XI, A, 5 Witt: Philippine Paving-brick Materials 209 



ratory by the stiff-mud process. When burned to only cone 02 

 (1,110°), they developed a crushing strength of 393 kilograms 

 per square centimeter. A number of tests have been made on 

 this clay ; they are given in Tables III and IV. It seems obvious 

 that the poor quality of the product made at the San Pedro 

 Macati factory is due to the process of molding and to in- 

 sufficient burning. The clay seems better adapted to the stiff- 

 mud process. A view of the kiln, while in use, showing the 

 permanent front, is given on Plate I. The small fire in the fore- 

 ground furnishes the only heat for the kiln. One of the work- 

 men stated that the fire is maintained at about the same inten- 

 sity during the entire burning. Plate II shows the molding and 

 drying room. 



A building-brick and floor-tile factory is located on Cebu Island, 

 about 600 meters north of Mabolo barrio. The clay used (Tables 

 III and IV, clay 1) is in some respects superior to clay 2. Ap- 

 parently it is molded by the soft-mud process, though I did 

 not see the operation. The kiln is similar to a drawing shown 

 by Adams and Pratt.^^ The shape somewhat resembles a trun- 

 cated cone placed in a horizontal position. It is 26 meters in 

 length. At the small end the height is 1.15 meters and the 

 width 0.85 meter, inside measurements. At the large end the 

 height is 2.20 meters and the width 2.30 meters, inside measure- 

 ments. There are three fire boxes : one at the small end and two 

 at the sides. Wood is used for fuel, and the kiln seems to be 

 efficient. As a result of a better raw material and a more 

 efficient kiln, the product is much superior to the San Pedro 

 Macati brick. 



CHEMICAL AND PHYSICAL TESTS 



While the primary object of the present work is to find a 

 suitable material for the manufacture of paving brick, it is also 

 desired to obtain as much information as possible about Phil- 

 ippine clays in general. Consequently all clays that have been 

 received have been tested, though in some cases it was evident 

 that the material was not the one sought. A number of the sam- 

 ples appear to be excellent building-brick materials, though it is 

 difficult to decide finally on a clay until full-size bricks have been 

 molded and subjected, as nearly as possible, to the processes that 

 are to be used in the manufacture. 



"^ This Journal, Sec. A (1910), 5, 145. 



