The colouring medium of the pale yellow is antimony combined with a proportion of lead, and iron oxide is added to give the glaze an orange or brown tinge.[347] It is noticeable that the yellow applied to the biscuit is usually browner in tone. This is the nature, if we may judge from the excellent coloured illustrations in the Walters catalogue,[348] of the eel yellow (_shan yü huang_), a brownish colour of clouded smoky appearance, and one of the few glazes named in the _T’ao lu_ as a speciality of the directorate of Ts’ang Ying-hsüan. The other yellow associated with the name of Ts’ang is the “spotted yellow” (_huang pan t’ien_), discussed on p. 127. Its identification is uncertain, and Brinkley describes it as “stoneware with a dark olive green glaze with yellow speckles,” while Bushell (_O. C. A._, p. 317) regards it as a “tiger skin” glaze with large patches of yellow and green enamel, the same as the _huang lü tien_ (yellow and green spotted), which he quotes from another context. All these varieties belong to the _couleurs de demi-grand feu_; but there are besides several varieties of yellow enamels fired in the muffle kiln. Of these the transparent yellow was used as a ground colour in the K’ang Hsi period, but the opaque varieties, such as the lemon yellow, etc., belong rather to a later period. Among the latter I should include the crackled mustard yellow, though examples of it have often been assigned to the K’ang Hsi and even earlier reigns. There is, for instance, a bottle-shaped vase with two elephant handles in the Victoria and Albert Museum, which Bushell[349] regarded as a specimen of the old _mi-sê_ (“millet colour”) glaze of the Sung dynasty. A careful examination shows that this crackled brownish yellow is made in much the same fashion as the apple green and the sage green crackles, viz. a yellow glaze or enamel overlying a stone-coloured crackle. This is not a Sung technique, but rather an imitative method belonging perhaps to the Yung Chêng period, when old glazes and archaic shapes were reproduced with wonderful skill and truth. There is a solitary specimen of a high-fired glaze of pale buff yellow colour in the British Museum, which perhaps should be ranked with the yellow monochromes, though its appearance suggests an exceptional effect of the pale _tzŭ chin_ or “Nanking yellow” glaze. And a rare vase in the Peters Collection has a minutely crackled brownish yellow glaze clouded with dark olive in bold markings like those of tortoiseshell.