Before passing to the enamel colours, we must say something of a class of glazes which may be looked upon as to some extent of an intermediate character. These are the glazes associated with the ‘San tsai,’ the ‘three colours’ first used in combination by the Chinese. These coloured glazes were applied, not, as is usually the case in China, to the raw paste, but they were, it would seem, painted on the surface after a preliminary firing. Being applied with a brush, the whole surface of the biscuit was not necessarily covered, and glazes of all these colours could be used upon the same piece of porcelain. Glazes of this class were rendered more fusible by the addition of a certain quantity of lead, and on this ground, and still more in their historical relation, as we shall see later on, these ‘painted glazes’ may be considered as a link connecting the old refractory glazes of the monochrome and ‘blue and white’ wares on the one hand, with the fusible enamels which were at a later time _superimposed_ upon the glaze on the other. The three colours which are applied in this way by the Chinese are: (1) A turquoise blue derived from copper with the addition of some soda or potash. (2) The manganese purple, often described as aubergine. (3) A yellow prepared from an iron ore containing some amount of antimony. None of these colours would stand the full heat of the furnace, and for a reason which will be explained further on, they are known as the colours of the _demi grand feu_.[21] COLOURED ENAMELS. We have now to describe [Illustration: _PLATE II._ CHINESE MING PORCELAIN, BLACK GROUND] the decoration that is applied to the surface of the glaze. In these coloured enamels the colouring matter is dissolved in a flux which contains a large quantity of lead. The comparatively gentle heat at which such enamels fuse allows of the use of a much larger palette than is available for the decoration under the glaze. It is well to point out at the outset the marked distinction in composition and in appearance between the brilliant enamels of the Chinese and the dull tints of the ‘porcelain colours’ found in the hard pastes of Meissen and Sèvres. To make clear the cause of this difference it will be necessary to enter into some little detail.