Chemistry is the study of matter on a macroscopic and microscopic. It helps us explain how subatomic particles--unimaginably small electrons, neutrons, and protons, and the even smaller quarks, positrons, neutrinos, and so on--interact to form the world around us.

All that we touch and all that we see (not to mention all that we buy, beg, borrow, or steal) is made up of tiny atoms of various chemical elements such as oxygen, nitrogen, sodium, and chlorine. These elements come together to form molecules and compounds. When you breathe in the air, the oxygen molecules you breathe are each made up of two independent oxygen atoms that have joined together. Common table salt is not an element, but rather two elements--sodium and chlorine--joined together to form a compound: sodium chloride.

In today's chemistry lesson, we'll examine the various elements and compounds that turn up in Pink Floyd's lyrics. For example, in "Word Song", Syd Barrett seems to have taken lyrics from a variety of sources (textiles, economics, cooking, geography, botany, military terminology, etc.). He included the names of several common elements: gold, helium, lead, neon, silver, tin, and copper. (Most of these are metals, and could have come from a geologic source, but it seems less likely that 'helium' and 'neon' did.) The lyrics include the chemical glycerine, a sugar alcohol widely used in industry, pharmaceuticals, and personal hygiene products. Barrett also mentions "liquids", a common enough word, but worth mentioning here because liquid is one of the four phases of matter.

And speaking of phases of matter, it should be noted that "Money" is, in fact, a solid and not a gas, as Roger Waters' lyric would suggest. (But mine certainly does seem to evaporate quickly enough.)

Chemically speaking, hydrogen is the simplest element: a single, lonely little electron orbiting a single proton... and yet it is estimated that about 75% of the universe's matter is hydrogen. Hydrogen is found abundantly in water, proteins, carbohydrates, petroleum, and so on. And carbon is almost as simple (six electrons orbiting a nucleus of just six protons and six neutrons) and seemingly just as abundant--it forms the backbone of carbohydrates, fats, petroleum, coal, graphite, diamonds, and so on.

Compounds of hydrogen and carbon are called (straightforwardly enough) hydrocarbons. If you string a dozen or so carbon atoms together and then fill up all the vacant bonding sites with hydrogen atoms, what you have, basically, is crude oil or petroleum. Petroleum is formed underground when millions of years' worth of biological matter (dead plants of the dinosaur era, primarily) undergoes millions of years of pressure and heating. And as petroleum-based fuels are the foundation of our modern economy, it is no wonder that petroleum-rich lands become the focus of political maneuvering. Roger Waters alludes to this in "Towers of Faith" from When the Wind Blows. After Muslim, Jew, and Christian has each made his case for a stake in the Middle East, a New York City businessman (no doubt representing everything that is wrong with American capitalist colonialism) sweeps in and declares:

Another Waters lyric mentions hydrogen and carbon in connection with another political hot-button issue: industrial pollution. In "Breathe" from Music from The Body, Waters warns us to "savor the grass while it lasts", decrying the "spidery fingers of industry" that threaten to ruin the environment and render the planet uninhabitable.

These are beautiful lyrics (and ones which would have been perfect for Waters' appearance at Live Earth, rather than Yet Another Rendition of "Money" and "Another Brick in the Wall"), as moving in 2007 as they must have been in 1970.

Sulfur (which is the accepted international spelling, rather than the British 'sulphur') is a common element that, like carbon and hydrogen, is essential for life. Nonetheless, sulfur has a nasty reputation for a couple of good reasons. First of all, it stinks. Sort of. Elemental sulfur is odorless, but it readily binds with hydrogen to form hydrogen sulfide, which gives the foul, rotten-egg smell that is commonly associated with sulfur. Hydrogen sulfide is generated during the refining of petroleum, and is quite toxic in high concentrations. More importantly, industrial combustion of coal and petroleum produces large amounts of sulfur dioxide, which reacts with water in the atmosphere to form sulfuric acid, contributing to acid rain.

Lime is not an element, but is rather a general name for a group of calcium salts such as calcium carbonate, calcium oxide, calcium hydroxide, and so on. It is widely used in industry and agriculture in various forms, and although some forms of lime are caustic, most are benign.

Nicotine is an organic molecule made up of carbon and hydrogen along with two atoms of nitrogen. Occurring naturally in tobacco and other plants, it acts as a stimulant in humans (and is highly toxic to insects). It also stains the clothes, teeth, lips, and fingers of smokers, as noted in "Nobody Home" ("I got nicotine stains on my fingers").

