﻿CLAYS FKOM LUZON. 



423 



6, and 7 would be classed as pure kaolins: 8 and 9 as alkaline; 10, 11 

 and 12 as silicious : 13, 14, 15, 16, IT and 18 as alkaline silieious ; and 

 10, 20, 21, 22 and 23 as ferruginous kaolins. 



A satisfactory classification of common clays is more difficult and of 

 less importance; therefore we will group all the remainder, namely 

 numbers 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36 and 37 under 

 this class. 



Analyses numbers 1, 2, 3, 4, 5, <j and 7 compare favorably with the 

 analyses of the best cjuality of kaolin from all parts of the world which 

 are given below : 



Table II. 1 - — Analyses of the best quality of kaolin from all parts of the world. 



Source. 



Silica. 



Al-ina. » 



Lime. 



Mag- 

 nesia. 



Alkalies. 



Ignition. 



England _ _ 



Do . 



47.10 

 43.32 

 45.52 



37.33 j 1.11 

 39.74 0.27 

 40.76 



0.14 

 0.36 



0.47 



0.20 



13.45 

 12.67 

 9.61 

 13.47 

 13.34 

 13.00 

 11.20 

 13.64 

 12. 76 

 13.00 



Do_ ... 



2.17 



Trace. 



1.90 

 0.25 

 0.48 

 2.00 

 1.90 

 0.45 

 0.82 

 0.66 



America 



Do 



France 



47.66 

 46.47 



48.00 



37.56 1.39 

 38.82 ] 0.89 

 36.00 



0.20 

 0.28 



0.36 

 0.25 



China 50.50 



33.70 





Japan (Schiraye) 



Germany (Dolau) 



Bohemia (Zettlitz) 



47.74 

 48.15 

 45.68 



36.68 0.42 

 37.03 0.60 

 38.54 ! 0.90 



0.99 



0.27 

 0.08 



0.30 



0.30 

 0.38 



The analyses of porcelains from China, Vienna, Meissen, Berlin, Sevres, 

 etc., show a composition of — 



Constituent. 

 Silica 



Minimum 

 (per cent). 



53 



Maximum 

 (per cent). 



75 



Average 



(per cent). 



66 



Alumina 



18 



35 



28 



1 ron 



As little 



as possible 



0.8 



Lime 







5 



1 



Magnesia 







1.5 



0.2 



Potash 







5 



2.5, 

 1.5/ 



Soda 







3 



=4.0 



The water from kaolin passes off at a temperature somewhat above 330° 

 ( Hillebrand). If we recalculate the analyses numbered 1, 2, 3, 4, 5, 6 

 and 7 of Table 1 to the anhydrous clays as is shown by Table III, we 

 have an average of fluxing materials much below that in the finished 

 product given above. The alumina is higher and the silica lower, and 

 this condition, as no flint has been added, is to be expected. The proper 

 percentages of alumina and silica would lie produced by the addition of 

 the latter, and the fluxes would be reduced still lower, or a greater margin 

 for impurities in the flint would be obtained. 



'- Binns. ('. F. : Ceramic Technology. Loud, i 1897 I. 11 ; Bourrv: Loc. cit., 65. 



