Economical considerations

—The cost of gas-light depends upon so many local circumstances, that no estimate of it can be made of general application; only a few leading points may be stated. The coals required for heating the retorts used to constitute one half of the quantity required for charging the retorts themselves. When five retorts are heated by one fire, the expenditure for fuel is only one third of that when each retort has a fire. The coak which remains in the retorts constitutes about 60 per cent. of the weight of the original coal; but the volume is increased by the coaking in the proportion of 100 to 75. When the coak is used for heating the retorts, about one half of the whole is required. If we estimate the coak by its comparative heating power, it represents 65 per cent. of the coals consumed. One hundred pounds of good coal yield in distillation 10 pounds of ammoniacal liquor, from which sulphate or muriate of ammonia may be made, by saturation with sulphuric or muriatic acid, and evaporation. The liquor contains likewise some cyanide of ammonia, which may be converted into pru ian blue by the addition of sulphate of iron, after saturation with muriatic acid. Two hundred pounds of coal afford about 17 pounds of tar. This contains in 100 pounds 26 pounds of coal oil, and 48 pounds of pitch. The tar is sometimes employed as a paint to preserve wood and walls from the influence of moisture, but its disagreeable smell limits its use. The coal oil when rectified by distillation, is extensively employed for di olving caoutchouc in making the varnish of waterproof cloth, and also for burning in a peculiar kind of lamps under the name of naphtha. Oil of turpentine however is often sold and used for this purpose, by the same name. If the coal oil be mixed with its volume of water, and the mixture be made to boil in a kettle, the mingled vapours when pa ed through a perforated nozzle may be kindled, and employed as a powerful means of artificial heat. The water is not decomposed, but it serves by its vapour to expand the bulk of the volatile oil, and to make it thereby come into contact with a larger volume of atmospherical air, so as to burn without smoke, under a boiler or any other ve el. The pitch may be decomposed into a light-gas. The relative cost of light from coal gas and oil gas may be estimated as one to six, at least. Rosin gas is cheaper than oil gas. See Rosin . I shall conclude this article with a summary of the comparative expense of different modes of illumination, and some statistical tables. One pound of tallow will last 40 hours in six mould candles burned in succe ion, and costs 8 d. ; a gallon of oil, capable of affording the light of 15 candles, for 40 hours costs 5 s. , being therefore 1 ⁄ 2 of the price of mould candles, and 6 ⁄ 15 of the price of dips. The cost of wax is about 3 1 ⁄ 2 times that of tallow; and coal gas, as sold at the rate of 9 s. for 1000 cubic feet, will be one sixth the price of mould candles; for 500 cubic inches of coal gas give a light equal to the above candle for an hour; therefore 40 × 500 = 20,000 cubic inches = 11·57 cubic feet, worth 1 1 ⁄ 4 d. , which multiplied by 6 gives 7 1 ⁄ 2 d. the average price of mould candles per pound. The author of the article Gas-light in the Encyclopædia Britannica, observes, in reference to the economy of this mode of illumination, that while the price of coal, in consequence of the abundant and regular supply of that article, is liable to little fluctuation, the cost of wax, tallow, and oil, on account of the more precarious nature of the sources from which they are obtained, varies exceedingly in different seasons. “A uming that a pound of tallow candles, which last when burned in succe ion forty hours, costs nine-pence,” (seven-pence