Silicon is similar to carbon in many ways, but is much less chemically reactive. It shares some properties with metals, but doesn't quite meet the chemical criteria for metals, and is thus one of a handful of elements called 'metalloids'. Silicon is a semiconductor, which means (basically) that it can be made to conduct electricity under the right conditions. As such, silicon is widely used in electronics. In "The Tide is Turning", Waters depicts a communications satellite's "silicon heart" being warmed by the sight of human beings communicating and working together instead of blowing up one another. Silicon is also mentioned in "Not Now John", perhaps as a reminder that the Japanese domination of electronics manufacturing, like shipbuilding, has caused a shift in global economic power and puts new strain on the British working class.

(As a point of clarification, the element silicon is to be distinguished from silicone, which is a group of polymers made of silicon and oxygen. That is, Waters was not blaming Pamela Anderson for the downfall of the British working class.)

Poetically speaking, gold is used to describe something exceedingly beautiful and desirable. It is also used because it seems more romantic and expressive than more common colors like 'yellow'. Barrett borrowed James Joyce's poem "Golden Hair" for a lyric, and it is impossible to think the song (or the poem) would be as compelling under the title "Blondie". Likewise, the chorus of "Stay" speaks of "Midnight blue, burning gold", which conjures up the romance of the love affair the song describes.

One of my favorite early lyrics by Roger Waters is from "Grantchester Meadows":

The image of sunshine coming down in little 'flakes' is lovely--a summertime corollary to the snowflakes that settle on the same ground in the winter months. (And from a scientific point of view, I wonder how much Waters knew about photons and the wave-particle duality of light when he described light in discreet particles rather than sunbeams or rays. But this is chemistry class, not physics.) Calling these sun flakes 'golden' is surely a testament to their beauty and warmth.

Sometimes 'gold' literally means... gold. "San Tropez" speaks of 'digging for gold', a phrase that refers to mining gold out of the ground. (It isn't clear to me what the lyric actually refers to, however, but I don't think he's actually looking for gold in a hole in his hand.) Prospecting for gold is also referenced in "The Gold It's In The..." from Obscured by Clouds. The title and the first verse call to mind the cliched phrase "There's gold in them thar hills!" In this case, the song's speaker is joining a group whose quest is for gold, though his particular aim is for adventure and 'thrills' rather than riches. But the idea of going on a journey in search of gold comes from the plot of La Vallee, in which the characters go off in search of valuable feathers and the mysterious paradise in the hidden valley.

In "Sea Shell and Stone" from Music from The Body, we are urged to "search for the gold", though in context this seems not to be a quest for material wealth but rather a search for something more valuable: harmony with nature. The lyrics seem to speak of the Earth in its pristine state, untainted by mankind (in stark contrast to the lyrics of "Breathe", which are sung to a nearly-identical backing track), and "gold" is used as a symbol of value.

Gold is also used to represent money, wealth, and prosperity. In the Zabriskie Point outtake "Country Song", the Red Queen gives instructions to 'Run to the Treasury and bring me back some gold,' making payment to the messenger pawn. "Your Possible Pasts" speaks of speaks of a woman who wants to separate men from "the gold in their bags". In "What God Wants, Part 2", God is said to want both silver and gold, along with various other forms of currency (dollars, pounds, guilders, kroner, francs, escudos, pesetas). In "Perfect Sense, Part 1", P.P. Arnold sings "When you add it all up.../There's an ounce of gold/And an ounce of pride in each ledger". I have always taken this as an accusation that war is conducted primarily for money (gold) and for national glory (pride).

Sometimes, however, 'gold' is literally gold. In "The Powers That Be" it is said that the rich and powerful like 'gold taps' (that is, plumbing fixtures made of gold) and 'platinum hubcaps' (platinum being a metal even more valuable than gold). "Burning Bridges" speaks of a 'golden band', which might be a gold ring or wedding band. (Who knows? I can't even begin to guess what the lyrics are trying to say.)

And it would be impossible to review the appearance of gold in Pink Floyd lyrics without a brief discussion of alchemy, an ancient practice that was a forerunner of modern chemistry and pharmacology. The alchemist was part philosopher, part scientist, and often part astrologer. One of the best-known goals of alchemy was to discover a way to change base metals (often lead, but also tin, iron, copper, etc.) into gold or silver through a process known as transmutation.

