incorrectly called _Cullen's Earth_, is a native bituminous earth, containing less bitumen than Cassel earth, and therefore drying more quickly. Darker than that variety, it is less transparent, and covers better. In its general qualities it resembles Vandyke brown, except that in combination with white, it affords a range of cooler brown tints. Useful for the shadows of buildings, it does not wash so well as sepia, and is preferred occasionally on that account. By some it has been called durable, by others branded as fugacious. According to Bouvier, brown hair represented by this colour has been known to disappear in six months, all the brown vanishing, and nothing remaining but a few black lines of the sketch. As it is similar in composition to Cassel earth, the safest course would be to mix it with umber, and not to employ it alone. Calcined, it acquires a reddish hue. 250. INDELIBLE BROWN INK. Although this cannot be classed as a pigment, yet, being very useful in water-colours, it may be proper to describe its qualities. The ink is a rich brown fluid, and, as its name imports, is indelibly fixed on the paper as soon as it is dry; thus allowing the artist to work or wash over it repeatedly, without its being disturbed. If diluted with water to its faintest tint, it still continues to retain its indelible properties undiminished. It is generally used with a reed pen, and employed chiefly in architectural details and outlines. Various brown inks, principally solutions of bistre and sepia, were adopted in sketching by Claude, Rembrandt, and many of the old masters. In modern times, a beautiful transparent brown for water-colour artists, known as _Liquid Prout's Brown_, has been extensively employed. This contains less fixative than the indelible ink, and is the vehicle with which nearly all Samuel Prout's drawings were executed. 251. LEITCH'S BROWN is a permanent pigment peculiar to water painting. A most beautiful olive brown, soft and rich, it is admirably adapted for autumnal foliage tints and the like, either alone or compounded with burnt Sienna or cadmium orange. Transparent and clear in its washes, this is a most serviceable colour in landscape generally. 252. MIXED BROWN