fire. See the articles on backdraft and flashover for more details. 67.169.177.176 (talk) 08:16, 20 August 2011 (UTC)

You have obviously never overwinternighted in a slum, the situation is extremely common. μηδείς (talk) 02:38, 21 August 2011 (UTC)

Never been inside one. Why would I, unless I have to? 67.169.177.176 (talk) 23:20, 22 August 2011 (UTC)

The kitchen would be nowhere near combustion temperatures. An oven can warm an entire kitchen, but not by hundreds of degrees. StuRat (talk) 07:06, 21 August 2011 (UTC)

Yes, on second thought that is right. Thanks for the correction. The more likely scenario is that an explosive mixture would form, and if the burners are still lit (or if they have gone out but there's another ignition source -- maybe a light switch or something), there could well be an explosion. 67.169.177.176 (talk) 23:20, 22 August 2011 (UTC)

Gas fires turned down too low, giving a yellow flame, release more CO and sometime enough to kill. [14] --Aspro (talk) 15:25, 20 August 2011 (UTC)

Anyhow; in my 1960s London childhood, it was a common expression for exasperated adults to say "It's enough to make you want to put your head in the oven". It was a well known method of suicide back then. See also "I tried to commit suicide by sticking my head in the oven, but there was a cake in it" and "I never said I was an optimist. I have hope because what's the alternative to hope? Despair? If you have despair, you might as well put your head in the oven"[15]. Alansplodge (talk) 19:37, 21 August 2011 (UTC)

BTW our own article says

Natural gas heating systems are a minor source of carbon monoxide deaths in the United States. According to the US Consumer Product Safety Commission (2008), 56% of unintentional deaths from non-fire CO poisoning were associated with engine-driven tools like gas-powered generators and lawn mowers. Natural gas heating systems accounted for 4% of these deaths. Improvements in natural gas furnace designs have greatly reduced CO poisoning concerns. Detectors are also available that warn of carbon monoxide and/or explosive gas (methane, propane, etc.).

Nil Einne (talk) 13:09, 22 August 2011 (UTC)

AFAIK most of those deaths are due to obstructions in the flues, which cause the gases to back up into the house. 67.169.177.176 (talk) 23:23, 22 August 2011 (UTC)

What flue? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 20:34, 31 August 2011 (UTC)