Webster 1913 Edition
imp. & p. p.
p. pr. & vb. n.
To subject to great heat, and then cool slowly, as glass, cast iron, steel, or other metal, for the purpose of rendering it less brittle; to temper; to toughen.
To heat, as glass, tiles, or earthenware, in order to fix the colors laid on them.
Webster 1828 Edition
1.To heat; to heat, as glass and iron for the purpose of rendering them less brittle, or to fix colors; vulgarly called nealing. This is done by heating the metal nearly to fluidity, in an oven or furnace,and suffering it to cool gradually. Metals made hard and brittle by hammering. by this process recover their malleability. The word is applied also to the baking of tiles.
2.To temper by heat; and Shenstone uses it for tempering by cold.