There is a direct lyrical reference to alchemy and transmutation in "Take Up Thy Stethoscope and Walk", which says "Gold is lead", and goes on to mention Christian religious ideas ("Jesus bled") and modern medicine and healing. I think Waters was making some comment on the way that science, medicine, money, and religion have all been tied up together over the course of human history.

Alchemy is also very much in view in the line "Turn my lead into gold" from the chorus of "Wots... Uh the Deal". But on other levels the song is about the quest for wealth and the quest for paradise ('the promised land'), just as alchemists searched for ways to make gold out of base metals and to find a cure for any ailment and the secret of eternal life. In modern times, alchemy is considered a joke, but or hundreds of years it was considered a very serious science and a noble academic pursuit. Great minds (including Roger Bacon and Sir Isaac Newton) spent many years pursuing alchemical studies, and while their efforts produced many useful and profitable substances (gunpowder, inks and dyes, medicines), they were ultimately frustrated by their complete failure to turn lead into gold. Lyrics such as "I'm the man on the outside looking in", "Try to keep up with the turning of the wheel", and "There's chill wind blowing in my soul/And I think I'm growing old" seem to speak of this frustration and the emptiness that comes from being a failure at your life's primary pursuit.

Gold, of course, is not the only precious metal used for coinage and money. Silver is listed along with gold and other currencies in "What God Wants, Part 2". And the French word for silver is 'argent'... which also happens to be French for 'money'. This turns up in "Leaving Beirut", as Waters tells the Lebanese cab driver "J'ai pas de l'argent" (meaning "I have no money").

A more 'poetic' use of silver comes not from Waters but from David Gilmour in "Fat Old Sun", which mentions "The silver sound from a time so strange". It's a lovely line, but I'm not entirely sure what it means. In context, I think of ringing bells. Silver is used to make small hand bells, and the phrase 'silver sound' suggests to me the clear, piercing ring of such a bell. Bells are heard on the record and are mentioned in the lyrics, but they are the enormous tower bells of Cambridge's colleges, typically made of bronze, not silver.

Perhaps the 'silver sound' is meant to suggest aging, as 'silver' is often used to describe the graying hair of the elderly (as in "The Gunners Dream", which says "And the silver in her hair shines in the cold November air" (and then goes on to mention a tolling bell, interestingly enough). It is possible that as Gilmour was thinking back to Cambridge and writing "Fat Old Sun", he was struck by how much time had passed since he was that young boy enjoying a summer evening, and in reaching for a metaphor for his sense of maturity he decided that the sound he heard should be 'silver'.

Traditionally, silver has been used for cutlery (which is why we still call knives and forks 'silverware' in the U.S., even though they are more commonly made of less expensive metals these days), and the phrase 'born with a silver spoon in his mouth' is used as a derogatory description of someone born into family wealth. 'Silver spoons' turn up three times in Pink Floyd lyrics. The earliest is in "San Tropez", in which the speaker says "Born in a home with no silver spoon/I'm drinking champagne like a good tycoon", indicating that although he was not born into wealth, he can certainly live it up like a wealthy man now. (Saint-Tropez, on the French Riviera, is known as a destination for the wealthy.)

In "Nobody Home" from The Wall, Waters lists 'a silver spoon on a chain' as one of Pink's possessions. Some fans believe that this line (which, along with the rest of the song, was composed while the album was in production) refers not to wealth but to a silver 'coke spoon' used to measure out cocaine for snorting, and worn around the neck on a chain. This is may have to do with Rick Wright's purported cocaine habit during this time, and Roger Waters' notorious animosity toward Wright and his apparent lack of participation in the Wall sessions. (The song's next line--"Got a grand piano to prop up my mortal remains"--is seen as further reference of Wright and his musically moribund state.) Unfortunately, I don't believe Waters has ever substantiated this particular interpretation, and since the drug-addled Pink is based more upon Syd Barrett (who was never known as a cocaine user) and Waters himself than upon Wright, I'm not sure how well it holds up.

And in "Home" from Radio KAOS, Waters mentions lists "our leaders in their concrete tombs/With their tinned food and their silver spoons". The lyric describes a politician or other wealthy leader hunkered down in a bomb shelter, eating canned food rather than the usual delicacies of the rich and famous. The preceding lyric describes a family on the other end of the socioeconomic spectrum, and the idea is that no amount of wealth in the world will save you in the event of nuclear war--we'll all be equal in the end (an idea he also explored in "Two Suns in the Sunset").

