Estivation, Bot. The arrangement of the unexpanded leaves of the flower-bud which burst in Summer; as opposed to Vernation, the arrangement of the leaves of the bud which burst in Spring.
Estoc, Fr. (Med. Lat. estoquum). A short sword worn at the girdle; also called a “tuck” (temp. Elizabeth).
Estoile, Her. A star with wavy rays or points, which are six, eight, or sometimes more in number.
Estrade, Fr., Arch. A platform raised three or four inches above the rest of the floor of a chamber, upon which to place a bed or a throne, &c.
Estrif or Estref, Med. A kind of arrow for the balista.
Etching. In this process the copper plate is covered with an etching-ground, which is a preparation of bees’-wax, Burgundy pitch, black pitch, and asphaltum (or other ingredients); and the lines of the design are traced out with etching-needles, which remove the etching-ground from the copper wherever they pass, and slightly scratch the surface of the plate. Next, a border of banking-wax is put round the sides of the plate, making a trough of it. The banking-wax is made of bees’-wax, common pitch, Burgundy pitch, and sweet oil melted in a crucible and poured into cold water. The next operation is to pour in nitrous acid reduced with water to a proper strength (about one part acid to four parts water). When the acid has been on a sufficient time to corrode the fainter parts of the subject, it is to be poured off, the plate washed with water, and left to dry. These fainter parts are then to be varnished with a mixture called stopping-ground, made of lamp-black and Venice turpentine, applied with a camel’s-hair pencil. This stops the further action of the acid on these parts. When the surface is dry, fresh acid is poured on to bite in the bolder parts, and the processes of stopping and biting-in are alternated for every gradation of tint. The wax is removed from the plate by heat, and cleaned away with a rag moistened with olive oil; and the work is then complete, or it may be finished off with the graver. Etching-points or needles resemble common needles, fixed in handles four or five inches long; some are made oval to produce broader lines. The dry point is only a very fine-pointed needle for the delicate lines. Imitations of chalk and pencil drawings are sometimes produced by etching on soft ground. Etching on steel is done in the same way as on copper. For etching on glass, a ground of bees’-wax is laid on, and the design traced as above. Sulphuric acid is then poured on, and fluor-spar sprinkled on it, or fluoric acid may be at once used; this is allowed to remain four or five hours, and is then removed with oil of turpentine. (See also Stipple, Mezzotinto, Aquatinta.)
Eterea of Padua. One of the Italian literary academies. Their device, a charioteer in his car in the air, drawn by a white and black horse, the one endeavouring to touch the earth, the other to ascend. Motto, “Victor se tollit ad auras.”
Etiolation. The process of blanching to which plants are subject in dark places.
Ettwee. O. E. for Etui (q.v.).
