or, more correctly, _Semi_-Neutral Tint, is a compound shadow colour of a cool character. It is permanent, except that on exposure the gray is apt to become grey, a change which may be prevented by a slight addition of ultramarine ash. So protected, it becomes serviceable in landscape for the extreme distance, which, it may be laid down as a general principle, should be painted rather cold than otherwise. Blue being the principal compound of atmosphere, it is of the utmost importance to obtain this in the first instance, particularly as, from its being only of a blue tint, not blue colour, it is so immediately altered and acted upon by subsequent washes; whereas, the blue tone once lost, it will be found very difficult to be recovered. Wherever a picture is wanting in air effect, the cause will, upon examination, be seen to rest entirely upon the absence of pure grays, bordering upon a bluish tone, not tending, be it observed, to brown or purple. A bluish gray, then, of rather a cold tone, such as the neutral tint, is recommended as the prevailing hue with which to begin the extreme distances; and, as a rule, it is better to pass with this over as much of the landscape as possible, and thus lay the foundation for a general atmosphere. 286. PAYNE'S GRAY resembles the preceding in being a compound colour and liable to assume a grey cast by time, but differs from it in having more lilac in its hue, and being therefore of a warmer tone. Giving by itself a clear violet shadow, it may be rendered more neutral by a small portion of burnt Sienna, an admixture which, whether the gray or Sienna predominates, affords useful tints. Compounded with light red or Vandyke brown, the gray is good for shipping and sails, or the stems and branches of trees; while with gamboge or aureolin it is suited to glossy leaves in high light, also to very cold tones in foregrounds, herbage, &c. Yellow ochre, light red, and Payne's gray form a mixture for banks and roads; the ochre, gray, and sepia, a most beautiful tint for stones; and brown madder and the gray, a fine shade for the black head and feet of cattle. Alone, the gray is serviceable for slate; and compounded with light red, for bricks or tiles in shadow. 287. ULTRAMARINE ASH