Matrass

A matrass is built simply: a rounded or slightly oval body, wide enough to hold a useful volume of liquid, drawn out at the top into a neck narrow enough to be stoppered, sealed, or fitted with a still head as the operation required. Used as a digesting vessel, the matrass was sealed at the neck and left standing, undisturbed, over gentle heat for an extended stretch, sometimes weeks, allowing whatever slow chemical change was underway inside to proceed without evaporation loss or outside contamination, the narrow neck minimizing the surface area exposed to air even before it was sealed.

Used instead as a distilling vessel, the same matrass took the place of a cucurbit: it was set over heat with its neck left open and a separate head fitted onto that neck, so vapor rising from the liquid inside condensed in the head exactly as it would in any alembic assembly. That dual use, digestion when sealed, distillation when capped, made the matrass one of the most generally useful vessels an alchemist owned, and its long neck, whether left open, stoppered, or extended into the particularly long form called a bolthead, gave the operator room to grip, seal, or fit apparatus onto the vessel without disturbing the body holding the liquid.

The matrass, sometimes called a bolthead, especially where its neck was drawn out unusually long, was among the most common vessels on an alchemist's bench, used interchangeably as a sealed digester and, fitted with a head, as a distilling flask. The word's origin is not fully settled: one plausible line connects it to the French materas or matelas, the bolt fired from a crossbow, the source of the alternate name bolthead, while another traces it to Arabic matra, a leather bottle; either way, the matrass and the bolthead are documented as names for the same round-bodied, long-necked shape rather than as two separate vessels, and treating them as identical here reflects that record rather than manufacturing a distinction between them.

The matrass's basic shape did not vanish with alchemy; it passed directly into early modern and modern chemistry as the Florence flask, a round-bottomed flask with a long neck used for boiling and distilling, which occupies essentially the same role on a chemistry bench today that the matrass occupied on an alchemist's. That continuity of shape, more than any single named inventor, is the real story this vessel has to tell: a simple round body and a long neck proved useful enough, across a thousand years of glassblowing, that nobody ever found a strong reason to redesign it from the ground up.