THE FUEL OF THE FUTURE. 217 



committee of the Engineers' Society of Western Pennsylvania, and for 

 the use of which I am indebted to that association : 



COMMON GAS. 



Hydrogen 46 - 



Light carbureted hydrogen (marsh-gas) 395 



Condensible hydrocarbon 3"8 



Carbonic oxide.. Y'5 



" acid 0-G 



Aqueous vapor 2*0 



Oxygen 01 



Nitrogen 0"5 



100-00 



Natural gas is now conveyed to Pittsburg through four lines of 

 5f-inch pipe, and one line of eight-inch pipe. A line of ten-inch pipe is 

 also being laid. The pressure of the gas at the wells is from 150 to 

 230 pounds to the square inch. As the wells are on one side eighteen 

 and on the other about twenty-five miles distant, and as the consump- 

 tion is variable, the pressure at the city can not be given. Greater 

 pressure might be obtained at the wells, but this would increase the 

 liability to leakage and bursting of pipes. For the prevention of such 

 casualties safety-valves are provided at the wells, permitting the escape 

 of all superfluous gas. The enormous force of this gas may be appre- 

 ciated from a comparison of, say, 200 pounds pressure at the wells with a 

 two-ounce pressure of common gas for ordinary lighting. The amount 

 of natural gas now furnished for use in Pittsburg is supposed to be 

 something like 25,000,000 cubic feet per day ; the ten-inch pipe now 

 laying is estimated to increase the supply to 40,000,000 feet. The 

 amount of manufactured gas used for lighting the same city probably 

 falls below 3,000,000 feet. About fifty mills and factories of various 

 kinds in Pittsburg now use natural gas. It is used for domestic pur- 

 poses in two hundred houses. Its superiority over coal in the manu- 

 facture of window-glass is unquestioned. That it is not used in all 

 the glass-houses of Pittsburg is due to the fact that its advantages 

 were not fully known when the furnaces were fired last summer, and 

 it costs a large sum to permit the furnaces to cool off after being 

 heated for melting. When the fires cool down, and before they are 

 started up again, the furnaces now using coal will doubtless all be 

 changed so as to admit natural gas. The superiority of French over 

 American glass is said to be due to the fact that the French use wood 

 and the Americans coal in their furnaces, wood being free from sulphur, 

 phosphorus, etc. The substitution of gas for coal, while not increas- 

 ing the cost, improves the quality of American glass, making it as 

 nearly perfect as possible. 



While the gas is not used as yet in any smelting-furnace nor in 

 the Bessemer converters, it is preferred in open-hearth and crucible 

 steel furnaces, and is said to be vastly superior to coal for puddling. 