Tin is an element with some interesting physical properties, and although it is cheap, widely available, and very malleable, it degrades fairly easily and, and is therefore somewhat useless for many purposes. When bonded to other metals, however, it prevents corrosion. Tin-coated steel containers were commonly used to store food; in the U.S. these are often called 'tin cans', and in the U.K. they are simply called 'tins'. (The names 'tin' and 'tin can' persist although the cans themselves are now generally made of aluminum, not unlike the steel 'silverware' mentioned above.)

Waters used the phrase 'tin cans' in "Late Home Tonight", presumably to describe the American fighter plane ('tin can' being a slang term for any number of military vessels, from planes and ships to even spacecraft). With American military and an American pilot in mind, this would explain Waters' use of the decidedly American phrase 'tin can', and should not necessarily be taken as evidence that Waters has again abandoned his British voice for the sake of the American audience.

Syd Barrett used the phrase 'tin and lead pail' in "Gigolo Aunt", presumably because buckets were commonly made of lead and tin in the days of his youth. Nowadays most such pails are made of cheap plastic, as I'm sure the toxic nature of lead makes it unpopular for carrying potable water. Or perhaps the 'tin and lead pail' is a reference to a 'lunch pail' or lunch box, although these were traditionally made of steel, not lead.

Lead is also mentioned in "Sorrow", from A Momentary Lapse of Reason, which says "Plumes of smoke rise and merge into the leaden sky". Lead is dark in color, dull in luster, and notably heavy and dense. I would classify this as another 'poetic' usage, as "leaden" suggests the heaviness, darkness, and oppressive mood of the overcast sky he is describing.

Barrett uses iron in a similarly poetic way in "Baby Lemonade", in which he sings, "In the sad town/Cold iron hands/Clap the party of clowns outside". Like many of Barrett's songs, the lyrics are more about conjuring feelings and impressions rather than definite 'meanings'. But here the strongest impression is that of the harshness of metal, heavy and cold. These are not warm, inviting hands, but rather impersonal, inhuman hands--in keeping with the general feelings inspired by phrases like 'sad town' and 'Rain falls in gray far away'.

Iron alloys are used in a wide variety of manufactured goods, and although pure iron is a relatively soft metal, iron is combined with various amounts of carbon, silicon, and other metals to make it remarkably sturdy. Iron is used to cast bells (such as the tolling iron bell that calls the faithful to their knees in "Breathe (Reprise)"), iron skillets (as mentioned in "Leaving Beirut"), and branding irons (as mentioned in "Each Small Candle"). And as David Gilmour notes in "Childhood's End", iron readily oxidizes in the presence of oxygen and water to form rust.

The most widely-used iron product is steel, which is not an element but an alloy of iron, carbon, and other elements, according to the desired properties. For instance, stainless steel has 10-20% chromium and often 8-10% nickel, in order to make it more rust-resistant. Waters almost always uses 'steel' to create a cold, impersonal, and often threatening mood. In "Pigs (3 Different Ones)", the 'bus stop rat bag' is described as liking the "feel of steel", either in the form of a hat pin or handgun, used a weapon in either case. In "Sheep", the slaughterhouse is described as a "valley of steel", and in "Lost Boys Calling", the ocean liner is described as a "steel tomb", foreshadowing the character's death.

Waters and Barrett each used the phrase "steel rail" in lyrics (in "Wish You Were Here" and "If It's In You", respectively), apparently referring to a hand rail. Waters' lyric again emphasizes the 'cold' aspect of steel in direct contrast to the warmth of a 'green field'. But Barrett's lyric "Hold you tighter so close.../Please hold on to the steel rail" seems to imply that there is a certain amount of security from the strength and reliability of the metal railing.

And on a decidedly lighter final note, I will close with the Carla Bley-penned song "I'm a Mineralist", released on Nick Mason's Fictitious Sports. In the spirit of "Arnold Layne", the song is a tongue-in-cheek look at a man whose fetish is not women's clothes but rather minerals and metals. Using a hefty dose of poetic license, the lyrics rattle off a stream of groan-worthy puns about balling bearings, tickling ivories, and so on. If this were geology class instead of chemistry, we could discuss jade, granite, and various other minerals. But sticking to chemical elements, we have iron (and rust and steel), lead, and mercury, just to name a few.