This article records tradition as it has been passed down and reported. Its sources are not yet part of the atlas's verified catalogue.
Spirit gathers four alchemical substances that share a name rather than a single kind of thing, and the clearest way to read the group is as two literal liquids sitting beside two ideas nobody ever isolated. Aqua Vitae and Spirit of Hartshorn are the literal pair. Aqua Vitae is the flammable spirit distilled from fermented wine or grain mash, prized across medieval and early modern Europe both as a medicine believed to prolong life, which is where its name comes from, and as the ancestor of nearly every distilled liquor made since. Spirit of Hartshorn is its alkaline opposite, the sharp volatile alkali obtained by dry distilling the horns, hooves and bones of deer and other animals, valued in the sickroom for reviving a fainting person under its later name, smelling salts. Both map cleanly onto a modern chemical identity, ethanol for one and ammonia dissolved in water for the other.
Azoth and The Alkahest are the conceptual pair, and neither names a substance any chymist ever actually held. Azoth is the alchemical term for a universal, animating spirit or mercury believed to underlie all matter, central to several traditions and used by Paracelsus in a second, narrower sense for a specific medicinal mercury preparation. The Alkahest is the hypothetical universal solvent Jan Baptist van Helmont and others pursued as though achievable, a liquid able to dissolve anything without being consumed itself. No recipe for it has ever been verified, and modern chemistry treats a true universal solvent as a physical impossibility, since it would have to dissolve its own container. What unites all four under one heading is only the word spirit, not a shared chemistry: two a modern chemist can name outright, and two a modern chemist can point to nowhere at all.