halfpenny is the average price), “that a gallon of oil, yielding the light of 600 candles for an hour, costs two shillings,” (five shillings is the lowest price of a gallon of such oil as a gentleman would choose to burn in his lamp), “that the expense of the light from wax is three times as great as from tallow, and that a you sand cubic feet of coal gas cost nine shillings;” he concludes the relative cost to be for the same quantity of light,—from wax, 100; tallow, 25; oil, 5; and coal-gas, 3. I conceive the estimate given above to be much nearer the truth; when referred to wax called 100, it becomes, for tallow, 28·6; oil, 14·3; coal gas, 4·76. Gas-lighting has received a marvellous development in London. In the year 1834, the number of gas lamps in this city was 168,000, which consumed daily about 4,200,000 cubic feet of gas. For the purpose of generating this gas, more than 200,000 chaldrons, or 10,800,000 cubic feet of coals were required. For the following valuable statistical details upon gas-light, my readers are indebted to Joseph Hedley, Esq., engineer, of the Alliance Gas Works, Dublin; a gentleman who to a sound knowledge of chemistry, joins such mechanical talent and indefatigable diligence, as qualify him to conduct with succe , any great undertaking committed to his care. He has long endeavoured to induce the directors of the London gas-works to employ a better coal, and generate a more richly carburetted gas, which in much smaller quantity would give as brilliant a light, without heating the apartments unpleasantly, as their highly hydrogenated gas now does. Were his judicious views adopted, coal gas would soon supersede oil, and even wax candles, for illuminating private mansions. Copy of a paper laid before a Committee of the House of Commons, showing not only the relative values of the Gases produced at the undermentioned places, but showing in like manner the relative economy of Gas as produced at the different places, over candles. By Joseph Hedley, Esq. | Names of the Places where Experiments were made. | Illuminating power of a single Jet of Gas-flame four inches high, taken by a comparison of Shadows. | The Jet of Gas burnt, four inches high, consumed per hour and was equal to the Candles in the last column. | Gas required to be equal to 100 lbs. of mould Candles, 6 to the lb., 9 inches long each. [A] | Selling price of Gas per meter per 1000 cubic feet. | Cost of Gas equal in illumi- nating power to 100 lbs. of candles. [B] | Average discount allowed off the charge for Gas. | Net cost of Gas equal to 100 lbs. of Candles. | Specific gravity of the Gas. | | Equal to Candles. | Cubic Feet. | Cubic Feet. | s. | d. | L. | s. | d. | Per Cent. | L. | s. | d. | | | Birmingham; | | - | 2·572 | 1 | ·22 | 2704 | 10 | 0 | 1 | 7 | 0 | 9 | | 1 | 4 | 7 | ·541 | | Birmingham and Staff ords hire; two Companies | | Stock port | 3·254 | | ·85 | 1489 | 10 | 0 | 0 | 14 | 11 | 12 | 1⁄2 | 0 | 13 | 0 | ·539 | | Manchester | 3·060 | | ·825 | 1536 | 8 | 0 | 0 | 12 | 3 | 11 | 1⁄4 | 0 | 10 | 10 | ·534 | | Liverpool Old Company [C] | 2·369 | 1 | ·1 | 2646 | 10 | 0 | 1 | 6 | 5 | 6 | 1⁄4 | 1 | 4 | 9 | ·462 | | Liverpool New Gas Company | 4·408 | | ·9 | 1164 | 10 | 0 | 0 | 11 | 8 | 6 | 1⁄4 | 0 | 9 | 10 | ·580 | | Bradford | 2·190 | 1 | ·2 | 3123 | 9 | 0 | 1 | 8 | 1 | 12 | 1⁄2 | 1 | 4 | 6 | ·420 | | Leeds | 2·970 | | ·855 | 1644 | 8 | 0 | 0 | 13 | 2 | 6 | 1⁄4 | 0 | 12 | 4 | ·530 | | Sheffield | 2·434 | 1 | ·04 | 2440 | 8 | 0 | 0 | 19 | 6 | 6 | 1⁄4 | 0 | 18 | 3 | ·466 | | Leicester | 2·435 | 1 | ·1 | 2575 | 7 | 6 | 0 | 19 | 3 | 15 | | 0 | 16 | 5 | ·528 | | Nottingham | 1·645 | 1 | ·3 | 4200 | 9 | 0 | 1 | 17 | 9 | 15 | | 1 | 11 | 3 | ·424 | | Derby | 1·937 | 1 | ·2 | 3521 | 10 | 0 | 1 | 15 | 4 | 15 | | 1 | 10 | 0 | ·448 | | Preston | 2·136 | 