# Saltpetre

**Nitrum*, *sal petrae*, the salt of the stone; niter*

**Known today as.** Potassium nitrate, scraped as a white bloom from cellar walls, stables, and dung heaps.

Kind: Mineral  
Poisoning: Nitrate and the blue blood (https://thethinkingpress.org/materia-medica/poisons/nitrate)

## What was it used for?

Cooling, for fevers, burning urine, and sore throats, in the *sal prunella* lozenges; and in pills (see [Niter, pills of](https://thethinkingpress.org/materia-medica/niter-pills-of)).

## What does modern science say?

Still in some toothpastes for sensitive teeth; a poison in large doses.

## Pharmacognosy and toxicology

- **potassium nitrate**: 

**Mechanism.** A cooling salt in the Galenic sense because it dissolves endothermically; a diuretic; and, by its reduction to nitrite in the mouth, a source of nitric oxide that dilates vessels, the pathway now studied with beetroot juice. The sal prunella lozenge for sore throat was saltpetre fused with a little sulfur. The anaphrodisiac reputation of army saltpetre is a myth: it has no such action. At 5 per cent in toothpaste it is the standard home treatment for sensitive teeth, with evidence the reviews call variable.

**Dose.** Grams give gastritis; 30 g has killed, with methaemoglobinaemia.

**Standing.** In toothpastes for dentine sensitivity (the FDA monograph allows 5 per cent); a curing salt (E252); the cardiovascular use is investigational.

## What lore surrounds it?

The ancient *nitron* was natron, a soda; the name passed to saltpetre, and with it much confusion, in the Middle Ages. It is the chief part of gunpowder.

## What did the older authorities say?

**Pliny.** Pliny's nitrum “in its properties does not greatly differ from salt,” and he complains that “the medical men who have written upon it were ignorant of its nature.” Native nitrum is found in Media, in Thrace, and best of all “at Litæ, in Macedonia, where it is known as ‘Chalastricum:’ it is white and pure, and closely resembles salt,” forming on a lake “for nine days, about the rising of the Dog-star.” In Egypt it is made artificially in nitre-beds flooded by the Nile, “tawny and full of stones.” What the ancients called nitrum is not the modern saltpetre, and Pliny's chapter is the classical root of the name rather than of the substance.

## Sources

- Pomet, P. (1694). *Histoire générale des drogues* (English, *A Compleat History of Druggs*, 1712).
- Pliny the Elder, *Natural History* 31.46, trans. J. Bostock & H. T. Riley (1855), Perseus Digital Library.
- Lundberg, J. O., et al. (2008). “The nitrate–nitrite–nitric oxide pathway in physiology and therapeutics.” *Nature Reviews Drug Discovery* 7.
- Orchardson, R., and Gillam, D. G. (2006). “Managing dentin hypersensitivity.” *Journal of the American Dental Association* 137.

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*Saltpetre.* In *Materia Medica*, edited by B. C. P. Statema. Version 1, revised 2026-10-01. The Thinking Press. https://thethinkingpress.org/materia-medica/saltpetre

Historical description, not medical advice.