舌质无苔，亦有分别。有质紫无苔者；有质红无苔者；有舌上无苔质光如镜者；有
质干如刺无苔者；有中凹如驳去者；有中有直沟，如刀背印成者；有舌质横裂者；有舌生裂后，如冰片纹者
；有前半光滑如镜，后根上有肉瘤二粒，色如舌肉色者；有表面无苔，而皮内隐一块如钱大，
或黄或白者；有苔上见圆晕，分二三色者；有苔见青绿二色者，
此皆表面无苔，而所主之症，各不同也，亦详于后。
正黄色，为胃土正色，为温病始传之候。其为湿温、温热，当以脉之滑涩有力无力
老黄色，为胃中阳气旺盛之候。若浓腐堆起，此胃中饮食消化腐浊之气上达之后，为湿温化热
之始，为温热传入中焦阳明之候。
黄如炒枳壳色，为胃阳盛极，阳亢阴虚之候。胃气欲伤，胃汁干槁，故苔黄色如枳壳炒过状
，以其干枯不润泽也。
黄黑相间，如锅焦黄色，摸之棘手，看之不泽，为胃中津液焦灼，口燥舌干之候；然亦有阳气
为阴邪所阻，不能上蒸而化为津液者。当以脉诊分别断之，脉涩有力鼓指者，火灼津也；
脉滑无力鼓指，只有往来而无起伏者，痰饮瘀血阻抑阳气，
嫩黄色，由白而变为黄，为嫩黄色。此为用药当，胃阳初醒之候。吉兆也。为饮食消化腐浊初升
牙黄色，胃中腐浊之气始升也。牙黄无孔，谓之腻苔，中焦有痰也。
裱心纸兼灰青色，苔虽黄而兼灰青，此伤风初候。或阳气抑郁，黄苔无正色，当舒气化郁。
黄如粟米染着，颗粒分明，此为胃阳太旺，胃热之候。
黄如虎斑纹，气血两燔之候。
黄如蜡敷舌上，湿温痰滞之候，故苔无孔而腻。
水黄苔，如鸡子黄白相间染成，此黄而润滑之苔，为痰饮停积，是湿温正候。或为温热症而
有水饮者，或热入胃阴，误服燥药，而变生此苔式者，宜以诊脉分别断之。
黄腐苔，如豆渣炒黄堆舌，下症也。如中有直裂，气虚也，不可下，当补气，以气不足以运气也。
The tongue body without coating also presents various distinctions. There are cases where the tongue body is purple without coating; cases where the tongue body is red without coating; cases where there is no coating on the tongue surface and the tongue body is smooth like a mirror; cases where the tongue body is dry and prickly without coating; cases where the center is concave as if peeled off; cases where there is a straight groove in the center, resembling an imprint from the back of a knife; cases with transverse cracks on the tongue body; cases where cracks appear after fissuring, resembling ice-crack patterns; cases where the anterior half is smooth like a mirror, while the posterior root has two small fleshy nodules colored like the tongue flesh; cases where the surface lacks coating, but within the mucosa, a coin-sized patch is faintly visible, which may be yellow or white; cases where circular halos appear on the coating, divided into two or three colors; cases where the coating exhibits cyan-green colors. Although these all present a lack of surface coating, the symptoms they indicate differ significantly, as detailed later.
True yellow represents the proper color of the Stomach Earth and indicates the initial transmission stage of Warm Diseases (Wenbing). In cases of Damp-Warmth or Warm-Heat, differentiation should be based on the pulse's slippery or choppy quality, and whether it is forceful or weak.
Old yellow indicates vigorous Yang Qi in the Stomach. If the coating is thick, putrid, and piled up, this signifies that turbid qi from digested food has reached the upper jiao, marking the beginning of Damp-Warmth transforming into Heat, or the transmission of Warm-Heat to the Middle Jiao and Yangming channel.
Yellow resembling the color of stir-fried Zhiqiao (Fructus Aurantii) indicates extreme excess of Stomach Yang, characterized by hyperactive Yang and deficient Yin. The Stomach Qi is about to be damaged, and Stomach fluids are dried up; thus, the coating appears yellow like stir-fried Zhiqiao due to its dryness and lack of moisture.
Yellow intermixed with black, resembling scorched pot residue, feels rough to the touch and lacks luster. This indicates scorching of Stomach fluids, resulting in dry mouth and tongue. However, it can also occur when Yang Qi is obstructed by Yin pathogens, preventing it from steaming upward to transform into fluids. Differentiation must rely on pulse diagnosis: a choppy, forceful pulse that beats against the finger indicates Fire scorching fluids; a slippery, weak pulse that flows without distinct rising and falling indicates obstruction of Yang Qi by Phlegm-Fluids and Blood Stasis.
Tender yellow, changing from white to tender yellow, results from appropriate medication and indicates the initial awakening of Stomach Yang. This is an auspicious sign, representing the initial rise of turbid qi from digested food.
Tooth-yellow indicates the initial rise of turbid qi in the Stomach. Tooth-yellow coating without pores is called Greasy Coating, indicating Phlegm in the Middle Jiao.
A combination of mounting paper gray and cyan-green, where the coating is yellow but mixed with gray-cyan, indicates the initial stage of Wind-Cold injury. Alternatively, it may result from depressed Yang Qi, where the yellow coating lacks its true color; in such cases, one should soothe Qi flow to resolve stagnation.
Yellow resembling millet grains, with distinct particles, indicates excessive Stomach Yang and Stomach Heat.
Yellow resembling tiger stripes indicates simultaneous burning of Qi and Blood.
Yellow resembling wax applied to the tongue indicates Damp-Warmth with Phlegm stagnation; hence, the coating is poreless and greasy.
Watery yellow coating, resembling the intermingled yellow and white of an egg yolk, is a moist and slippery yellow coating. It indicates accumulation of Phlegm-Fluids and is a typical presentation of Damp-Warmth. It may also occur in Warm-Heat diseases accompanied by Fluid retention, or when Heat enters Stomach Yin and dry herbs are mistakenly administered, generating this type of coating. Pulse diagnosis should be used for differentiation.
Yellow putrid coating, resembling fried bean dregs piled on the tongue, indicates a Excess syndrome requiring purgation. If there is a central vertical crack, it indicates Qi deficiency; purgation is contraindicated, and one should tonify Qi because insufficient Qi fails to propel movement.