KILN 



19 



d, an archway for setting and drawing the kilns, made up with bricks daubed with 

 clay, so as to be air-tight while the bricks are burning. The system of firing is the 

 same as in the ordinary end firing ovens. The mode of working is simple : No. 1 kiln 

 when fired, is put into communication with No. 2, this kiln having had the opening 

 in front closed up, and the damper in the chimney opened. No. 2 kiln acts as a chimney 

 to No. 1 during the time that the moisture is being driven off from the bricks in it. 

 While this operation is going on, No. 3 kiln can be set, and as soon as the moisture 

 is expelled from the bricks in the first kiln, communication can be closed with No. 2, 

 and that with No. 3 opened. The waste heat will then pass into No. 3. This can be 

 repeated as many times as there are kilns, and the firing up of the kiln with the dried 

 bricks effected. 



In Hellmann's brick-kiln, at his works near Hanover, the firing-chamber is 8 foot 

 from side to side, 1 2 feet 8 inches to the top of the .arch, and 20 feet 4 inches in length. 

 This space, which is much larger than that in the kiln just described, will contain 

 24,000 bricks. The mean quantity of coal consumed in firing this kiln is 260 cwts. 

 The kiln is heated from 4 grates, which join in the centre. 



The open Dutch kilns are much larger. Heren describes one 51 feet wide, 110 feet 

 long, and 25 feet high, containing 56 layers of bricks, one above the other, consisting 

 of more than 3,000,000 bricks, which are burnt in 36 days by the flames from 10 fires. 

 The Bihl kiln (fig. 1298) used in "Waiblingen is of a similar character. This kiln 

 is heated by two fires; between the fires and the chimney A there are two working 

 chambers, a lower chamber c for burning, and an upper chamber B for drying the 

 bricks. The working chambers and chimney are separated from each other by per- 

 forated arches ; the lower arch a a above the fire being perforated with 25 apertures 

 for the passage of the flames, while between the drying chamber and the chimney 

 there are 13 similar passages. The fuel is placed below the chief chamber c and in 

 front of it, in a prolongation of the fire channels a a, in which the grates are set. 

 Several modifications of these kilns have been from time to time introduced, and they 

 have been specially varied to meet the conditions for burning roofing tiles, pipes, &c., 

 but in principle they are essentially the same. 



Hoffmann's Straight Kiln. The following ./z^. (1299) represents in section a kiln on 

 Hoffmann's system as arranged by Chamberlain and Wedekind. 



a a is the brick-work of the kiln ; b, the fire-place at one end, the opposite end 

 opening with a chimney c, by a flue d; a number of openings e e, provided with 

 closely-fitting covers are constructed along the roof of the kilns for the introduction of 

 small fuel. The entire length of the kilns having been filled with bricks, in a fit state 

 for burning, a fire is lighted in the fire-place b, and air is allowed to enter freely through 

 the fire-door. When the heat at this end of the kiln is sufficiently high, fuel is intro- 



1299 



duced through the openings e e on the top. The hot air and products of combustion 

 pass along the entire length of the kiln, between the goods stacked in it, gradually 

 heats it, and finally passes off by the flue d to the chimney c. So soon as that portion 

 of the stacked bricks, into and amongst which the fuel has been supplied, has become 

 sufficiently burnt, the further supply of fuel is stopped, and the supply is then carried 

 on through other openings e in advance, so as td mingle the fuel with the adjoining 

 bricks, which by this time will bo sufficiently heated to ensure the coinbustion 

 of such fuel. Those bricks which have been thoroughly burnt are now allowed 

 to cool gradually by the action of the cold air which passes amongst them and takes 

 up the caloric, which is transferred to the succeeding bricks on its way to the chimney. 

 In this manner the process of burning is continued until the extreme end of the 

 kiln has been reached, some of the goods having, in the meantime, been drawn 

 and replaced by fresh ones, so that the kiln will be ready for relighting by the time 

 the last of the goods is withdrawn. These kilns may be provided at intervals with 

 sliding doors, which extend across the kiln, and subdivide it into a number of separata 

 compartments, facility is thus afforded for making use of these compartments as drying 



c 2 



