There are many histories of the chemical industry but very few systematic studies that portray the changing relations between chemistry and industry. This essay tackles the issue by looking to evolving practices and to changes in semantics in particular. On the practical level, both chemistry and industry changed greatly between about 1750 and 1950, which led to different types of interactions over the course of time. Special attention is paid to the emergence and subsequent history of the concept of the Second Industrial Revolution (ca. 1870-1900). It is arguedand illustrated by several examplesthat historians using that concept have tended to underestimate the role of chemistry in industry before about 1870 and have overestimated its role after that date. The rhetorical repertoires of historical actors had great influence on the ways historians later perceived the period of the Second Industrial Revolution. Moreover, the meanings of the key words that we use to describe historical processes have changed considerably over time. The meanings of the terms chemistry and industry both changed, as did those of terms such as technology, art, science, philosophy, and knowledge. This happened most fundamentally between about 1750 and 1850, a period called a Sattelzeit (transition period) by the German historian Reinhart Koselleck for that very reason. Awareness of those semantic changes is crucial for a better understanding of the changing relationships between chemistry and industry, especially for the period before about 1850.