crucibles

Noun

crucible (plural crucibles)

1. A cup-shaped piece of laboratory equipment used to contain chemical compounds when heating them to very high temperatures.
   • In one corner of the closet was a very small furnace, with a glowing fire in it, and on the fire a kind of duplicate crucible—two crucibles connected by a tube. One of these crucibles was nearly full of lead in a state of fusion, but not reaching up to the aperture of the tube, which was close to...1850, Edgar Allan Poe, “Von Kempelen and His Discovery”, in The Works of the Late Edgar Allan Poe
2. A heat-resistant container in which metals are melted, usually at temperatures above 500°C, commonly made of graphite with clay as a binder.
3. The bottom and hottest part of a blast furnace; the hearth.
4. (figuratively) A very difficult and trying experience, that acts as a refining or hardening process.
   • But, in considering an author and his works as one, a sufficient distinction is not drawn between the ideal and the real: the last is only given by being past through the crucible of the first.1837, L[etitia] E[lizabeth] L[andon], “A First Night”, in Ethel Churchill: Or, The Two Brides. […], volume II, London: Henry Colburn, […], →OCLC, page 70