escheln.

1728 Linckius in Philos. Trans. 1726–7 (Royal Soc.) 34 202 Tum ad separationem pulveris illius cinerei albicantis levioris, quem Eschel appellant.]

1753 Chambers's Cycl. Suppl. Eschel, a term used by the smalt workers, to express a sort of grey substance resembling ashes, which is usually mixed with the smalt when in fusion. This is carefully separated from it, before it is powdered for use, otherwise it would debase the colour.

1875 A. Ure Dict. Arts 874 [Cobalt] In commerce, smalts are classified both according to their contents in cobalt, and the size of the grain, the following being the chief marks..[e.g.] O.E. Ordinary Eschel. Ordinary indicates the relative quantity in cobalt..Eschel the state of division.