LIMB 



117 



slabs. In the third and fourth stories the workmen lodge at night. See fig. 1 389. Some 

 enter their apartments by the upper door q, others by the lower door s. r is one of 

 the chimneys for the several fireplaces of the workmen ; t, u, v are stairs. 



1386 



1388 



1387 



1389 



As the limestone is introduced at top, the mouth of the kiln is surrounded with a 

 strong iron balustrade to prevent the danger of the people tumbling in. The platform 

 (fig. 1388) is laid with rails w, for the waggons of limestone, drawn by horses, to run 

 upon, x is another railway, leading to another kiln. Such kilns are named after 

 the number of their fire-doors, single, twofold, threefold, fourfold, &c. ; from three 

 to five being the most usual. The outer form of the kiln also is determined by the 

 number of the furnaces, being a truncated pyramid of equal sides, and in the middle 

 of each alternate side there is a fireplace, and a discharge outlet. A cubic foot of 

 limestone requires for burning, one and five-twelfths of a cubic foot of wood, and one 

 and a half of turf. 



When the kiln is to be set in action, it is filled with rough limestone, to the height 

 c D, or to the level of the firing ; a wood fire is kindled in a, and kept up till the lime 

 is calcined. Upon this mass of quicklime a fresh quantity of limestone is introduced, 

 not thrown in at the mouth, but let down in buckets, till the kiln is quite full ; while 

 over the top a cone of limestones is piled up, about 4 feet high. A turf-fire is now 

 kindled in the furnaces b. Whenever the upper stones are well calcined, the lime 

 under the fire-level is taken out, the superior column falls in, a new cone is piled up, 

 and the process goes on thus without interruption, and without the necessity of onco 

 putting a fire into a ; for in the space c B, the lime must be always well calcined. The 

 discharge of lime takes place every 12 hours, and it amounts at each time in a three- 

 fold kiln, to from 20 to 24 Prussian tonnes of 6 imperial bushels each ; or to 130 bushels 

 imperial upon the average. It is found by experience that fresh-broken limestone, 

 which contains a little moisture, calcines more readily than what has been dried by 

 exposure for some time to the air : in consequence of the vapour of water promoting 

 the escape of the carbonic acid gas ; a fact well exemplified in distilling essential oils, 

 as oil of turpentine and naphtha, which come over with the steam of water at upwards 

 of 100 Fahr. below their natural term of ebullition. Six bushels of Eiidersdorf 

 quicklime weigh from 280 to 306 pounds. See KILNS. 



