Chimica Arcana

To grasp the invisible elements, to attract them by their material correspondence, to control, purify and transform them by the living power of the spirit, this is true alchemy. 

~Paracelsus (1493-1541)

Before any sort of chemical bonding was even thought of there were charts of so-called affinities.  I found this interesting chart dating from 1718 on Wiki. It teaches how the then-known "elements" combined with each other. The top row identifies an element and the columns contain those elements with which it combines. Note that sulfur (middle column) was considered the most promiscuous element, consistent with its primacy as the "soul" of matter according to alchemy. Also bear in mind that this simple chart condenses the then known science of chemisty, ca. 1718.  I like the arcane symbols and could see using some them as avatars depending on my mood:

Click to enlarge or see link above

______________________
Here are my translations of the "elements."

Esprit acides : Acidic (acerbic) spirits

Acide du sel marin: Lit. acid of sea salt, HCl (which was thought to contain oxygen until Davy showed otherwise: link)

Acide nitreux: Nitric and nitrous acids, HNO₃, HNO₂

Acide vitriolique: Sulfuric and sulfurous acids, derived from oleum & vitriol.

Sel alcali fixe: Sodium & potassium hydroxides and carbonates.

Sel alcali volatil: Sal ammoniac, NH₄Cl, which sublimed and was endlessly fascinating.

Terre absorbante: Silicates (sand) and diatomaceous earth.

Substances metalliques: Metallic substances

Mercure: Mercury was considered to be the spirit of matter.

Regule d'Antimoine: Regulus of antimony--metallic antimony. Regulus means "little King"

Or: Gold

Argent: Silver

Cuivre: Copper

Fer: Iron

Plomb: lead

Etain: Tin

Zinc

Pierre Calaminaire: Lit. calamine stone, i.e., calamine ore. Note the French place name.

Soufre mineral: Sulfur or brimstone.  This material held a special place in alchemy, along with mercury and salt.

Principe huileux ou Soufre: The oily essence of organic substances from plants, also called the "sulfur." See the interesting discussion under Spagyric.

Esprit de vinaigre: Vinegar or acetic acid

Eau: water

Sel: Salt held a special place in alchemy along with mercury and sulfur.  

Esprit de vin et Esprit ardents: Any of the flammable alcohols derived from fermentation, e.g., ethanol, methanol, etc.

Let's take a closer look at those copper atoms

How small can we see? Pretty small, it turns out. We can see atoms (see above)--not with light but with electrons (light is too crude of a yardstick and can't "measure-down" to the job). In Scanning Electron Tunneling Microscopy (STM), a tiny metal wand just an atom or two thick approaches a surface. Electrons, dripping from the tip of the sweeping probe, jump to a surface below, feeding signal back and mapping the atomic topography:

original

Successive traces of electronic signals become a "photo" of the surface. The way STM works reminds me of the spark of life implied so long ago here. The technique is more fully explained here.

Suppose we could zoom a microscope down onto a pure copper surface to find out what's really there. I mean really there there. We'd find, even for ultra pure copper--heterogeneity. What looks the same is really different. No matter where we look, about one in three copper atoms has two "extra" neutrons because native copper comes in two isotopic flavors: ⁶³Cu and ⁶⁵Cu.

A while back, Michael Haz mentioned that pure copper native to Upper Michigan was distinguishable from pure copper native to South America. It's true. Copper sources have isotopic signatures. The natural ratio of the two copper isotopes varies slightly from place to place for various reasons. The reason(s) why they vary are complex and altogether unimportant here. The point is that they differ and they do so in a way that can be reliably measured--like fingerprints. A similar isotopic method has been used to trace the influx of South American silver into European coinage: link

Copper's Special Nature

GOLD is for the mistress--silver for the maid --
Copper for the craftsman cunning at his trade.

from Cold Iron by Rudyard Kipling (1910)

Copper, silver, and gold--we call them coinage metals for obvious reasons. They antedate recorded history because all three were found essentially pure in their uncombined "native" state. Later came smelting and the secrets for winning even more of them from their ores. I once read that around 85 % of all the copper ever mined is still in use.

We had a Copper Age followed by a Bronze Age, during which the metal played a paramount role. But ever since electrification, copper's biggest use has been for wire to conduct electricity. The secrets to copper's utility are its ductility, its conductivity, and its longevity; all three are related to electronics.

Here's a recipe for a metal having high ductility, conductivity, and nobility: Give it a full set of d-orbitals--a resilient layer of 10 perfectly paired electrons surrounding an inner core of 18 perfectly paired electrons (28 in all)--to fend off rapacious oxygen and the harsh world of oxidation. The perfection of copper's 3d subshell adds a sort of resonance like that in the noble gases.

