Alum
Alumen
- Known today as
- Potassium aluminum sulfate.
- Kind
- Mineral, in 3 older authorities
- Constituents
- potassium aluminium sulfate
- Earliest authority here
- Tolfa
- In other databases
- Wikidata search
Revised October 1, 2026: Tradition, lore, modern assessment, and sources extended. Version 1, first published September 25, 2026.
Alum: what was it used for?
A styptic for bleeding and a drying wash for ulcers and the gums; above all, the mordant that fixed dyes.
Alum: what does modern science say?
Genuinely astringent and styptic; still used in shaving blocks. Alum tightens the proteins of skin and blood, which is why the styptic pencil stops a shaving cut; it is the mordant that lets natural dyes take, the flocculant that clears drinking water, and the base of the aluminium salts in antiperspirants. English bakers whitened bread with it until the adulteration acts of the nineteenth century.
Pharmacognosy & Toxicology
- Constituents
- Mechanism
- Aluminium ions cross-link proteins at the surface: astringency and the stopping of small bleeding.
- Toxic dose
- Non-toxic in use; grams by mouth irritate.
- Standing
- In styptic pencils, antiperspirants, and water treatment.
- Pliny, Natural History XXXV. Primary text
Constituent names open the compound’s record at PubChem, and “ChEMBL” beside a name opens its record at ChEMBL, the European Bioinformatics Institute’s database of bioactive molecules. Where a mechanism line was checked against ChEMBL (ChEMBL 37, read 1 October 2026), the check is shown with the measured value and its source paper, or says plainly that nothing has been measured. Doses are as the references give them, for description only; this is not medical advice. Each source carries the result of its check against Crossref, PubMed, or the authority’s page: see Verification.
Alum: what lore surrounds it?
Until Giovanni da Castro found the alum of Tolfa in 1461 the whole supply came from the Turkish lands, and the Pope made the new mine a crusade: alum bought from the infidel was forbidden under pain of excommunication. In Yorkshire the alum shale was burned for a century from 1600 and the liquor set with human urine, shipped from London in barrels, and the cliffs of Ravenscar are still red with the waste.
Alum: what did the older authorities say?
- Tolfa
- The discovery of alum near Tolfa in the 1460s gave the papacy a profitable monopoly, defended with excommunication.
- Herodotus
- Records that Amasis of Egypt sent a thousand talents of alum toward the rebuilding of the temple at Delphi, the first notice of it as a thing of value.
- Pliny
- Distinguishes many kinds of alumen, gives it to stop bleeding and to check the spread of ulcers, and says the dyers can do nothing without it.
Sources
- Pliny, Natural History XXXV. Primary text
- Herodotus, Histories II.180. Verified against its record · doi:10.1093/oseo/instance.00271233
Verification
- Checked
- October 1, 2026
- Passes
- Every sentence read against its sources, in the pass over the remaining 343 entries
- The Standing line checked against the authority it names (EMA, WHO, FDA, CITES, Commission E)
- Every dated or regulatory claim checked by category across the database
- Sources
- 2 cited: 1 verified against its record, 1 primary text.
- Corrections
- None were needed.
What was checked, how, and what was found is set out on the Verification page. A checked source is one whose record was found; it does not make the entry medical advice.
Cite This Entry
Version 1 · first published September 25, 2026 · last revised October 1, 2026
- Chicago
“Alum.” In Materia Medica, edited by B. C. P. Statema. Version 1. The Thinking Press, 2026–. Last modified October 1, 2026. https://thethinkingpress.org/materia-medica/alum.
- MLA
“Alum.” Materia Medica, edited by B. C. P. Statema, version 1, The Thinking Press, 1 Oct. 2026, thethinkingpress.org/materia-medica/alum. Accessed 8 Oct. 2026.
- APA
Alum. (2026, October 1). In B. C. P. Statema (Ed.), Materia medica (Version 1). The Thinking Press. Retrieved October 8, 2026, from https://thethinkingpress.org/materia-medica/alum
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See Also
Also in Herodotus
Castor-oil plant, seeds of in Herodotus · Storax calamite in Herodotus · Cinnamon in Herodotus · Radish in Herodotus · everything Herodotus names →
Also in Pliny the Elder
Amber in Pliny the Elder · Aloe in Pliny the Elder · Aniseed in Pliny the Elder · Alkanet in Pliny the Elder · everything Pliny the Elder names →
Drawing on the same sources: Pliny, Herodotus
Yarrow · Balm of Gilead · Garlic · Onion · Hemp · the bibliography →
Nearby in the alphabet
Ambergris (A waxy substance formed in the gut of the sperm whale) · The amulet herbs (See each above) · Agrimony (Agrimonia eupatoria) · Angel’s wings (fan-shaped fungus that rots conifer wood) · Agnus Dei (blessed by the pope (note LXX))
Historical description, not medical advice.