Page 59 - J. P Morgan Collection of Chinese Art and Porcelain

HISTORICAL INTRODUCTION

varies very widely in composition. A special paste

made of hiiang tun, or "yellow bricks," derived from
a very tough compact rock, pounded on the spot in

larger water mills, is used for coarser ware, and is
said to be indispensable for the proper development of
some of the single-colored glazes of the high fire.

The glaze (yu) of Chinese porcelain, is made of the
same felspathic rock that is used in the composition

of the body, the best pieces of petuntse being reserved
for the glaze, selected for their uniform greenish tone,

especially when veined with dendrites like leaves of
the arbor vitcu. This is mixed with lime, prepared by

repeated combustion of gray limestone, piled in alter-
nate layers with ferns and brushwood cut from the
mountainside. The action of the lime is to increase the

fusibility of the felspathic stone. The finest petuntse,
called yu kuo or "glaze essence," and the purified
lime, called lien hut, separately made with the addi-
tion of water into purees of the same thickness, are
afterwards mixed by measure in difi"erent proportions
to make a liquid glaze. This glaze is finally put on
the raw body with the brush, by dipping, or by in-
sufflation. T'ang Ying tells us that in his time the
glaze of the highest class of porcelain was composed
of ten measure of the petuntse puree with one measure
of the liquid lime. Seven or eight ladles of petuntse
with three or two ladles of lime were used for the glazes
of the middle class. With petuntse and lime in equal
proportions, or with lime predominating, the glaze was
described by him as fit only for coarse ware.

The glaze of Chinese porcelain always contains lime.
It is the lime which gives it a characteristic tinge of
green or blue, but at the same time conduces to a bril-
liancy of surface and a pellucid depth never found in
more refractory glazes which contain no lime. This
has been proved, moreover, at Sevres, and it is interest-
ing to note that, according to M. Vogt, the glaze of the

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