But copper needs one more electron--29 in all. The 29th electron, the outer valence electron, is spherically symmetric. This 29th electron is responsible for copper binding to copper. In theory, just two copper atoms could couple to make a dicopper molecule and it's been studied. But Cu₂ is unstable because the bonding is too weak. Instead, the atoms associate into metal.  But there's no directionality to their bonding and the bonds are very weak, lacking covalent character. In a sense, copper is like frozen mercury. This means that copper should easily deform--and so it does. What's more, because each copper atom has a single valence electron, there's room for easily moving electrons; this property translates from metal atoms to bulk metal and copper has an awesome conduction band--thus the conductivity exceeded only by silver for a pure metal.

What about copper's pretty red color? That comes from bathing in visible light. But copper only gives back the reddish portion of the spectrum.

The chemistry of copper is dominated by the chemistry of copper (I), "cuprous ion," from the loss of the 29th electron. But copper can also lose a second electron to make copper (II), "cupric" ion. I once got into an argument over on Althouse over whether copper has one or two valence electrons. Clearly it has two. The word "valence" derives from an atom's combining power and indicates how many electrons an atom can give or take.

The Language of Chemistry

Original

Beginning students of chemistry encounter chemical symbols which bear little resemblance to their English names. The roots of several common and especially more historical elements caught my fancy, just as other Latin words buried in English did earlier. link

Several names and symbols come from Latin:

• Sb stands for antimony which comes from the Latin Stibium. The Italians still call antimony stibio. We did too until the Middle Ages. link

• Cu for copper comes from Cuprum, which is related to the word Cyprus, an ancient source of copper for the Romans.

• Fe for iron comes from Ferrum. The Italians call their railroads la ferrovia and Spanish calls hardware ferreteria (cf. bilingual signs at Home Depot). English has the vestigial word, farrier.

• Au for gold comes from Aurum.  We've lost that word in English except for some pretentious words like aureate, aurelia, aureole and the like.

• Pb for lead comes from Plumbum. There are lots of English cognates, including plumbago, plumbing, plumb lines and plumb bobs.

• Hg for mercury comes from hydrargyrum. That's confusing because at first glance it could be water-silver. But "hydra" is more generic and means liquid. Mercury used to be called quicksilver which sort of conveys the same notion as hydrargyrum.

• Ag for silver comes from Argentum. The French still call money l'argent.

A couple names look like Latin but are neologisms coined by Sir Humphry Davy:

• K for potassium comes from Kalium which derives from Arabic al-kali.

• Na for sodium comes from Natrium. The Germans still use both words Natrium and Kalium; they never adopted sodium and potassium. I guess they weren't as impressed with Davy as we were.

Also:

• Sn for tin comes from the Latin Stannum. There is some irony here.  The word Stannum is Latin but appears to derive from Irish or Welsh. The Romans got their tin from the British Isles.  Tin is still mined in Cornwall.

• W for Tungsten comes from an older name, Wolfram, which is still used by the Germans. Tungsten derives from Swedish tung heavy + sten stone. 

Wartime Nickels

Reverse side of a 1942-P Jefferson nickel

While reading and thinking about wartime coinage, I remembered that nickel was also in such short supply during WW II that the mint replaced it with silver. Link  Nickel was needed to harden steel for armor plating. Special nickels were marked with huge mint marks P, D, and S over Monticello on the reverse to facilitate re-collection and melting.  But Gresham's Law kicked in after the war and the silver nickels were hoarded when the price of nickel fell. I still have a few, found in change, darkened with age due to their manganese content.

Lastly, copper was in such short supply during WW II that the Treasury loaned out 14,700 tons of coinage silver for use in making electrical coils for uranium isotope separation at Oak Ridge National Labs. Link

Cold Iron

GOLD is for the mistress -- silver for the maid --
Copper for the craftsman cunning at his trade.
"Good!" said the Baron, sitting in his hall,
"But Iron -- Cold Iron -- is master of them all."

from Cold Iron by Rudyard Kipling (1910)

Silver, Gold, & Lead

This news story about Mel Fisher's stolen gold this morning reminded me of two things:

(1) John Wayne, confronting and shooting a cattle rustler in the movie Chisum (1970):

Bandito: Did you bring any gold? 

John Wayne: Nope! 

Bandito: Did you bring any silver? 

John Wayne: Nope, just lead!

and (2)  My father, who met Mel Fisher: