Wikipedia:Reference desk/Archives/Science/2016 April 23

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April 23

Meaning of Berl. Ber.

In citations in scientific papers, I've seen German sources cited as [Author name] Ber. Ber. [year]. What does Berl. Ber. mean? Something or other Berlin?? 121.215.1.130 (talk) 03:54, 23 April 2016 (UTC)

I believe it's an abbreviation of berliner sitzungsberichte, meaning 'Berlin meeting reports,' and it refers specifically to the Proceedings of the Royal Prussian Academy of Sciences in Berlin. Sandbh (talk) 05:58, 23 April 2016 (UTC)

How can I get a copy of a paper that does not appear to be available anywhere online?

I am looking for LeMessurier and Hills. (1965) Decompression Sickness. A thermodynamic approach arising from a study on Torres Strait diving techniques. Hvalradets Skrifter, Nr. 48, 54–84. I cannot find it on the internet and none of my academic contacts have been able to get it through their university libraries. I live outside of Cape Town in South Africa and have no access to major libraries. I need the paper both to verify existing article content and to write an article on the content of the article, which is a major landmark in its field. • • • Peter (Southwood) ^(talk): 06:45, 23 April 2016 (UTC)

The best place to go to on Wikipedia is WP:REX. If that is not successful, many libraries (even smaller ones) offer interlibrary loans for a small fee. --Stephan Schulz (talk) 08:01, 23 April 2016 (UTC)

You could try emailing the Academy itself. Their email address is at the bottom of this page.[1]--Aspro (talk) 11:51, 23 April 2016 (UTC)

Thanks, I have e-mailed them, • • • Peter (Southwood) ^(talk): 17:14, 23 April 2016 (UTC)

Let us know how you get on. This journal is now defunct (the tide against whale hunting I suppose) but as these two guy did much of their reseach in Australia, their libraries show this Journal on their catalogs.--Aspro (talk) 01:25, 24 April 2016 (UTC)

I should be able to email this article to you in a couple of days, if that would help. Sandbh (talk) 10:05, 27 April 2016 (UTC)

Salts

I need a few answers when it comes to chemistry. After finishing a unit on acids, bases, and salts, I got a good score but I honestly don't understand a thing. So my questions are, how do precipitation and titration work? (like really work, not: they work because ... science), what defines a salt?, and what is the difference between an acid and a base? (not just pH-wise, chemically). Thanks. Jdbepono (talk) 06:49, 23 April 2016 (UTC)

The term salt is used broadly in chemistry to refer to any ionic compound where the cation is not the hydrogen ion and the anion is not the oxide or hydroxide ion. A more narrow definition is that a salt is the ionic compound that results from the reaction of an acid with a base, but that is practically restricted to Arrhenius theory (wherein acids were substances that produce hydrogen ions in solution and that bases were substances that produce hydroxide ions in solution). A simple salt like magnesium chloride (MgCl₂) satisfies both definitions in that it is ionic with cation Mg²⁺ and anion Cl⁻ and the salt can be produced from an Arrhenius acid-base reaction:

2 HCl + Mg(OH)₂ → MgCl₂ + 2 H₂O

However, if I describe Zeise's salt with formula K[PtCl₃(C₂H₄)]·H₂O as a salt, you will struggle to produce it in an Arrhenius acid-base reaction. The base would be potassium hydroxide (KOH) but the required acid would have the anion [PtCl₃(C₂H₄)]⁻ and thus be H[PtCl₃(C₂H₄)], which is unlikely to exist (especially in water).

The definitions of acid and base change depending on the level of theory used, from Arrhenius to Lowry-Brønsted to Lewis theory. Under Arrhenius theory, HCl is an acid because the gas ionises to produce the hydrogen ion in aqueous solution

HCl (g) → H⁺(aq) + Cl⁻(aq)

and NaOH is a base because it dissociates to produce the hydroxide ion in solution.

