Colcothar

Salts solvents and liquid preparations · A Chymical Dictionary

At a Glance

The word. Vitriol named through calcination or through the residue of its oil.

In the book. Caput mortuum defines residue remaining after distillation and sublimation.

A place to read. The historical definition below, 1650 dictionary, unnumbered definition page 16; facsimile PDF page 344.

Historical Definition

Colcothar is calcined vitriol, or the caput mortuum of oil of vitriol.

Meaning

Two descriptions identify the material. One names a treatment, calcination; the other names its relation to oil of vitriol as a caput mortuum, a residual “dead head.” The wording does not give a modern formula or establish the composition of every historical specimen called vitriol.

The residue language is the most useful interpretive clue. A text may mention a substance through what remains after another preparation, rather than through the name of a starting mineral. That distinction prevents an apparently familiar material name from concealing a difference in its preparation or position within a sequence.

Use in the Book

Caput mortuum defines residue remaining after distillation and sublimation. Henricus rubeus is another route to the Colcothar of vitriol, while Sal Calcotharinum names a salt made from Colcothar. These linked entries distinguish the residue from something subsequently made from it; they do not make all three names interchangeable.

Places to Read

Caput mortuum. The material left behind by distillation or sublimation.

Henricus rubeus. An alternative name for a vitriolic residue.

Sal Calcotharinum. A salt derived from vitriolic colcothar.

In This Edition

“Calcined” and “residue” are retained as historical descriptions of preparation. They do not warrant identifying the entry with a single modern chemical product or reconstructing a method from this short definition.

Historical source: 1650 dictionary, unnumbered definition page 16; facsimile PDF page 344 — Facsimile

Sources. A Chymicall Dictionary 1650, s.v. Colcothar

See also. Caput mortuum; Henricus rubeus; Sal Calcotharinum