Is prepared in Paris, and differs in no essential particular from ordinary chromate of lead, except in the paleness of its colour. The chrome yellows have also obtained other names from places or persons, whence they have been brought or by whom they have been made. Another lead yellow, not a chromate, has likewise been called jaune minérale. 29. CITRON YELLOW Is chromate of zinc, a bright pale lemon-like yellow, slightly soluble in water. It is not affected by foul gas, but does not preserve its colour on exposure to light and air, or even when kept in a book. In contact with organic substances it is apt to turn green. Compounded, especially for foliage tints, this yellow is eligible; but if purity of hue be desired, it should certainly not be employed alone. In this chromate, as in many others, the affinity of the chromic acid to the base is small; the former is liable to separate from the latter, and, by deoxidation, to become converted into green oxide of chromium. 30. GALLSTONE Is a deep-toned gorgeous yellow, affording richer tints than most other yellows, but it cannot be depended on for permanency, and therefore is seldom employed. Its colour is soon changed and destroyed by strong light, though not subject to alteration by impure air. In oil it is ineligible. A true gallstone is an animal calculus formed in the gall-bladder, chiefly of oxen; but the pigment sold under that name is often replaced by a substitute, resembling the original in colour, but of greater stability. 31. GAMBOGE,