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An encyclopedic survey that first catalogs marine animals, algae, and shellfish, describing habitats, curious behaviors, reported antipathies, and numerous folk remedies and practical uses attributed to specific species, organized by ailments and applications. The later portion treats metals and their ores—including gold, silver, mercury, copper, and brass—describing modes of occurrence, extraction, alloying, testing, gilding, and decorative and monetary uses, alongside technical observations and medicinal remedies derived from metallic substances, with systematic lists and practical instructions interwoven throughout.
Of eretria, or Eretrian2282 earth, there are also the same number of varieties; one white, and the other of an ashy colour, this last being preferred in medicine. To be good, this earth should be of a soft consistency, and when rubbed upon copper it should leave a violet tint. The virtues of eretria in a medicinal point of view, and the methods of using it, have been already mentioned2283 in our description of the pigments.