110 THE IRON ORE DISTRICT OF EAST TEXAS. 



temperature kept up for seven hours, after which it was allowed to cool 

 down and the fire die out. On opening the furnace the clays, which had 

 been marked A, B, and C, representing, 



A, upper deposit on Jefferson and Linden road; 



B, lower deposit on same road; 



C, sandy clay on Daingerfield and Linden road, 



were found to be changed in color from a whitish gray to a pale buff or yel- 

 low color, except that one end of B, which had been placed close to the side 

 of the muffle and consequently somewhat more exposed to the fire, had be- 

 come a light shade of brown. Although considerable shrinkage had taken 

 place, the sharp angles of the corners were not visibly affected and showed 

 no signs of even incipient fusion. On breaking, A and B exhibited a close 

 body of a cream or buff color, with small specks of bright red scattered 

 through the mass. In C the texture of the brick is more open and granular, 

 and the contained iron not so pronounced, although more diffused through- 

 out the mass. 



These clays may be used for the manufacture of the ordinary earthenware 

 of every day use, and also for the manufacture of pressed ornamental and 

 front bricks. They may also be used for the manufacture of a low grade of 

 fire brick suitable for such work as building fireplaces or for grate linings, 

 and may also be used as a boiler setting. For a high class refractory brick 

 suitable for furnace purposes the clays will require to be treated in such a 

 manner as to get rid of the large quantity of mica these clays appear to con- 

 tain. Mica, being largely composed of soda or potash, is apt, under an in- 

 tense and prolonged heat such as is usual in iron furnaces, to resolve itself 

 into its primary constituents, thus setting free the alkalies the mica may con- 

 tain. These alkalies have an affinity for and are apt to combine with what- 

 ever ferric oxide may be in the clay, and this combination forming a slag or 

 glass destroys the brick completely. It is due to this action on the part of the 

 mica that many of the micaceous clays found extensively developed in places, 

 and which are otherwise suitable for many purposes, are rendered quite 

 worthless. The treatment to which these clays will have to be subjected will 

 probably be too costly if necessary to get rid of the whole of the contained 

 mica, but it is probable that by a systematic course of winter curing and 

 afterwards careful washing before using sufficient may be removed to render 

 the Jefferson clays suitable for a medium grade of fire bricks, and also for 

 the manufacture of fire clay goods of a lower grade than necessary for fur- 

 nace purposes. Any neglect or carelessness in the preparation of the clay 

 will inevitably lead to failure. 



These clays may also be used for the manufacture of ordinary drain tiling, 

 and as they will admit of glazing, may be used for a medium grade of sewer 



