# Glass powder

**Polvere di vetro**

**Known today as.** Powdered glass.

Kind: Mineral  
Toxic: yes

> **Caution.** 

## What did Canale use it for?

In the distilled oil for hexes (ch. 9).

## What does modern science say?

Inert; in the distillation it served only as a filler. Finely powdered glass passes through the gut without harm, as Paré found; coarse fragments can cut. In a distillation it is inert, and served, as Canale’s recipe shows, to carry the other ingredients.

## Pharmacognosy and toxicology

- **silica**: amorphous silicon dioxide, 70 per cent
- **soda and lime**: 
- **lead oxide**: in crystal glass

**Mechanism.** Finely ground glass is inert in the gut and passes; coarsely broken glass cuts. The poisoner’s ground glass is largely a myth, since a powder fine enough to hide in food does no harm, which the toxicologists of the nineteenth century showed by experiment. In a distilled oil it contributes nothing, being non-volatile.

**Dose.** Fine powder is inert; shards lacerate.

**Standing.** A material of the glazier.

## What lore surrounds it?

The belief that ground glass kills was tested by Ambroise Paré, who fed it to a dog and found no harm; it was nevertheless a stock accusation in the poisoning trials of Italy and France.

## What did the older authorities say?

**The old pharmacy.** Powdered glass stood in the antidotaries as a drying, abrasive medicine for the teeth and for the stone, and Dioscorides gives burnt glass for the teeth; it was also a famous poison in the legends of the Renaissance, swallowed in food.

## Sources

- Paré, A. (1575). *Œuvres*, on poisons.
- Christison, R. (1845). *A Treatise on Poisons*, 4th ed., “Of powdered glass.”

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

Historical description, not medical advice.