140 GEOLOGY OF OHIO. 



The use of the sedimentary clays of the Ohio River in the produc- 

 tion of vitrified wares began some six or eight years ago at Middleport. 

 Ohio is now represented by three factories, two at Middleport and one 

 at Addyston, below Cincinnati. 



Thes£ clays evidently owe their origin to deposition in eddies of 

 the Ohio River, as they alternate with deposits of sand and gravel. 

 Where they occur, they are 20 to 30 feet deep, almost without a pebble or 

 stone in them. They present the cheapest form of clay which can be 

 used for paving material, as they can be dug by steam shovel for a nom- 

 inal cost and the work involved in preparing the clay for use is almost 

 nothing. 



The plastic nature of the material is against it however as it is diffi- 

 cult to prevent faults of structure in producing the brick. 



An analysis of the clay from a large test of twelve car loads from 

 Columbia which was worked into vitrified wares of high grade shows the 

 following composition : 



Silica (total) 63.73 



Alumina 17.17 



Water (combined) j 4.90 



Clay and Sand 85.80 



Oxide of iron 5.85 



Lime 58 



Magnesia 97 



Potash 2.33 



Soda 67 



Clay and sand 85.80. 



Fl^es 10.40 Fluxes 10.40. 



Water (free) 2.96 Water 2.96. 



Total 99.16 Total 99.16. 



E. Orton, Jr., Chemist. 

 The oxygen of ratio of this clay shows : 



3.12 acid to 1 base and 2.77 alumina to 1 flux 



which indicates a clay less fusible than the average shales, but much 

 more fusible than the fire clays. 



Under fire this clay vitrifies beautifully, but unfortunately it begins 

 to bend and lose its shape also, unless the burning is managed with great 

 dexterity. 



The quantity of these clays along the banks of the Ohio River is 

 enormous, and the discovery of the vitrifying qualities coupled with the 

 close proximity of shales and fire clay clays, at various intervals, forms a 

 most valuable addition to the mineral resources of the state. The gen- 

 eral character of the vitrifying clay deposits may be summed up as 

 follows: 



