Also powder. A medicinal preparation made by grinding medicinal materials finely. Powders are suitable for both internal and external useand are convenient for the patient. Orally taken powders are more easily absorbed than pills. Materials that cannot be heated, or do not easily dissolve in water are particularly suitable for preparation in powder form.
Method: The materials are first carefully dried, then blended and ground together. The coarser particles are sifted off and reground until everything has been ground to a uniformly fine powder. High oil content materials such as bitter apricot kernel (Armeniacae Semen Amarum, 苦杏仁kǔ xìng rén) or spiny jujube (Ziziphi Spinosi Semen, 酸枣仁suān zǎo rén) that are not suited to baking are first set aside while the other medicinals are ground. They are then ground together with a part of the pre-ground powder, which absorbs the oil and facilitates the grinding process. Soft sticky agents such as cooked rehmannia (Rehmanniae Radix Praeparata, 熟地黄shú dì huáng), cornus (Corni Fructus, 山茱萸shān zhū yú), and lycium berry (Lycii Fructus, 枸杞子gǒu qǐ zǐ) may also be ground with part of the pre-ground agents, then sun-dried or oven-dried, and finally ground to a fine powder. Agents such as bovine bezoar (Bovis Calculus, 牛黄niú huáng) and borneol (Borneolum, 冰片bīng piàn), which, being used in such small quantities, may be lost if ground together with the other medicinals, may be ground in a porcelain mortar and added to the other powdered agents. Finally, medicinals such as realgar (Realgar, 雄黄xióng huáng), sulfur (Sulphur, 石硫黄shí liú huáng), and niter (Nitrum, 硝石xiāo shí) should not be ground since they may catch fire or explode.