62 JOURNAL AND PROCEEDINGS 



would be somewhat the color of iron chemically treated by natural 

 causes, mostly by oxidation ; or from the vicinity of springs containing 

 sulphur, iron and copper, would be of a greenish tint ; when these 

 mix with cobalt, haematite or manganese, black is the result. In 

 white clay, cobalt or black neutralizes and has the effect of whitening, 

 as the blue does in the laundry. The white clays are found near 

 silver beds, quartz, silicate of lime, felspar and oxides of tin and silver. 



Terra Cotta. — Now our flower pot or piece of Terra Cotta has 

 certain characteristics ; it is somewhat brittle, porous, gives a dry, 

 adhesive sensation to the tongue, is more or less gritty to the 

 touch, and on the whole not a very useful thing for the higher 

 purposes of civilized life. But for many ages the pottery was of 

 this rough kind, as seen by the drawings, photographs and 

 diagrams hung around the room to illustrate the lecture. It is very 

 doubtful if the Greeks ever, or the Romans up to the time of 

 Augustus, knew of any other kind of pottery. The next stage was . 

 to find out either a clay which would fuse, so as to be non-porous, 

 or to coat a porous body with a non-porous coating of glaze (glaze 

 simply meaning a film of glass) The former process, that of 

 rendering the body impervious, applies mainly to two kinds of ware : 

 i st, China, or as it is sometimes called Porcelain, made from 

 Kaolin clay ; and 2nd, Stoneware. 



It will be seen, therefore, that the potter's art is progressive. 

 The " sun dried," gave place to " fired earthenware " or terra cotta, 

 and this in turn gave place to "glazed earthenware," which was 

 impervious to moisture, dirt and ordinary chemicals, including most 

 acids, which practically means the ware was quite indestructible. 



Antiquity of Glazed Ware. — Certainly the potters of Babylon 

 knew the process of glazing, as the fragments of tiles still in existence 

 show ; but many centuries elapsed before the secret of manufacture 

 was transmitted to the western world. Specimens of glazed pottery 

 of decidedly moresque origin have been found in Spain, and could 

 not have been later than the 9th century. 



Glaze. — Glaze and glass are made out of the same materials. 

 Flint, sand and soda, when fused together, make glass ; the addition of 

 a metallic oxide gives color, opacity and the better power of cohesion 

 to glass ; and these are precisely the conditions of glaze as applied to 

 pottery. Some writers try to distinguish between "pottery" and 



