The Han pottery is usually of red or slaty grey colour, varying in hardness from a soft earthenware to something approaching stoneware, and in texture from that of a brick to the fineness of delft. These variations are due to the nature of the clay in different localities and to the degree of heat in which the ware was fired. No chronological significance can be attached to the variations of colour, and to place the grey ware earlier than the red is both, unscientific and patently incorrect. Most of the Szechuan ware is grey and comparatively soft, while of the specimens sent from Northern China the majority seem to be of the red clay. Some of the ware from both parts is unglazed, and in certain cases it has been washed over with a white clay and even painted with unfired pigment, chiefly red and black. The bulk of it, however, is glazed, the typical Han glaze being a translucent greenish yellow, which, over the red body, produces a colour varying from leaf green to olive brown, according to the thickness of the glaze and the extent to which the colour of the underlying body appears through it. Age and burial have wonderfully affected this green glaze, and in many cases the surface is encrusted in the process of decay with iridescent layers of beautiful gold and silver lustre. In other cases the decay has gone too far, and the glaze has scaled and flaked off. Another feature which it shares with many of the later glazes is a minute and almost imperceptible crackle. This feature is almost universal on the softer Chinese pottery glazes, and has nothing to do[19] with the deliberate and pronounced crackle of later Chinese porcelain, being purely accidental in its formation. The colour of the glaze shows considerable variations, being sometimes brownish yellow, sometimes deep brown, and occasionally mottled like that of our mediæval pottery. A passage in the _T´ao shuo_[20] seems to imply the existence of a black glaze as well, but it is a solitary literary reference, and it is not perfectly clear whether a black earthenware or a black glaze is meant. It was thought at one time that the fine white ware with pale straw-coloured or greenish glaze, of which much of the T´ang mortuary pottery is made, was in use as early as the Han period, but I am now convinced that this is a later development, and cannot be included in the ware of the Han dynasty.