20 



KILN 



1300 



chambers, whilst the other portion of the kiln 'is burning. The drying may be 

 facilitated by bringing hot air from the cooling portions of the kiln into the drying 

 chamber for the time being, by means of a moveable pipe or flue, which may be 

 adjusted to any of the holes, e, in roof. When the bricks are sumcently dry, the doors 

 and flue are removed so as to bring them within the direct range of the hot air and 

 products of combustion from the burning bricks, preparatory to their being tired from 

 above. In this arrangement flues provided with dampers should be employed, leading 

 from each compartment to separate chimneys, or to one common flue leading to a single 

 chimney, and each compartment should have near its upper part a flue for carrying off 

 the steam and vapour, evolved during the process of drying. 



Pottery -kilns are sometimes constructed upon this principle, in compartments ; the 

 number varying considerably according to the conditions required : these are not 

 usually continuous. The greatest possible heat is required for baking porcelain. The 

 porcelain kiln consists of a round chamber, on the floor of which the porcelain vessels, 

 enclosed in seggars, are arranged in columns. The flames fill the whole space, cir- 

 culating between the columns, and escaping through different apertures in the top of 



the chamber ; from thence they 

 enter a second chamber, and their 

 heat is still sufficient for baking 

 biscuit-ware. Fig. 1300 repre- 

 sents the Sevres porcelain kiln. 

 The kiln is surrounded by four 

 separate fires A A, which first heat 

 the space i,, which is intended for 

 completely burning the porcelain ; 

 the upper chamber i/ being used 

 for baking the biscuit; while the 

 third space i/'may be used for the 

 same purpose, or for drying the 

 seggars, the flame escaping through 

 the chimney c. The hearths of 

 the porcelain kiln are peculiar ; 

 they are constructed without any 

 grate, and built in such a manner 

 that the draught is forced to take 

 a contrary direction to that which 

 it usually takes in other kilns. 

 The space c is filled with red-hot 

 fuel, which is passed in through 

 the aperture b, and completely fill 

 the space f. The draught in the 

 first instance is downward, in the 

 direction of the arrow, through //, 

 and the spaces between the fuel in 

 f and c ; this creates a long flame, 

 which escapes through p into the 

 chamber L. The round aperture o 

 is usually closed with a clay 

 stopper ; through this opening the 

 fire is stirred ; b, at the foot of the 

 hearth is used for removing the 



ashes when necessary, the draught being always regulated by the lid b'. The flue is divi- 

 ded by three tongues into three channels p, in order that the flame may be dispersed ; D 

 and E are the doors for the insertion of the goods. In the arched covering of the space 

 L twenty-five apertures 1 1 are left to conduct the flame into the chamber i/. Any 

 single opening would draw all the flame together the object is to spread it. Half the 

 number of openings are made in the roof of i/ f t', for a similar purpose. Small 

 openings are made in the walls of the chamber L, through which the colour of the fire 

 may be watched. The whole of the kiln is bound together with iron bands to prevent 

 its falling to pieces. Such furnaces are usually 20 feet in diameter, they are con- 

 structed internally with fire-stone, aud surrounded on the outside with bricks. 



Hoffmann's Continuous Kiln. Fig. 1302 represents a vertical section, andfy. 1301 

 a sectional plan of a continuous kiln, combined with a second or inner chamber, by 

 which dry or warm air may be taken from any of the heated chambers of the kiln to 

 any of the other chambers, for the purpose of drying green bricks or other articles 

 from which it is desired to drive off the moisture, a, the brickwork of the kiln, a 

 portion of the annular burning and drying space of which may be shut off or sepa- 



