238 GEOLOGY OF OHIO 



cooling in pre-heating the air to be used for combustion in the chamber 

 which is burning, and the use of the heat from the burning chamber in 

 drying off and heating up the chambers in advance. 



The method of accomplishing this result however is defective, in 

 every style of continuous kiln which has yet been erected in the state. 

 The failure usually is in the waste of heat in the rear of the fuel cham- 

 ber. One chamber in the rear of the fire is ample to pre-heat all the air re- 

 quired for combustion, and it has been determined by practical tests that 

 no drying takes place further than three chambers ahead of the fire. 



If the maximum speed and the minimum consumption of fuel is to 

 be reached, it must be through some plan by which the surplus heat of 

 the cooling chambers can be made to assist in the drying off and heating 

 up of the chambers which are too far ahead of the fire to benefit by the 

 waste heat of combustion. 



The faults of the continuous kiln as it stands are mainly against the 

 speed of its operation. Only three chambers ahead of the fire can be 

 benefitte i by the heat of combustion, and from six to seven days are re- 

 quired to the kiln. Hence a chamber can only be burned off every two 

 days. If, by transfer of heat from rear of the fire to the fourth, fifth, or 

 sixth chambers ahead of the fire, it could be managed to bring these cham- 

 bers up to three or four hundred degrees before their time came for direct 

 heat, then the burning could progress with nearly twice the speed, with- 

 out any more fuel being used. However, the economy in fuel which is 

 attained by use of even the most imperfect of the continuous kilns, is so 

 very great compared with that obtained by down-draft or up-draft kilns 

 that it cannot but prove attractive to any brick maker who sees it. 

 The obstacles in the way of its general adoption are, 1st, the great cost 

 of the kiln; 2d, the comparatively limited out-put; 3d, the skill required 

 in the proper management of the kiln. These three reasons stand in the 

 way of any rapid changes to this plan from the older methods, though 

 the economy in fuel cannot be questioned or doubted by anyone familiar 

 with its work. 



Enameled Bricks, have been produced in Ohio for eleven or twelve 

 years to a limited extent. At one time the industry seemed to be likely 

 to go forward rapidly to a substantial development. Comparatively little 

 headway has been made however in the last ten years. There are three 

 factories which produce enameled brick in Ohio — W. B. Harris & Co., of 

 Zanesville, T. B. Townsend & Co., of Zanesville, and The North Balti- 

 more Pressed Brick Co., of North Baltimore. Possibly there are others 

 who have taken up this line recently, but none others are known to the 

 Survey. The enamels, which are thick, opaque, colored glazes, are laid 

 on the burnt bricks, which are then put into saggers and burned, just as 

 any pottery ware would be. 



