CLAY WORKING INDUSTRIES. 89 



of the qualities sought in the manufacture of each kind of material and 

 the differences of material and the processes involved, justify their separ- 

 ate consideration. 



I. THE MANUFACTURE OF POTTERY. 



• ** 



The manufacture of pottery is the oldest form of clay working 

 known to man. His earliest efforts to establish a home are coupled 

 with the need of utensils to contain the supplies for his immediate 

 necessities. 



In Ohio the manufacture of primitive stoneware began along the 

 valleys on the margin of the Coal Measures where the fire clays had been 

 mellowed and softened into plasticity by the exposure of centuries. 

 From such beginnings the industry has grown to the present importance. 



The pottery manufactures of Ohio may conveniently be divided 

 into the following classes. 



(a.) Earthen wares. 



(5.) Stone wares. 



(c.) Yellow and Rockingham wares. 



(d.) C. C. wares. 



(<?.) White granite wares. 



(/.) China wares. 



(g) Ornamental pottery. 



A more detailed description of pottery makes necessary a much 

 closer division, classifying the higher grades of pottery in many groups 

 according to the method of decoration or special character of body 

 employed. But these distinctions belong to the technical treatise on 

 pottery only and not to a document for general use. 



(a) Earthenwares. 



Earthenwares are perhaps the lowest form of pottery manufactures. 

 The technical distinction between earthenware and stoneware lies in 

 the degree of heat used in the burning, or rather the degree of change 

 which it is desired to produce in the body of the ware by heat. Earthern 

 wares are expected to be comparatively soft burned and porous, and except 

 in certain cases where the glazes are used, they are not fit for containing 

 liquids. The types of earthenware most familiar to the public are the 

 red and yellow flower pots which are sold in such enormous numbers 

 every fall for the preservation of the summer's floral treasures. 



The production of earthernware in Ohio, while it includes the pro- 

 duction of flower pots, etc., on a small scale in a good many small shops, 

 is represented by only three large and responsible concerns, all located in 

 the Zanesville district. 



The clays suitable for the production of earthenware have a very 

 wide range of composition. Inasmuch as it is not designed to bring the 



