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the various porcelains. The scheme has obvious drawbacks. A softly-burned cup or dish would go into Class I. ; another of precisely the same make burned in a different part of the same kiln might go into Class II. By making it sufficiently thin the same body might gain an entrance into the third class. In Germany, Knapp divides pottery into two classes, dense and porous. The first includes china and stoneware ; the second, earthenware, or bricks, tiles, etc. Kerl divides this second class into (a) bricks, tiles, terracotta ; (b) refractory ware ; (c) art ware ; (d) common pottery ; (e) earthenware ; (/) faience ; (g) pipes. To the mind of the present writer the most sensible classification is the most obvious, that some bodies are unglazed, some glazed in various ways, some consist entirely CERAMIC CHEMISTRY. 83 of glaze i.e., glass, also that bodies can be grouped into three main divisions according to their absorption. One would then get a table which could be filled in ad lib. Absorption Absorption Absorption to 0.5 to over 0.5 per cent.