Page 474 - Oriental Series Japan and China, Brinkly

CHINA

appears to have been a specialty at one time, and it is
recorded that frauds were often practised by the man-

ufacturers, who increased the bulk of the liquid by

adding water and fibrous gypsum, the result of course
being an evolution of sulphuric acid in the furnace
and consequent imperfections in the surface of the

porcelain. An idea of the pains lavished on the
manufacture may be gathered from the " History of

Ching-te-chen Keramics," where it is stated that the
potters of the Hung-woo era (13681398) used to dry
the unbaked vases during a year, at the end of which

time they were replaced on the wheel, thinned down

and covered with the glazing material. Then, after
having been again thoroughly dried, they were put in

the oven. When they emerged, if any faults were

found in the glaze, it was removed on the wheel by
means of a tool, and the piece, having been re-glazed,
was again fired. " By these means," writes the author
of the history, " a glaze lustrous and rich as congealed
fat was obtained." It is, indeed, the perfection of
their glazes which places the porcelains of China at
the head of all the keramic wares in the world.

To what particular methods of manufacture is this
excellence of glaze due ? The question has naturally

received attention in Europe, especially at the hands

of the well-known chemist, M. Salvetat, of the Im-
perial Factory at Sevres. " The glaze," he writes,

" of European porcelain is generally composed the
fact is certain in the case of Sevres ware of pure
pegmatite, finely ground and attached by immersion
to the ware while in the condition of ' biscuit.' In

Germany certain substances are mixed with the felspar

to modify its fusibility : often kaolin is added to pro-
duce greater resistance to the action of heat. But at

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