NaOH (s) → Na⁺(aq) + OH⁻(aq)

The reaction of HCl with NaOH can be written as

HCl (aq) + NaOH(aq) → NaCl(aq) + H₂O(l)

and can reduced (like all acid-base reactions under Arrhenius terms) to:

H⁺(aq) + OH⁻(aq) → H₂O(l)

Under L-B theory, acidity relies on the ability to donate protons (H⁺) and so HCl(g) is acidic as it donates protons to its solvent in water:

HCl (g) + H₂O(l) → H₃O⁺(aq) + Cl⁻(aq)

The resulting hydronium ions react with the hydroxide ions from the NaOH in another L-B acid-base reaction:

H₃O⁺(aq) + OH⁻(aq) → 2 H₂O(l)

Lowry theory is not really a great way to look at aqueous reactions of simple acids and bases like these.

Turing to an acid–base titration with the acid in the burette and the base in the conical flask. A small amount of indicator is added and the acid-form of the indicator (colour A) will react with the base in the flask producing the base form (colour B). As the acid is slowly added from the burette, the reaction occurring is mostly between the acid and the base. However some acid + base form of the indicator occurs, leading to colour changes as small amounts of the acid form of the indicator are formed. Since the amount of base present is still large (compared to the amount of indicator), this reaction is quickly reversed. The idea of a titration is to find the equivalence point, when the acid added from the burette is exactly the amount needed to react with all of the base in the conical flask. If the indicator chosen is appropriate then the next drop after the equivalence point will react to change the base form of the indicator to the acid form and produce a permanent colour change. We measure the end point (the colour change) and assume that it is a good to very good approximation to the equivalence point we sought. If our technique is good and the indicator is appropriate (which means the pH range within which it changes colour corresponds to the pH at the equivalence point) then the assumption is valid and we get useful results. If we choose poorly, the end point may not be near to the equivalence point. The equivalence point cannot be directly measured using colourimetric titration. EdChem (talk) 08:06, 23 April 2016 (UTC)

The numeric scale called pH that specifies the acidity or basicity (alkalinity) of solutions may give more general understanding than individual reactions. pH is a physical electric measure of the activity of the hydrogen ion: solutions with a pH less than 7 are acidic and solutions with a pH greater than 7 are basic. Titration is the quantitative measurement of the amounts of an acid and a base that together yield a neutral solution i.e. their "salt plus water" product, that is detected by eye with the aid of a pH indicator substance. A well known example of a pH indicator is Litmus which consists of organic dyestuffs, typically dried on paper strips, and displays the colors Red = strong acidic or Blue = string basic. The point of change between these colors i.e. purple indicates that the titration product is close to neutral (pH = 7 approx.). The linked article mentions other indicators, their colors and pH ranges; what they have in common is that they are chemical detectors for hydronium ions (H₃O⁺) or hydrogen ions (H⁺) in the Arrhenius model. AllBestFaith (talk) 09:48, 23 April 2016 (UTC)

That first answer kind of makes my eyes glaze over, so I think I'll try to give you another bite at the apple. I don't promise this will be any better. :)

• To start with, precipitation is a matter of solubility. If a given set of compounds stays uniformly distributed in solution, they stay dissolved. But sometimes you get a positive and a negative ion that get together and create an attractive place for more positive and negative ions to stick. Or you have a chemical in solution but you add another solvent, and now it sticks to itself better than it sticks to the combined solvent. So at some point there is nucleation and the compound manages to get a small organized particle set up that keeps pulling more and more out of solution. Eventually, a saturated solution (mother liquor) remains, and the rest is usually some sort of crystal (though if the process is rushed the substance can come out as an oil or something with a less well defined structure).

• titration is something completely different. You're just slowly adding solution A to solution B, stirring carefully, until something happens. Usually that something is a color change in an indicator dye as the pH changes. The pH changes depend on the buffers present in solution, but if you have just strong acid versus strong base you have a sharp equivalence point even if your pH indicator works over a large range, because the pH changes so fast in the middle.

• A salt can be defined as an acid + a base, or as something without H+ or OH- (as described above). The definition can get technical, as described well above; I'd say the main effect of all that qualification is that people expect "salts" to be sort of neutral-ish, but you can come up with some weird cases where they are quite corrosive.

