628 



PRACTICE OF AGRICULTURE. 



Pari III. 



587 



3868. Heathorh's combination of a lime-kiln and coke oven {fig. 587.) has for its object to prepare quick. 



lime and coke in the same kiln by a 

 single operation ; and the arrange, 

 ments to effect it are at once so simple 

 and so complete, as seemingly to pre. 

 elude the capability of any material 

 improvement. The economy of the 

 process is likewise carried to the 

 greatest possible degree ; for that 

 portion of the coal which is separated 

 from it to form coke is, by its com- 

 bustion, rendered subservient to the 

 burning of the limestone; and the 

 coke, owing to its increased bulk, 

 being nearly, if not quite, as valuable 

 as coal in the market, the expense of 

 burning is very much reduced. This 

 kiln and oven are raised on a flat 

 surface, the lime being raised by 

 means of a jib and crane, though, like 

 other kilns, it might be placed on the 

 side of a bank for supply in the usual 

 manner. The kiln is now, and has 

 for some time past been, in full oper- 

 ation, at the patentee's lime- works at 

 Maidstone. In districts where coal 

 is dear, this will probably be found a 

 valuable improvement; but with 

 some descriptions of coal it is im- 

 practicable, and in all cases the labour 

 will be considerably increased. The 

 side walls of this kiln {a a) are four 

 feet thick ; the iron bars at the bot- 

 tom {bb) are drawn out when the 

 kiln is to be emptied. The limestone 

 is raised in a box (rf), by means of a 

 jib and crane (e) ; when raised, the 

 jib is swung round, and the lime-box 

 tilted, by which the whole contents 

 are thrown down the shaft. The 

 coke ovens (//) may be two, or a 

 greater or less number, according to 

 the magnitude of the works. They 

 are supplied with coal through iron 

 doors, which doors have a long and 

 narrow horizontal opening in the 

 upper part of them, to admit sufficient 

 atmospheric air to produce combus- 

 tion in the inflammable part of the 

 coal ; the flames thus produced pass 

 into the lime shaft, and the flues [gg) 

 are prevented from interfering with 

 each other by a partition wall (A). 

 When the kiln is charged, the open- 

 ings in front and beneath the irorj 

 bars {it) are closed, as are certain 

 openings made in the shaft (Ar), and 

 in the coke ovens (Z), at convenient 

 distances, for the purpose of intro- 

 ducing iron bars as pokers, to acceler- 

 ate the process. "When the coal is 

 reduced to coke, it is taken out by a 

 long-handled iron hoe. {Reg. of Arts 

 and Sci. vol. iv. p. 290.) 



3869. A Yorkshire lime-kiln, (said to be a very good one), for burning lime with coal or coke, is thus 

 described in the Mechanics' Magazine :" Bottom part, where the lime is drawn out, a circle of about 

 eighteen inches diameter, and widening gradually upwards (in the shape of an inverted cone, with the apex 

 cut off) to about one half or one third of the whole depth, and then the remainder carried up perfectly 

 cylindrical to the top ; the diameter of the cylinder being about one third of the whole depth. In fixing 

 6n a place to build such a kiln, the side of a hill, near the rock to be burnt into lime, is always preferred. 

 The workmen begin by excavating a large hole in the place where it is to be erected, of sufficient dimen. 

 sions to bury the back part of it in the ground. In building up the kiln, there are two walls carried up ; 

 the space betwixt them is filled with small rubble, to keep in the heat, and next to the inner wall the 

 kiln has a lining, about a foot or half a yard in width, of a slaty gritstone that will stand heat well. "When 

 the lining wants repairs or renewing, the wall behind it keeps the rest of the materials from falling in. 

 IGdrd. Mag. vol. ii. p. 402.) 



. 3870. Burning lime in heaps. "Wliere fuel is abundant, lime may be burned in heaps, as in charring 

 tvood, or in clumps like bricks. The fuel is intermixed, and the whole covered with turf or mud, in which 

 a few holes are pierced to admit the passage of the smoke. 



' 3871. Machines for pounding limestone have been erected, but the effect of the powder so obtained, 

 both as a manure and for cement, is so much inferior to that of burnt lime, that they have long since been 

 generally laid aside. 



3872. Salt is procured from rocks, springs, and from the sea. In Chester, parti- 

 cularly in the neighbourhood of Northwich, the salt works are very extensive. Great 

 quantities are got in the solid form, but not sufficiently pure for use. In this state it is 

 conveyed from the mines to the Cheshire side of the river, nearly opposite to Livei-pool. 

 It is at this place dissolved in the sea- water, from which it is afterwards separated by 

 evaporation and crystallisation. There are also in the same district salt works, at which 

 the salt called Cheshire salt is extracted from brine. These works are described very 

 intelligibly by Dr. Holland, in The Report of Jgriculture for the County of Cheshire. 



