S3 



and maintain even drafts. After the ware has been burned 

 to the consistency of red brick, they must undergo the fur- 

 ther process of glazing. For this purpose common salt is 

 thrown into the fire-boxes with the fuel, and the temperature 

 raised to such a point that the surfaces of the tile are just 

 fusing. This heat is maintained for a short time, the salt 

 fumes are carried through the kiln, and on meeting the clay, 

 which is just at the fusion point, form a sodium iron silicate 

 with the clay, forming a glaze, covering the tile very per- 

 fectly. It is easily seen that this must not be carried too 

 far. or the ware would fuse down and become distorted and 

 quite misshapen. After the glazing the kiln must be cooled 

 very gradually, a process usually distributed over three days, 

 and even then the tile are as hot as the men can handle with 

 buckskin gloves. 