• The fundamental difference between acids and bases is that some are electron haves and some are electron have-nots. The classic acid is a proton, a lone hydrogen nucleus with no electrons, H+. It tends to wander around looking for anybody with electrons to hang off of, including water molecules so it is usually hydronium. By contrast, a base is something like ammonia, which has a lone pair because nitrogen starts with 5/8 electrons in a quantum shell. The shells are determined by the geometry of how waves of electrons can circulate around an atom in orbitals (this is quantum mechanics), and they mean that nuclei with some numbers of protons will tend to want more electrons around them than protons, and other numbers of protons will tend to want less. Some things like hydrogen can kind of go either way to get to a preferred quantum shell, losing or gaining an electron (the H- is called hydride and much rarer to see though). Anyway, these funny rules create all kinds of compounds that are looking to gain or lose electrons, hence the Lewis acid definition. But in aqueous solution most of them get cashed in for H+ or OH- in the end, which is why simpler definitions in terms of H+ and OH- are useful in many situations. Wnt (talk) 21:00, 24 April 2016 (UTC)

• As the resident chemistry teacher, let me take a go at this:

  A salt is a crystalline ionic solid, which is also not an Arrhenius acid or an Arrhenius base. That's probably the best, most inclusive definition I can give.

  Precipitation is the process whereby you mix two solutions and a solid (powdery) product forms. If you have two clear solutions, and mix them, and it goes all cloudy, that's precipitation. It's usually a type of double replacement reaction, and it happens when one of the products of that reaction is relatively insoluble, compared to the reactants. The easiest heuristic is known as the solubility rules, but eventually you'll learn to deal in equilibrium expressions like the solubility product to predict this.

  Titration means careful mixing of two solutions for the purpose of quantitative measurements; that is how much of solution A needs to be mixed into solution B to produce some sort of visible chemical change (color change, pH change, precipitation, etc.)

  What defines the difference between an acid and a base depends on which theory you're working with (theory = model). That is,

  Arrhenius acid base theory explains that an acid produces hydronium ions in water, while a base produces hydroxide ions in water.

  Bronsted-Lowry theory removes water from the explanation, and attempts to make acids & bases defined in relation to one another. Picture a simple chemical reaction where a hydrogen ion (H+) is exchanged between two substances. The one that gave the hydrogen ion is an acid; the one that got the hydrogen ion is a base.

  Lewis acid-base theory is sometimes also brought into the discussion, and it explains acids and bases in terms of bond formation: in the formation of new chemical bond (where a bond has 2 electrons) you often get a situation where one substance has a "lone pair" of electrons (more negative), while another substance has an open orbital (more positive) in which to receive those electrons. In this case, the species giving up the extra electrons is a base, and the one getting the extra electrons is the acid. Lewis theory is often considered too broad by many chemists, so when one talks about "Lewis acids" or "Lewis bases", one is considering substances that don't often meet the strict definition of an acid or a base. Many who don't like these terms (often organic chemists) have come to using the terms electrophile and nucleophile to avoid the confusion between this theory, and the other two.

  Hope that helps a bit. --Jayron32 21:16, 24 April 2016 (UTC)

I resolved two redlinks in your post. DMacks (talk) 02:19, 25 April 2016 (UTC)

Leyden jar

Was the Leyden jar ever used in warfare to zap enemies? 2601:646:8E01:515D:D52:C360:441C:37B8 (talk) 10:47, 23 April 2016 (UTC)

I've not found any examples of such .It was used to zap friends, such as a group of soldiers to amuse their rulers or a group of monks who somehow got volunteered to all take a shock. It was at least powerful enough to kill birds. It could have been used as a gimmicky novelty defense of a structure, as when they grab the doorknob, not knowing it is connected to a Leyden Jar with the other terminal connected to earth, they get knocked on their ass as if Tasered.The challenge was keeping the hot lead insulated so the charge did not drain off. In experiments in the 1740's they used insulated wires (supported by insulators) to carry the charge a mile or more See the book The History and Present State of Electricity, 1775 edition, by Joseph Priestly at [2]. It would have been effective for torture, but once batteries were developed an induction coil would have made a more effective torture device, and they already knew all about lots of other simple to use torture devices. Edison (talk) 12:39, 23 April 2016 (UTC)

Back in the day, they were regularly used to zap schoolboys for the nefarious amusement of physics teachers. Alansplodge (talk) 16:49, 23 April 2016 (UTC)

In the next World War, you might find one useful as a simple electroscope-ionization chamber fallout meter with which fallout radiation can be measured accurately.[3]. The ionizing radiation depletes the charge in the jar, giving you a good estimate of hour many hours, days or months it will take you to die from radioactive fall out.--Aspro (talk) 01:39, 24 April 2016 (UTC)

Maybe. --Jayron32 21:05, 24 April 2016 (UTC)

Yes,condensers are well know for self-charging which is why large ones are shipped with a shorting link - but it takes time. In a dry climate and given enough time, the ark may have done what it is reputed to have done.--Aspro (talk) 19:52, 27 April 2016 (UTC)

Who was it?

