of which the following are the most worthy of attention :— II. ZINC WHITE is an oxide of zinc, which has been more celebrated as a pigment than used, being perfectly durable in water and oil, but wanting the body and brightness of fine white leads in oil; while in water, constant or barytic white, and pearl white, are superior to it in colour, and equal in durability. Nevertheless, zinc white is valuable, as far as its powers extend in painting, on account of its durability both in oil and water, and its innocence with regard to health. And when duly and skilfully prepared, the colour and body of this pigment are sufficient to qualify it for a general use upon the palette, although the pure white of lead must merit a preference in oil. III. TIN WHITE resembles zinc white in many respects, but dries badly, and has even less body and colour in oil, though superior to it in water. It is the basis of the best white in enamel painting. There are various other metallic whites of great body and beauty,- such are those of bismuth, antimony, quicksilver, and arsenic; but none of them are of any value or reputation in painting, on account of their great disposition to change of colour, both by light and foul air, in water and in oil. IV. PEARL WHITE. There are two pigments of this denomination: one falsely so called, prepared from bismuth, which turns black in sulphuretted hydrogen gas or any impure air, and is used as a cosmetic; the other, prepared from the waste of pearls and mother-of-pearl, which is exquisitely white, and of good body in water, but of little force in oil or varnish: it combines, however, with all other colours, without injuring the most delicate, and is itself perfectly permanent and innoxious;—witness Cleopatra's potation of pearls. V. CONSTANT WHITE, permanent white, or Barytic white, is a sulphate of barytes, and when well prepared and free from acid is one of our best whites for water-painting, being of superior body in water, but destitute of this quality in oil. As it is of a poisonous nature, it must be kept from the mouth;—in other respects and properties it resembles the true pearl white. Both these pigments should be employed with as little gum as possible, as it destroys their body, opacity, or whiteness; and solution of gum ammoniac answers better than gum arabic, which is commonly used: but the best way of preparing this pigment, and other terrene whites, so as to preserve their opacity, is to grind them in simple water, and to add toward the end of the grinding sufficient only of clear cold gelly of gum tragacanth to connect them in a body, and attach them to the paper in paint ing. Cold starch, or other vegetal or animal gelly, will answer the same purpose. Barytic white is seldom well purified from free acid, and, therefore, apt to act injuriously on other pigments. VI. WHITE CHALK is a well-known native carbonate of lime, used by the artist only as a crayon, or for tracing his designs; for which purpose it is sawed into lengths suited to the portcrayon. White crayons and tracing-chalks, to be good, must work and cut free from grit. From this material whitening and lime are prepared, and are the bases of many common pigments and colours used in distemper, paper-staining, &c. There are many other terrene whites under equivocal names, from the famed Melinum, or white earth of Melos, mentioned by Pliny to have been used by the Greek painters, to common whitening prepared from chalk. Among them are Morat or Modan white, Spanish white, or Troys, or Troy white, Rouen white, Bougeval white, Paris white, Blanc de Roi, China white, Satin white, the latter of which is a sulphate of lime and alumine which dries with a glossy surface, &c. The common oyster-shell contains also a soft white in its thick part, which is good in water; and egg-shells have been prepared for the same purpose; as may likewise an endless variety of native earths, as well as those produced by art. From this unlimited variety of terrene whites we have selected above such only as are reputed, or as principally merit the attention of the artist;—the rest may be variously useful to the paper-stainer, plasterer, and painter in distemper; but the whole of them are destitute of body in oil, and, owing to their alkaline nature, are injurious to many colours in water, as they are to all colours which cannot be employed in fresco. See Table 9, Chap. xxii. CHAPTER IX. OF THE PRIMARY COLOURS. OF YELLOW. "What is here? Gold? yellow, glittering, precious gold? No, Gods, Thus much of this, will make black, white; foul, fair; Shaksp.: Timon of Athens. Yellow is the first of the primary or simple colours, nearest in relation to, and partaking most of the nature of, the neutral white; it is accordingly a most advancing colour, of great power in reflecting light. Compounded with the primary red, it constitutes the secondary orange, and its relatives, scarlet, &c. and other warm colours. It is the archeus, or prime colour of the tertiary citrine;—it characterizes in like manner the endless variety of the semineutral colours called brown, and enters largely into the complex colours denominated buff, bay, tawny, tan, dan, dun, drab, |