Technical Investigation of Chinese Pottery 87 



The analysis proves that this body has all the chemical characters 

 of a true porcelain. Its resemblance to the analyses of Japanese porce- 

 lains made by Seger 1 is remarkable. 



The silica and alumina both fall within the rather narrow limits 

 set by Seger for this ware. The important deviations from the com- 

 position of Japanese porcelain are precisely those which characterize 

 modern Chinese porcelains. These are: the high content of iron, in 

 this instance of little significance; the high alkali content; and the 

 excess of potash over soda. An important feature in the composition 

 of porcelain and pottery bodies is the silica-alumina ratio. The ware 

 presents, in this feature, a decidedly Japanese aspect. The Chinese 

 porcelains analyzed by Salvetat generally are higher in alumina, and 

 lower in silica, than this specimen and the Japanese bodies. The 

 analyses of Chinese porcelain indicate a decidedly variable composition, 

 as might be expected from Julien's description of the rather haphazard 

 way in which the mixtures are made. In respect to this silica-alumina 

 ratio, which sharply distinguishes Oriental from Occidental porcelains, 

 the ancient bit of pottery under consideration comes distinctly into the 

 Oriental class. 



The quantity of alkali is essentially the same as in Salvdtat's analyses 

 of modern Chinese porcelains. Salvetat 's average is 5.59%, while 

 this ware contains 5.80%. The quantity of iron in some of Salvetat 's 

 specimens is essentially as great as that of this specimen. The varia- 

 tion among themselves of the analyses of modern Chinese porcelain 

 is fully as great as the difference between these and the pottery under 

 discussion. As the chemical composition of the ware is that of a good 

 porcelain, the reason it failed to make a fine ware must be sought in 

 those physical features which are consequent on the handling of the 

 materials during manufacture, and not in any qualities inherent in 

 the nature of the materials themselves. 



Physical Characters of the Body. — The body is composed of a 

 gray vitrified material, with the slightly greasy lustre characteristic of 

 some varieties of vitrified ware. Under an ordinary hand magnifying- 

 glass, it appears as a kind of solidified froth composed of pores enclosed 

 by thin walls of a translucent porcelain-like substance. These pores 

 are elongated, so that there is a well-defined laminated structure. 

 There are numerous inclusions of a black and glassy iron slag. Each of 

 these glassy inclusions surrounds a minute spherical bubble. Through- 

 out the body there are angular patches of lighter and darker gray which 

 are vestiges of coarse particles in the mixture from which the body 



1 Collected Writings, Vol. II, pp. 687 and 716. 



