OBINA 0LAT8. 121 



The clay fused at cone 27 in the Deville furnace. 

 The clay has to be heated very slowly in burning in 

 order to prevent cracking. 



The tensile strength of the briquettes was tried In sev- 

 eral different ways. 



One lot was made from clay ground to pass through 

 a 20 mesh sieve, and these showed a tensile strength of 

 137 lbs. per square inch, the maximum being 154 lbs, 

 the variation in the different briquettes being 20 per 

 cent. A second lot was ground to pass through a 60 

 mesh sieve, and here the average strength was 138 lbs. 

 per square inch, the maximum being 143 lbs. and the 

 variation 12 per cent. 



A third lot was ground to pass through a 1 00 mesh 

 sieve and here the average tensile strength was 1 32 lbs. 

 per square inch with a maximum of 150 lbs. and a vari- 

 ation of 15 per cent. 



The chemical analysis of this clay yielded: 



Analysis of China Clay, J. B. BugUee. Gadsden. (No. 190.) 



Silica ••■ 67.95^ 



Alumina 20.15 



Ferric oxide l-OO 



Lime ■■■.■•• ^-O" 



Magnesia tr. 



Allsalies 1-87 



Ignition 8.00 



99.97 

 Total fluxds 2.00 



There are many points of a desireable nature ttD be 

 found in this material, viz.; its high plasticity, its^ great 

 density on burning, and its good tensile strengtl}, .^ll.ot 

 which would combine to mfike it a ball clay of good qiial- 

 ity. The color on burning is not quite as white as could 

 be desired but no doubt washing would improve this. 



