From the book
A Chymical Dictionary
Gerhard Dorn and John French · Diotimos Editions · 2026
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At a Glance
- The wordVitriol named through calcination or through the residue of its oil.
- In the bookCaput mortuum defines residue remaining after distillation and sublimation.
- A place to readThe 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
- ColcotharRead the complete historical definition and its commentary.
- Caput mortuumThe material left behind by distillation or sublimation.
- Henricus rubeusAn alternative name for a vitriolic residue.
- Sal CalcotharinumA 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.
Source note
Historical source. 1650 dictionary, unnumbered definition page 16; facsimile PDF page 344 — Facsimile