1836.] 



FARMERS REGISTER. 



4.3S 



tre the pjaseous matter has escaped, unless new 

 surfaces lie exposed to air. 



In heaps of ijreater diameter and heicrht than 

 we have described, the combustion would be too 

 Blow at first to form a porous coke, and so rapi<l at 

 the end as to render it difficult to extin(i;uish. Yet 

 RO larije is the quantity of coke which is required 

 in some insuiuces, and particularly in the manu- 

 facture of iron, that heaps of so small a size would 

 be attended with inconveifience. The shape of 

 the heap is therefore changed in such case from a 

 cone to a lorifj prism. The breadth oi' this nuist 

 not exceed fifteen feet, nor its height three feet, 

 but its leniith may be unlimited. This prism 

 must be set on fire in the mode we have mention- 

 ed at several points on its upper ed<ie. In this 

 way not only may a greater quantity of coke be 

 prepared at a sintjle operation, but the time is 

 shortened, the conical heaps requiring three or 

 four days for their conversion into coke, while the 

 prisms are finished in twenty-four hours. 



The product is usually about forty per cent., 

 but some coals, that ofVu'ginia lor instance, yield 

 filty per cent. If a coal, inconsequence of its con- 

 taining but little hydrogen, does not burn freelj^, it 

 cannot be converted into coke in this way. Such 

 a coal was found in Yorkshire, (England,) in as- 

 sociation with minerals which would render the 

 manufacture of iron profitable. In order to apply 

 it to this purpose, an intelligent manufacturer 

 (Wiikiiison) imagined the application of a chim- 

 ney, for the purpose of obtaining a more powerful 

 draught. This chimney is conical in form, about a 

 yard in height, and as much in diampierat bottom; 

 the diameter at t0|) is two ieet ; it is built of brick, 

 the lower courses of which are laid in such man- 

 ner as to leave openings. Around the chimney 

 the coal is piled in n heap, whose radius is about 

 six feet greater than the outer radius ol'the chim- 

 ne3^ This heap is composed of allernale layers 

 of large and small coal, the lowermost layer being 

 of pieces of the largest size. The surface of the 

 heap is covered witli ashes or refuse coke, and fire 

 is applied by throwing burning fuel into the chim- 

 ney. Wet ashes are kept on hand to close any 

 cracks which may occur in the cover of the bean. 

 Dense smoke flows from the chimney, and is fol- 

 lowed by a blue flame; as soon as this appears, 

 the top of the chimney must be closed by a plate 

 of cast iron and the combustion will speedily 

 cease. 



The coal of Pittsburg, Pa. as ihr as we can 

 learn,, must resemble in quality the coal employed 

 by Wilkinson; for although tar removed in char- 

 acter from anthrache, it has not hitherto been con- 

 verted into coke by the use of the mode first de- 

 scribed. We cannot but express our belief that 

 the method of Wilkinson would be found sufficient 

 for the purpose, and that by its aid the manufac- 

 ture of iron fi"om the ores might be introduced into 

 that city, which at present receives almost all the 

 pig iron used in its extensive foundries and forges, 

 from the opposite side of the Alleghany range of 

 mountains. 



This method has also been introduced, with 

 some modifications in Stafibrdshire, where the 

 coal IS of better quality. Here the coarser coal is 

 placed in contact with the chimney, and the finer 

 at the outside of the heap, the whole being cover- 

 ed Avith ashes, or refuse coke, leaving a few open- 

 ings lor the admission of air. As soon as the coke 



Vol. IV— 55 



is finished, wafer is poured on the heap to extin- 

 (jiiish the combustion. In this way the product of 

 coke is raised from liirty to fifty per cent. 



All the methods of which we have spoken re- 

 fiuire that tfie coal should be principally of that 

 size which is of most value lor other purposes, 

 namely, in coarse fragments. Much however of 

 all good coal is reduced to dust in its extraction 

 from the mines, and in the handling it must un- 

 dergo. This, in most parts of England, is totally 

 lost, and it has even been necessary to burn it in 

 heaps in order to get rid of it. In France, where 

 coal is more scarce, and consequently of more va- 

 lue, it has become an important object, that none 

 but such refuse coal should be converted info coke, 

 and the coarser pieces left to be employed fbcother 

 purposes. This object has been successfully ac- 

 com[)lished in the neighborhood of St. Elienne. 



The heap in which the coal is burnt may have 

 the form either of a truncated cone, or oblong trun- 

 cated p3'ramid. The latter form is most easily 

 constructed, and descrilied. A case of plank is 

 liirmed, having the desired figure, say a base of 

 fifty or sixty feet in lenixth by four feet in breadth, 

 a height ol'Sh feet ; and the planks are so inclined 

 as to make the dimensions of the upper surface 

 two feet less in each direction than that of the 

 base. 



The planks which lorm the ends of the case are 

 each pierced with four holes : one at the base, one 

 directly over it and near the top, the other two at 

 half the height of the plank, and in the vertical 

 plane of the upper edge of Ilie sides. Each side 

 is also pierced with three ranges of holes, having 

 the same arranijement in quincunx as those of ihe 

 ends, and at the same distances. 



These holes serve lor the introduction of taper- 

 ing spars. The spars of the lowermost layer are 

 passed through the holes in the sides and ends, at 

 right angles to the respective direction of- these 

 .=:urfaces, and at the angles where the spars meet 

 each other, vertical spars are set up. The second 

 range of spars is inclined to the sides in such man- 

 ner as to meet Ihe vertical spars; and the third 

 layer has the same direction as the first. 



The fine coal is prepared by mixing it into a 

 paste with water, by means of a hoe. It is then 

 thrown into the case, and well rammed upon the 

 lower range of spars, until a bed has been formed 

 to receive the second range of spars. This latter 

 range being placed, more coal is thrown in and 

 rammed, until the height of the third range of 

 spars has been reached, and this being introduced, 

 the rest of the case is filled in the same manner. 



In order to lessen the expense of the wood em- 

 ployed, the heap may be built in successive por- 

 tions, each ten or twelve feet in length, and wlien 

 one pttrtion has been finished, the planks and 

 spars are removed to enclose and form passages 

 in a second portion. The spars form conical pas- 

 sages in the mass, by wliich air may be admitted 

 during the combustion. When the heap has thus 

 been completed and covered with ashes and refuse 

 coke, all the wood is removed, and the heap is set 

 on fire by igniting small heaps of coarse coal upon 

 ear-h of the openings left in the upper surface bv 

 withdrawing the vertical spars. It has been found 

 that in pyramidal heaps, about -^^ part of the coal 

 to be coked is required for this purpose ; but in 

 small conical heaps, where a single vertical spar 

 win suffice no more than % will be used. 



