130 
Improved Kilns for burning Lime. 
4tli. That in agricultural districts some portion of the lime is 
generally required for building purposes, and that lime burnt in 
this manner is generally not well suited for such purposes, as it 
usually contains cinders and other refuse from the coal. 
I have found in practice that it is better, instead of merely 
trusting to a bri( k lining to the conical hole cut in the chalk or 
limestone, to build five counterforts round the kiln, and to fill in 
the spaces between them with lumps of chalk or limestone built 
in mortar, as, unless the hill is of an unusually solid character 
and impervious to water, the conical brick lining is very apt to 
expand and crack with the heat. 
11. — The Intermittent Kiln. 
In this description of kiln the fuel is not mixed with the 
material used, but is placed in a furnace either at the side or 
bottom of the kiln, and always laid upon a grating of fixed fire- 
bars, being replenished from time to time, until the whole of 
the material in the kiln has been properly calcined. 
As soon as the kiln arrives at this state it is allowed to cool 
down gradually, and the whole of the charge is withdrawn when 
it is cool enough to handle. 
These kilns are built of various forms, and are generally, like 
the " Perpetual Kilns," constructed, if possible, on the side of a 
hill. They are most commonly rectangular, similar to the " Brick 
Kiln," about 14 feet wide, 12 feet deep, and from 9 feet to 10 
feet high, internally, from the floor to the top. 
Fig. 4. — Section of Intermittent Kiln. 
The walls should be 3 feet thick, lined on the inside with 
fire-brick. The outer wall need not be solid, but may be con- 
structed with 3-feet buttresses in brickwork, an 18-inch lining 
on the inside, and the space in the outside between the but- 
tresses filled in solidly with lumps of chalk or limestone set in 
mortar. Three fire-holes are constructed from front to back of 
the kiln, 1 foot 6 inch, wide, 1 foot 6 inch, high from the bottom 
of the ashpit to the under side of the bearing-bars, and 1 foot 
9 inch, high from the top of the bearing-bar to the under side of 