1 | ·15 | 3069 | 10 | 0 | 1 | 10 | 8 | 15 | | 1 | 6 | 2 | ·419 | | London | 2·083 | 1 | ·13 | 3092 | 10 | 0 | 1 | 10 | 11 | none allowed. | 1 | 10 | 11 | ·412 | | [A] 100 lbs. of candles are estimated to burn 5700 hours. | | [B] The candles cost 3 l. 2 s. 6 d. | | [C] The Liverpool Old Company have since resorted to the use of Cannel coal, and consequently very nearly a imilate to the Liverpool New Company in illuminating power. | | Names of the Places where Experiments were made. | Illuminating power of a single Jet of Gas-flame four inches high, taken by a comparison of Shadows. | The Jet of Gas burnt, four inches high, consumed per hour and was equal to the Candles in the last column. | Gas required to be equal to 100 lbs. of mould Candles, 6 to the lb., 9 inches long each. [A] | Selling price of Gas per meter per 1000 cubic feet. | | Equal to Candles. | Cubic Feet. | Cubic Feet. | s. | d. | | Birmingham; | | - | 2·572 | 1 | ·22 | 2704 | 10 | 0 | | Birmingham and Staff ords hire; two Companies | | Stock port | 3·254 | | ·85 | 1489 | 10 | 0 | | Manchester | 3·060 | | ·825 | 1536 | 8 | 0 | | Liverpool Old Company [C] | 2·369 | 1 | ·1 | 2646 | 10 | 0 | | Liverpool New Gas Company | 4·408 | | ·9 | 1164 | 10 | 0 | | Bradford | 2·190 | 1 | ·2 | 3123 | 9 | 0 | | Leeds | 2·970 | | ·855 | 1644 | 8 | 0 | | Sheffield | 2·434 | 1 | ·04 | 2440 | 8 | 0 | | Leicester | 2·435 | 1 | ·1 | 2575 | 7 | 6 | | Nottingham | 1·645 | 1 | ·3 | 4200 | 9 | 0 | | Derby | 1·937 | 1 | ·2 | 3521 | 10 | 0 | | Preston | 2·136 | 1 | ·15 | 3069 | 10 | 0 | | London | 2·083 | 1 | ·13 | 3092 | 10 | 0 | | [A] 100 lbs. of candles are estimated to burn 5700 hours. | | [C] The Liverpool Old Company have since resorted to the use of Cannel coal, and consequently very nearly a imilate to the Liverpool New Company in illuminating power. | | Names of the Places where Experiments were made. | Cost of Gas equal in illumi- nating power to 100 lbs. of candles. [B] | Average discount allowed off the charge for Gas. | Net cost of Gas equal to 100 lbs. of Candles. | Specific gravity of the Gas. | | L. | s. | d. | Per Cent. | L. | s. | d. | | | Birmingham; | | - | 1 | 7 | 0 | 9 | | 1 | 4 | 7 | ·541 | | Birmingham and Staff ords hire; two Companies | | Stock port | 0 | 14 | 11 | 12 | 1⁄2 | 0 | 13 | 0 | ·539 | | Manchester | 0 | 12 | 3 | 11 | 1⁄4 | 0 | 10 | 10 | ·534 | | Liverpool Old Company [C] | 1 | 6 | 5 | 6 | 1⁄4 | 1 | 4 | 9 | ·462 | | Liverpool New Gas Company | 0 | 11 | 8 | 6 | 1⁄4 | 0 | 9 | 10 | ·580 | | Bradford | 1 | 8 | 1 | 12 | 1⁄2 | 1 | 4 | 6 | ·420 | | Leeds | 0 | 13 | 2 | 6 | 1⁄4 | 0 | 12 | 4 | ·530 | | Sheffield | 0 | 19 | 6 | 6 | 1⁄4 | 0 | 18 | 3 | ·466 | | Leicester | 0 | 19 | 3 | 15 | | 0 | 16 | 5 | ·528 | | Nottingham | 1 | 17 | 9 | 15 | | 1 | 11 | 3 | ·424 | | Derby | 1 | 15 | 4 | 15 | | 1 | 10 | 0 | ·448 | | Preston | 1 | 10 | 8 | 15 | | 1 | 6 | 2 | ·419 | | London | 1 | 10 | 11 | none allowed. | 1 | 10 | 11 | ·412 | | [B] The candles cost 3 l. 2 s. 6 d. | | [C] The Liverpool Old Company have since resorted to the use of Cannel coal, and consequently very nearly a imilate to the Liverpool New Company in illuminating power. | Memorandum. —It will not fail to be observed that in deducing the comparative value between candles and gas by these experiments, the single jet (and in every instance, of course, it was the same), has been the medium. This however, though decidedly the most correct way of making the comparative estimate of the illuminating power of the several gases, is highly disadvantageous in the economical comparison, inasmuch as gas burnt in a properly regulated argand burner, with its proper sized gla , air aperture, and sufficient number of holes, gives an advantage in favour of gas consumed in an argand, over a jet burner, of from 30 to 40 per cent. At