0290 - Photos On Science And Technology. Luo Zhongjian, an associate Profes...Front

Photos On Science And Technology. Luo Zhongjian, an associate Professor of Chemistry of the Teachers' College in Sichuan Province, has invented an exercise-paper that can be used repeatedly. He dips a writing-brush in clear water and then writes on a piece of grayish paper with it. What he writes on the paper immediately appears in black as if written with Chinese ink. But it disappears gradually as it gets dried. Then the paper can be used again. It is made of materials of plentiful supply and the whole cost is low. Photo by Chem Jie