STATE GEOLOGIST. viele 
Per Cents. 
Sill Capertee eer NING nner ae ited, ant aicya, heme fiat 59.43 
SIMI GEATAN CEE CI CLO eee ene IR TE base era ee aces ele See do, tettne 0.95 
INROADS ay Se ee A eee BE Se ccs ee ES 26.76 
He Tar: Ca Osx Gl Otte eet eee Aer cna) OR eer om tas aot 1 2 
VEpteayey 3 ease cas eas ee ee Th REE a SD ea oR 0.60 
Miao CS Tame weceenen aap tice nse. feiss etic tm ttn Oe Cell co es gow 0.32 
TE XG KP EVST ETS: 5 shire Wess co etn ea eae SU Taree nee mt a 1.00 
SO GET eee enn nN EER IPM Aicee (soiree ARNG Se we cas Trace 
GOO une Gea Ge eee ee eee ese tials ee atoy SURO sae 10.07 
~The hard fire clays, the so-called flint clays of Ohio, are of much 
greater purity than our plastic fire clays. They close'y approach kaolin in 
composition. 
The following analysis represents a typical Ohio flint clay, from 
Scioto County :* 
Per Cents. 
PUIG RY Fs ates ak am ic ols Ue nelle CORT Oe Mace Pa ee CO 44.60 
AN pret oe yea. fa BR! cease ei ae eine SRN eka SO eA A ee 40.05 
PETE CAO el CL Cee epRR Grnaate ec rcdree Ha yt Ry ec caret or te ote 0.80 
TWA Waa ys) 25-25 <a os airy rane oe Pe mie AO tea Ne RN On2 
Ot aS ee ae ae ee er nae cod sean eae ee ones oc eek Fey tn 4a eee 
SO Clee ae arene a rire 8 oS omen aria Cong! tn, She 
C@hemrcalliviat ce reeereee ete anh See so enn S| Ee At 4b BB 
Physically flint clays are hard, conchoidal in fracture and when 
moistened with water show but slight plasticity. On being exposed to the 
atmosphere they break up into sharp fragments and after longer periods of 
storing the plasticity is increased, but the clay never becomes sufficiently 
plastic to be molded with ease. 
Second Grade or Number 2 Fire Clays and Stoneware Clays.— 
Beside the clay materials representing the highest grades of refractori- 
ness we have a great number of clays in Ohio which are much less 
refractory, being higher in fluxes and free silica. 
These clays associated with the coal measures of Ohio are the result 
of the leaching process already mentioned, by means of which the fluxing 
impurities have been removed more or less completely by organic agencies. 
These clays are found in great variety of composition, as will be 
shown by the accompanying table of analyses. The main characteristics 
of the number two fire clays are, first, the ease with which they vitrify, 
which makes them particularly suitable for the manufacture of stoneware, 
though vitrification takes place very slowly and gradually; second, their 
fire resisting property, which corresponds approximately to the melting 
point of the Seger cone number 16, 1450° C., and third, the light buff 
color to which they burn. These clays are apt to contain concretionary 
iron sulphide in considerable quantities, which causes considerable diffi- 
culty and irregularity in the behavior of the materials on firing. 
The following table} of analyses will show the chemical charactcr- 
istics of these clays: 
*Vol. VII, part I, Ohio Geological Survey, p. 220. 
+Prof. Edward Orton, Jr., Geology of Ohio, Vol. VII, Part I. p. 94. 
