From workshop to works
Before the late 1700s, chemicals were made in small batches by apothecaries, dyers, soap boilers, glassmakers and metalworkers. Potash came from wood ashes, acids from distilling mineral salts, and dyes from plants and insects. Industrial chemistry begins when a few simple substances, above all acids and alkalis, were needed in such quantity that making them in a workshop no longer made sense. The need came from factories that already existed: cloth bleachers, soap makers, glass and paper makers.
The story is not one of steady progress. Many early processes were wasteful, dirty and badly understood, and they were often replaced less because of their harm than because a cheaper route appeared.
Sulfuric acid: the first bulk chemical
Sulfuric acid is the usual starting point because so many other processes depend on it. Small amounts had long been made by heating minerals. In the mid-1700s, makers began burning sulfur with saltpeter in large lead-lined chambers, with the acid collecting as a weak solution. John Roebuck is often credited with setting up an early lead chamber works in Birmingham in the 1740s, and the method spread through Britain and Europe over the following decades.
The lead chamber process made acid cheap enough to use freely. Later in the nineteenth century, the contact process, which passes sulfur dioxide over a catalyst, gradually took over because it could make stronger acid. Sulfuric acid consumption has often been treated as a rough yardstick of a country’s industrial activity, though that is a rule of thumb rather than a precise measure.
Soda and the Leblanc process
Glass, soap and textile finishing all needed alkali. Natural sources such as plant ashes were limited, and in the 1780s and 1790s France offered a prize for a way to make soda from common salt. Nicolas Leblanc developed a method around 1790 that treated salt with sulfuric acid and then heated the product with limestone and coal. A related account of how alkali shaped the soap trade appears in the history of soap making and saponification.
The Leblanc process worked, but it released large quantities of hydrochloric acid gas and left piles of foul-smelling waste. In Britain, complaints about damaged crops and vegetation near the works contributed to Alkali Act regulation in the 1860s, among the earlier pollution laws aimed at an industry. Some of the gas was later captured and turned into bleaching powder, an example of waste becoming a product.
The Solvay process and the electrolytic route
Ernest Solvay developed a different route in the 1860s using salt, ammonia and limestone. The ammonia was recovered and reused, which made the process cleaner and cheaper than Leblanc’s. By the end of the century it had largely displaced the older method for making soda ash. Meanwhile, passing electricity through salt water became practical once generators were available, and this provided chlorine and caustic soda directly. Chlorine would later matter for bleaching and, eventually, for water chlorination.
Coal tar, dyes and the research laboratory
Coal gas works produced coal tar as an awkward byproduct. In 1856, the young English chemist William Perkin made a purple dye from aniline while trying to make something else, and set up a works to produce it. Germany went on to build large dye firms that employed many trained chemists and kept laboratories as part of the business. This was a real change: research became a company activity, not only a university one. The full story of synthetic dyes belongs to textile history, but the business model, combining science, patents and scale, spread to pharmaceuticals and other products.
Nitrogen, fertilizer and the Haber-Bosch process
By the late 1800s, farmers relied on natural nitrate deposits and guano, and chemists warned that supplies were limited. Fritz Haber showed in 1909 that nitrogen and hydrogen could be combined into ammonia under high pressure with a catalyst. Carl Bosch and engineers at BASF then solved the large-scale engineering, and the first plant at Oppau began operating around 1913. Ammonia became the basis of synthetic fertilizer and also of explosives, which is why the process is tied to both agriculture and war. The mix of peaceful and military uses is a recurring theme in the history of gunpowder and explosives chemistry.
Metals, oil and plastics
Chemistry also moved into metals. Aluminum was a costly curiosity until the Hall-Heroult electrolytic method of 1886 made it cheap, and the later development of aluminum smelting depended on abundant electricity. Steelmaking, with processes such as the bessemer process, involved careful control of carbon, oxygen and impurities in molten iron.
Petroleum added another large branch. Refining crude oil into kerosene and later gasoline created a chemical industry beside the oil fields, and in the 1900s chemists began making new materials from the fractions: first Bakelite, then a succession of plastics and fibers. Synthetic fibers such as nylon followed in the 1930s.
What drove the growth
Several pressures repeat across these stories:
- Demand from existing industries such as cloth, soap, glass and paper.
- Cheap energy and raw materials, such as coal, salt, limestone and later oil.
- Patent law and company research, especially in Germany, Britain and the United States.
- Regulation, usually arriving after local damage was obvious.
- War, which pushed governments to support production of nitrates, explosives and fuels.
It is worth remembering that most of these processes were improved incrementally by engineers and chemists working in companies, and credit in popular accounts often falls on one or two names. Dates for plant openings and patents vary slightly between sources, so treat the years above as approximate guides rather than exact records.