BUILDING MATERIAL. 467 



most of it is inclined to be variegated. Some of the beds are light yellow 

 and some of them are reddish. 



Several quarries have been opened near Henrietta that have proven to be 

 good. The stone is even-bedded and uniform in color, is very easily quar- 

 ried and works well under the hammer, does not color on exposure to the 

 weather, is free from nodules of pyrites, and is a very desirable building 

 stone. 



The court house, jail, and many other buildings in the town of Henrietta 

 are constructed of this material. 



At a great many other places there are beds of fine sandstone that can be 

 used where there is a demand for such material. 



BUILDING MATERIAL. 



CLAYS. 



The clays in this part of the State may be divided into two classes; first, 

 that which occupies its original position in the formation and has been broken 

 down on exposure to the atmosphere; second, the residual clays, more or 

 less mixed with other material, which lias been deposited in its present posi- 

 tion by the action of the water during the time of the erosion, and more 

 lately by the rivers and creeks. 



The most of the bricks manufactured at present in this district are from this 

 residual clay. That this clay should vary very much in different localities is 

 to be expected from the very mode of its occurrence. It differs in value 

 as a brick making material, owing to composition, texture, and different 

 degrees of fusibility. That there should be failures sometimes in making 

 good bricks is not to be wondered at; but the failure can generally be traced 

 to the want of skill in the manufacturer rather than to the composition of the 

 clays. Different clays require different handling, from the mixing to the final 

 burning. 



Pure clay will not make brick by itself, nor will clay and sand, even of 

 proper proportions, unless there is some material to act as flux when they are 

 burnt in the kiln. 



Pure clay must furnish the largest part of the material for brick making 

 and give body to the brick; yet by itself it would crack and crumble in dry- 

 ing, would shrink and melt and warp in burning, and be too hard to be 

 broken by a stroke of the trowel, which is often necessary in building. Sand 

 prevents the brick from cracking when drying and shrinking when burning. 

 Lime, magnesia, and the metallic oxides, acting upon the other material, 

 cause sufficient fusion in burning to cement the whole in a compact mass. 

 The most of the clays in this district contain a sufficient amount of peroxide 

 of iron to color the bricks a beautiful red. 



