Extraction of saltpetre, Earth containing saltpetre is mixed with a powder, ash and water, and the solution is boiled. The lye solidifies on rods in vats to form a saltpetre, woodcut, p. 456, (Liber duodecimus), Manuel, Hans Rudolf (graveur sur bois), 1556, Georgius Agricola: De re metallica libri XII: quibus officia, instrumenta, machinae, ac omnia denique ad metallicam spectantia, non modo luculentissime describuntur, sed & per effigies (...). Basileae: [Froben], 1556

- Image ID: 2A2RNFR
Extraction of saltpetre, Earth containing saltpetre is mixed with a powder, ash and water, and the solution is boiled. The lye solidifies on rods in vats to form a saltpetre, woodcut, p. 456, (Liber duodecimus), Manuel, Hans Rudolf (graveur sur bois), 1556, Georgius Agricola: De re metallica libri XII: quibus officia, instrumenta, machinae, ac omnia denique ad metallicam spectantia, non modo luculentissime describuntur, sed & per effigies (...). Basileae: [Froben], 1556
Artokoloro / Alamy Stock Photo
Image ID: 2A2RNFR
Extraction of saltpetre, Earth containing saltpetre is mixed with a powder, ash and water, and the solution is boiled. The lye solidifies on rods in vats to form a saltpetre, woodcut, p. 456, (Liber duodecimus), Manuel, Hans Rudolf (graveur sur bois), 1556, Georgius Agricola: De re metallica libri XII: quibus officia, instrumenta, machinae, ac omnia denique ad metallicam spectantia, non modo luculentissime describuntur, sed & per effigies (...). Basileae: [Froben], 1556.