carried off by the gases is easily calculated if we know their composition and their temperature. It is only necessary to consider separately each constituent of the gaseous mixture. Taking the specific heats determined by Regnault we have per lb. and for each degree Centigrade: and we find further on, that, according to the mean composition of the gases of blast furnaces (coke), the specific heat is as a general average very nearly 0.237. § 14. Caloric lost by radiation from the walls of furnace, etc. -The caloric thus lost is composed of several parts. There is the heat carried off by the cooling water, which is easily determined; there is the heat dispersed by radiation from the walls; that which the air carries off in its currents past the walls, and that which passes into the base of the furnace by conduction. These two latter cannot be determined, but we may attempt to determine what is lost by radiation. Mr. Bell made experiments on this subject on a blast furnace on the Wear. He used an oblong vessel of copper holding about nine quarts of water, every side of which except that put to the furnace was cased with flannel and with wood, with interposed thin strata of air. By applying this uncovered side to different parts of the wall of the furnace, Mr. Bell ascertained the caloric given off per unit of surface, and hence for the whole surface of the furnace. In this way he found— For the Wear furnace per lb. of iron And for the caloric carried off by the water of the twyres, 10,150 lb. of water heated to 9°.16 Centigrade Total And to this must be added an allowance for caloric carried off by the air currents, and that lost in the foundations. And thus the number 300 or even 400 calories may be adopted for this source of loss of caloric. § 15. Determination of the Caloric received by a Blast Furnace.-Let us now return to the caloric produced in the interior of the furnace. Neglecting the caloric resulting from the combination of the elements constituting pig-iron and the slags, the caloric produced is derived solely from the transformation of carbon into a certain mixture of CO2 and CO. This caloric may be calculated, either by deduction from the analysis of the gases, or by considering separately the zone of combustion near the twyre and the zone of reduction in which CO is transferred into CO2. Let us first apply a knowledge of the analysis of the gases. Making use of the notation of § 7, we have y = the weight 3 of CO, and my = the weight of CO2, and hence y 7 the carbon in CO, and my the carbon in CO2. But the 3 11 of Cart carbonic acid contains b of carbon derived from the limestone, therefore the carbonic acid produced by combustion only The caloric produced is therefore composed of the two pro Let us now ascertain how this caloric is divided between the two zones. One portion of carbon is transformed into CO in the upper part of the furnace, the remainder descends to the sphere of the twyres, and there again produces CO, and lastly a part of the total CO arising from these two sources is definitively burned to CO2 by the oxygen of the ores and fluxes. The caloric generated in the zone of reduction is thus composed of the sum of the quantities of caloric produced (1) by this partial combustion of carbon into CO in the upper part of the furnace, and (2) by the formation of CO2 under the action of the ores and fluxes. It is easy to calculate those quantities of caloric respectively. The 0.94 of iron in a lb. of pig-iron were united in the per3 oxide to × 0.94 0.403 of oxygen, and this oxygen 7 unites with a portion of CO containing × 0.403 = 0·302 carbon. If, then, the CO2 thus produced were not partially reconverted to CO, if, in other words, the working of the furnace were what we have termed the ideal, we should find in the escaping gases a weight of CO2 containing 01b 302 + b of carbon, b being, as we have said, the weight of carbon in the limestone. But the gases of the furnace contain only 3 3 ( my) of carbon in CO2; therefore 01-302 + b— - (1/4 my) 11 G 11 represents the carbon of the portion of CO2 which has been reconverted to CO, and as CO2 burns exactly the weight of carbon which it already possessed, this expression will represent the carbon burned to CO in the region of reduction. On the other hand, as (a — 0·03) is, according to § 7, the total carbon of the coke, minus the 3 % taken up by the pig-iron, we perceive that the carbon burned at the twyres is given by the difference and hence the caloric produced near the twyres will be As to the caloric produced in the zone of reduction, it, as we have seen, arises from (1) Carbon burned to CO by the ores, or (0·302 + b — 3 11 my)× 2473 calories. (2) The CO transformed into CO2 by the ores. Now the CO2 thus formed contains (31 7 3 11 my -b carbon, and corresponds to my — b) of CO; The sum of these three products must equal the number we have found above by the first method—that is, in starting simply from the analysis of the gases—that is, they reproduce the expression And this, in fact, is easily verified. The sum of the two first expressions (5) and (6) come in the first place to (a 0·03) × 2473 calories. This is the caloric produced by the total carbon of the coke transformed to CO. As to the third expression (7), which gives the caloric produced by the transformation of CO2, it may be written thus 3 my b 11 7 3 3 X 2403 ( 11 my − b ) × 5607; and as 5607 8080-2473, we have finally, = 2473 and hence the sum of the three expressions (5), (6), and which is evidently equal to total sum (4); for, according to our notation and equation (1) of § 7, we have so that the coefficient 2473 in the expression (8) becomes as in the sum (4). From what we have above said it will now be easy to compare the caloric consumed and the caloric received. It is CO2 sufficient to know for each particular case the ratio = m, CO and the values of a and b in the charges referred to the lb. of iron yielded. Let us apply the formulas we have developed to some examples, and first let us take the Cleveland furnaces, which were the subject of Mr. Bell's investigations. § 16. First example.—As a first example we take the small furnace of Clarence Works of 1853, already mentioned, § 8, and shown in fig. 2. The height is 48 feet and the internal |