I've been doing some research into chemical and alchemical names lately, in order to name the elements in Verdurian, and I've found the old names (those used before Lavoisier's reform of the nomenclature) curiously charming. For instance:
the green lion (iron sulphate)-- a typical term from alchemy, which was never concerned to make its recipes and references too clear
spirit of salt (hydrochloric acid)-- because it was made from salt
butter of antimony (antimony trichloride)-- because of its waxy quality
flower of zinc (zinc oxide)-- found as a deposit in zinc chimneys. "Flower" means "flour" here; the words are etymologically the same.
spirit of hartshorn (acqueous ammonia)-- a perfectly straightforward name; it was distilled from harts' horns! The same substance derived from another and less attractive process was called volatile salt of urine. There was also salt of hartshorn (smelling salts)
narcotic salt of vitriol (boric acid)-- made from (green) vitriol, another name for iron sulphate, not to be confused with blue vitriol, or copper sulphate.
fixed air (carbon dioxide); it got that name because it's denser than regular air, so it settles to the bottom of your container and doesn't mix with other gases.
regulus of antimony-- A regulus ('little king') was the heavy substance that sank to the bottom of your crucible. 'Antimony' then referred to kohl (antimony trisulphide), regulus of antimony thus referred to the pure metal isolated from kohl-- what we now call antimony.
sal ammoniac (ammonium chloride)-- because it was made from camel dung from the Temple of Jupiter Ammon in Egypt.
bismuth glance (bismuth sulphide)-- a glance was apparently a shiny substance
acqua regia 'kingly water', a mixture of hydrochloric and nitric acids, which could dissolve gold
lunar caustic, sticks of silver nitrate used in surgery; 'luna' was an old alchemical term for silver [thanx to Peter Blinn for this one]
Many names of minerals derive from mining, and express disappointment over not finding something else:
fool's gold (iron sulphide)
blende (German 'deceptive': zinc sulphide)--because it looked like galena (lead sulphide), but produced no lead
cobalt, named for the demon (D&Ders will know it as a kobold) because of its uselessness and unhealthiness (it was often found mixed with arsenic), and because it resembled silver but wasn't
copper-nickel, named for another devil, because it looked like copper but wasn't-- our nickel
There's hardly any semantic area which is so dependent on theory and practical knowledge. You can't name something "carbon dioxide" or "iron sulphate" until you can reduce it to its elementary components (and you know that its components really are elementary).
And many a name refers to the source (geographic or alchemical) of a substance, and thus encodes important information about the substance. Even in the middle ages a name like calx of mercury (mercuric oxide) was virtually a recipe for its creation; a calx was a powder formed by roasting a mineral or metal, generally what we would call an oxide.
Particularly charming are names which encode a wrong theory about the substance:
flowers of antimony (arsenic trioxide), obtained by roasting orpiment or realgar (arsenic di- and trisulphide)-- which are beautiful names themselves. Antimony and arsenic have similar properties and were often confused; their compounds were not really disentangled till the 19th century. Antimony was very popular in medieval times as a medicine, and the confusion with arsenic probably prematurely dispatched many a patient.
green copperas, yet another name for green vitriol (iron sulphate). Copperas, 'coppery water', should have been restricted to copper sulphate.
manganese, a corruption of ancient magnesia-- which however didn't refer to manganese, but either to talc or to magnets.
plumbago or black lead-- not lead at all but graphite (carbon); we still use this misnomer when we speak of a pencil lead (graphite + clay).
molybdena (molybdenum disulphide)-- the name derives from Greek molübdaina 'lead'-- it seems that miners saw lead everywhere
mercury of life, Paracelsus's PR-savvy name for one of his curative concoctions; he may have used mercury in its preparation, but it was actually antimony trichloride.
dephlogisticated air, Priestly's name for oxygen. According to phlogiston theory, oxides were formed not by the metal gaining something from the air (oxygen), but by losing phlogiston. It made sense, in a crazy sort of way, that oxygen was a material particularly bereft of phlogiston. A difficulty turned up, however: oxides are heavier than the original metals. Priestly and others however had a clever solution: phlogiston had negative weight.
oxygen, Lavoisier's name for oxygen, so called because he thought it was the formative principle of acids (Greek oxüs). Close but no cigar-- hydrogen is. One of Lavoisier's few mistakes. Scheele's name, fire air, would have been better.
oxygenated muriatic acid was Lavoisier's name for a gas derived from muriatic (hydrochloric) acid. He obviously saw it as a compound of oxygen; in fact it's an element-- chlorine.
the rare earths-- which are not at all rare.
And while we're at it, isn't it a little strange that a single tiny village in Sweden, Ytterby, provided the name for no less than four elements?