Heating by the Circulatioji of Fluids. 



281 



preventing it from clogging, and in swelling (for lime in slack- 

 ing increases greatly in bulk) bulging out the boilers. When 

 the lime is all slacked, the stoppers h h are to be pulled out, 

 and, by touching a trigger, the grates b b fall down, and per- 

 mit the lime to be raked out at the bottom. One of the two 

 kilns must be always burning, and the lime slacking in the 

 other, that the draught of the former may turn the axis for 

 the latter. 



Fig. 83. is another arrangement for the same purpose. 

 Here only one of the two boiler-kilns is shown. The 

 boiler is here a hollow cylinder ; the lime is thrown in at the 

 end a, and raked out at bx c c c are the tubes for the 

 affusion of water ; d d, the pipes for the circulation of the 

 hot water. The flame from the fireplace, e, passes up 

 through the lime, down on the outside of the boiler, by the 

 flue J"; and, finally, up the funnel g : or the boiler may be 

 used as a common one, independent of the lime, by shutting 

 the damper h, and opening two, placed one at each side, as 

 at /, by which the flame passes only on the outside of the 

 boiler. This latter arrangement may be adopted also during 

 the time the lime may be slacking in the internal part of the 

 boiler. The lime is sustained from falling down into the 

 flues, by a grate at ^ ; Z is an air tube to burn the smoke of 

 the fuel in the fireplace. 



