In a paper on ” The Commercial Value of Acetylene for an an Illuminant ” recently read by Louis A. Ferguson, of the Chicago Edison Company before the National Electric Light Association, the author described a visit to Spray, N. C., where calcium carbide, from which acetylene gas is obtained, was being manufactured in considerable quantities by T. L. Willson and Major Morehead. The plant consisted of a Leftel waterwheel, which operated two general electric 120 kilowatt alternating dynamos. These gave a pressure of 1,000 volts, worked in parallel, and this pressure was reduced by transformers to 100 volts. The electric furnaces in which the calcium carbide was made were each 3 feet square and 8 feet high. Current was supplied to them by copper cables capable of transmitting 1,000 amperes. The bottom of each furnace was a carbon plate, to which one of the poles was attached. The other pole was attached to six huge carbons, each 4 inches square and 36 inches long; weighing 35 pounds. The material out of which the calcium carbide was made consisted of Pocahontas coke, ground into fine powder and mixed with freshly slaked lime. Theoretically, 100 pounds of calcium carbide required 87 1-2 pounds of lime and 59 1-2 pounds of carbon,whith allowed 37 12 pounds of the carbon to combine directly with the lime, while 18 3-4 pounds passed off up the chimney combined with oxygen as carjon monoxide. A trial was made May 15, 1895, by Mr. Wilson and Major Morehead, in the presence of Mr. Ferguson, to determine the cost of the manufacture of calcium carbide. There were 800 pounds of lime and 390 pounds of powdered coke taken for this experiment, making altogether 1,190 pounds of material. Of this quantity, 180 pounds were unused, leaving 1,010 pounds delivered to the furnace. The test was continued for four hours, the quantity of current used being steady at 1,000 amperes and the pressure nearly constant at 100 volts. Mr. Ferguson found the temperature of the e;ectric furnace was from 3.500 degrees to 4,000 degrees centigrade, whereas the temperatureof an ordinary smelting furnace is only from 1,200 to 1,500 degrees. At the end of the four hours the weight of calcium carbine produced was 139 pounds, leaving unused 60 pounds. Counting 65 pounds of water used to slack the lime, it took 228 pounds of coke and lime to make 138 pounds of calcium carbide, thus showing an efficiency of 58.4 per cent. M r. Ferguson took up the methods of getting acetylene gas from calcium carbide by pouring water upon it. He said Professor Crafts, of the Boston I nstitute of Technologv had calculated that, taking the heat of an incandescent electric light bulb as 1, the heat of burning acetylene gas was 3, while the heat of ordinary illuminating water gas was 9.

As to the question of cost of production, concerning which so many contradictory statements have been made, Mr. Ferguson showed that 8.3 pounds of calcium carbidecould be produced by one electric horse-powerin twenty-four hours. The carbons cost 6 cents a pound, lime ccst $5 a ton, and coke $2.50 a ton. The cheapest electrical horse-power in the world was that of Niagara, at $20 for each horse-power a year of 8,760 hours. Labor would cost $45 a day or $4.50 a. ton, and the cost of packing $1 a ton, if barrels could be used for this purpose. The total cost by this estimate was $33.85 a ton for calcium carbide at Niagara Falls. But the plant would cost at least $25,000, on which the interest at 6 per cent, would be $1,500, and depreciation at 5 per cent, would amount to $1,250 a year, while taxes would be $10 on $1,000, and insurance $3 on $1,000. These items would add 84 cents to the cost of each ton of calcium carbide, while the lowest rate at which ipcould be shipped to New York, Chicago, or Philadelphia would be $3 a ton, making a total cost in these cities of $37.69 a ton. Moreover, these figures would not apply to a new firm,with agencies and canvassers, but only to a large gas company or similar concern, which would not have to incur such expenses.

Comparing acetylene gas with ordinary water gas, as used in New York, Mr. Ferguson found that a ton of calcium carbide would give 10,500 cubic feet of acetylene. But acetylene gas would give 240 candle power for each five cubic feet consumed, whereas five cubic feet of water gas would only give twenty-five candle power. Acetylene was, therefore, ten times as brilliant as water gas. Comparing candle power with candle-power, Mr. Ferguson found ordinary water gas cost 30 cents a 1,000 cubic feet, and an equivalent illuminating quantity of acetylene at the figures previously given would cost 37 7-10 cents, or 20 per cent. more. Mr. Ferguson discussed the use of acetylene gas in a liquefied form in iron cylinders only to condemn it. He pointed out that acetylene is useless for reinforcing water gas. He proved that it could not be made as a by-product of electric light stations, because the average cost of a horse-power a year, in the best, largest, and most economically controled electric light station is $65, which would bring up the cost of calcium carbi !e to $68.49 a ton.

The paper did not deal with the dangers attaching to the manufacture or the storage of acetylene gas, which at present render it very risky to handle,and an object of great suspicion as well to underwriters as to fire departments everywhere, especially in large and densely populated cities.

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