156 



Indiana University Studies 



are piled till the kiln is full. The fire is then built and the tempera- 

 ture of the whole mass is slowly raised during 6 or 8 hours till a 

 full red heat is obtained. This heating must be slow in order to 

 prevent the arch from crumbling. The high temperature is 

 maintained for about 2 days, after which the fire is allowed to 

 burn out and the kiln to cool. The material is removed and the 

 kiln recharged, much time being lost in the process. 



The first method of burning lime and one occasionally used 

 at the present time for fertilizing lime was to pile together heaps 

 of logs on which blocks of limestone were piled. The whole mass 

 was fired and the overburned or underburned blocks were thrown 

 aside and the remaining material used. This method was fol- 

 lowed by the heap or ditch method in which the limestone was 

 piled in long heaps on a bed of wood and long openings for draft 

 channels were left thru the piles. These huge heaps were fired 

 as the smaller heaps had been fibred before, but the burning took 

 a much longer time. These ditches were modified into trenches 

 upon hillsides where the material to be burned slid down thru 

 the trench much as it does in the lime kilns of today; the burned 

 product came out at the lowest level. This type of kiln required 

 four times as much wood fuel as the amount of lime burned, 

 but the small cost of wood in the earlier days made this method 

 practicable. Next came the stone-pot kilns which were square 

 chambers of stone about 18 to 20 feet high and about 12 feet 

 square. These w^ould produce as much as 800 cubic feet in 24 

 hours. They were the forerunners of the modern type of inter- 

 mittent kiln, and many of them are still in use. The modern 

 lime plant has 3 floors. The top one is for charging the kilns, 

 the middle one for charging the fires, and the bottom one for re- 

 moving the burned product. The upper floor is connected with 

 the inclines to the quarry up which the limestone is drawn in 

 cars to be dumped in the top of the kiln. The second floor is on 

 a level with the coal bins and is usually level with the ash dump. 

 The lowest floor is at the ground level so that the product can be 

 loaded in cars. 



Under present conditions one ton of coal will burn from 3 to 

 5 tons of lime, the problem being to keep the fires at their greatest 

 efficiency and to force or draw the hot gases up into the kilns. 

 These things can best be done by means of forced or induced 

 draft put on the fires. There are four methods of securing 

 better draft on lime kilns at present in use, and they are as 



