Making It and Using It

Glauber's Salt was first isolated and described in detail by the German-Dutch chymist Johann Rudolph Glauber around the 1620s to 1650s, who obtained it both from natural mineral spring water and as a byproduct of his own large scale preparation of hydrochloric and other mineral acids, where sodium sulfate forms when sulfuric acid reacts with common salt. Glauber recognized it as a distinct, previously undescribed salt, crystallizing from solution as large, colorless, transparent prisms that lost their water and crumbled to powder on exposure to dry air, a behavior called efflorescence that he documented carefully as one of the salt's defining properties. He promoted it energetically, publishing works that praised its medicinal virtues at length and gave it its enduring name, the wonderful or miraculous salt, sal mirabilis.

It entered pharmacy quickly as a mild purgative and remained a standard laxative salt for centuries afterward, sold well into the modern era under Glauber's own name. Because Glauber documented both the preparation and the properties of his salt in unusually careful published detail for the period, historians of chemistry treat it as one of the better attested individual discoveries in the whole history of early modern chemistry, in sharp contrast to substances whose origin is lost in an anonymous, centuries deep manuscript tradition.