CLAY WORKING INDUSTRIES. 221 



No. 1. Flint Clay from C. E. Holden, Mineral Point, Ohio, Lower Kittanning, 

 Horizon, used for high grade refractory material sampled in 1883 — analysis by Lord. 



No. 2. Same clay, finely ground and averaged, sampled 1892, analysis by Orton. 



No. 3. Flint Clay from Carter County, Kentucky, furnished by Portsmouth 

 Fire Brick Co., analysis by Otto Wuth. 



No. 4. Same clay , sampled and analyzed by Kentucky Geological Survey. 



No. 5. Gaylord Clay, Scioto Co., Ohio, from Portsmouth Firebrick Co. — by 

 Kremer & DeDeken. 



No. 6. Eifert Clay, Carter Co., Kentucky, from Portsmouth Fire Brick Co., by 

 Kremer & DeDeken. 



No. 7. Tiplan Clay, Carter Co., Kentucky, from Portsmouth Fire Brick Co., by 

 Kremer & DeDeken. 



No. 8. Stone City Flint Clay, Stone City, Kentucky. 



No. 9. Salineville Flint Clay, Furnace Fire Brick Co., Salineville, Ohio. 



No. 10. Mount Savage Clay ; New Jersey Report. 



These clays are seen to be of great purity, the average contents of 

 fluxing materials being only 1.54 per cent. 



The oxygen ratio of the average of these clays is: 



Oxygen in acid, 1.36 ; oxygen in base, 1. 

 Oxygen in alumina, 51 ; oxygen in flux, 1. 



indicating a compound between a protosilicate and a sesquisilicate with 

 very low proportion of fluxing bases. 



Silicates of most of the bases are most fusible between the subsili- 

 cates and bi-silicates with pure compounds of silica and alumina; how- 

 ever, the point of greatest fusibility seem to be above the bi-silicate ratio 

 and below the trisilicate ratio. 



These flint clays constitute the body mixture of all of the refractory 

 materials of the state, but on account of their non-plasticity, it is neces- 

 sary to use plastic fireclays to act as a bond material. 



The aim in selecting the plastic clays for a refractory mixture, is to 

 get as sandy a clay as can be had which will develop plasticity well; the 

 more sandy the clay is, the less it shrinks, except by vitrification. A clay 

 free from any impurity but sand will stand a high heat and shrink but 

 little and it is a clay of the nature that is sought. 



In the following table, No. XII, the analysis of five Ohio plastic fire- 

 clays, which are actually used as bond clays for the flint clays of the state 



arecompared. 



Also the analysis of a very superior high grade plastic clay which is 

 imported from Germany for use as bond to flint clays in glass pot manu- 

 facture is given. 



This clay is far superior to anything which we find in this state in 



the way of a plastic clay. 



