UTILITY OF THE GAS-LIGHT ILLUMINATION WITH REGARD TO PUBLIC AND PRIVATE ECONOMY. 99. Objects to which the new system of lighting with gas may be beneficially applied.--Capital advantages of the gas-light illumina- tion.--Places and public edifices lighted with coal-gas in this metro- polis.--Situations best suited for the application of gas-lights.-- places where it cannot be used to advantage.--Illumination of barracks, arsenals, dock yards, &c. with coal-gas.--Further observa- tions on this subject.--Great heat produced by gas-lights.--Reason why the flame of coal-gas produces more heat than the flame of candles and lamps.--Admeasurement of the comparative degrees of heat produced by gas-lights, oil lamps, tallow and wax candles, &c.--Gas lamps and burners, various kinds of.--Ornamental chandeliers and candelabras, for applying coal-gas as a substitute for oil.--Other products obtain- able from coal besides gas.--_Coke._--Its nature.--Combustion of it.-- Produces a more strong and lasting heat than coal.--Explanation of this fact.--Advantages resulting from the use of coke as fuel.--Disad- vantages of its application in certain circumstances.--Relative effect of heat produced by equal quantities of coke and charcoal.--Method of measuring the comparative effect of different kinds of fuel in pro- ducing heat.--Capital advantages resulting from the application of coke, as fuel, in the art of burning lime.--Plaster of Paris, bricks, &c.--Quantity of coke obtainable from a certain quantity of pit-coal. --Kind of coke best suited for metallurgical operations.--Mode of obtaining it in the gas-light process.--Sort of coke best adapted for kitchen and parlour fires.--Manufacture of it.--_Coal tar._--How obtained.--Its properties.--Earl of Dundonald’s method of manufac- turing tar from coal.--Quantity of coal-tar produced in the gas-light process from a given quantity of coal.--Characters of coal tar obtained from Newcastle coal, differ from that produced from canel coal.--_Coal pitch._--Process for obtaining it.--Properties of coal- pitch.--Use of it in the arts.--quantity of coal-pitch obtainable from a given quantity of tar.--_Ammoniacal liquor_ produced during the distillation of coal.--Its chemical constitution.--Quantity obtained from a given quantity of coal.--General observation respecting the scheme of applying coal-gas as a substitute for candles and lamps.-- Effects which it must produce upon the arts and upon domestic economy. --Its views.--Primary advantages.--Resources which it presents to industry and public economy.--In what respect it is entitled to public approbation and national encouragement.--Effects of prejudice against the introduction of new and useful discoveries.--Have operated strongly in retarding the gas-light illumination.--Remarkable slowness