Patent Yellow. Syn. Cassel Yellow, Montpellier y., Turner’s y. Prep. Take of dry chloride of lead, 28 parts; pure carbonate of lead, 27 parts; grind them together, fuse, and powder.
2. Common salt, 1 part, and litharge, 4 parts, are ground together with water, and digested at a gentle heat for some time, water being added to supply the loss by evaporation; the carbonate of soda formed is then washed out with more water, and the white residuum heated until it acquires a fine yellow colour. Works well in oil. Chiefly used in coach-painting. See Oxychloride of lead.
Weld Yellow. Prepared from a decoction of weld brightened with a little alum, in the same manner as Dutch pink. Used chiefly for paper hangings.
YTTRIUM. Y. The oxide of this metal (yttria), a rare, white earth, was discovered by Gadolin, in 1794, in a mineral from Ytterby, in Sweden, since called gadolinite. Yttrium was obtained by Wöhler in 1828, as a brittle, dark-grey metal, made from the chloride by the action of sodium. Its salts have in general a sweetish taste, and the sulphate and several others an amethystine colour. Its solutions are precipitated by pure alkalies, but alkaline carbonates, especially carbonate of ammonium, dissolve it in the cold. They are distinguished from glucinium salts by the colour of the sulphate by being insoluble in pure alkalies, and by yielding a white precipitate with ferrocyanide of potassium. Yttria may be obtained from gadolinite by a similar process to that by which glucina is extracted from the beryl.
According to Professor Mosander, ordinary yttria is a mixture of the oxides of not less than three metals—yttrium, erbium, and terbium. These metals differ from each other
in many important particulars. The first is a powerful base, and the others are said to be weak ones. They are separated with extreme difficulty, and are only interesting in a scientific point of view.
ZAF′FRE. Syn. Saffra, Safflor, Zaffer. Crude oxide of cobalt, obtained by roasting cobalt ore, reduced to an impalpable powder, and then ground with 2 or 3 parts of very pure quartzose or siliceous sand. Used as a blue colour by enamellers and painters on porcelain and glass. Chiefly imported from Saxony. See Smalts.
ZE′′RO. See Thermometer.
ZESTS. See Powders, Sauce, Spice, &c.
ZINC. Zn. Syn. Zink, Spelter; Zincum. (Ph. L., E., & D.), L. This metal was first noticed by Paracelsus, in the 16th century, who called it ‘zinetum,’ but its ores must have been known at a much earlier period, as the ancients were acquainted with the manufacture of brass.