﻿416 cox. 



Crater Lakes of Taal Volcano" lias recorded that aluminium hydrate is 

 continually heing deposited as a sediment from these 4akes. It appears 

 probable that many of the clay beds of the Philippines may have been 

 deposited as a result of the chemical action of similar waters. 



As the raw materials vary, so in a similar way do the uses to which 

 clays are put, namely, the manufacture of porcelain, stoneware, earthen- 

 ware, tiles (drain and roof), terra cotta, sewer pipes, common bricks, 

 "vitrified" bricks for paving, doorknobs, playing marbles, as a filler for 

 paper, 7 a food adulterant, etc. At one end of a series we find the 

 analyses of the fine European porcelain, which is made from practically 

 pure kaolin with admixtures of flint, feldspar, etc., and at or near the 

 other we encounter the crude pottery of the majority of savage tribes, 

 which is usually made from clay very high in iron and containing very 

 little kaolin. If we continue in the direction of silicious dilution, we 

 find the analyses of fire-clay wares and of the so-called "dinas brick" 

 much used for building purposes in many places, for example in western 

 Germany. The latter are pure, crushed quartz, excepting the residue 

 from the milk of lime or clay in the water used for moistening the 

 material before it is molded into the bricks and which is the cementing 

 constituent. 



EXPERIMENTAL. 



The object of this paper is rather to show in a preliminary way the 

 geologic distribution and quality of clays on Luzon than to pronounce 

 upon their economic values. The chemical composition is the first step 

 toward a complete knowledge of the quality of these materials and I 

 therefore give, in the following table, analyses and tests of a few specimens 

 of the Luzon clays : 



Sample DESCRIPTION OE THE CLAYS. 



No. 



1. Kaolinite calculated from the theoretical formula Al 2 3 -2Si0 2 -2H 2 0. 



2. Koalin or china clay from Los Baflos, Laguna. Approaches closely to koalin- 



ite in composition. 

 a. Kaolin or china clay from the Vicenti Jesus mine, Laguna. Approaches 

 closely to kaolinite in composition. 



4. Kaolin or china clay, not from Luzon, but from Roniblon. It approaches 



closely to kaolinite in composition and is given for the purpose of com- 

 parison. 



5. Koalin or china clay from Laguna Province. 



6. Kaolin or china clay from Los Banos, Laguna Province. Approaches closely 



to kaolinite in composition. 



7 Attention has already been directed by Richmond ( This Journal, Sec. A, 6en. 

 Sci. (1907), 2, 81) to the probable usefulness of Philippine clays as a filler and 

 a glazing material for paper manufacture. Standards for the purchasing and 

 testing of such filling materials are given by Schacht, W., Papier Ztg. (1906), 

 31, 4234; Gliem. Abstracts (1907), 1, 485. 



