Glauber, Johann Rudolf (1604–1670), German physician and chemist. Glauber was both an alchemist and a serious chemist. As an alchemist he was a follower of Paracelsus and dealt extensively in secret chemicals and medicinals. As a chemist he made several important contributions. In 1648 he first prepared hydrochloric acid from common salt and sulfuric acid. Substituting potassium nitrate for common salt, he observed the formation of nitric acid. Of the various salts he prepared, the most important is the one now known as Glauber's salt, which he first made in 1656. His observations on dyeing are also noteworthy.