FUEL, GASEOUS. 



degree. At first, after the coal has been ignited, 

 and sends its gases into the chamber above, to 

 meet the heated air-blast, the combustion there 

 becomes progressively intense, and the whole 

 mass of perforated fire-brick (amounting to 

 many tons in the large furnace at Wallace's 

 brass-works in Ansonia) is soon at a white 

 heat as dazzling as the sun. No metal can be 

 used in the structure, but in an exterior pro- 

 tected from the heat by great thicknesses of 

 non-conducting material; for no metal could 

 stand for one minute the temperature at which 

 the air and fuel gases of this furnace are called 

 to meet each other, thousands of degrees above 

 the hot condition in which they enter the 

 gas-chamber. The upper stratum of coal and 

 its inclosure are wholly of the same sun-like 

 whiteness and brilliance as the fire-bricks above, 

 upon which no human eye could look without 

 flinching. But practically no combustion is 

 going on there, at least when the furnace is 

 run intelligently, according to its true ideal, 

 and with its greatest actual economy. In such 

 case the air-blast is mainly shut oif from the 

 crude-fuel chamber, leaving only a minor press- 

 ure under the grate to balance the pressure 

 from above, but not to penetrate the coal ; the 

 main strength of the blast being thrown into 

 the labyrinths of the gas-combustion chamber. 

 The unparalleled heat to which the coal is evi- 

 dently being subjected is therefore entirely due 

 to hot products of combustion containing no 

 free oxygen, which beat down on it from the 

 excess of pressure above so violently as to give 

 visibility to the motion of the transparent con- 

 flicting currents. The grate-bars are not even 

 red hot. The dazzling-white coals, when taken 

 out and cooled instantly, exhibit no traces of 

 combustion. The solid anthracite is unpene- 

 trated by oxygen, and as clean and lustrous in 

 fracture, throughout, as any lump just taken 

 from the mine. Its specific gravity is not in 

 the least diminished. All it has lost has been 

 taken off by a volatilizing heat and sent up in 

 gases of various kinds various, for not even 

 the mineral ash is left behind. After tons of 

 coal have been consumed, hardly anything is 

 found in the ash-pit save a small quantity of 

 crumbled coal-dust, perfectly black, and a still 

 smaller proportion of what may be called acci- 

 dental ashes. A small amount of melted slag 

 is occasionally cleared from the surface of the 

 grate ; very little of this, however, unless the 

 inveterate persistence of old notions in the en- 

 gineer misapplies the combustion-blast to the 

 coal. The proper place for the whole of com- 

 bustion and of the combustion-blast is the gas- 

 chamber. There the oxidization is made as 

 sudden, as complete, and as exact as possible, 

 and thence the pure products of perfect com- 

 bustion pass into the boiler at their hottest 

 from the hottest part of the furnace, which is 

 the top, and farthest from what seems to be 

 the fire; while in part they beat down upon 

 the coal, as already mentioned, and find per- 

 haps a partial vent from the coal-chamber, 

 VOL. xxv. 25 A 



where there is a minor flue into the boiler, 

 which may or may not be opened. 



Calorific Results. Ten pounds of water made 

 into steam at 60 pounds pressure by a pound 

 of coal is standard practice for the best sta- 

 tionary boilers. The writer of this article as- 

 sisted at a twenty-four-hour test, made by 

 competent civil engineers, of the Blanch ard 

 furnace and boiler at the Ansonia Brass-Works. 

 The first twelve hours were given to practice 

 somewhat on the usual theory of progressive 

 combustion beginning in the coal, and com- 

 pleted from carbon monoxide to dioxide in the 

 gas-chamber. The results were decidedly un- 

 der the standard. The next twelve hours were 

 run with some regard to the true idea of the 

 system as above explained, and resulted in 

 nearly doubling the standard and actually ex- 

 ceeding the theoretical value of the fuel as 

 hitherto supposed to be established. Every 

 pound of coal was weighed as it went in; all 

 the water used was measured with equal care ; 

 the temperature of the water and the pressure 

 in the boiler were recorded every half-hour; 

 and the .sum of the figures showed incontesta- 

 bly that over 17 pounds of water at lower than 

 standard temperature had been made into steam 

 under ten pounds more than standard pressure, 

 for every pound of coal that had been con- 

 sumed in the twelve hours. The proper cor- 

 rections for the standard of comparison raised 

 the result to 19 pounds. A fact equally strange, 

 and even more staggering to natural belief, is 

 that the hotter the furnace was run, the less 

 fuel was actually consumed not less in pro- 

 portion, but absolutely less! This was the 

 writer's observation on a number of occasions, 

 both with the large furnace and with a small- 

 er and less complete one elsewhere, and also 

 on many occasions with the other (oil) appara- 

 tus for high-temperature gas-combustion be- 

 fore referred to. Of course, there is a limit to 

 the operation of such a rule as this ; but the 

 limit had not yet been found. 



Fuel-Gas for Domestic Use. Much attention has 

 been given to the problem of consolidating coal- 

 dust for an economical fuel ; but, with this ma- 

 terial as with others, improvement seems to He 

 in thedirection of volatilization. Thecost of coal 

 is little more than that of the labor of mining 

 and transporting it, and the difference in favor 

 of coal-dust in these respects is not so much as 

 to overbalance very greatly the cost of recon- 

 structing it in coals. Vast stores of this com- 

 minuted fuel are accumulated at the mines, 

 and will yet be made available. But coal-dust 

 is practically much nearer to gas than to coal. 

 The Strong process transforms it into one of 

 the most powerful of calorific gases, carbonic 

 oxide, and also, in so doing, obtains from wa- 

 ter the most powerful fuel in the universe, hy- 

 drogen. By placing the gas-works as deep as 

 practicable underground, these gases will be 

 made nearly self-transporting, as well as the 

 dust-heaps that are to be brought from short 

 distances to the works. Whenever this scheme 



