In the classification of old celadons due account must be taken of the imitations made from the earliest times at Ching-tê Chên. Many of these would be distinguishable by their white porcelain body, the ordinary porcelain clay of the district not having the peculiar qualities of the Lung-ch´üan and Ch´u-chou Fu material. In fact, we know that it has been a common practice in recent times among the Ching-tê Chên potters to dress the exposed parts of their ware with brown ferruginous earth when they wished to reproduce the "brown mouth or iron foot" of the archaic wares. Another method which was found effective by imitators of the antique was to use a coarse yellowish clay for the body of the ware. This, however, should be generally recognisable. But the skill of the Chinese copyist is proverbial, and a good instance of his cunning is given in the now celebrated letters of Père d'Entrecolles, a Jesuit missionary stationed at Ching-tê Chên in the K´ang Hsi period. The passage[175] is interesting enough to be quoted in full: "The mandarin of _Kim tê Chim_, who honours me with his friendship, makes for his patrons at the Court presents of old porcelain which he has himself a genius for fabricating. I mean that he has discovered the art of imitating antique porcelain, or at least that of comparative antiquity; and he employs a number of workmen for this purpose. The material of these false _Kou tom_, viz. counterfeit antiques, is a yellowish clay, obtained in a place quite near _Kim tê Chim_, called _Ma ngan chan_. They are constructed very thick. The mandarin has given me a plate of this make, which weighs as much as ten ordinary plates. There is nothing peculiar in the manufacture of these kinds of porcelain beyond that they are covered with a glaze made of yellow stone, mingled with the ordinary glaze, the latter predominating in the mixture, which gives the porcelain a sea green colour. When it is fired it is placed in a very rich broth made of chicken and other meats; in this it is baked a second time, and after that it is put in the foulest drain that can be found and left for a month or more. On issuing from this drain it passes for three or four hundred years old, or at any rate for a representative of the preceding Ming dynasty, when porcelain of this colour and thickness was appreciated at Court. These counterfeit antiques resemble the genuine pieces also in their want of timbre when struck, and if one holds them to the ear they produce no reverberation." The worthy father's acquaintance with the antiques was probably limited, or he would not have instanced the last quality as evidence of good imitation. On the contrary, the lack of timbre would be regarded by Chinese connoisseurs as indication of a spurious ware, the note of the old porcelains being one of the criteria of their excellence. But the passage is otherwise most instructive.