obrussa | obrȳzum aurum (noun F) : (pure Gr. collat. form = χρυσίον ὄβρυζον, , Vulg. 2 Par. 3, 5; Isid. 16, 18, 2), , = ὄβρυζον
* The testing or assaying of gold by fire in a cupel (class.).
* Lit.: auri experimentum ignis est: id ipsum obrussam vocant,Plin. 33, 3, 19, § 59: aurum ad obrussam,refined, pure gold,Suet. Ner. 44.
* Trop., a test, touchstone, proof: adhibenda tamquam obrussa ratio,Cic. Brut. 74, 258: sic verus ille animus probatur: haec ejus obrussa est,this is its touchstone, its test,Sen. Ep. 13, 1: si omnia argumenta ad obrussam coeperimus exigere,to put to the proof, test accurately,id. Q. N. 4, 5, 1.

s. TLL