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粉笔是由石膏制成的。石膏的成分是硫酸钙。石膏性能稳定、无毒。数千年来,中医用生石膏(含有结晶水的硫酸钙)煎服,外用煅石膏(熟石膏)敷患处,认为能清凉解热、生津止渴、生肌敛疮。用粉笔书写板书,是将石膏粉末涂在黑板上。擦拭黑板时,石膏粉尘(粉笔灰)在空气中短暂飘扬后坠落
Chalks are made from gypsum. Gypsum ingredients are calcium sulfate. Gypsum stable performance, non-toxic. For thousands of years, Chinese medical gypsum (calcium sulfate containing water of crystallization) decoction, topical calcined gypsum (plaster of Paris) applied to the affected area, that can cool and heat, thirst, muscle soreness. Writing a board with chalk is done by applying gypsum powder to a blackboard. When wiping the blackboard, gypsum dust (chalk ash) crashes in the air and falls