626 



PRACTICE QF AGRICULTURE. 



Part III. 



times, though seldom, covered with sods or turf, in order to keep the heat as intense as possible. The fire 

 is then lighted in the apertures ; and when the limestone towards the bottom is completely calcined, the 

 luel being considerably exhausted, the limestone at the top subsides. The labourers then put in an addi- 

 tion of limestone and coal at the top, and draw out at bottom as much as they find thoroughly burned; 

 and thus go on, till any quantity required be calcined. When limestone is burned with coals, from two 

 bushels and a half to three and a half of calcined 1 mestone are produced for every bushel of coal used. 

 _ Lime will, in all cases, be most economically burned 



C^ 579 by fuel which produces little or no smoke ; because 



the necessary mixture of the fuel with the broken 

 limestone renders it impossible to bring it in contact 

 with a red heat, which may ignite the smoke. Dry 

 fuel must also, in all cases, be more advantageous 

 than moist fuel, because in the latter case a certain 

 quantity of heat is lost in expelling the moisture in 

 the form of vapour or smoke. 



3863. Booker's lime-kiln {fig. 579.) is the best of all 

 forms that have hitherto been brought into notice for 

 burning lime with coke or other dry smokeless fuel. 

 The kiln of this description at Closeburn is built on 

 the side of a bank ; it is circular within, thirty-two 

 feet high from the furnace, three feet in diameter 

 top and bottom, and seven feet in diameter at 

 eighteen feet from the bottom ; it has cast-iron doors 



jbT^ at 

 SvtiLZ to 



580 



to the fuel-chamber [fig. 580. a) and 

 ash-pit (A), and a cast-iron cap or cover 

 {fig. 579. c, d.), which turns on a pivot, 

 and rests on a curb-ring fixed on tiie 

 top of the masonry of the kiln (rf). 

 The use of this cover is to prevent the 

 escape of more heat than is necessary 

 to keep the fuel burning, for which ; 

 last purpose the cover has only an ^ 

 opening at top {d), twelve inches in 

 diameter. The principal advantage of 

 this construction is, that very little heat is lost, and 

 that lime may be burned with almost as little fuel 

 in winter as in summer. Another advantage, and 

 one of considerable importance in a country sale, 

 where a kiln is not worked sometimes for two or 

 three days together, is, that by closing the orifice 

 (rf) at top, and the furnace doors {fig, 580. a b) below, 

 the fire may be kept alive for four or five days. In 

 the ordinary descriptions of kilns without covers, 

 the fire is usually extinguished in twenty-four 

 hours, especially in the winter season. In Booker's 

 kiln, one measure of coke will burn four measures 

 of limestone. The fuel for the lime-kilns at Close . 

 burn is brought from a distance of twenty-five miles, 

 and it is found that one third of the expense of car- 

 riage is saved by coking it at the coal-pits. A mea- 

 sure of this coke burns as much lime as the same 

 measure of coal ; as when coal is used in the lime- 

 kiln it may be said to be coked before it has much 

 effect on the limestone. One of Booker's kilns, 

 when coke is used, yields nearly three fourths of its 

 contents of well burned lime every day. 

 S86i. Menteath or Closeburn coal lime-kiln. When lime is to be burnetl with coal or smoky fuel, a form 



581 



584 



582 



4t.., 



invented by me has been adopted 

 at Closeburn, which, from a very 

 extensive experience, I have proved 

 to be much superior to those in com- 

 mon use. This kiln, which may be 

 designated the Closeburn coal lime- 

 kiln {fig. 581.), is built in a similar 

 situation to the other. It is oval in 

 ground plan, both at top (^^'. 582.), 

 r-Qo and bottom 

 ^^^* {fig. 583.), 

 with doors 

 to the fuel- 

 chamber and 

 ash-pit {fig. 

 581. e/), and 

 an arched 

 cover to the 

 top ( fig- 584, 

 g), which 

 moves on 



small wheels, 



is drawn off 

 and on by windlasses {h h) and has 

 two small openings serving as chim- 

 neys for the exit of the smoke (/ i). 

 The height of the kiln is thirty-five 

 feet : the short diameter at the fuel- 

 chamber is twenty-two inches {fig.. 

 583.) ; at the height of twenty feet 

 the short diameter has gradual'y ex- 

 tended to five feet {fi^. .581.), and 

 this dimension is contmued to the- 

 top, where the oval is nine feet by 

 five feet {fig. 582.). As the fuel- 

 chamber to this kiln is very broad in proportion to its depth, three (separate doors or openings become 



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