150 ADAMS AND PRATT. 



It will be seen that the clays from the region of Mount Maquiling, 

 commonly referred to as the Los Banos and Calamba clays, are high in 

 alumina and relatively low in silica. Some of them approximate the 

 composition of kaolinite. The clays from the region of ISTasugbu in 

 Batangas Province are low in alumina and relatively high in silica. It 

 will be remembered that a strong ware made at Zobel's kiln was obtained 

 by mixing 10 parts of Los Bahos clay and 4 parts of Batangas clay, which 

 brought up the percentage of silica, and that the best and strongest ware 

 from Philippine materials was obtained by using 10 parts of Los Bahos 

 clay and 2 parts of Laoag "silica." 



The clay from Matiquio on the east side of Jalajala Peninsula, Laguna 

 Province, is low in alumina but is high in iron. In addition to the 

 physical tests reported by Cox, a practical test has been made by burning 

 some ware made from it in the kiln at San Pedro Tunasan. It is not 

 certain that the clay used in the ware is the same as the sample analysed. 

 On burning it showed a peculiar, old-rose color. The practical test 

 demonstrated that it is suitable for hard earthenware in which the color 

 would be covered by a glaze. 



The analyses of alluvial clays show a rather low percentage of silica 

 and a high total of fluxes. They fuse at a low temperature and show 

 more shrinkage than is desirable. 



An analysis of a clay from Albay Province, locality not definitely, 

 known, shows the highest percentage of silica of any of the Philippine 

 clays outside of one sample from Nasugbu, and is inserted for the sake 

 of comparison and as an example of silicious clay such as it is desirable 

 to find. 



In general it may be stated that the Philippine clays are deficient 

 in silica, and, moreover, that the only source of additional silica thus 

 far discovered is at Laoag, in Ilocos Norte, far removed from the pottery 

 industry which at present centers near Manila. According to Dr. W. D. 

 Smith, of the division of mines, this material is obtained from a decom- 

 posed granulite dyke. 2 It is disintegrated by heating, so that the ma- 

 terial which was used in Manila at Zobel's kiln, and to a small extent 

 at the bottle factory, was received in the form of a sand. 



Pottery Tciln at the Santa Cruz trade school. — Mr. A. G. McLeod, 

 superintendent of the schools of Laguna Province, in December, 1909, 

 in accordance with the plans of the Director of Education, had con- 

 structed under the direction of K. Kato a down-draft kiln with two ovens, 

 and began the making of pottery from alluvial clay. It is proposed soon 

 to introduce the use of clay from Matiquio which will permit of pro- 

 ducing a better ware. This venture promises to meet with success, since 

 there is a good local demand for pottery. 



2 The Asbestos and Manganese Deposits of Ilocos Norte, with notes on the 

 geology of the region. This Journal, Sec. A, (1907), 2, 3, 145-175. 





