388 



cox. 



Physical properties. 



Water 

 added 

 to give 

 a work- 

 able 

 paste 

 (per cent 



total 

 weight). 



Tensile strength. 



Shrinkage (percent). 



Color. 



Air dried, 6 de- 

 terminations 

 averaged. 



Burned." 



Air. 



Fire. 



Total. 



Air dried. 



1 



Burned with 



free access 



of air. 



1 



Kilos 

 per 

 square 

 centi- 

 meter. 



Pounds 



per 

 square 

 inch. 



Kilos 

 per 

 square 

 centi- 

 meter. 



Pounds 



per 

 square 

 inch. 



34.9 



1.81 



25.8 



1.9 



27.1 



6.1 



13.3 



19.4 



Bluish-white - 



Cream. 



" Crackles badly. 



The physical properties of the grayish clay are as follows : 



Water 

 added 

 to give 

 a work- 

 able paste 

 (per cent 



total 

 weight). 



Tensile strength. 



Shrinkage (per cent). 



Color. 



Air dried. 



Burned.' 



Air. 



Fire 

 at cone 

 No. 9. 



Total. 



Air dried. 



1 



Burned with 



free access 



of air. 



Kilos 



per 



sq uare 



centi- 

 meter. 



Pounds 



per 

 square 

 inch. 



Kilos 



per 



square 



centi- 

 meter. 



Pounds 



per 

 square 

 inch. 



33.4 



1.75 



24.9 



2.39 



34 



4.65 



14,2 



18.85 



Grayish-white _ 



Cream. 



" Crackles badly. 



Still another very light-gray sample was taken at a distance of 30 or 

 40 meters. Three determinations gave its tensile strength as 2.4 kilo- 

 grams per square centimeter (34.2 pounds per square inch) and its air 

 shrinkage as 2.4 per cent. 



At some future time the disintegration of this deposit will have 

 produced a sufficient quantity of clay to justify its use for the manu- 

 facture of potteiy. 



There is a Japanese in^Los Bahos who is successfully molding various 

 kinds of small objects from C'alamba clay. He has very primitive ap- 

 pliances and his products are all underburned, but his work indicates 

 that with proper handling, satisfactory results probablj^ could be obtained 

 with this clay. 



The indications are that all of the high grade clays of Laguna Prov- 

 ince are more or less mixed with clay of poorer quality. It is a question 

 what percentage of the mixture is useful and whether the expense of 

 sorting will not be so great that it can not compete with kaolin from 

 other sources. 



