POTTERY OR STONEWARE OLAYB. 169 



tests of two Missouri clays quoted in Vol. XI of Missouri 

 Geological Survey. The one has a much higher tensile 

 strength however: 



Analyses of Missouri Clays. 



1. 2. 



Silica 85.32 66.26 



Alumina 22.63 20.32 



Water ' 7.42 7.80 



Ferric oxide 1.81 2.30 



Lime 25 .63 



Magnesia .67 .48 



Alkalies 1.72 2.04 



Total fluxes 4.45 5.45 



Incip. fusion 2000° 200o°F 



Vitrification 2200° 2200°F 



Viscosity 2400° 2400°F 



Ayerage tensile str., lbs. per sq. in 87 122 



Maximum tensile strength 98 135 



No. 1 is from Waltman's, Barton Co., used for stoneware. 

 No. 2 is from Lanigan shaft, Moberly, Randolph Co. 



In composition it also resembles somewhat two clays 

 from Ohio.* 



Analysis of Ohio Clays. 



1. 2. 



Combined silica 25.40 27.68 



Free silica 40.81 36.58 



Alumina , 21.13 22.95 



Water 6.29 6.74 



Ferric oxide 1.28 1.28 



Lime .51 .45 



Magnesia .18 .37 



Alkalies 1.80 1.98 



Moisture 1.65 2.05 



Total fluxes 4.77 5.86 



No. 1. Cooking ware clay, Laresville, Muskingum Co. 

 No. 2. stoneware clay, Akron, Summit Co. 



In all of these analyses it will be noticed that the per- 

 centage of alkalies is higher, but the total fluxes are 

 nearly the same, except in the la^t one. 



•O. Geol. Surv. VII, 1893. 



