The author and chemist Theodor Meyer describes the production of sulfate and hydrochloric acid in this volume. Hydrochloric acid is one of the most important basic chemicals with significant relevance in the chemical industry as an inorganic acid. For example, it is used in metal processing for pickling, etching, and soldering. Hydrochloric acid is also an important reagent in chemical analysis. It can separate a group of metals that form insoluble chlorides by precipitating them from other metals. These can then be further analyzed separately. Alkalimetry is another application of hydrochloric acid. As a food additive, hydrochloric acid is designated E 507. In the pharmaceutical industry, hydrochloric acid is used to convert basic, poorly or insoluble drugs in water into more soluble hydrochlorides. This is a reprint of the original edition.