Also 7–8 coppel, cuppel, (7 copel(l, coppell, -ill, -le). [a. F. coupelle (15th c.), med.L. cūpella, dim. of cūpa cask, to which the current form is adjusted.]
1. A small flat circular porous vessel, with a shallow depression in the middle, made of pounded bone-ash pressed into shape by a mold, and used in assaying gold or silver with lead. Also the similarly shaped ‘test’ or movable hearth of the reverberatory furnace in which silver is separated from lead by cupellation.
1605. Timme, Quersit., I. xvi. 82. Euery goldsmith and mint-man … know how to dispearse … such mettals into smoake with their cupels.
1611. Cotgr., Coupelle, a Coppell; the little Ashen pot, or vessell.
1626. Bacon, Sylva, § 799. As wee see in the Stuffe, whereof Coppells are made … Upon which Fire worketh not.
1678. Phil. Trans., XII. 955. It was … first Refined with Lead upon a Copel, for separation of any Copper that might be in it.
1759. B. Martin, Nat. Hist. Eng., II. 232. A large Coppel, where the Lead is now made.
1791. Lane, in Phil. Trans., LXXXI. 224. The contents of each paper were placed in separate cupels, under a muffle.
1862. Lond. Rev., 23 Aug., 175. The argentiferous lead … is then submitted to the process of cupellation. This operation is performed in a reverberatory furnace, on the hearth of which is placed the cupel, which is of an oval form about 4 feet long and 21/2 feet broad.
b. fig. (Cf. TEST.)
1673. O. Walker, Educ. (1677), 52. Suffering is the great trial and cupel of gallant spirits.
1847. Disraeli, Tancred, II. i. Money is to be the cupel of their worth.
2. attrib. and Comb., as cupel-furnace, -mo(u)ld; † cupel-ashes, † cupel-dust, ashes and dust used in purifying metals.
a. 1626. Bacon, Wks (1740), III. 212 (J.). It may be also tried, by incorporating powder of steel, or copple-dust.
1683. Pettus, Fleta Min., I. (1686), 9. There must first be a smooth fire-place, and upon that Copell-Ashes are to be laid the breadth or thickness of a finger.
1800. trans. Lagrange’s Chem., I. 28. It is employed as a cuppel-furnace by means of a small semicircular aperture.
1875. Ure, Dict. Arts, III. 822. The cupels are formed in a cupel-mould made of cast steel.
