COKE.
Coke is produced by the partial burning of coal, in the same way that charcoal is from wood. The great source of coke is the gas manufactory, where it is sold in large quantities, being the result left in the retorts after the gas has all been driven off; but the consumption of coke by locomotive engines, &c., where coal would not be admissible on account of the smoke produced, has become so great that it is necessary to burn coals for its production; this is done by a range of ovens fitted up for that purpose, having iron doors which can be closed to any extent required so as to regulate the draught of air. Dr. Ure gives the following in his account of the coke ovens belonging to the London and North Western Railway Company:—“An excellent range of furnaces for making a superior article of coke for the service of the locomotive engines of the London and Birmingham Railway Company, has been erected at the Camden Town Station, consisting of eighteen ovens, in two lines, the whole discharging their products of combustion into a horizontal flue which terminates in a chimney-stalk one hundred and fifteen feet high. Each alternate oven is charged, between eight and ten o’clock every morning, with three-and-a-hall tons of good coals, a wisp of straw is thrown in on the top of the heap, which takes fire by the radiation from the dome, which is in a state of dull ignition from the preceding operation, and inflames the smoke then rising from the surface by the reaction of the hot sides and bottom upon the body of the fuel, in this way the smoke is consumed at the very commencement of the process, when it would otherwise be most abundant. The coke being perfectly freed from all fuliginous and volatile matters by a calcination of upwards of forty hours, is cooled down to moderate ignition by sliding in the dampers and sliding up the doors, which had been partially closed during the latter part of the process. It is now observed to form prismatic concretions, somewhat like a columnar mass of basalt. These are loosened by means of iron bars, lifted out upon shovels furnished with long iron shanks, which are poised upon swung chains with hooked ends, and the lumps are thrown upon the pavement, to be extinguished by sprinkling water upon them from the rose of a watering can, or they may be transferred into a large chest of sheet iron set on wheels, and then covered up. Good coals, thus treated, yield eighty per cent. of an excellent, compact, glistening coke, weighing fourteen cwt. per chaldron.”
Coke burns without smoke, and not so rapidly by far as charcoal, it is, moreover, considerably cheaper than that article is.