PREFATORY NOTE. The Art Primers of the Pennsylvania Museum and School of Industrial Art are designed to furnish, for the use of collectors, historical and art students and artisans, the most reliable information, based on the latest discoveries relating to the various industrial arts. Each monograph, complete in itself, contains a historical sketch, review of processes, description of characteristic examples of the best productions, and all available data that will help to facilitate the identification of specimens. In other words, these booklets are intended to serve as authoritative and permanent reference works on the various subjects treated. The illustrations employed, unless otherwise stated, are reproductions of examples in the Pennsylvania Museum collections. In reviewing the branches of ceramics, the geographical arrangement used by other writers has given place to the natural or technical classification, to permit the grouping together of similar wares of all countries and times, whereby pottery, or opaque ware, is classified according to glaze, its most distinctive feature, and porcelain, or translucent ware, is grouped according to body, or paste. Soft porcelain may be divided into two groups a Artificial soft paste containing various compositions, as in the fritted porcelain of Sbvres and the other early French manufactories. b. Natural soft paste containing china clays as a basis, usually combined with calcined bone, as in English porcelain....