60 CONSTRUCTION OF RETORTS. 



PLATES I. AND II. 



MODE OF SETTING A BENCH OF FIVE D RETORTS. 



These Plates represent a front elevation, two sections and plan of a "bench" 

 of five common retorts, such as are in general use. 



Plate I. Fig. 1. is a front elevation. Fig. 2. A transverse section, through 

 a 6 in Fig. 3. Fig. 3. A longitudinal section, through c d in Fig. 2. 



Plate II. Fig. 1. is a plan showing the furnace and side-openings below the 

 fire-tiles, on which the lower retorts rest, and the bedding of the lower retorts. 

 Fig. 2. is a plan over the three lower retorts, the two upper retorts being re- 

 moved. Fig. 3. is a plan over the oven-arch, showing the flues, etc. 



The same letters refer to corresponding parts in the several views. 



A. Retorts of the kind called D's. Some engineers prefer those of a cylin- 

 drical form, but D's allow of the coal being laid in thinner strata, consequently 

 it is more evenly acted upon by the heat, an advantage under every circum- 

 stance. Set in the manner shown in the Plates, the bottoms of those retorts 

 placed immediately over the furnace are well protected. The dimensions are 

 length 7 feet, diameter 1 foot 2 inches, thickness of metal 1^ inch. Their 

 weight is about 15 cwt. 



The most oeconomical charge is two bushels, or 1^ cwt. of coal to each retort, 

 drawn at the end of six hours. This charge will fill the retort to the depth of 

 about five inches ; if the coal be moderately small, the layer will be rather less 

 in thickness. At a heat of 27 of Wedgewood's pyrometer, or that of melting 

 copper, each charge ought to produce about 650 cubic feet of gas, of the spe- 

 cific gravity '400*, from Newcastle coal, making the products of the entire 

 bench equal to 3250 cubic feet in six hours. 



To introduce the coal into the retorts, a " scoop " ought to be employed, in 

 preference to the primitive mode, with a shovel. The scoop is a semi-cylinder 

 made of thin plate iron, six feet six inches long, and twelve inches in diame- 

 ter, with a cross-handle at one end, represented in Fig. 10. 



* The specific gravity varies between "390 and -420, according to the heat at which the retorts 

 are worked, and the quality of the coal carbonized. 