Who was the person who invented scissors ? 210.56.124.57 (talk) 16:05, 23 April 2016 (UTC)

See Scissors#History. --Dr Dima (talk) 16:45, 23 April 2016 (UTC)

Overload question

In Arthur Hailey's novel Overload, there is a scene where a lineman gets zapped with 500 kV (!) from a high-voltage power line, gets badly burned (including getting his dick vaporized), but survives -- is this even remotely plausible? 2601:646:8E01:515D:D52:C360:441C:37B8 (talk) 11:23, 23 April 2016 (UTC)

I've posted the above on the user's behalf due to an edit filter false positive. Jackmcbarn (talk) 18:19, 23 April 2016 (UTC)

I've disambiguated the OP's link to the novel, and fixed the spelling of the author's name to avoid the redlink. Loraof (talk) 18:38, 23 April 2016 (UTC)

According to our Electric shock article, the record is held by one Harry F McGrew of Utah, who survived 340 kV. However, although our article states that this is from Guinness World Records, it doesn't appear on their site, and no reference to the book is given. Appropriate tags have been added to the article. To answer the OP's question, 500 kV is (just about) plausible, but rather more than the actual maximum that (apparently) has been survived. Tevildo (talk) 19:08, 23 April 2016 (UTC)

Thanks to Wnt, we have a more definite reference for one Brian Latasa, who survived 230 kV in 1967. Further away from 500 kV, of course - it might be possible to survive it, as it's possible to survive falling 30,000 feet out of an aeroplane, but it's extremely unlikely. Tevildo (talk) 21:24, 23 April 2016 (UTC)

Well, it's a reference, but it's a reference to a Guinness comic strip. There's no motivation for them not to overstate the case. For example, he might not have been grounded, and been shocked solely from the capacitance of his body and perhaps some other object as the alternating current went back and forth. (I think people working on high tension lines can touch them safely if not grounded, but I don't know if that holds for extreme voltages. In any case, you need merely postulate a lump of metal as large as needed to make the capacitance cause a small burn!) The other one, well, I commented on the talk page that it was "fixed" from an initial "Mgcrew" by someone who apparently didn't have access to the source. At this point, I think I'm going to take it out because it is at least nominally an unsourced statement about a WP:BLP, and in any case, looks like dumpster scrapings on a plate. Wnt (talk) 21:30, 23 April 2016 (UTC)

Tevildo came up with a better reference for that case, which I've added ... the poor kid was reportedly burned over 40% of his body and completely paralyzed "except for the eyelids". Wnt (talk) 00:45, 24 April 2016 (UTC)

Do ostriches ever fledge?

I've just looked through multiple definitions of fledging/fledge. They almost all relate to flying or developing feathers enabling them to fly. Does this mean that flightless birds never fledge? Some (very few from my survey) definitions focus on the bird's ability to leave a nest. What about birds that do not make a nest - does this mean they don't fledge? (At this point, I am trying to think of a flightless bird that does not build a nest! - got one, the emperor penguin.) DrChrissy ^(talk) 19:04, 23 April 2016 (UTC)

Think the equivalent of 'fledge' for a penguin would be when the parents no longer look after the chick – left the bio-nest so to speak. Of course it can't fly or swim but is just stuck there on the ice looking cute and fluffy. It then becomes a fledgling when it molts away it downy feathers. --Aspro (talk) 02:16, 24 April 2016 (UTC)

• According to a story by (iirc) Larry Niven, an ostrich is a roc that never matures. —Tamfang (talk) 06:58, 25 April 2016 (UTC)

