===== CHEMISTRY =====

Low-tech chemical technology bears little resemblance to the modern version. Concentrations are low, purity is
dubious, and time and temperature are matters of feel rather than precise measurement. Nevertheless, low-tech
chemists can practice many important and lucrative trades.

==== Alcohol ====

Ethyl alcohol was first produced by fermentation late in TL0, and has remained an important commodity ever
since. Alcohol solutions produced by the most common yeasts start to top out at 5-6%. Even the hardiest microbes can’t manage concentrations greater than 18% – the strongest drink available until TL3.

Heat distillation appeared as an experimental technology in the early days of the Roman Empire, and became
available on a useful scale at TL3 (see Distillation, pp. 11-12). Early chemists could easily double the alcohol content of a solution, perhaps even triple it, but the process was very inefficient. Much alcohol escaped as vapor, chemists worked in batches of a quart or less, and without accurate temperature control it was difficult to vaporize alcohol without vaporizing too much water as well. Consequently, multiple distillations faced diminishing returns. Nevertheless, distillers achieved concentrations of up to 90% alcohol by late TL4. Batch size also increased at TL4, with early industrial boilers capable of distilling barrels of liquid at a time.

People in colder climates developed freeze distillation. Alcohol solutions could be left to partly freeze during winter. Because alcohol freezes at a lower temperature than water, the initial phases of freezing form ice with a lower proportion of alcohol. When this ice is scooped out, the solution left behind has higher alcohol content. This can be done repeatedly – once again, with diminishing returns – to concentrate the alcohol to 30%.

Methyl alcohol, or wood alcohol, was produced in minute quantities by heating wood in an oxygen-free environment, perhaps as early as TL1. It was made only sporadically thereafter through late TL4. While intoxicating, it’s extremely toxic. Half an ounce of pure methanol can cause blindness and five ounces can be lethal – although producing that much of it before TL5 would be a long and difficult undertaking.

==== Acids ====

Several acids were available in antiquity, although not at
concentrations found in modern labs.

//Acetic Acid// (TL0). The most commonly available acid, acetic acid gives vinegar its sharpness. It’s produced by the oxidation of alcohol – and like alcohol, was typically found at concentrations of 5% to 18% (although TL3 Muslim alchemists were able to distill it). It had uses in chemistry, but was widely used as a cleaning agent. Concentrated acetic acid isn’t as corrosive as the generic “acid” on p. B428: Being splashed with it causes 1 point of corrosion damage; being immersed in it, 1d-3 corrosion damage per second; and swallowing
it, 1d+1 corrosion damage at the rate of 1 HP per 15 minutes. All HT rolls to avoid eye damage are at +1. It won’t dissolve metal objects. Ordinary vinegar inflicts no injury, but splashing it in the eyes causes severe pain (p. B428).

//Inorganic Acids// (TL3). These acids were manufactured in small quantities by heating mixtures including sulfite ores: alum and sulfite ores for sulfuric acid; salt and sulfite ores for hydrochloric acid; and saltpeter and sulfite ores for nitric acid. This produced acidic vapors that were condensed into a liquid. Such acids were more than 30% pure, but limited to batches of a few ounces at a time. Nitric acid dissolves silver, making it useful in gold refining. These acids inflict damage as on p. B428.

//Aqua Regia// (TL3). This mixture of nitric and hydrochloric acid was invented by an eighth-century Muslim
alchemist. The name – meaning “royal water” – comes from the mixture’s ability to dissolve gold, the "royal metal."

==== Pigments ====

Pound for pound, pigments for paints and dyes (along with spices and medicines) were the most valuable historical goods. Pigments have a base cost of $5 to $30 per pound, adjusted by Luxury Pricing (p. 37).

Mineral pigments require minimal chemical processing, and are resistant to light and air. (Exception: Green pigments are frequently light-sensitive.) Earth tones are the most common, and provided mainly by iron oxides in abundant minerals. Other mineral colors tend to be either toxic (one of the best and most widespread reds is a lead ore) or expensive (lapis lazuli, a blue semiprecious stone, is ground to powder for use in paints).

Organic pigments can require considerable processing, and fade much faster than mineral pigments. For example,
berry juices might provide a purple color, but start to fade in a few hours. Some organic pigments require more
sophisticated chemistry, too. Indigo – derived from several plants and a few mollusks – can be used as a dye, but is colorless while dissolved in water; once exposed to the oxygen in air, it gains color.

==== Other Chemicals ====

A surprising range of chemicals could be derived easily from natural raw materials, or simply taken directly from the environment.

//Salt// (TL0). Obtained by mining or by evaporating water in natural or artificial seaside pans, salt (sodium
chloride) was an economically significant and frequently government-controlled commodity. The term “salt” was
applied to numerous compounds: borax (sodium tetraborate), natron (sodium carbonate, with bicarbonate impurities), nitre (sodium and potassium nitrate), sodium bicarbonate (known to us as baking soda, but used historically as a cleaning agent and a flux), and others. Often found together in varying proportions, these chemicals were difficult to distinguish from one another. As a result, ancient craft procedures might specify the salt of one place as useful for pottery glazes, the salt of another as a superior flux, and so on.

//Alum// (TL1). A family of metallic sulfides, alum has been used as a mordant and in papermaking (alum creates a smooth-faced paper), medicine (for its styptic and antimicrobial effects), leatherworking (as an aid to tanning), and water purification. It is sometimes mined in a naturally pure form, but is more often found in deposits that must be refined by roasting or boiling. It’s used in enough industrial processes that access to alum supplies became a significant political and economic issue by TL3.

//Potash// (TL1). This alkaline potassium compound is manufactured by soaking hardwood ashes. In a liquid solution (lye), it was combined with fats to make soap. In solid form, it was an important glassmaking ingredient. While it can be used as a fertilizer, it rarely was.

//Petroleum// (TL2). Alchemists around the Middle East experimented with surface pools of petroleum as early as
the Iron Age. It was mostly used as a treatment for skin diseases, but petroleum-rich rocks were sometimes burned for heat. By early TL3, petroleum was distilled in small quantities to produce naphtha, used as lamp oil and probably in Greek fire (see Combustibles, p. 84).

//Ether// (TL3). Ether was first isolated in the late 13th century A.D., but its anesthetic properties weren’t noted until late in the 16th. Dosage wasn’t established, so it wasn’t a safe anesthetic – the patient could easily overdose, go into a coma, or even die.

//Saltpeter// (TL3). Nitrate compounds were used in firelighters at least as early as TL1, but pure saltpeter wasn’t refined until TL3. Although saltpeter was mined from guano deposits in a few locations, it was mostly manufactured. Dung was mixed with slaked lime or wood ash and kept damp for months. Saltpeter was washed out of the mixture and dried into crystals. Saltpeter gives off oxygen when heated, making it an accelerant for combustion (see Combustibles, p. 84).