As the pace of scientific advancements quickened and resulted in greater practical benefits, science exercised growing influence on human thought. The intellectual achievements of the Scientific Revolution had resulted in few such benefits, and theoretical knowledge had also played a relatively small role in the Industrial Revolution in England (see “Industry and Population” in Chapter 20). But breakthroughs in industrial technology in the late eighteenth century enormously stimulated basic scientific inquiry as researchers sought to explain theoretically how such things as steam engines and blast furnaces actually worked. The result was an explosive growth of fundamental scientific discoveries from the 1830s onward. In contrast to earlier periods, these theoretical discoveries were increasingly transformed into material improvements for the general population.

A perfect example of the translation of better scientific knowledge into practical human benefits was the work of Louis Pasteur and his followers in biology and the medical sciences (see page 723). Another was the development of the branch of physics known as thermodynamics. Building on Isaac Newton’s laws of mechanics and on studies of steam engines, thermodynamics investigated the relationship between heat and mechanical energy. The law of conservation of energy held that different forms of energy — such as heat, electricity, and magnetism — could be converted but neither created nor destroyed. By midcentury, physicists had formulated the fundamental laws of thermodynamics, which were then applied to mechanical engineering, chemical processes, and many other fields.

Chemistry and electricity were two other fields characterized by extremely rapid scientific progress. And in both fields, “science was put in the service of industry,” as the influential economist Alfred Marshall (1842–1924) argued at the time. Chemists devised ways of measuring the atomic weight of different elements, and in 1869 the Russian chemist Dmitri Mendeleev (mehn-duh-LAY-uhf) (1834–1907) codified the rules of chemistry in the periodic law and the periodic table. Chemistry was subdivided into many specialized branches, including organic chemistry — the study of the compounds of carbon. Applying theoretical insights gleaned from this new field, researchers in large German chemical companies discovered ways of transforming the dirty, useless coal tar that accumulated in coke ovens into beautiful, expensive synthetic dyes for the world of fashion. German production of synthetic dyes soared, and by 1900 German chemical companies controlled 90 percent of world production.

Electricity, a scientific curiosity in 1800, was totally transformed by a century of tremendous technological advancement. It became a commercial form of energy, first used in communications (the telegraph, which spurred quick international communication with the laying of underwater cables), then in electrochemistry (refining aluminum, for example), and finally in central power generation (for lighting, transportation, and industrial motors). And by 1890 the internal combustion engine fueled by petroleum was an emerging competitor to steam and electricity alike.

The successful application of scientific research in the fast-growing electrical and organic chemical industries between 1880 and 1913 provided a model for other industries. Systematic “R&D” — research and development — was born in the late nineteenth century. Above all, the burst of industrial creativity and technological innovation, often called the Second Industrial Revolution, promoted the strong economic growth in the last third of the nineteenth century that drove the urban reforms and the rising standard of living considered in this chapter.

The triumph of science and technology had three other significant consequences. First, though ordinary citizens continued to lack detailed scientific knowledge, everyday experience and innumerable articles in newspapers and magazines impressed the importance of science on the popular mind. Second, as science became more prominent in popular thinking, the philosophical implications of science formulated in the Enlightenment spread to broad sections of the population. Natural processes appeared to be determined by rigid laws, leaving little room for either divine intervention or human will. Yet scientific and technical advances had also fed the Enlightenment’s optimistic faith in human progress, which now appeared endless and automatic to growing numbers of people. Third, the methods of science acquired unrivaled prestige after 1850. For many, the union of careful experiment and abstract theory was the only reliable route to truth and objective reality. The “unscientific” intuitions of poets and the revelations of saints seemed hopelessly inferior.