IKON 969 



emptied. The circular space around the funnel, inside the furnace, forms a chamber 

 for the reception of the gases, from which they are conveyed by brick tunnels or iron 

 piping to the place of combustion. The whole arrangement will be clearly understood 

 by an inspection of the accompanying plans, figs. 1238, 1239, 1240, 1241, 1242, kindly 

 furnished to the writer by the proprietor of the Cwm Celyn and Blaina Iron Works. 



Fig. 1243 shows the plan of extracting the gases which is adopted at the Brymbo 

 Iron Works, near Wrexham, the same being the patent of C. E. Darby. 



It consists of a large pipe or tube inserted into the middle of the top part of the 

 furnace, which descends a short distance down into the materials, and is carried over 

 the top of the side of the furnace in the form of a siphon, a continuation of which 

 pipe is taken to the boilers, or hot air-stoves, where the gas is burned in the usual 

 way. The principal advantage claimed by this method, is that it puts no check on 

 the free escape of the gases, by which the driving of the furnace is impeded, and th.e 

 quality of the iron deteriorated. The patentee estimates the saving of fuel with two 

 furnaces making 240 tons of iron per week, by applying the gas to the blast-engine 

 boilers and hot air-stoves, 1,200Z. a year. Thus : Consumption of fuel at engine 

 and stoves equal to 7 cwts. of good coal per ton of iron, made at 3%d. per cwt., is 

 2s. Qid., say 2s. per ton on 12,480 tons, or 1.248J. 



The causes of derangement in the working of blast-furnaces when the gases are 

 drawn off to be utilised elsewhere, have been diligently studied by Mr. George Parry, 

 of Ebbw Vale ; and he has kindly furnished us with the following resume of his ob- 

 servations, for insertion in this article 



The manner in which the waste gases were formerly collected was by sinking an 

 iron tube, 7 feet deep, into the throat of the furnace, the diameter of the tube being 

 about 3 feet less than that of the throat, thus leaving an annular space of 18 inches 

 between the walls of the furnace and the sides of the tube. From this space the 

 gases were allowed to pass off by the pressure within the furnace, through a pipe 

 which penetrated the ring and walls. When the tube was kept full of minerals, about 

 ^rd or th only of the gas escaped into the open air, the rest passing into the annular 

 chamber ; and when this state of things was continued, those troublesome adhesions 

 of masses of semifused materials above and around the boshes, technically termed 

 'scaffolds,' occurred, with the usual accompaniments of black cinder and inferior 

 iron. It is evident that when the tube was kept full of materials, the contents acted as 

 a loose stopper to the current of hot gases forced up by pressure from beneath, and 

 diverted them towards the annular space where there was no such resistance, thus 

 leaving the minerals in the central parts of the furnace insufficiently supplied with the 

 upward current, and consequently with heat ; the minerals, on the other hand, sur- 

 rounding this cold central cone, were supplied with more than their usual quantity of 

 heat, as was evidenced by the burning of tuyeres, and by the destruction of the 

 brickwork in their neighbourhood. In this state of things, the ores in the external 

 portions of the furnace would become reduced and converted into grey metal ; while 

 those in the central portion would, according to the degree of deviation of the 

 ascending current of heated gases from them, descend to the point of fusion either 

 thoroughly deoxidised, and slightly carbonised, or possibly with a portion still in the 

 state of oxide, and mixing there with the properly-reduced ores, enter into fusion with 

 them, producing a mixture of irons which must necessarily prove of inferior quality, 

 and a black cinder from the unreduced oxides. When the iron tube in the throat of 

 the furnace was kept only partially filled with minerals, much more gas escaped into 

 the open air, as might have been expected, and consequently more traversed the 

 central parts of the furnace ; and it was always observed that when that mode of filling 

 was adopted, the furnace worked much better ; but then the object, viz. that of eco- 

 nomising the gases, was not attained. Differently-formed furnaces were found to be 

 disturbed in different degrees by this system of drawing off the gases : the old conical 

 narrow topped furnaces were affected very much less than the improved modern 

 domed top furnace of large capacity, from which all attempts to take off any useful 

 portion of the gases proved absolute ruin.. It might be argued, that as the same 

 quantity of blast and fuel were used as heretofore, the ascending current of heated 

 gases ought to produce the same deoxidising and carbonising effect on the superin- 

 cumbent mass, whatever direction they might take in making their escape at the 

 upper region of the furnace ; for if the central part should not have been sufficiently 

 acted upon, the external annulus would have more than its usual share of chemical 

 influences. But when it is considered that iron is only capable of taking up a certain 

 quantity of carbon, and no more, it follows that after having received this dose, its 

 further exposure in the external parts of the furnace where the heated gases abound 

 can do nothing towards supplying the deficiency of carbon in the metal reduced in 

 the central part. From these considerations it became evident, that no system of 

 drawing off the gases around the sides, whether by the insertion of an iron tube into 



