Page:The American Cyclopædia (1879) Volume XII.djvu/819

 PAINTS heavy spar, which destroys its opacity and also its affinity for the oil, so that it soon washes away. Sulphate of lime, or gypsum, and chalk are also sometimes used as an adulteration for white lead, and zinc blende is sometimes used as a substitute, and is said to cover well. The finest white leads are made at Krems in Lower Austria, and their preparation is attended with great labor. Next to these the Dutch and English white leads are regarded with the most favor ; the former have the greater opa- city, but are said to be rather more apt to be- come yellow by age than the English. The most durable paints intended for covering or- dinary objects are made with white lead as a basis, the coloring being given by other ma- terials, such as lampblack, umber, ochre, red lead, vermilion, verdigris, &c. ; although cheap paints are sometimes made by mixing oils, particularly those that are cheap, such as fish oils and petroleum, with fuller's earth, ochre, or lime. It has been asserted that the use of zinc in place of white lead relieves the work- man from disease ; but the effects of zinc un- der similar circumstances have not perhaps been sufficiently observed to form a correct opinion. The following are some of the finer paints, called artists' colors. Flake white is made of carbonate of lead with an excess of oxide, mixed with boiled linseed oil, to which is often added a varnish. By the Krems, and also by the Dutch process of manufacture, white lead is rendered amorphous and very opaque, in consequence of the oxide of lead being in excess, a portion of the carbonic acid being replaced by water. Silver white is a term applied to a similar kind of white lead, and some whites are called Koman and Vene- tian. The whites of bismuth, zinc, tin, and barytes are of too feeble opacity. Strontian yellow is a color in which the base is chromate of strontia, of a pale canary color, resisting the action of foul gases and light, and being per- fectly durable. Cadmium yellow, sulphuret of cadmia, is a rich and brilliant orange, and also resists the action of foul gases and light. There are other yellows, such as the chromates of lead; Naples yellow, made of the oxides of lead, antimony, and zinc ; yellow orpiment, sulphuret of antimony, forming the base of King's yellow ; the zinc yellows, and the chro- mates of cadmium, mercury, and barytes. These are objectionable on account of want of durability, either from blacking by sulphu- retted hydrogen, or for changing color from disintegration and other causes. The native earths, or ochres, such as yellow, Oxford, Ro J man, stone, brown, and Sienna, consisting of silica and alumina, colored by oxide of iron, are permanent colors, and furnish the painter with some of his soundest materials. Indian red, made of a native silicate and oxide of iron, is also a durable and valuable color. Venetian red is an inferior kind of Indian red. Vermilion, cinnabar, or sulphide of mercury (HgS, for- merly called bisulphide), is a permanent paint PAISIELLO 805 of a beautiful red, and not affected by acids or ** alkalies. The madder lakes, which are vegeta- ble dyes mixed with earthy bases, are rich and beautiful colors; but all vegetable compounds should be regarded with suspicion, although madders have the best reputation. Palladium red, ammonio-chloride of palladium, is a rich, deep, beautiful red, and a valuable pigment, but not much used. Ultramarine, made from native lapis lazuli, or artificially by heating to- gether kaolin, carbonate of soda, and sulphur, is a brilliant purplish blue, not destroyed by foul gases or light, and, although affected by acids, is durable for the painter. There are many processes for artificial ultramarine, and a method has been found by Prtickner (see " Colors in Painting," by Eiffault, Vergnaud, and Toussaint, Philadelphia, 1874) to determine their durability by treatment with hydrogen. Silicate of cobalt and potassa form cobalt blue, but it is not so strong a pigment as ultra- marine. Prussian blue is liable to change, and indigo fades in the light. Chromium green, sesquioxide of chromium, made by strongly igniting chromate of mercury, is a strong, opaque, permanent light green ; it is the color- ing matter of the emerald. Scheele's green, arsenite of copper, verdigris, a mixture of sub- acetates of copper, and other mineral greens, are not considered as durable as chromium green ; many of them form black sulphides by continued action of foul air. Terre verte, a native silicate of protoxide of iron, with water, potash, and magnesia, is a delicate green, re- sisting all ordinary destructive agencies, but de- stroyed, like ultramarine, by acids. Vandyke, Eubens, Cassel, and Cologne browns are made of decomposed vegetable and bituminous mat- ter, and are deep and rich, with a certain degree of translucency, for which they are valued. Ivory black, or burnt ivory, is a pigment much used by painters ; also lampblack, and the blue blacks, made of burnt vine twigs, and that 'of the ancients made of the lees of wine. Man- ganese black, peroxide of manganese, and black ochres or earths are also used. PAISIELLO, Giovanni, an Italian composer, born in Taranto, May 9, 1741, died in Naples, June 5, 1816. He was educated in the con- servatory of St. Onofrio at Naples under Du- rante, and at the age of 20 was a prolific com- poser of masses, psalms, motets, &c. His first opera was produced in 1763 at Bologna, and during the next 13 years he is said to have composed upward of 50 for the chief cities of Italy. Most of these speedily sunk into ob- livion. The most celebrated of his earlier operas was Dal Jlnto al vero. In 1776 he ac- cepted an invitation from Catharine II. to es- tablish himself in St. Petersburg, where he remained nine years, producing several operas and oratorios, and a variety of miscellaneous pieces. Some of his best works belong to this period, particularly II T)arT>iere di Seviglia. Going to Vienna, he composed for the emperor Joseph II. 12 symphonies, and the opera buffa