" acid 0.6
Aqueous vapor 2.0
Oxygen 0.1
Nitrogen 0.5
-----
100.0

Natural gas is now conveyed to Pittsburg through four lines of 5-5/8
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 consumption is
variable, the pressure at the city cannot 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 appreciated 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 purposes in two hundred houses.
Its superiority over coal in the manufacture 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