Many different forms of kiln are used for burning Portland cement.
The manufactured goods are either removed gradually from a constant source of heat by means of a train of small iron trucks drawn along a tramway by an endless chain, or are placed in a heated kiln in which the fire is allowed gradually to die out.
In the working of this type of kiln the rotation and slight inclination of the cylinder cause the raw material to descend towards the lower end.
Therefore, allowing adequate time for loading and unloading, each kiln will require about one week for a complete run.
When the floor of the kiln has been covered with slabs of glass the opening is carefully built up and luted with fire-bricks and fire-clay, and the whole is then allowed to cool.
The construction of an ordinary chamber kiln may be gathered from the accompanying diagram (fig.
The kiln consists of two (or more) connected cells which are both charged with the ore.
The carbonic acid gas injected into the highly limed juice in the saturators is made by the calcination of limestone in a kiln provided with three cleaning doors, so arranged as to allow the lime to be removed simultaneously from them every six hours.
When thoroughly softened - the time occupied depending on the heat of the water and nature of the silk - the contents of the kiln are taken out and placed into vats of hot water, and allowed to soak there for some time.
Thus the buildings forming the residence of a well-to-do farmer of the bo-aire class as described in the Laws, consisted of a living-house in which he slept and took his meals, a cookinghouse, a kiln for drying corn, a barn, a byre for calves, a sheepfold and a pigsty.