POTTERY OR STONEWARE OLATS. 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 C5.32 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 200oP 



Vitrification 2200 2200P 



Viscosity 2400 2400F 



Average tensile str., Ibs. 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 1.90 



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. 



