 (2) Alchemy.Among the large number of Chinese scholars who have expressed their views about the date of the "Cantong qi", the opinions of Chen Guofu (who was for several decades the main Chinese expert in this field) are especially worthy of attention.As he pointed out, no extant alchemical work dating from the Han period is based on the doctrinal principles of the "Cantong qi", or uses its cosmological model and its language (Chen Guofu, 1983