the same time it must not be overlooked that in many situations where great light is not required, it will be found far more economical to adopt the use of single jets, which by means of swing brackets and light elegant shades, becomes splendid substitutes for candles, in banking establishments, offices, libraries, . . Note. —In Glasgow, Edinburgh, Dundee, Perth, and the Scotch towns generally the Parrot or Scotch Cannel coal is used; in illuminating power and specific gravity the gas produced is equal to that from the best description of Cannel coal in England. The price per 1000 cubic feet ranges about 9 s. , with from 5 to 30 per cent. off for discounts, leaving the net price about 9 s. to be equal in the above table to 100 lbs. of candles. Epitome of Experiments made in Gas produced from different qualities of Coal, and consumed in different kinds of Burners: Tried at the Sheffield Gas Light Company’s Works, and laid before a Committee of the House of Commons. By Joseph Hedley, Esq. | Date 1835. | Description of Burner. | Species of Coal. | Specific Gravity of Gas. | Distance of Candle from Shadow. | Gas consumed per Hour. | Height of Gas Flame. | Equal to Mould Tallow Candles, 6 to the pound, 9 inches long each. | Gas equal to 100 lbs. of Mould Candles. | Cost of Gas at 8 s. per 1000 cubic feet. | Cost of 100 lbs. of Mould Candles at 7 s. 6 d. per dozen lbs. | | May. | | | | Inches. | Cubic Feet. | Inches. | Candles. | Cubic Feet. | L. | s. | d. | | L. | s. | d. | | 8 | | Single Jet | | Deep Pit | ·410 | 75 | | 1 | · | 4 | | 2 | ·36 | 2415 | 0 | 19 | 3 | 1⁄2 | | - | 3 | 2 | 6 | | 9 | | Ditto | | Mortormley | ·450 | 74 | | | ·95 | 4 | | 2 | ·434 | 2224 | 0 | 17 | 9 | 1⁄2 | | 9 | | Ditto | | Cannel | ·660 | 61 | 1⁄4 | | ·7 | 4 | | 3 | ·54 | 1127 | 0 | 9 | 0 | | | 8 | - | | Argand 14 holes | | - | Deep Pit | ·410 | 34 | | 3 | ·3 | 3 | 1⁄2 | 11 | ·53 | 1631 | 0 | 13 | 0 | 1⁄2 | | 9 | | Ditto | | Mortormley | ·450 | 33 | | 3 | ·1 | 3 | 1⁄2 | 12 | ·24 | 1443 | 0 | 11 | 6 | 1⁄2 | | 9 | | Ditto | | Cannel | ·660 | 29 | | 2 | ·6 | 3 | 1⁄3 | 15 | ·85 | 935 | 0 | 7 | 5 | 3⁄4 | | Date 1835. | Description of Burner. | Species of Coal. | Specific Gravity of Gas. | Distance of Candle from Shadow. | Gas consumed per Hour. | Height of Gas Flame. | | May. | | | | Inches. | Cubic Feet. | Inches. | | 8 | | Single Jet | | Deep Pit | ·410 | 75 | | 1 | · | 4 | | | 9 | | Ditto | | Mortormley | ·450 | 74 | | | ·95 | 4 | | | 9 | | Ditto | | Cannel | ·660 | 61 | 1⁄4 | | ·7 | 4 | | | 8 | - | | Argand 14 holes | | - | Deep Pit | ·410 | 34 | | 3 | ·3 | 3 | 1⁄2 | | 9 | | Ditto | | Mortormley | ·450 | 33 | | 3 | ·1 | 3 | 1⁄2 | | 9 | | Ditto | | Cannel | ·660 | 29 | | 2 | ·6 | 3 | 1⁄3 | | Date 1835. | Description of Burner. | Species of Coal. | Equal to Mould Tallow Candles, 6 to the pound, 9 inches long each. | Gas equal to 100 lbs. of Mould Candles. | Cost of Gas at 8 s. per 1000 cubic feet. | Cost of 100 lbs. of Mould Candles at 7 s. 6 d. per dozen lbs. | | May. | | | Candles. | Cubic Feet. | L. | s. | d. | | L. | s. | d. | | 8 | | Single Jet | | Deep Pit | 2 | ·36 | 2415 | 0 | 19 | 3 | 1⁄2 | | - | 3 | 2 | 6 | | 9 | | Ditto | | Mortormley | 2 | ·434 | 2224 | 0 | 17 | 9 | 1⁄2 | | 9 | | Ditto | | Cannel | 3 | ·54 | 1127 | 0 | 9 | 0 | | | 8 | - | | Argand 14 holes | | - | Deep Pit | 11 | ·53 | 1631 | 0 | 13 | 0 | 1⁄2 | | 9 | | Ditto | | Mortormley | 12 | ·24 | 1443 | 0 | 11 | 6 | 1⁄2 | | 9 | | Ditto | | Cannel | 15 | ·85 | 935 | 0 | 7 | 5 | 3⁄4 | Copy of Experiments made at the Alliance Gas Company’s Works in Dublin, during the past year 1837. By Joseph Hedley, Esq. Results of experiments on the qualities of various coals for the production of gas; its value in illuminating power; produce of coke, and quality; and other particulars important in gas-making :—