This is like "Is a hamburger a sandwich?" right? Maybe yes, maybe no; if it matters just clarify. Anyway, fledgling-as-first-flight is basically the same time as leaving the nest for many birds, but not for e.g. ducks and geese. So the murkiness of the term comes up even for flying birds- if I say a wood duck fledged- do I mean it left the nest, flew, or did something else? The general gist of fledging is maturation, less dependence on parental care, etc. Flightless, non-nest-building birds generally all go through that process, and it might make sense to call it fledging. If you want to be guided by usage rather than definitions, here [4] [5] are a few peer-reviewed journal articles that discuss penguins fledging, meaning leaving the nest. SemanticMantis (talk) 14:09, 25 April 2016 (UTC)

There are several shades of meaning of "fledge".[6] One is to acquire feathers. Another is to be fit to fly. Another is to be ready to leave the nest. ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:46, 25 April 2016 (UTC)

That definition is not suitable for flightless birds though. Look a chicken (and this probable goes for penguins as well considering the temperature) they emerge out of the egg with downy feathers and not naked like other birds. A chicken chick can and does start pecking away and anything edible (an ostrich chick possible the same but I've never met one). They also follow mum around (or you if you incubated them yourself) A penguin chick has to be protected from the elements under one of the parents (bio-nest)and fed regurgitated food. Eventually they fledge and leave mum and dad to huddle with other baby penguins. Finely they become fledgling when the develop proper waterproof feathers. The evolution is the same, save that they already have feathers when hatching and the time taken to become fledglings is longer. Whether these chicks can be properly said to 'fledge' though I am uncertain but they do become fledgling. Lifecycle of the Emperor Penguin. By now DrChrissyhas probably emailed Dr. Lorenz and received a definitive answer back so can put us out of our misery, incase someone else posts a similar question here in the future. --Aspro (talk) 20:18, 25 April 2016 (UTC)

I think you are trying to draw a difference between precocious and altricial chicks. I'm not sure why you have included domestic chicken as flightless birds. They (egg laying chickens) can fly, although this is limited. My reason for raising question this is that our own Fledge article does not contain any sources and I wanted to get some feedback from others. I'll edit the article tomorrow. I think the summary to this one is - "depends which book you read"! DrChrissy ^(talk) 22:46, 25 April 2016 (UTC)

I included chickens as flightless birds as it is not their primary means of locomotion. Even I can run faster than they can fly. My observations are (from having kept them) is that retain some ability simply for the purposes that they can fly up into the branches of a tree to roost over-night out of the reach of predators. Country people that don't have fox proof en-closers, just put a roosting box onto top of a post. In the evening, the chickens make their way up the sloping tread-way that even a small fox won't climb. Given the choice, top hen (in the pecking order) roosts the highest.--Aspro (talk) 11:29, 27 April 2016 (UTC)

Stellar classification

If the entitled article is for population I stars, than what is for population II & III? -- Apostle (talk) 19:33, 23 April 2016 (UTC)

Population III stars are a theoretical concept - so far none have actually been identified. Population II stars are very rare - only a handful have been observed. That simply means that there are not enough of them to classify them. 81.132.106.10 (talk) 19:44, 23 April 2016 (UTC)

I thought subdwarfs (VI) were metal deficient hydrogen-burning stars. Like G2VI for a Sun-colored subdwarf. Metal deficient enough to be Population II? Sagittarian Milky Way (talk) 19:53, 23 April 2016 (UTC)

Any ideas/assumption/presumtion/hypothesis say for, if there was a population IV, V, VI stars and so on? Whether the temperature/K would be hotter than the current ones or not, at any stage/phase? -- Apostle (talk) 05:26, 24 April 2016 (UTC)

Astronomy is just starting to become capable of getting real evidence about what is out there (or in here). Just realize the contrast between all these wild theories about "dark matter" and the fact that we have no clue yet, nomatter its supposed to be everywhere around us. --Kharon (talk) 05:47, 24 April 2016 (UTC)

Please note that stellar population and spectral type (as discussed in the stellar classification article) are separate concepts. 91.155.193.199 (talk) 10:53, 24 April 2016 (UTC)

Yes I know, I'm concerned about the temperature of the populations because of primodial atom. - I understand everything roughly, but this thing is a confusion... -- Apostle (talk) 18:40, 24 April 2016 (UTC)

81.132.106.10, Sagittarian Milky Way, Kharon, 91.155.193.199: Thanks so far peeps -- Apostle (talk) 20:07, 27 April 2016 (UTC)